Testing of Materials for Fire Protection Needs: European Standard Test Methods for the Building Sector (The Society of Fire Protection Engineers Series) [1st ed. 2023] 303139710X, 9783031397103

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The Society of Fire Protection Engineers Series

Linda Makovická Osvaldová Widya Fatriasari

Testing of Materials for Fire Protection Needs European Standard Test Methods for the Building Sector

The Society of Fire Protection Engineers Series Series Editor Chris Jelenewicz, Society of Fire Protection Engineers, Gaithersburg, MD, USA

The Society of Fire Protection Engineers Series provides rapid dissemination of the most recent and advanced work in fire protection engineering, fire science, and the social/human dimensions of fire. The Series publishes outstanding, high-level research monographs, professional volumes, contributed collections, and textbooks.

Linda Makovická Osvaldová • Widya Fatriasari

Testing of Materials for Fire Protection Needs European Standard Test Methods for the Building Sector

Linda Makovická Osvaldová Faculty of Security Engineering University of Žilina Žilina, Slovakia

Widya Fatriasari Research Center for Biomass and Bioproducts National Research and Innovation Agency Cibinong Bogor, Indonesia

ISSN 2731-3638 ISSN 2731-3646 (electronic) The Society of Fire Protection Engineers Series ISBN 978-3-031-39710-3 ISBN 978-3-031-39711-0 (eBook) https://doi.org/10.1007/978-3-031-39711-0 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Paper in this product is recyclable.

To all people

Preface

One of humanity’s greatest inventions is fire, which become a friend that can provide many benefits for human life or in some cases become an enemy if attacking the materials in the building. Fire can contribute a significant part to the creation of various materials or products for people’s needs if it is controlled properly. Fire is learned to establish the way for managing well. Therefore, handling fire is not causing dangerous since it is rough, robust, and forceful. Many accidents that cause not only human loss but also high materials loss have been reported worldwide. Therefore, it is important to study and observe more in employed materials and the fire behavior that is relevant to slow down the combustion or completely stop burning. Buildings serve as the hub of human activity and utilize a variety of materials for both their interior and outer façade. In a fire case of building in unsolicited period and planetary, time even in seconds is very crucial for giving a chance to evacuate, or flee from the fire building. It has been observed that large-scale building fires are impacted by mechanical and electrical issues associated with the building in addition to human negligence in controlling them. The installation device system in a building also has a profound effect on ignitibility and fire spread, with the influence of fixings, the façade support structure, and joint details being significant aspects to consider. Using slow-burning materials can assist prevent burning from getting worse because all materials can change to fuel by fire action. Or the materials that have been employed were used as a fire-retardant agent, depending on the type, amount, and mode of treatment. This book, Testing of Materials for Fire Protection Needs – European Standard Test Methods for the Building Sector, offers detailed information and investigation to help in preventing uncontrolled fires from occurring in the building sector, particularly by the method of testing dedicated materials. This anatomy of book contents brings an approach and powerful knowledge importance to test cables, facades, roofs, interior materials, products, and furniture that are used in building for their ignition and burning. The comprehensive information on test methods of those materials, especially construction materials, provide insight into relevant vii

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stakeholder. Some testing standards or methods for that concern have been developed, however, not present by European Standard Test Methods in a comprehensive way. This method also can become an effective reference in materials testing in other constructions worldwide and contribute important information to save human and materials loss if unwanted fire attacks. We are confident that this textbook will assist students and scholars in deepening their understanding of the material behavior contacting to fire, which will lead to future advancements in testing procedures and a higher standard of impartial evaluation of materials and products for the sake of fire prevention. Žilina, Slovakia Cibinong Bogor, Indonesia May 2023

Linda Makovicka Osvaldova Widya Fatriasari

Acknowledgments

We would like to express our special thanks of gratitude to company FIRES s. r. o. Slovakia.

ix

Introduction

We are fascinated by fires, their power, and their beauty, and by people’s attitudes about fires. We love to teach about fires and to learn about fires from observing fires themselves, and the many conversations, science, and stories about fires. Like all humans, we are fire people. [1]

Perhaps every publication related to the issue of fire protection would deserve such an introduction. Fire is strong, wild, and powerful and so should be the people dealing with it. This includes the people who put out dangerous fires as well as those who observe the burning behavior of materials in laboratories. Many times a sample, still too hot to touch, ends up on the ground. Reason says to wait, but the impatience and curiosity of the researcher often win over reason. But in addition to the curiosity that drives scientific exploration, researchers have to pay attention to details and take advantage of all their senses, not just sight. The sense of smell is equally important. Each tested sample behaves differently – on some, fire blazes merrily and burns with joy; on another, it struggles and clings to life until it is completely extinguished. Even the old Greek philosopher Plutarch (46–119 BC) said that “Fire is like a living being – if it is not fed, it perishes, if it is attacked, it defends itself, and before it goes out, it flares up again, which resembles the dying of a person.” [2] One could think and philosophize for a long time about fire, this powerful force of nature that man has learned to control and use. But we must not regard ourselves too highly and forget about uncontrolled fires. Although fire can be a friend (in the fireplace, a brightly burning candle, or the Olympic torch), it is also our enemy. Though one in substance and process, these types of fires are complete opposites: one serves and pleases, while the other destroys. The goal of this textbook is to help prevent uncontrolled fires. The first part of this book defines fire in all its forms and outlines the conditions under which it can occur. Statistical information and the knowledge of first responders and fire brigades are used to more fully understand this phenomenon, not just through material samples tested under laboratory conditions. It is, however, also necessary to turn this practical knowledge into mathematical formulations of physical processes that arise during a fire and be able to implement them in xi

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Introduction

laboratory practice. The last chapter of the first part follows the development of test methods; there is much to learn even from historical testing methods. The second, main, part of the book deals with current test methods, mainly of building materials. In order to effectively prevent dangerous fires, only reliably evaluated and tested materials can be applied in construction. Of course, fire cannot always be prevented. However, it is possible to prevent the fire from spreading and thus endangering other premises, which enables a quick and safe evacuation from the affected area as well as a quick, effective, and safe intervention. This section of the text is complemented by test methods for testing cables, facades, and roofs and methods for determining fire resistance. We consider fire resistance to be the limiting test for material application in buildings. The third part of the textbook deals with the testing of interior materials and products, such as plastic and textile materials and products, as well as furniture as a product intended mainly for the interior. It is necessary to give due attention to all these materials, especially when they are used in public buildings where many people may be gathered simultaneously. Another type of testing, which we cover in the fourth part, is that which takes place in the industrial environment. This includes the testing of dust and dust mixtures, testing of smoke, testing of toxicity of combustion products, and testing of flammable liquids. The penultimate part consists of special methods for the scientific field, and the field of basic research, from which the test methods of ignition and burning of materials can be modified for practice as well. The final chapter discusses fire retardants and retardation. In creating the book, it would have been possible to include a section on retardants for each chapter, but in the end, we decided to dedicate a separate chapter to retardants and confronting them with the given test methods in individual subsections. The overall goal of this book is to provide comprehensive information on test methods for ignition and burning of materials, especially construction materials. We believe that by proper testing and use of safe materials, especially in public places with higher concentrations of people, fire can be considered a friend, not an enemy.

References 1. F. Castro Rego et al., Fire Science, Springer Textbooks in Earth Sciences, Geography and Environment (Springer, 2021). https://doi.org/10.1007/978-3030-69815-7_1 2. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection). (Technical University, Zvolen, 2009)

Contents

Part I

Fire, Learning About Fire, the Science of Fire, and the Beginnings of Testing

1

Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Conditions for the Occurrence of Fire . . . . . . . . . . . . . . . . . . . 1.2 Other Characteristics of Fires . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Fire in an Enclosed Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Statistic Indicators Related to Fire . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 5 12 13 24 28

2

The Theoretical Basis for Materials Testing . . . . . . . . . . . . . . . . . . 2.1 Heat as a Source of Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Heat Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.1 Heat Transfer by Conduction . . . . . . . . . . . . . . . . . . . 2.2.2 Heat Transfer by Radiation . . . . . . . . . . . . . . . . . . . . 2.2.3 Heat Transfer by Radiation Is Characterized by the Following Laws . . . . . . . . . . . . . . . . . . . . . . . 2.3 Theory of Heat Transfer in Test Methods . . . . . . . . . . . . . . . . 2.4 Specifics of the Combustion Process of the Materials to Be Applied in the Test Methods . . . . . . . . . . . . . . . . . . . . . 2.4.1 Initiation of the Combustion Process . . . . . . . . . . . . . 2.4.2 Propagation of Burning . . . . . . . . . . . . . . . . . . . . . . . 2.4.3 Termination of the Combustion Process . . . . . . . . . . . 2.5 Perfect and Imperfect Combustion, Explosive Combustion . . . . 2.6 Homogeneous and Heterogeneous Combustion . . . . . . . . . . . . 2.7 Kinetic and Diffusion Combustion . . . . . . . . . . . . . . . . . . . . . 2.8 Flameless Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 Combustion of Dust Mixtures . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33 33 36 38 40 41 43 48 49 49 50 51 51 55 55 57 59

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3

Contents

Testing of Materials for Fire Protection Use . . . . . . . . . . . . . . . . . 3.1 Principles of Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Overview of the History of Testing . . . . . . . . . . . . . . . . . . . 3.3 Principles of Testing Prior to the Introduction of European Union Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 CSN 730853 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 CSN 730862 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 DIN 4102 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part II

. . .

63 63 65

. . . . .

69 69 70 73 76

Building Materials

4

Testing of Building Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 4.1 Testing of Building Materials According to EU Standards . . . . 81 4.2 Test Methods and Equipment According to EU Standards . . . . 84 4.2.1 EN ISO 1182 Tests for Reaction-to-Fire Performance of Construction Products: Non-flammability Test . . . . 84 4.2.2 EN ISO 1716 Tests for Reaction-to-Fire Performance of Construction Products: Determination of Combustion Heat . . . . . . . . . . . . . . . . . . . . . . . . . 86 4.2.3 EN 13823+A1 Tests for Reaction-to-Fire Performance of Construction Products Except Floorings, Exposed to the Heat of a Single Burning Element [11] . . . . . . . 92 4.2.4 EN ISO 11925-2 Reaction-to-Fire Test: Fire Resistance of Construction Products Exposed to Direct Flame Burning – Part 2: Single Flame Source Test . . . . . . . . 104 4.2.5 EN 9239-1 Tests for Reaction-to-Fire Performance of Floorings: Part 1: Determination of Burning Behavior Using a Radiant Heat Source . . . . . . . . . . . 107 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

5

Testing of Cables, Conductors, and Wiring . . . . . . . . . . . . . . . . . . . 5.1 Reaction to Fire Performance Class for Electric Cables and Conductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Classification of Methods for Testing Cables . . . . . . . . . . . . . . 5.2.1 Development of Heat and Spread of Fire Along the Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.2 Smoke Characteristics in a Fire . . . . . . . . . . . . . . . . . 5.2.3 Determination of the Function Class of Cables and the Cable Cover Systems in the Case of Fire . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

113 114 116 116 118 120 122

Testing of Insulation Systems, Facades, and Roofs . . . . . . . . . . . . . 125 6.1 Assessment of Materials for Facade Cladding Structures . . . . . 126 6.1.1 ISO 13785-1 Reaction to Fire Test for Facades: Part 1 – Middle-size Test . . . . . . . . . . . . . . . . . . . . . 126

Contents

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6.1.2

ISO 13785-2 Reaction to Fire Test for Facades: Part 2 – Large-scale Test . . . . . . . . . . . . . . . . . . . . . . 129 6.2 Assessment of Materials for Roof Structures . . . . . . . . . . . . . . 131 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 7

Resistance to Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Fire Resistance Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Load Capacity: R . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.2 Integrity: E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3 Thermal Insulation: I . . . . . . . . . . . . . . . . . . . . . . . . 7.1.4 Radiation: W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.5 Mechanical Resistance: M . . . . . . . . . . . . . . . . . . . . . 7.1.6 Self-Closing: C . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.7 Smoke Tightness: S . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.8 Resistance to Soot Fire: G . . . . . . . . . . . . . . . . . . . . . 7.1.9 Fire Protection Capability: K . . . . . . . . . . . . . . . . . . . 7.2 Fire Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.1 Temperature/Time Standard Curve (Fire After Volume Ignition) . . . . . . . . . . . . . . . . . . . 7.2.2 Slow Heat Curve (Fire by Smoldering) . . . . . . . . . . . 7.2.3 A Fire Test Simulating a Natural Fire . . . . . . . . . . . . 7.2.4 External Fire Action Curve . . . . . . . . . . . . . . . . . . . . 7.2.5 Constant Temperature Strain . . . . . . . . . . . . . . . . . . . 7.3 Procedures for Classifying Fire Resistance . . . . . . . . . . . . . . . 7.4 Fire Resistance of Electric Cables . . . . . . . . . . . . . . . . . . . . . . 7.5 Fire Resistance Assessment Equipment . . . . . . . . . . . . . . . . . . 7.6 The Model: Informative Fire Resistance Test . . . . . . . . . . . . . 7.6.1 Designing the Test . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.2 Mounting Samples for the Model Fire Resistance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.3 Test Course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.4 Evaluation of the Experiment . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part III 8

137 140 140 140 141 142 142 143 143 143 144 144 145 146 147 147 148 148 150 151 151 152 152 153 157 161

Interior Materials

Testing of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Laboratory Testing Methods of Plastics for Fire Protection Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.1 ISO 871:2022 Plastics: Determination of Ignition Temperature Using a Hot-Air Furnace . . . . . . . . . . . . 8.1.2 EN ISO 4589-2:2017 Plastics: Determination of Burning Behaviour by Oxygen Index – Part 2: Ambient-Temperature Test (ISO 4589-2:2017) . . . . . .

167 167 168

170

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EN ISO 5659-2:2017 Plastics: Smoke Generation – Part 2: Determination of Optical Density by a Single-Chamber Test . . . . . . . . . . . . . . . . . . . . . 8.2 Thermoanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 EN ISO 11358: 2000 Plastics: Thermogravimetry (TG) of Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2 EN ISO 11357-1: 2000 Plastics: Differential Scanning Calorimetry (DSC) – Part 1: General Principles . . . . . 8.2.3 Other Methods of Thermal Analysis . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3

9

10

Testing of Fabrics and Clothing . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 Evaluation of Textiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1 EN ISO 6990:1997 Textiles: Flammability – Detection of Ignition of Vertically Positioned Samples . . . . . . . . 9.1.2 EN ISO 6991: 2009 Textiles: Flammability – Measurement of Flame Spread Rate on Vertically Positioned Samples . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 Assessment of Garments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.1 Testing of Resistance of Protective Clothing Samples to Surface Wetting According to EN ISO 9920:2012 Textile Fabrics: Determination of Resistance to Surface Wetting (Spray Test) . . . . . . . . . . . . . . . . . 9.2.2 EN ISO 9151:2017 Protective Clothing Against Heat and Flame Determination of Heat Transmission on Exposure to Flame . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.3 EN 1986:2007 Protective Clothing for Fire-Fighters: Test Methods and Requirements for Reflective Clothing for Specialised Fire-Fighting . . . . . . . . . . . . 9.2.4 EN ISO 6992:2022 Protective Clothing: Protection Against Heat and Fire – Method of Test – Evaluation of Materials and Material Assemblies When Exposed to a Source of Radiant Heat . . . . . . . . . . . . . . . . . . . . 9.2.5 EN ISO 15025:2000: Protective Clothing – Protection Against Heat and Flame – Test Methods for Limited Flame Spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 Other Test Methods for Textiles in Various Functions . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

173 177 177 180 182 184 187 187 188

189 193

194

195

196

197

199 199 200

Testing of Furniture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 10.1 Characteristics of Upholstered Furniture and Its Analysis for Fire Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 10.2 Tests for Upholstered Furniture . . . . . . . . . . . . . . . . . . . . . . . 207

Contents

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10.2.1

10.2.2

10.2.3 10.2.4 10.2.5 10.2.6 References . . . Part IV

EN 1021-1:2014 Furniture: Flammability Assessment of Upholstered Furniture Part 1: Ignition Source – Smoldering Cigarette . . . . . . . . . . . . . . . . . . . . . . . . EN 1021-2: 2014 Furniture Flammability Assessment of Upholstered Furniture Part 2: Ignition Source: Flame Equivalent of a Match . . . . . . . . . . . . . . . . . . . Test Methods for Evaluating the Flammability of BS 5852 Upholstered Seating Groups . . . . . . . . . . Test According to UIC 564/2 (Procedure 1) . . . . . . . . ÖNORM S 1456 Test . . . . . . . . . . . . . . . . . . . . . . . . Furniture Calorimeters . . . . . . . . . . . . . . . . . . . . . . . .........................................

207

209 210 211 212 212 213

Tests for Dust, Smoke, Flammable Liquids

Testing of Dust and Dust Mixtures . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Methodology for the Testing of Settled Dust . . . . . . . . . . . . . . 11.1.1 Determination of Flame Spread Rate Over a Layer of Settled Dust in an Oxygen Atmosphere (RO Test) . . . 11.1.2 EN 50281-2-1: 2000 Electrical Equipment for Areas with Flammable Dust. Part 2-1: Test Methods for Determining Minimum Dust Ignition Temperatures . . 11.2 Test Methodology for Raised Dust . . . . . . . . . . . . . . . . . . . . . 11.2.1 EN 50281-2-1 Electrical Equipment for Areas with Flammable Dust. Part 2-1: Test Methods for Determining Minimum Dust Ignition Temperatures . . 11.2.2 Explosion Chambers . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

222 223 226

12

Smoke and Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 Smoke Assessment Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Determination of the Toxicity of Burning Products . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

227 227 228 230

13

Testing of Flammable Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 EN ISO 3679:2022 Determination of Flash Point – Rapid Equilibrium Closed Cup Method . . . . . . . . . . . . . . . . . . . . . . 13.2 EN ISO 2592:2017 Determination of Flash and Fire Points – Cleveland Open Cup Method . . . . . . . . . . . . . . . . . . . . . . . . . 13.3 EN ISO 2719: 2016 Determination of Flash Point, PenskyMartens Closed Cup Method . . . . . . . . . . . . . . . . . . . . . . . . . 13.4 EN 924:2003 Adhesives – Solvent-Borne and Solvent-Free Adhesives – Determination of Flash-Point . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

231

11

217 218 218

220 222

231 231 233 233 234

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Part V

Other Test Methods

14

Special Test Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1 Cone Calorimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2 Spatial Ignition Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

239 239 243 246

15

Large-Scale Test Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1 Box Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2 Test Sample of a Building Fragment . . . . . . . . . . . . . . . . . . . . 15.3 Test of the Whole Building . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3.1 Old Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3.2 Newly Built One-Story Building with Metal Supporting Elements for Testing Purposes . . . . . . . . . 15.3.3 Newly Built Two-Story Building with Wooden Supporting Elements and Wooden Sheathing for Testing Purposes . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

249 249 250 251 252

Non-standardized Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1 Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2 Assessment Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.1 Weight Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.2 Relative Burning Rate . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3 P Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4 Difference in Weight Loss 0–48 . . . . . . . . . . . . . . . . 16.2.5 Burned Area and Its Size . . . . . . . . . . . . . . . . . . . . . 16.3 Monitoring the Differences Between Tree Species . . . . . . . . . . 16.3.1 Description of Experiment I . . . . . . . . . . . . . . . . . . . 16.3.2 Results of the Experiment I . . . . . . . . . . . . . . . . . . . . 16.3.3 Description of Experiment II . . . . . . . . . . . . . . . . . . . 16.3.4 Results of Experiment II . . . . . . . . . . . . . . . . . . . . . . 16.4 Monitoring the Effects of Wood Density and Retardants . . . . . 16.4.1 Description of the Experiment . . . . . . . . . . . . . . . . . . 16.4.2 Results of the Experiment . . . . . . . . . . . . . . . . . . . . . 16.5 Monitoring the Effect of Joints . . . . . . . . . . . . . . . . . . . . . . . . 16.5.1 Description of the Experiment . . . . . . . . . . . . . . . . . . 16.5.2 Results of the Experiment . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

263 263 265 265 266 266 267 268 268 268 270 270 271 272 272 273 273 274 275 279

16

Part VI 17

253

255 261

Retarders and Fire Retardancy

Flame Retardants: Principle of Retardation . . . . . . . . . . . . . . . . . 17.1 Retarding Effects of Various Flame Retardants . . . . . . . . . . . 17.2 Application of Flame Retardant . . . . . . . . . . . . . . . . . . . . . . 17.2.1 Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . .

283 283 284 284

Contents

17.2.2 17.2.3 17.2.4 17.2.5 References . . . 18

xix

Dipping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Impregnation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modification of Raw Material Inputs . . . . . . . . . . . . Modification of Technology . . . . . . . . . . . . . . . . . . ........................................

. . . . .

285 285 286 287 290

Effects of Flame Retardants in Individual Tests . . . . . . . . . . . . . . . 18.1 Fire and Flame Retardants . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.2 The Theoretical Basis for Materials Testing . . . . . . . . . . . . . . 18.3 Testing of Materials for Fire Protection Use . . . . . . . . . . . . . . 18.4 Testing of Building Materials . . . . . . . . . . . . . . . . . . . . . . . . . 18.5 Testing of Cables, Conductors, and Wiring . . . . . . . . . . . . . . . 18.6 Testing of Insulation Systems, Facades, and Roofs . . . . . . . . . 18.7 Resistance to Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.8 Testing of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.9 Testing of Fabrics and Clothing . . . . . . . . . . . . . . . . . . . . . . . 18.10 Testing of Furniture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.11 Testing of Dust and Dust Mixtures . . . . . . . . . . . . . . . . . . . . . 18.12 Smoke and Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.13 Testing of Flammable Liquid . . . . . . . . . . . . . . . . . . . . . . . . . 18.14 Special Test Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.15 Large-Scale Test Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.16 Non-standardized Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

293 293 294 294 295 296 296 297 298 298 298 299 299 299 299 300 300

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

About the Authors

Linda Makovická Osvaldová is professor at the Department of Fire Engineering, Faculty of Security Engineering, University of Žilina, Slovakia. She studied at the Faculty of Wood at the Technical University in Zvolen, the study program “Fire Protection” in the engineering study and the study program “Wood Processing Technology” in doctoral degree. She obtained a Bachelor of Law degree from the Matej Bel University in Banská Bystrica, Slovakia. She deals with safety issues testing of materials used in technological processes, building constructions, as well as natural materials in forest fires and their impact on the safety of rescue components during firefighting. https://scholar.google.com/citations?user=-Cs94 fIAAAAJ&hl=sk Widya Fatriasari is professor at the Research Center for Biomass and Bioproducts, National Research and Innovation Agency (BRIN), Indonesia. She has been the research group head of Polyphenol-Based Bioproduct since 2019. She has obtained a Doctor of Forest Product Technology from IPB University, Indonesia and pursued her Bachelor’s and Master’s degrees from IPB University, Indonesia. Her research interests include biomass conversion, natural fiber and composite technology, biorefinery, and biopolymer. https://scholar.google.co.id/citations?user= YoeHDZ8AAAAJ&hl=

xxi

List of Symbols

Roman Symbols a1 a2 a3 a ABS ACA A1 A2 Aca A1fl A2fl A A1

A2

A1 A2 A A b

B

conductivity < 25 μS/mm and pH > 43 conductivity < 10 μS/mm and pH > 43 no a1 or a2 (cables) coefficient of thermal conductivity (m2/s) acrylonitrile butadiene styrene (Robinia pseudoacacia L.) class reaction-to-fire class reaction-to-fire class reaction-to-fire – cables class reaction-to-fire – floorings class reaction-to-fire – floorings starting point – the intersection of the line of initial mass and the tangent to the TG curve at the point of the maximum gradient starting point – the intersection of the line of initial mass and the tangent to the TG curve at the point of the maximum gradient in point 1 starting point – the intersection of the line of initial mass and the tangent to the TG curve at the point of the maximum gradient in point 2 flammability class DIN 4102 flammability class DIN 4102 flammability class CSN 73 0862 oxidizer correction in MJ for the thermal content of “fuel” used in the test, i.e., ignition wire (nickel-chrome = 1403 MJ/kg platinum = 0419 MJ/kg pure iron = 7490 MJ/kg), cotton thread, cigarette paper, and benzoic acid or a burning agent class reaction-to-fire xxiii

xxiv

Bfl B1ca B2ca BEE BIR BS B B1 B2 B1 B2 B3 B c c1 cp cor c C C1-C4 Cca Cfl CBA CEET CHF CMFM CMSM CSA CSN CSR CVUT CYKY CZU C C2 CB C

List of Symbols

class reaction-to-fire – floorings class reaction-to-fire – cables class reaction-to-fire – cables (Fagus sylvatica L.) (Betula verrucosa Ehrh.) British Standard endpoint – the intersection of the line of final mass and the tangent to the TG curve at the point of the maximum gradient endpoint – the intersection of the line of final mass and the tangent to the TG curve at the point of the maximum gradient in point 1 endpoint – the intersection of the line of final mass and the tangent to the TG curve at the point of the maximum gradient in point 2 flammability class DIN 4102 flammability class DIN 4102 flammability class DIN 4102 flammable substance mass temperature capacity specific heat (J/kg.K) final oxygen value (vol %) specific heat of copper 0385 (kg/°C) correction temperature correction (K) for heat exchange with the surrounding area. It is zero when using an adiabatic jacket class reaction-to-fire thermocouples class reaction-to-fire – cables class reaction-to-fire – floorings toxicity test equipment Energy and Environmental Technologies VSB-TUO Ostrava critical heat flux control and electronics cables control and electronics cables chemical safety assessment of substances Czechoslovak state norm chemical safety reports Czech Technical University in Prague installation cables Czech University of Life Sciences Prague radiation coefficient of a gray body (J/K4) (because it is always ε < 1) a constant (-) radiation coefficient of a blackbody (J/K4) center point – the intersection of the TG curve and the line constructed parallel to the x-axis at a point midway between points A and B

List of Symbols

C1

C2

C C1 C2 C3 C d0 d1 d2 (dp/dt)max d D Dfl Dca DDC DEA DETA DIN DMA DSC DTA DTD DTG Ds Ds E Eca Efl EC EEC EN ETA EU E En E0 Ej E

xxv

center point – the intersection of the TG curve and constructed parallel to the x-axis at a point midway points A and B in point 1 center point – the intersection of the TG curve and constructed parallel to the x-axis at a point midway points A and B in point 2 self-closing (fire resistance criterion) flammability class CSN 73 0862 flammability class CSN 73 0862 flammability class CSN 73 0862 substance products no flaming droplets/particles in the test according no flaming droplets/particles persisting longer than 10 s fails to meet d0 or d1 maximum rate of increase in explosion pressure interval between oxygen concentrations (%) class reaction-to-fire class reaction-to-fire – floorings class reaction-to-fire – cables differential dynamic calorimetry dielectric analysis dielectric thermal analysis Deutsches Institut für Normung e. V dynamic mechanical analysis differential scanning calorimetry differential thermal analysis chipboard derivative thermogravimetric optical density of smoke (m2/kg) specific optical density (%) class reaction-to-fire class reaction-to-fire – cables class reaction-to-fire floorings European Community European Economic Community European Standard electrothermal analysis European Union radiated energy (J) emissivity perpendicular to the surface (effective) (J) radiation energy (J) energy emitted at the given angle (J) integrity (fire resistance criterion)

the line between the line between

xxvi

E F Fca Ffl FIPEC FIT FRNC FIGRA FIGRA0.2MJ FIGRA0.4MJ Fs grad T G H H05RR-F H07RN-F H05V H07V-U/K HD HD0 HD1 HD2 HF-10 HF-20 HF-30 HFFR HFX HRR(t) HRR30s HRRav HRRav_burner HRRburner(t) HRRtotal HRRtotal(t) HS i ing I ISO I I(t) Io Itox

List of Symbols

water value of calorimeter bomb its accessories and water poured into the calorimeter expressed in (MJ/K) class reaction-to-fire class reaction-to-fire – cables class reaction-to-fire – floorings Fédération des Industries des Peintures, Encres, Couleurs Flash ignition temperature Flame Retardant Non-Corrosive fire growth rate index (W/s) fire growth rate indices fire growth rate indices flame spread temperature gradient (K/m) resistance to soot fire (fire resistance criterion) flame spread rubber cables rubber cables mounting cables mounting cables high density high sample density without coating high density sample with one coating high sample density with double coating heat flux at 10 min heat flux at 20 min heat flux at 30 min Halogen-Free Flame Retardant heat flux at X min heat release rate from the sample (kW) average value of HRR(t) over 30 s (kW) average value of HRR(t) (kW) average heat release rate from the burner (kW) heat release rate from the burner (kW) total rate of heat release from the sample and the burner (kW) total rate of heat release from the sample and burner (kW) death limit unit vectors in the direction of the x axis exhaust gas (combustion products) speed (m/s) flame retardant impregnation International Organization for Standardization the intensity of the light passing through the smoke layer (lx) light receiver signal (%) units of intensity of input light (lx) index of toxicity (-)

List of Symbols

I I j J-Y(St)Y) JYTY k k kρ kg k kt Kst K l ℓ ℓf ℓp LD LD0 LD1 LD2 LEL LFHC LOC LOI LSOH L L LC50

LFS max. (a b) max. (a(t)) m m(0) m(48) m(600) m1 m2 mf mf2

xxvii

thermal insulation (fire resistance criterion) signal from the light receiver unit vectors in the direction of the y axis communication cables and conductors control and electronics cables unit vectors in the direction of the z axis thermal conductivity (kW/m.K) Reynolds number correction for a bi-directional sensor entered as 1.08 thermal conductivity of gas (kW/m.K) factor obtained from the table (table stated in the standard) flow profile factor cubic constant fire protection capability (fire resistance criterion) length of the dust layer in the defined section (m) characteristic layer (m) flame length (m) height of burning zone (pyrolytic zone) (m) low density low sample density without coating low density sample with one coating low sample density with double coating lower explosion limit Low Fire Hazard Cables limit oxygen concentration limiting oxygen index Low Smoke Zero Halogen length of the light path through the suction pipe (m) which is given by the diameter of the suction pipe thickness of the smoke layer (m) sample size expressed in grams of the sample per 1 L of the chamber size with a mortality rate of 50% of the experimental animals edge of the test sample maximum of the two values of a and b maximum a(t) at a given time weight of the test sample (kg) weight of the sample in time (τ0) (g) weight of the sample in time (τ48) (g) weight of the sample in time (τ600) (g) weight of sample before test (g) weight of sample after test (g) mass at the final temperature (mg) mass at second final temperature (mg)

xxviii

mfk mi1 mi2 mmax msm(τ) m(τ+Δτ) m_ 00 m_ gas ðt Þ m MAP MG ML ML1 ML2 M n n N NSGAFONA OAK OI ÖNORM OSB p P2 P3 PA PC PE PES PET PH PMMA PP PS PTFE PUR PVC PVDC P PCI PCS

List of Symbols

mass at last final temperature (mg) mass at first initial temperature (mg) mass at second initial temperature (mg) maximum mass (mg) mass before heating (mg) sample weight in time (τ) (g) sample weight in time (τ + Δτ) (g) mass burning rate (g) propane mass flow rate (kg/s) copper plate weight (kg) (Acer platanoides L.) mass before heating (mg) mass loss (%) first loss in mass (%) second mass loss (%) mechanical resistance (fire resistance criterion) number of data points (n = 21) distance of isothermal areas in the direction of the normal (m) non-retarded material rubber cables (Quercus petraea Liebl.) oxygen index (%) Austrian Standards oriented strand board height of the burning zone (pyrolytic zone) non-combustible products Box 2 non-combustible products (solid or gaseous) polyamide polycarbonate polyethylene polyester polyethylene terephthalate solid polymer plexiglass polypropylene polystyrene polytetrafluoroethylene polyurethane polyvinyl chloride polyvinylidene chloride ratio of maximum burning rate divided by the time when it is reached calorific value (J/kg) combustion heat (MJ/kg)

List of Symbols

P q qc q0 qgas(t) qgas(t) qgas30s(t) qv q_ 00conv q_ 00net q_ 00rr q_ 00e q Q Q′ Q0 Q1 Q2 Q3 Q QcQcv Qe QrQs Qa Qρ Qτ 00 Q_ HRR Q ‘R’ Reℓ RH RHTI RO Rz R S S S s1 s1a s1 s1b s1

xxix

system pressure (Pa) heat flow density (W/m2) density of the incident heat (W/m2) radiant heat transfer (W/m2) theoretical rate of heat release from propane mass flow (kW) theoretical rate of heat release of the propane mass flow (kW) diameter qgas(t) over 30 s (kW) air flow velocity (mm/s) loss of heat flow from convection (W/m2) heat flow onto the material (W/m2) loss of heat flow from radiation (W/m2) external thermal flow (W/m2) 2 449.W (J) (evaporation heat value of water) heat decomposition heat external source into Box 1 the fuel RH in Box 1 the fuel RH in Box 2 heat loss to the surroundings heat total fire heat flow total energy (J) energy released outside the fire area by convection (J) overall impact (J) energy released outside the fire area by radiation (J) energy distributed to heat the structure (J) absorbed part (J) reflected part (J) part that penetrates the body (J) heat required for thermal burning rate (J) relative number (-) plastic-insulated cables Reynolds number (-) polymeric fuel radiant heat transfer index dust test resistant residue (%) load capacity (fire resistance criterion) surface area of the copper plate (m2) area (m2) the cross-section area of the suction pipe in the main measuring section (m2) SMOGRA 30 m2/s2 and TSP600s 3 kWÞ and ðTHRðt Þ > 0:2 MJÞ a ð300 s ≤ t ≤ 1500 sÞ

ð4:17Þ

ðHRRav ðt Þ > 3 kWÞ and ðTHRðt Þ > 0:4 MJÞ a ð300 s < t ≤ 1500 sÞ

ð4:18Þ

Using (4.19) FIGRA = 1000: max:

HRRav ðt Þ t - 300

ð4:19Þ

where: FIGRA – fire growth rate index (W/s), HRRav – average value of HRR(t) (kW), max.(a(t)) – maximum a(t) at a given time. In the case that the sample has a value of HRRav of less than 3 kW or a value of THR of less than 0.2 MJ over the whole test period, the index of FIGRA0.2 MJ equals zero. A sample with a value of HRRav of less than 3 kW and THR of less than 0.4 MJ over the entire test period shall have an index of FIGRA0.4 MJ equaling zero. For each test, the smoke behavior of the product must be as the given graphs of SPRav(t), total smoke production TSP(t) and 10,000 × SPRav(t)/(t - 300) for a time interval of 0 ≤ t ≤ 1500 s; and the smoke growth rate index SMOGRA and the total smoke production in the first 600 s TSP600s are calculated according to the following procedures:

100

4

Testing of Building Materials

Total SPR of the sample and burner: SPRtotal, calculation V(t) (4.20): V ðt Þ = V 298 ðt Þ

T ms ðt Þ 298

ð4:20Þ

where: V(t) – volume flow in the suction pipe (m3/s), V298(t) – volume flow in the suction pipe standardized at 298 K (m3/s), Tms – temperature in the main measuring part (K). Calculation of SPRtotal(t) (4.21) SPRtotal ðt Þ =

V ðt Þ I ðt30 s . . . 90 sÞ ln L I ðt Þ

ð4:21Þ

where: SPRtotal(t) – total smoke release rate from the sample and burner (m2/s), V(t) – (not normalized) volume flow rate in suction pipe (m3/s), L – length of the light path through the suction pipe (m), which is given by the diameter of the suction pipe, I(t) – light receiver signal (%). SPR of the burner The smoke formation rate from the burner is equal to SPRtotal(t) during the baseline period. The average SPR of the burner is calculated as the average SPRtotal(t) over the baseline time (210 s ≤ t ≤ 270 s)) (Eq. 4.22): SPRav

burner

= SPRtotal ð210 s . . . 270 sÞ

ð4:22Þ

where: SPRtotal(t) – total rate of smoke production from the sample and burner (m2/s), SPRav_burne – average smoke production rate from the burner (m2/s). The standard deviation of SPRav_burner(t), σ bs, over 210 s ≤ t ≤ 270 s, is calculated using a method without a deviation or n – 1 method (4.23) as follows: 270s

n σbs =

210s

fSPRburner ðt Þg2 -

270s

2

SPRburner ðt Þ

210s

n ð n - 1Þ

where: SPRav_burner – average smoke production rate from the burner (m2/s), SPRburner(t) – smoke production rate from the burner (m2/s), n – number of data points (n = 24).

ð4:23Þ

4.2

Test Methods and Equipment According to EU Standards

101

The level and stability of the burner during the time of this baseline shall comply with the following criteria (4.24 and 4.25): SPR

= ð0 ± 0:1Þ m2 =s

ð4:24Þ

and σ bs < 0:01 m2 =s

ð4:25Þ

where: SPRav_burner – average smoke production rate from the burner (m2/s), σ bs – standard deviation of SPRburner(t) in the time interval 210 s ≤ t ≤ 270 s. SPR of the sample In general, the SPR of the sample is given as the total smoke production rate SPRtotal(t) as the difference in the rate of the average SPR of the burner, SPRav_burner. For t > 312 s (4.26): SPRðt Þ = SPRtotal ðt Þ–SPRav

burner

ð4:26Þ

where: SPRtotal (t) – total smoke production rate from the sample and burner (m2/s), SPRav_burner – average smoke production rate from the burner (m2/s), SPR(t) – smoke production rate from the sample (m2/s). During the switch from the auxiliary burner to the main burner at the beginning of the exposure period, the total smoke production from two burners may be less than SPRav_burner. Equation 4.29 can therefore have negative values of SPR(t) for a few seconds. These negative values and the value for t = 0 shall be reset, for t = 300 s, and for 300 s < t < 312 (4.27 and 4.28): SPRð300Þ = m2 =s, SPRðt Þ = max: 0, SPRtotal ðt Þ - SPRav

ð4:27Þ burner

where: SPRtotal(t) – total smoke production rate from the sample and burner (m2/s), SPRav_burner – average smoke production rate from the burner (m2/s), SPR(t) – smoke production rate from the sample (m2/s), max. (a, b) – maximum of the two values of a and b.

ð4:28Þ

102

4

Testing of Building Materials

Calculation of SPR60s SPR60s ðt Þ is the average of SPRðt Þ during 60 s ð4:29Þ SPR60 s ðt Þ =

f0:5SPRðt - 30 sÞ þ SPRðt - 27 sÞ þ . . . þ SPRðt þ 27 sÞ þ 0:5SPRðt þ 30 sÞg 20 ð4:29Þ

where: SPR60s(t) – average SPR(t) during 60 s (m2/s), SPR(t) – smoke production rate from the sample (m2/s). Calculation of TSP(t) and TSP600s The total smoke production from the sample TSP(t) and the total smoke production from the sample TSP600s in the first 600 s of the exposure time 300 s ≤ t ≤ 900 s is calculated as follows (4.30 and 4.31): ta

TSPðt a Þ = 3

ðmax:½SPRðt Þ, 0Þ

ð4:30Þ

300s 900s

TSPðt 600s Þ = 3

ðmax:½SPRðt Þ, 0Þ

ð4:31Þ

300s

where: TSP(ta) – total smoke production in 300 s ≤ t ≤ ta (m2), SPR(t) – smoke production rate from the sample (m2/s), TSP600s – total smoke production from the sample in 300 s ≤ t ≤ 900 s (m2) [equal TSP(900)], max. (a,b) – maximum of two values of a and b. SMGORA (smoke production rate coefficient) is defined as the maximum ratio of SPRav(t)/(t - 300) divided by 10,000. The ratio is calculated only for the part of the exposure time in which the threshold levels of SPRav and TSP are exceeded. If one or both of the threshold’s values are not exceeded during the exposure period, SMGORA shall be zero. SPRav used for the calculation of SMOGRA equals zero SPR60s except for the first 27 s of the exposure time. For data points in the first 27 s, the average value entered is only through the widest possible range of data points at the time of exposure:

4.2

Test Methods and Equipment According to EU Standards

103

for t = 300 s : SPRav ð300 sÞ = 0 m2 =s, or t = 303 s : SPRav ð303 s Þ = SPR ð300 s:::306 sÞ, for t = 306 s : SPRav ð306 sÞ = SPR ð300 s:::312 sÞ, for t = 327 s : SPRav ð327 sÞ = SPRav ð300 s:::354 sÞ,

ð4:32Þ

or t ≥ ≥ 330 s : SPRav ðt Þ = SPR60s ðt Þ: Calculation of SMOGRA for all t, where (4.33): SPRav ðt Þ > 0:1 m2 =s and TSPðt Þ > 6 m2 and ð300 s < t ≤ 1500 sÞ, SMOGRA = 10,000: max:

SPRav t - 300

ð4:33Þ

where: SMOGRA – smoke production rate coefficient (m2/s2), SPRav(t) – average SPRav(t), as prescribed in a) (m2/s), max.(a(t)) – maximum a(t) in a given period of time. In the case that the sample has an SPRav value of less than 0.1 (m2/s) throughout the whole test, or a TSP value of less than 6 m2 throughout the whole test, the value of SMOGRA is equal to zero. Calculations for calibration, heat released by propane The theoretical rate of heat release of the propane mass flow is calculated using Eq. 4.34: qgas ðt Þ = Δhc,eff m_ gas ðt Þ

ð4:34Þ

where: qgas(t) – theoretical rate of heat release of the propane mass flow (kW), Δhc,eff – lower calorific value of propane (= 46,360 kJ/kg), m_ gas ðt Þ – propane mass flow rate (kg/s). 30 s diameter qgas is calculated (4.35): qgas,30s ðt Þ =

0:5qgas ðt - 15Þ þ qgas ðt - 12Þ þ . . . þ qgas ðt þ 12Þ þ qgas ðt þ 15Þ 10

where: qgas,30s(t) – diameter qgas(t) over 30 s (kW), qgas(t) – theoretical rate of heat release from propane mass flow (kW).

ð4:35Þ

104

4

Testing of Building Materials

For each test, the behavior of the product with regard to the formation of burning drops and particles must be recorded as the presence or absence of one or both categories of falling burning droplets and particles. The test report shall contain information showing clear differences between the data provided by the project owner and the data obtained by the test.

4.2.4

EN ISO 11925-2 Reaction-to-Fire Test: Fire Resistance of Construction Products Exposed to Direct Flame Burning – Part 2: Single Flame Source Test

The test method determines the flammability of construction products by the application of a small, directed flame under zero additional radiation conditions, using samples tested in the vertical position. Two possible flame exposure times are available: 15 s or 30 s, as requested by the project owner. The starting time of the test is the application of a flame. The required air flow rate is checked in the flue of the combustion chamber. A series of six test samples is taken from the conditioned compartment; these samples must be tested within 30 min. If necessary, the test sample may be transferred from the conditioned area to the test facility in a tight container. The test specimen is attached to the specimen holder so that one end and both sides are fixed by the holder frame, and the exposed end is at a distance of 30 mm from the end of the frame. The distance of the burner from the sample is checked by means of an appropriate spacer with the burner inclined at 45° the vertical axis. Less than 3 min before the start of the test, two pieces of filter paper are placed on an aluminum foil dish under the sample. The vertically placed burner is turned on and the flame is allowed to settle. Using a burner valve, the flame height is set to 20 ± 0.1 mm. To prevent flame from accidentally falling onto the test specimen, this operation is performed further from the preset position. The flame height should be checked before each use of the flame. The height of the flame should be measured against a black background. The burner is tilted at an angle of 45° to the vertical axis and moved horizontally until the flame reaches a preset contact point with the test specimen. The timer is activated as soon as the flame contacts the test sample. The flame exposure is either 15 s or 30 s, depending on the requirements of the project owner, and then the burner is moved away at a steady rate. The tests can be performed by exposing the main surface, the side surfaces, or both. The scheme of the apparatus is shown in Fig. 4.8 the photo of the device is in Fig. 4.9. For all essentially flat products, the flame must be applied to the axis of the sample 40 mm above the lower edge. Any different surface that may be subjected to thermal load shall be tested.

4.2

Test Methods and Equipment According to EU Standards

105

Fig. 4.8 Diagram of the apparatus according to EN ISO 11925-2 [2, 9]

For single-layer or multi-layer essentially flat products of a total thickness up to 3 mm, the flame must be placed at the center point at the bottom of the test sample. For single-layer or multi-layer essentially flat products with a total thickness of more than 3 mm, the flame shall be placed at the center of the width of the lower side area of the test sample, 1.5 mm from the surface. For multi-layer products of a thickness of more than 10 mm, additional series of tests must be carried out with the sample turned 90° around its vertical axis and the flame must fall on the axis of the lower side face of each layer. For products that are not essentially flat, and which are tested in their end-use form, the flame shall be placed to the axis of the sample 40 mm above the lower edge. Any other surface that may be subjected to thermal stress must also be tested.

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Fig. 4.9 Laboratory equipment for the EN ISO 11925-2 test. (Photograph by J. Mitterpach 2023, CZU Praha)

In some cases, however, the burner may be improperly attached, and the ignition initiator may need to be held and applied manually. The product may stand freely or be clamped in its end-use orientation in a support frame which, in the simplest case scenario, may be a laboratory stand, or may require a stronger, specially designed frame. If the flame application time is 15 s, the total duration of the test shall be 20 s from the moment the sample is exposed to the flame. If the flame application time is 30 s, the total duration of the test shall be 60 s from the moment the sample is exposed to the flame. The location of flame application shall be recorded. For all test samples, the following shall be recorded: • if the sample ignited, • whether the top part of the flame reached a height of 150 mm above the point of application of the flame; and if so, the time when it occurred, • if the filter paper ignited, • observation of the physical behavior of the test sample.

4.2

Test Methods and Equipment According to EU Standards

4.2.5

107

EN 9239-1 Tests for Reaction-to-Fire Performance of Floorings: Part 1: Determination of Burning Behavior Using a Radiant Heat Source

This European standard describes the method for determining the burning and flame spread behavior against air flow of horizontally placed floorings exposed to the radiation flux gradient in the test chamber after ignition by the initiating flame. This method is applicable to all types of floor materials, i.e. textile carpet, cork, wooden, rubber and plastic flooring materials as well as to coatings. The results obtained using this method reflect the characteristics of the flooring materials including subfloors if used. Modifications of the subfloor, subfloor joining materials, reinforcements, or other changes in floor area may affect test results. The test equipment must be placed in a room at a distance of not less than 0.4 m from walls and ceilings. The following calibration procedure must be performed after any substantial modification of the equipment or at least once a month. If there are no changes in subsequent calibrations, this interval may be extended to 6 months. The air flow rate in the extraction flue is measured with the suction blower running and the door closed and set to 2.5 +/- 0.2 m/s if necessary. The radiation panel heats up. The apparatus heating time shall be at least 1 hour until the chamber temperature is stabilized. The initiator burner must then be switched off. The thermal flow sensor shall measure the heat flow level at the point of 410 mm. The thermal flux sensor is placed in the opening so that its surface is 2–3 mm above and parallel to the plane of the blind sample. The output is read out after 30 s. If it is 5.1 ± 0.2 kW/m2, the heat flow profile can be determined. If the heat flux level is not within this range, the air and gas flow control to the panel need to be regulated. The fuel flow is set in the panel at least 10 min before the new heat flux reading. The heat flux profile is determined. The heat flow sensor is inserted into each opening in the row, starting at 110 mm and ending at 910 mm from the zero point of the sample. To determine whether the heat flow level changed during these measurements, the figure at 410 mm shall be checked after reading out the value at 910 mm. The scheme of the device is shown in Fig. 4.10 and the photo of the device is in Fig. 4.11. The heat flow values shall be recorded as a function of the distance along the sample plane. A smoothed curve is carefully constructed across the data points. This curve is the thermal flow profile curve (see Fig. 4.12). If the heat flow profile curve is within the tolerance of the data in Table 4.3, the test device is calibrated, and the determination of the heat flow profile is complete. If the heat flow curve is not within tolerance, the fuel flow must be carefully adjusted, and a minimum of 10 min is given for the chamber temperature to stabilize. The procedure shall be repeated until the heat flow profile is set as specified in Table 4.3. Usually, only a change in gas flow is needed to correct the heat flux at the hotter end of the sample. To adjust the heat flow at the cooler end of the sample, a change in both gas and airflow may be necessary. The blind sample is removed and the door is closed. After 5 min, the radiation temperature of the radiation panel and

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Fig. 4.10 Prospective view showing the test principle (EN 9239-1) [2, 8] 1 – lighting unit, 2 – suction pipe, 3 – light receiver, 4 – flap valve, 5 – test chamber, 6 – gas– heated radiation panel, 7 – initiation flame from a linear burner, 8 – gauge, 9 – sample slide holder, 10 – air supply around sample at the bottom of the chamber

the chamber temperature are measured. The results of the daily calibration values are recorded. For the standard test procedure, the flow of air in the suction flue is adjusted. The blind sample is removed, and the door is closed. The panel heats up and the device is allowed to warm for at least 1 hour until the temperature in the chamber is stable. The radiation panel temperature is measured. The radiation temperature must be in the range of ±5 °C compared to the radiation temperature recorded during calibration. The temperature in the chamber must be in the range of ±10 °C compared to the chamber temperature recorded during calibration. If the radiation temperature or the temperature in the chamber differs more than the specified limit, the air and gas inlet to the radiation panel is adjusted. The test apparatus is allowed to stabilize for a minimum of 15 min before the temperature is measured again. If necessary, the smoke measuring system is set so that its output values are equal to 100%. The measuring system must be stabilized before the test begins. If not, it needs to be adjusted further. The air flowing to the lamp and the detection system shall be checked and adjusted if necessary. The test sample, including the pad(s) and the subfloor, is placed in the sample holder. Steel locking clamps are inserted through the rear of the assembly and the nuts are tightened, or another fastening method is used. If appropriate, the fibers of

4.2

Test Methods and Equipment According to EU Standards

109

Fig. 4.11 Laboratory equipment for the EN ISO 9239-1 test. (Photograph by J Mitterpach 2023 CZU Praha)

the textile flooring are lifted using a vacuum cleaner and the test specimen and its holder are fixed in a slide-in plate. The ignition torch is ignited and placed at least 50 mm from the intended zero point on the test specimen. The slide-in plate is retracted into the chamber and the door is closed immediately. This is considered as the beginning of the test. The time and recording equipment shall be started. After a 2-min pre-heating with the initiating burner, at least 50 mm from the zero point of the test sample, the flame of the initiating burner is brought into contact with the test sample for 10 min; then the initiating burner is moved away into a position at least 50 mm from the zero point of the test sample. The flame of the initiator burner is extinguished. During the test, the gas and air flow to the radiation panel must be constant. At 10-min intervals from the start of the test and when the flame is put out, the distances between the flame front and the zero point are measured to an accuracy of at least 10 mm. Significant phenomena such as transient combustion, melting, formation of blisters, smoldering time and position after extinguishing, flame penetration through the underlying material, etc. are observed and recorded. Additionally, the time when the flames reach each 50 mm mark is recorded. The test shall be considered complete after 30 min unless the project owner requires a longer duration of the test.

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Fig. 4.12 Heat flow profile curve [2] 1 – heat flow (kW/m2), 2 – distance from zero (mm), 3 – upper limit, 4 – nominal value, 5 – lower limit

One sample shall be tested in one direction and the other in the direction perpendicular to the first. The tests giving the lowest values of CHF and HF-30 shall be carried out twice in both directions, i.e., four tests shall be required. The further test shall not be started until the radiation temperature and the temperature in the chamber are as specified by the standard. Before fixing the new test sample, the sample holder must be cooled to laboratory temperature. Using the heat flow profile curve, the observed flame propagation distances are converted to kW/m2, and the critical heat flow is determined. It is read after each 0.2 kW/m2. Samples that do not ignite, or whose flame spreads to less than 110 mm, have a critical heat flux of 11 kW/m2. The test samples where the flame spread over a distance of more than 910 mm have a critical heat flux of ≤1.1 kW/m2. The samples put out after 30 min by the operator do not have a CHF but only an HF-30 value. A report of the results of the four tests is made with respect to the CHF and HF-30 values and a corresponding description of the direction. The average value of the critical heat flow from the test data of three samples at the same orientation is

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111

Table 4.3 Required heat flow distribution to the calibration board [3] processed by the authors Distance from the zero point of the sample (mm) 110

Heat flow (kW/m2) 10.9

Accuracy (kW/m2)

210

9.2

± 0.4

310

7.1

± 0.2

410

5.1

±0.2

510

3.5

±0.2

610

2.5

± 0.2

710

1.8

± 0.2

810

1.4

± 0.2

910

1.1

± 0.2

± 0.4

calculated. The values of CHF and HF-30 should also be included in the calculation of the average critical flow value of the three samples mentioned above. For a test lasting more than 30 min, the flame extinguishing time and the most distant point of the flame propagation are recorded and converted to CHF. The times at which the flame reached each 50 mm mark and the final distance of the flame spread for each 10th min are recorded to determine the HFX value, if required, i.e., HF-10, HF-20, HF-30. The final maximum flame spread distance and the time when the flame burnt out should also be recorded. If required, a report of the smoke measurement results is also made. Questions Experience the historical and current methods of testing materials for fire protection needs, what is more perfect? (You will focus on the method of testing and not on the convenience of current technology). What is the significance of additional criteria for individual tests? Which reaction to fire classes will rate the material so that flashover does not occur when it is applied in the space? Which test procedures enable the testing of retardation modifications of materials?

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References 1. A. Law, G. Spinardi, L. Bisby, The rise of the Euroclass: Inside the black box of fire test standardization. Fire Saf. J. 135, 103712 (2023). https://doi.org/10.1016/j.firesaf.2022.103712 2. L. Makovicka Osvaldova, S. Gaspercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 3. A. Osvald, et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection). (Technical University, Zvolen, 2009) 4. B.L. Östman, E. Mikkola, European classes for the reaction to fire performance of wood products. Holz Roh Werkst. 64, 327–337 (2006). https://doi.org/10.1007/s00107-006-0116-x 5. P. Vandervelde, Classification of fire performance, in Fire safe products in construction, (EGOLF, Luxembourg, 1999), pp. 1–12 6. EN ISO 1182:2020 Reaction to fire tests for products – non-combustibility test 7. EN ISO 1716:2018 Reaction to fire tests for products – Determination of the gross heat of combustion (calorific value) 8. EN ISO 9239-1:2010 – Reaction to fire tests for floorings – Part 1: Determination of the burning behavior using a radiant heat source 9. EN ISO 11925-2:2020 Reaction to fire tests – Ignitability of products subjected to direct impingement of flame – Part 2: Single-flame source test 10. EN ISO13501-1:2019 Fire classification of construction products and building elements – Part 1: Classification using test data from reaction to fire tests 11. EN 13823:2010+2020/prA1:2021Reaction to fire tests for building products – Building products excluding floorings exposed to the thermal attack by a single burning item

Chapter 5

Testing of Cables, Conductors, and Wiring

At present, the issue of cables and wires is not limited solely to monitoring and improving their electrical, mechanical, or transmission properties, but also includes the characteristics describing the behavior of cables and conductors under particular conditions of electrical wiring, and their environmental impact with emphasis on the recyclability of the materials used. Electrical cables and wires can generally be divided into the following groups [1, 2, 6, 7, 9]: • power cables and wires – for transmission and distribution of energy, • communication cables and wires – for transmission and distribution of signals and/or information, • winding wires – used for winding machines, transformers, coils. In more detail, they can be divided as follows [4, 8]: • • • • • • • • • • • • •

copper ropes, wiring cables, mounting cables (H05V, H07V-U/K), installation cables (CYKY), 0.6/1 kV power cables (1-CYKY, 1-AYY, 1-YY), isolated overhead lines (1-AES), control and electronics cables (CMSM, CMFM, JYTY), control cables (TCEKPFLE), communication cables and conductors (SYKFY, J-Y(St)Y), rubber cables (H05RR-F, H07RN-F, NSGAFONA), silicone cables (SIF, SiHF), halogen-free flexible power cable 0.6/1 kV, halogen-free data transmission cable, photovoltaic cables.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_5

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From the point of view of fire protection, it is important which “plastic” we use for the insulation or the jacket of the cable. If PVC is used, then the cable has certain positive and negative properties: PVC:

PE:

+ flame retarding, - heavy black smoke, - PVC cables contain up to 30% of chlorine, - the production of toxic gases causes corrosion + halogen-free, + generated non-toxic gases not causing corrosion, - spreads fire quickly

The risk of fires in electrical devices, and therefore also cables and cable networks, is relatively high. The event of a short circuit is, according to statistics, a frequent source of fire and is directly related to electrical devices incorporating cables and wiring. Therefore, cable modification in terms of fire protection has always been a necessity. Their modifications are not an easy matter. The required modifications are determined by the cable storage conditions, the environment, their functionality, etc. The marking of their retarding adjustments is as follows [6, 7]: FRNC – Flame Retardant Non-Corrosive, HFFR – Halogen Free Flame Retardant, LSOH – Low Smoke Zero Halogen, LFHC – Low Fire Hazard Cables. It is logical that such adjustments require testing and evaluation of both the adjustments themselves and the cables, or even of the wiring as a whole. Individual methods are also embedded in the classification of cables within their fire reaction.

5.1

Reaction to Fire Performance Class for Electric Cables and Conductors

The reaction-to-fire performance for electric cables and conductors is the capability of electric cables and conductors, under specified conditions, to contribute by their own decomposition to the fire which they are exposed to. The Commission Decision of 27 October 2006 amending Decision 2000/147/EC implementing Council Directive 89/106/EEC [3] As regards the Classification of the Reaction-to-fire Performance of Construction Products, establishes the classification of electric cables and conductors into different classes of reaction-to-fire performance. A description of the different classes of reaction to fire performance with test methods, classification criteria, and additional classifications is given in Table 5.1. The number placed next to THR, TSP, HRR indicates the duration of the test. For the FIPEC20 test, all calculated parameters shall be evaluated within 20 min of the start of the test (ignition of the burner). A more detailed description of the additional classification criteria is in Table 5.2.

5.1

Reaction to Fire Performance Class for Electric Cables and Conductors

115

Table 5.1 Classes of reaction to fire performance for electric cables and conductors processed by the authors Class

Test method

Classification criteria

Additional classification

Aca B1ca

EN ISO 1716 EN 50399 (source flame 30 kW) and

PCS ≤ 2.0 MJ/kg Fs ≤ 1.75 m THR1200s ≤ 10 MJ Peak HRRmax ≤ 20 kW FIGRA ≤ 120 W/s H ≤ 425 mm Fs ≤ 1.5 m THR1200s ≤ 15 MJ Peak HRRmax ≤ 30 kW FIGRA ≤ 150 W/s H ≤ 425 mm Fs ≤ 2 m THR1200s ≤ 30 MJ Peak HRRmax ≤ 60 kW FIGRA ≤ 300 W/s H ≤ 425 mm THR1200s ≤ 70 MJ Peak HRRmax ≤ 400 kW FIGRA ≤ 1300 W/s H ≤ 425 mm H ≤ 425 mm

– Smoke production burning droplets acidity

B2ca

EN 60332-1-2 EN 50399 (source flame 20.5 kW) and

Cca

EN 60332-1-2 EN 50399 (source flame 20.5 kW) and

Dca

EN 60332-1-2 EN 50399 (source flame 20.5 kW) and

Eca Fca

EN 60332-1-2 EN 60332-1-2 No definition

Smoke production burning droplets acidity

Smoke production burning droplets acidity

Smoke production burning droplets acidity

–

Explanatory notes for this table (1) For the product as a whole, without metallic materials and any external component (i.e., sheath) of the product (2) s1 = TSP1200 ≤ 50 m2 and a peak of SPR ≤ 0.25 m2/s s1a = s1 and transparency in accordance with EN 61034-2 ≥ 80% s1b = s1 and transparency in accordance with EN 61034-2 ≥ 60% < 80% s2 = TSP1200 ≤ 400 m2 and a peak of SPR ≤ 1.5 m2/s s3 = not s1 or s2. (3) For FIPEC20 scenarios 1 and 2: d0 = no burning droplets/particles within 1200 s; d1 = no burning droplets/particles lasting more than 10 s within 1200 s; d2 = no d0 or d1 (4) EN 50267-2-3: a1 = conductivity 4.3 a2 = conductivity 4.3 a3 = no a1 or a2 No declaration = no characteristics defined (5) The airflow to the chamber shall be set at 8000 + - 800 L/min FIPEC20 scenario EN 50399 [14] with mounting and fixing as shown below (6) The smoke-forming supplementary classification declared for Class B1ca must be based on the FIPEC20 Scen 2 test (7) The smoke rating supplementary classification declared for the B2ca, Cca, Dca class must come from the FIPEC20 Scen 1 test (8) The measurement of the hazardous properties of gases generated in the event of a fire which jeopardizes the effective escape of persons exposed to them in order to carry out the necessary escape operations does not contain data on the toxicity of these gases

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Table 5.2 A more detailed description of the additional classification criteria processed by the authors Class Smoke production

Burning droplets

Acidity

5.2

Test method d0 d1 d2 s1 s1a s1b s2 s3 a1 a2 a3

EN 50399

EN 50267-2-3

Classification criteria Within 1200 s no burning drops/particles are formed Within 1200 s no burning drops/particles that burn for longer than 10 s are formed Does not match d0 or d1 TPS1200s ≤ 50 m2 and peak SPRmax ≤ 0.25 m2/s s1 and permeability according to EN 61034-1 ≥ 80% s1 and permeability according to EN 61034-1 ≥ 60% > 80% TPS1200s ≤ 400 m2 and peak SPRmax ≤ 1.5 m2/s Does not match s1 or s2 Electrical conductivity 2.5 μS/mm and pH > 4.3 Electrical conductivity 10 μS/mm and pH > 4.3 Does not match a1 or a2

Classification of Methods for Testing Cables

In the context of the fire test, the test methods can be divided as follows: • • • •

development of heat and spread of fire along the surface, fire-smoke characteristics, cable functionality tests, determination of the function class of cables and cable covers in the event of fire.

5.2.1

Development of Heat and Spread of Fire Along the Surface

The issue of heat development and flame spread over the surface is implemented in the standards ISO 1716 [23], EN 50399 [14], EN 60332 [16], EN 60332-3 [18].

5.2.1.1

EN ISO 1716

This test determines the highest possible value of the total heat released by a product when fully burned, regardless of its end-use. The test determines the gross calorific value (PCS) and the heating value (PCI). For the reaction-to-fire class of electric cables and conductors Aca, the requirement is identical to the requirements EN 13501-1+A1 [10], EN 13501-6 [11], for the A1 class without the requirement for non-flammability test according to EN ISO 1182 [22] (i.e., less than 1.4 MJ/m2). Plastic-insulated cables (i.e., also currently used so-called ‘R’ or ‘V’ cables) cannot be classified in the reaction to fire class Aca.

5.2

Classification of Methods for Testing Cables

5.2.1.2

117

EN 50399

EN 50399 [14] is intended to specify the test equipment and test procedures for determining the classes of reaction-to-fire performance for electric cables B1ca, B2ca, Cca and Dca. It is currently in the process of being approved. The test shall be carried out on cables mounted on the vertical cable ladder. It uses the equipment according to EN 50266-1 [13] with additional instruments for measuring THR, HRR, FIGRA, and TSP. The following parameters shall be monitored and evaluated during the test: • • • • • • •

flame spread similar to EN 60332-1-2 [16] and EN 60332-2-2 (34 131) [17], heat release rate (calculated), total heat release (calculated from heat release rate), smoke production rate (calculated), total smoke production (calculated), fire growth rate index (calculated), occurrence of burning droplets/particles.

The scheme of the apparatus is shown in Fig. 5.1.

5.2.1.3

EN 60332-1-2

EN 60332-1-2 [16] monitors self-extinguishing. The flame must not spread over the surface of the cord. All PVC sheathed cables can be used in this test. Laboratory equipment is depicted in Fig. 5.2.

5.2.1.4

EN 60332-3

As with the previous method, EN 60332-3 [18] is used to monitor the selfextinguishing of cables. If one individual cable was tested in the previous case, a

Fig. 5.1 Test equipment according to EN 50399 [5]

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Fig. 5.2 Test equipment according to EN 60332 [5]

set of cables shall be tested according to this method. The flame must not spread over the surface of a bundle of cables. Laboratory equipment is depicted in Fig. 5.3.

5.2.2

Smoke Characteristics in a Fire

Several smoke parameters are evaluated for cables. A special test method is required for each smoke parameter. The smoke parameters which are evaluated are: • smoke corrosivity, • smoke density, • dynamic smoke density. The issue of heat development and flame spread over the surface is implemented in the standards EN 60754-1 [19], EN 60754-2 [20] EN 61034-2 [21], EN 50399 [14].

5.2.2.1

EN 50266-1

EN 50266-1 [13] monitors the corrosivity of smoke resulting from the burning of cables. As shown in Fig. 5.4, the thermal load occurs at 940 °C and the evaluation

5.2

Classification of Methods for Testing Cables

119

Fig. 5.3 Test equipment according to EN 60332-3 [5]

criteria are the pH of the smoke produced and the change in conductivity. The limit values are shown in Fig. 5.4.

5.2.2.2

EN 61034-2

EN 61034-2 [21] monitors the smoke density from the burning of cables. The assessment criterion is light transmittance ≥60%. Laboratory equipment is depicted in Fig. 5.5.

5.2.2.3

EN 50399

EN 50399 [14] is used to monitor the dynamic density of smoke resulting from the burning of cables. This method serves as a supplementary classification for the determination of the reaction to fire performance s1a, s1b, s2, s3. Laboratory equipment is depicted in Fig. 5.6.

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Fig. 5.4 Test apparatus according to EN 50266 [5] Fig. 5.5 Test apparatus according to EN 50267 [5]

Fig. 5.6 Test apparatus according to EN 50399 [5]

5.2.3

Determination of the Function Class of Cables and the Cable Cover Systems in the Case of Fire

As in the previous case, a number of different standardized test methods are used to determine the functionality of cables under fire-like conditions. These methods are used to monitor insulation functionality, insulation functionality for safety circuits,

5.2

Classification of Methods for Testing Cables

121

and cable routing functionality. The issue of heat development and flame spread over the surface is implemented in the standards EN 60331 [15], EN 50200 [12].

5.2.3.1

EN 60331

EN 60331 [15] monitors insulation functionality during cable burning. In addition to the thermal stress, the test also uses mechanical cyclic stress. Laboratory equipment is depicted in Fig. 5.7.

5.2.3.2

EN 50200

EN 50200 [12] is used to monitor insulation functionality for safety circuits when cables are burning. In addition to the thermal stress, the test also uses mechanical cyclic stresses. Laboratory equipment is depicted in Fig. 5.8.

Fig. 5.7 Test equipment according to EN 60331 [5]

Fig. 5.8 Test apparatus according to EN 50200 [5]

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Questions Which properties of cables are tested as part of fire testing? What tests need to be used for cable distribution? What properties must the cables that are used to control fire protection devices have? In which areas is it necessary to test the cables for mechanical stress?

References 1. CEN/TS 15117, Guidance on direct and extended application 2. L. Chenying et al., Research on fire prediction method of high-voltage power cable tunnel based on abnormal characteristic quantity monitoring. Front. Energy Res. (2022). https://doi.org/10. 3389/fenrg.2022.836588 3. F. Gilian, Nové prístupy k posudzovaniu požiarneho nebezpečenstva káblov s reak- ciou na oheň (New approaches to fire hazard assessment of cables with a reaction to fire), in 47. konferencia elektrotechnikov Slovenska: zborník prednášok (47th conference of electrical engineers of Slovakia: collection of lectures) (Slovenský elektrotechnický zväz – Komora elektrotechnikov Slovenska, Bratislava, 2017), pp. 102–107 4. T. Journeaux et al., CEMAC – CE Marking of Cables (SP Technical Research Institute of Sweden, Borås, 2010) 5. L. Makovicka Osvaldova, S. Gaspercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 6. J. Martinka, Fire Hazards of Electrical Cables, Springer briefs in fire (2022). https://doi.org/10. 1007/978-3-031-17050-8 7. I. Salin, J.C. Seferis, Kinetic analysis of high resolution TGA variable heating rate data. J. Appl. Polym. Sci. 47, 847–856 (1993). https://doi.org/10.1002/app.1993.07041612 8. G. Sarti, A new perspective on hydrogen chloride scavenging at high temperatures for reducing the smoke acidity of PVC cables in fires. I: An overview of the theory, test methods, and the European Union regulatory status. Fire 5, 127–138 (2022). https://doi.org/10.3390/fire5050127 9. J. Troitzsch, Testing plastics, textiles, and other materials according to international standards for building and furniture, in ATLAS SFTS BV Flammability Workshop, (Atlas, Bratislava, 1995) 10. EN 13501-1:2018 Fire classification of construction products and building elements – Part 1: Classification using data from reaction to fire tests 11. EN 13501-6:2018 Fire classification of construction products and building elements – Part 6: Classification using data from reaction to fire tests on power, control and communication cables 12. EN 50200:2015 Method of test for resistance to fire of unprotected small cables for use in emergency circuits 13. EN 50266-1:2001 Common test methods for cables under fire conditions. Test for vertical flame spread of vertically mounted bunched wires or cables. Apparatus 14. EN 50399:2022 Common test methods for cables under fire conditions – Heat release and smoke production measurement on cables during flame spread test – Test apparatus, procedures, results 15. EN 60331:2019 Tests for electric cables under fire conditions – Circuit integrity – Part 1: Test method for fire with shock at a temperature of at least 830 °C for cables of rated voltage up to and including 0.6/1.0 kV and with an overall diameter exceeding 20 mm

References

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16. EN 60332-1-2:2004/A12:2020 Tests on electric and optical fibre cables under fire conditions – Part 1–2: Test for vertical flame propagation for a single insulated wire or cable - Procedure for 1 kW pre-mixed flame 17. IEC 60332-2-2:2004 Tests on electric and optical fibre cables under fire conditions – Part 2–2: Test for vertical flame propagation for a single small, insulated wire or cable – Procedure for diffusion flame 18. EN 60332-3-25:2018 Tests on electric and optical fibre cables under fire conditions – Part 3-25: Test for vertical flame spread of vertically mounted bunched wires or cables – Category D 19. EN 60754-1 Test on gases evolved during combustion of materials from cables – Part 1: Determination of the halogen acid gas content 20. EN 60754-2 Test on gases evolved during combustion of materials from cables – Part 2: Determination of acidity (by pH measurement) and conductivity 21. EN 61034-2:2005/A2:2020 Measurement of smoke density of cables burning under defined conditions – Part 2: Test procedure and requirements 22. ISO 1182:2020 Reaction to fire tests for products non-combustibility test 23. ISO 1716:2002 Reaction to fire tests for building products – Determination of the heat of combustion

Chapter 6

Testing of Insulation Systems, Facades, and Roofs

A fire can spread through several routes as it moves through a building. The most important of these is the spread of the flame over the flammable outer building surface, vertically or horizontally through the air gaps between the cladding or facade systems, or through the core of the insulation itself as stated in the international standards ISO 13785-1 [17] On the Testing of the spread of fire along the exterior wall cladding. Furthermore, the standard discusses potential scenarios for the spread of fire: from the room through a window onto a facade; the fire of combustibles located outside near the facade (e.g., waste, vegetation), or fire of the neighboring building [1–9, 11–13]. The requirements for the construction of insulation systems in terms of fire safety vary from one European country to the next and are subject to continuous development. In many countries, including Slovakia’s neighbors, the fire safety of exterior wall cladding follows the national standards and is tested on large-scale samples. Often these large-scale tests give different results than the ones stated in the Reaction to Fire system (so-called Euro classes). This is because the European system for testing and classifying the reaction to fire performance of products and materials according to EN 13501-1+A1 [16] is used to verify the behavior of products and materials when exposed to a local source of heat, flame, or thermal radiation only in the early stages of fire. Cladding design is a multidisciplinary process. This multidisciplinary process aims to ensure technical and technological optimization to achieve the most optimal design of external cladding on the basis of several works, compiled a study of fundamental criteria for external cladding optimization. The optimization itself lies in a few basic criteria, such as sustainability, user friendliness of a building (thermal, acoustic and optical), architectural and design solution static resistance, fire safety and so on [10, 12]. In general, the legislation is based on fire scenarios concerning potential ignition and subsequent fire of façades, which are shown in Fig. 6.1 [12].

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_6

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Fig. 6.1 Fire scenarios for façade fires [12]

Scenario A: The fire spreads from the neighbouring buildings (or other fire sources defined in the legislation) onto the building. The fire risk analysis is, for the majority of applications, represented by ignition risk assessment when the façade is exposed to a thermal radiation source. If the buildings are in close proximity to each other, the contact with the flame and the ignition of materials can be analysed as well. This scenario also takes into consideration the spread of fire from a neighbouring building onto the neighbouring buildings. For flammable façades, it is necessary to take into consideration the heat from the burning façade-if the façade gets ignited—as well as radiant heat from openings and flames coming from the cavities on the façade of the neighbouring building. The issue of the distance between the adjacent buildings is also included in the fire protection legislation for this scenario. Scenario B: The fire spreads from an external source adjoining the façade (not a neighbouring building) e.g., a fire of a vehicle, litter bin, etc. including the balcony area (see the upper part of Fig. 6.1 scenario B). Scenario C: A vertical fire spreads between the cavities from a fully developed. Fire inside a building with at least one cavity on the façade.

6.1 6.1.1

Assessment of Materials for Facade Cladding Structures ISO 13785-1 Reaction to Fire Test for Facades: Part 1 – Middle-size Test

This middle-size test determines the reaction to fire of the materials used for facades and cladding. It simulates an external fire with flames touching the facade directly. The method is not intended for free-standing cladding and facades, but only for those used as external wall facades [14].

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Assessment of Materials for Facade Cladding Structures

127

Fig. 6.2 The layout of the apparatus [14] 1 – heat flow measurement, 2 – back panel, 3 – side wall of the apparatus, 4 – back wall of the sample, 5 – side wall of the sample, 6 – burner, x – thermocouples

The scheme of the apparatus is shown in Fig. 6.2. Test equipment consists of the sample, the support frame, and a flame source. The frame holding the sample consists of three walls, three parts of the back wall, and two parts of the side walls. The dimensions of the individual elements and the individual parts are shown in Fig. 6.1 The back side consists of mineral or stone wool with a thickness of 100 mm and a density of 100 kg/m3. The sample and holder must be compact. The sample is placed 0.4 m from the bottom of the holder (see Fig. 6.3). The source of fire is a rectangular propane burner of 1.2 × 0.1 × 0.15 m. The detail of the burner is given in Fig. 6.4. It is a surface burner of special construction filled with stone chipboard that guarantees the thermal flow onto the test sample 95% propane is used as fuel. The sample must be modified to simulate the way it is used in practice. It consists of cladding or facade panels covering the surface which is 1.2 m wide, 2.4 m high and 0.6 m wide, and 2.4 m high. As shown in Fig. 6.3, the sample consists of two parts, set perpendicular to each other. The arrangement of thermocouples on the sample can also be seen from the above figure. The thermocouple is a chromel alumel type 0.3 mm in diameter. The sample is mounted onto the frame. All measuring instruments are turned on 2 min before the test. The heat source is ignited. The test is photo-documented or recorded. The course of temperatures recorded by thermocouples is evaluated and at the same time, a verbal description of the behavior of materials during the test is given. As can be seen from Fig. 6.5 below, in addition to evaluation of the material itself, it is also possible to assess the quality of thermal insulation work. The combustible

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Fig. 6.3 A sample placed inside the apparatus (a) before the test (b) during the test [14] Fig. 6.4 Detail of the burner from the real experiment. (Photograph by A. Osvald 1991)

insulation material was installed in the sample according to the regulations (position of curve b) and then with flaws that tend to occur during the insulation works (curve position c). The two curves show the difference in reaction to fire, even if the material is the same [14].

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Assessment of Materials for Facade Cladding Structures

129

200

temperature (°C)

180

a)

160

b)

140

c)

120 100 80 60 40 20 0 0:00:00 0:01:26 0:02:53 0:04:19 0:05:46 0:07:12 0:08:38 0:10:05 0:11:31 0:12:58 0:14:24

time (h:min:s)

Fig. 6.5 Temperature course for individual materials [14] (a) non-combustible insulation system, (b) flammable insulation system (no flaws during installation), (c) flawed flammable insulation system

6.1.2

ISO 13785-2 Reaction to Fire Test for Facades: Part 2 – Large-scale Test

Just like the previous method, this method determines the reaction to fire of materials on facades and cladding structures. The method is applied to facades and cladding which are not load-bearing. Details such as balconies and windows, partition walls, etc. shall not be assessed by this test. This test does not include the risk of fire spreading through the windows; it is intended only for facade walls. The test apparatus consists of vertical support of the facade including the window or embrasure. The device consists of two parts that form a corner with an angle of 90°. The height of the apparatus is 4 m from the window, which is 1.20 m2 and is located 0.5 m from the ground. The width of the facade is 3 m. The window is 2 m long (see Fig. 6.6). The test can be performed in a combustion chamber in a room from 20 to 100 m3. Samples must be designed the way they are used in practice in order to represent the test facade. During the test, the temperature is measured by means of thermocouples, and the heat flux by means of radiometers. Chromel/alumel thermocouples (K type) are 0.3 mm in diameter. App. 60 L of fuel agents, e.g., heptane acetone can be used in special burners, as shown in Fig. 6.7, for the liquid fuel. Solid fuel consists of wooden cages made of wood with a density of 450–500 kg/m3 and a humidity of 10–12%. The location of the solid fuel as well as the details of the cage are shown in Fig. 6.8.

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Fig. 6.6 Test apparatus scheme for large-scale facade test [14] Fig. 6.7 Test apparatus scheme for large-scale facade test using liquid fuel [14]

6.2

Assessment of Materials for Roof Structures

131

Fig. 6.8 Detail of the amount and method of locating the solid fuel for the test according to ISO 13785-2 [14, 18]

6.2

Assessment of Materials for Roof Structures

Model test of roof structures and materials for roof structures. The issue of testing roof structures, roof sheets, and systems is stipulated in the standard tests, which are technically and economically demanding Many testing laboratories do not allow for experimental, verification, and comparison tests, as this is not their responsibility and they do not have time to carry them out. The second way of testing roof systems is to

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Fig. 6.9 Pre-test photograph of the device [14]

test the materials that cover them, i.e., the thermal load is applied from the top. Although these tests give some information, this information cannot be considered sufficient and other ways of dealing with and evaluating roof systems are necessary [15]. For this reason, a new methodology of the model test for testing the model fire resistance of roof structures was implemented. The testing method does not allow the issuance of certificates for the tested materials. However, it provides information on the behavior of materials during a fire. It allows for testing the material in the loaded state, where it is possible to select the mechanical load in certain jump intervals, with continuous measurement of deflection during the experiment. The thermocouples can measure the temperature during the entire experiment directly in the chamber, in the material structure, in its joints, and, of course, on the surface. The proposed test has a high informative value for experts in the field of fire design, as well as material evaluation itself (Fig. 6.9). It will allow companies to model the composition of the roof panel, to design optimal variants, modifications, and constructions, so that they can use a pre-tested composition for certification [14]. Other tests of roofing systems Another method for assessing roof systems is the method shown below in Fig. 6.9. It is a method based on empirical experience without further scientific evaluation. It consists of a roof system of the prescribed dimensions loaded with fuel in its center. This fuel can consist of wood wool (see Figs. 6.10 and 6.11) or wood chips that are placed in the shape of a cage [14]. The fuel is ignited and left to burn. Traces of fuel burnout are monitored, e.g., depth of the charred layer, size of the burnt area, and the like. During the test, the characteristic manifestations of the combustion process, such as flame size, smoke,

6.2

Assessment of Materials for Roof Structures

133

Fig. 6.10 Sample for the roof test – detail of wood wool fuel. (Photograph by A. Osvald 1991)

Fig. 6.11 Sample for the roof test results – comparison of two materials. (Photograph by A. Osvald 1991)

and the like are monitored. In general, two materials shall be tested at the same time – a reference sample and the material to be evaluated, in order to be able to assess whether the material to be evaluated contributes to burning and whether it changes the burning effects of the material used as fuel. Wood and wood wool usually burn

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with less intense flame and gray smoke is formed. If the flame intensity increases or the smoke color changes, it is obvious that the roof system or its components are also involved in the burning process. These tests can only be regarded as informative because they have a low accuracy, so we will not look into them in more detail [14]. Questions Is façade testing necessary if we know the reaction to fire of the materials that enter it? Can the construction of the façade affect the progress of the fire? Are there structural and technical solutions that prevent the rapid spread of fire along the façade?

References 1. J. Anderson et al., European approach to assess the fire performance of façades. Fire Mater., 1–11 (2020). https://doi.org/10.1002/fam.2878 2. S. Bahrami, D. Zeinali, The sustainability challenge of product information quality in the design and construction of facades: Lessons from the Grenfell Tower fire. Smart Sustain. Built Environ. 12(3), 488–506 (2023). https://doi.org/10.1108/SASBE-06-2021-0100 3. L. Boström et al., Development of a European Approach to Assess the Fire Performance of Facades (Publications Office of the European Union, Luxembourg, 2018). https://data.europa. eu/doi/10.2873/954759. Accessed 18 Feb 2023 4. L. Boström et al., Fire Test of Ventilated and Unventilated Wooden Façades, SP Report 2016: 16 (SP Technical Research Institute of Sweden, Borås, 2016) 5. A.H. Buchanan, A. Abu, Structural Design for Fire Safety, 2nd edn. (Wiley, Boca Raton, 2017). https://doi.org/10.1002/9781118700402 6. P. Cancelliere et al., A new test method to determine the fire behavior of façades with etic system. Fire Mater. 45, 624–637 (2021). https://doi.org/10.1002/fam.2886 7. X. Chen et al., Experimental study on flame extension and pattern analysis of jet fire impinging wood plates. Fire Technol. (2022). https://doi.org/10.1007/s10694-022-01338-8 8. M. Jelcic Rukavina, M. Carevic, I. Banjad Peur, Fire protection of Façades (University of Zagreb, Faculty of Civil Engineering, Zagreb, 2017), p. 64. https://www.grad.unizg.hr/images/ 50014277/Fire%20Protection%20of%20Facades.pdf. Accessed 17 Feb 2023 9. V. Kodur, P. Kumar, M.M. Rafi, Fire hazard in buildings: Review, assessment and strategies for improving fire safety. PSU Res. Rev. 4(1), 1–23 (2020). https://doi.org/10.1108/PRR-122018-0033 10. Y. Li, Z. Wang, X. Huang, An exploration of equivalent scenarios for building facade fire standard tests. J. Build. Eng. 52 (2022). https://doi.org/10.1016/j.jobe.2022.104399 11. A. Mårtensson, New methods for testing fire resistance of wood façade systems. MATEC web of conferences 46, 02003. https://doi.org/10.1051/matecconf/20164602003 12. L. Makovicka Osvaldova, Wooden Façades and Fire Safety, Springer briefs in fire (2020). https://doi.org/10.1007/978-3-030-48883-3 13. S.T. McKenna et al., Fire behaviour of modern façade materials – Understanding the Grenfell Tower fire. J. Hazard. Mater. 368, 115–123 (2019). https://doi.org/10.1016/j.jhazmat.2018. 12.077

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14. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection) (Technical University, Zvolen, 2009) 15. S. Rastocky, Skúšanie požiarno-technických vlastností stavebných výrobkov (Testing the fire– technical properties of construction products), in Wood and Fire Safety, (Technická univerzita, Zvolen, 2000), pp. 112–141 16. EN 13501-1+A1: 2009 Fire classification of construction products and building elements Part 1: Classification using test data from reaction to fire tests 17. ISO 13785-1:2002 Reaction-to-fire tests for façades – Part 1: Intermediate-scale test 18. ISO 13785-2:2002 Reaction-to-fire tests for façades – Part 2: Large-scale test

Chapter 7

Resistance to Fire

In addition to the evaluation of individual materials entering the building structure, there was a need to evaluate the building structure as a whole. The fire resistance of building structures began to be evaluated under the conditions in which the structure works in the building. Test methods for ignition and burning of materials have a history (see Chap. 3). The evaluation of constructions for fire resistance also has its own history. István Moder processed the chronology of important stages in the improvement of the regulations for testing the fire resistance of building structures. We present these stages in Tables 7.1 and 7.2. The harmonized procedure for classifying the fire resistance of construction products and building elements determines the procedure for classification on the basis of data from fire resistance tests and smoke leak tests, which are limited to the area of direct application according to the relevant test method. The following procedures [–, 1, 5, 10, 12, 13, 15] apply to: (a) supporting elements without a fire separation function, such as: • • • • • • • •

walls, ceilings, roofs, beams, columns, balconies, courtyard balconies, stairways,

(b) load-bearing elements with a fire separation function with glazing, and operating equipment and accessories (or without them), such as: • walls, • ceilings,

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_7

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Table 7.1 Significant stages in the improvement of regulations for testing the fire resistance of building structures Year 1916

Event The first standard curve

1918

First edition of ASTM E119 (originally known as C19) was issued in 1918. The test method provides a standard time-temperature curve (above figure) to which materials and components are exposed to evaluate their resistance to fire. Floors, columns, beams, and walls are commonly tested in such a temperature-controlled environment BS 476:1932 fire-resistance, incombustibility and non-in flammability of building materials and structures. DIN 4102 -1, -2, -3 DIN 4102-2:1965-09 Behaviour of building materials and structures in fire; definitions, requirements, and tests of structures ISO 834:1975 fire-resistance tests – Elements of building construction ISO 3008:1976 Fire-resistance tests Council Directive 89/106/EEC of 21 December 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products EN 1634-1, January 1, 2000, Fire Resistance Tests for Door and Shutter Assemblies – Part 1: Fire Doors and Shutters A description is not available for this item. Regulation (EU) No 305/2011 – construction products of 9 March 2011 laying down harmonised conditions for the marketing of construction products and repealing Council Directive 89/106/EEC (Latest update: 04/10/2017) EN 15269-x (see Table 7.2)

1932 1935 1965 1975 1976 1989

2000 2011

2012

Processed by the authors according to I. Moder

• roofs, • raised floors, (c) products and systems for the protection of elements or parts of structures, such as: • dropped ceilings without independent fire resistance, • fire protection coatings, facings and room dividers,

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Table 7.2 Detailed division of standards 15269-x [14] processed by the authors Standard status EN 15269-1 2019/ AC:2020 EN 15269-2 2012

EN 15269-3 2023

EN 15269-5 2014 +A1 2016 EN 15269-7 2019 EN 15269-10 2011

EN 15269-11 2019 EN 15269-20 2020

Content Extended application of test results for fire resistance and/or smoke control for door, shutter, and openable window assemblies, including their elements of building hardware [19] Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 2: Fire resistance of hinged and pivoted steel doorsets [20] Extended application of test results for fire resistance and/or smoke control for doorsets, shutter and openable window assemblies, including their elements of building hardware – Part 3: Fire resistance of hinged and pivoted timber doorsets and openable timber framed windows [21] Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 5: Fire resistance of hinged and pivoted metal framed glazed doorsets and openable windows [22] Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 7: Fire resistance for steel sliding doorsets [23] Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies including their elements of building hardware – Part 10: Fire resistance of steel rolling shutter assemblies [24] Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 1: General requirements [25] Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 20: Smoke control for doors, shutters, operable fabric curtains and openable windows [26]

(d) non-load-bearing elements or parts of structures with glazing, and operating equipment with or without accessories, such as: • • • • • • • • • •

dividing walls, facades and external walls, dropped ceilings with independent fire resistance, fire doors and caps and their closing mechanisms, smoke-proof doors, conveyor systems and their safety valves, seals, linear joint seals, installation channels and shafts, chimneys,

(e) wall and ceiling coverings with fire-fighting ability; (f) lift shaft doors.

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Fire Resistance Characteristics

A general requirement of fire resistance classification is to determine the load capacity, the integrity and the insulation characteristics. Other optional properties are also specified, namely radiation, mechanical aspects, self-closing ability, and smoke penetration. The need for classification on the basis of optional characteristics depends on national rules and may be specified for certain elements under certain conditions [2].

7.1.1

Load Capacity: R

Load capacity, R, is the ability of the structural element to withstand a fire acting on one or more sides at specified mechanical stress for a certain period of time without loss of its structural strength. The criteria for assessing imminent collapse vary depending on the type of load-bearing element. For elements loaded by bending, such as ceilings and roofs, this is the strain rate (deflection rate) and the limit state for actual deformation (deflection). Or for axially loaded elements, such as columns and walls, it is the strain rate (contraction rate) and limit state for true deformation (contraction) [16–18].

7.1.2

Integrity: E

Integrity, E, is the ability of a structural element that has a fire separation function to withstand a fire acting on one side only without transmitting the fire to the unstressed side due to the penetration of flames or hot gases. These can ignite either the unstressed surface or any material in its vicinity. The assessment of integrity is made on the basis of the following three states: • breaching the integrity of cracks or openings exceeding specified limits, • the ignition of a cotton pad, • permanent flame burning on the unstressed side. Integrity must be determined during the test in all three ways, with the cotton pad attached until it ignites, then removed; the test then continues until all three conditions have occurred (however, the test orderer has the option to stop the test as soon as the desired level of fire resistance has been reached). The time of the breach of integrity when each condition is reached is recorded. A breach of the load-bearing capacity criterion must also be considered as a breach of integrity. The classification of integrity depends on whether the element is also classified in terms of insulation, or not. If it classifies for both E, integrity, and I, Insulation, the value for the integrity classification shall be determined by any of the three integrity

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141

criteria violations, whichever occurs first. If an element is classified in terms of integrity, E, but not in terms of insulation, I, the value for classification of integrity shall determine the time until the integrity criterion has been breached by reaching the condition of crack/opening or permanent flame burning, whichever occurs first. The assessment of the integrity of some elements requires additional measurements; the integrity need not be determined according to any of the three criteria referred to in the preceding paragraph. The methodology for these cases is set out in specific test standards.

7.1.3

Thermal Insulation: I

Thermal insulation, I, is the ability of the structural element to withstand a fire acting on only one side without the transfer of fire as a result of a significant heat transfer from the stressed side onto the unstressed one. The heat transfer should be limited so that neither the unstressed side nor any other material in its immediate vicinity ignites. The element must also provide a barrier against heat propagation sufficient to protect people in its vicinity [16]. If a structural element is classified at different levels of thermal properties of several discrete surfaces, then its classification as a whole is determined on the basis of the “weakest link,” or the shortest time during which both the limitation criterion of the maximum temperature rise and the average temperature rise on any discrete surface are met. For all partitions except doors and safety valves, the limit of determination of thermal insulation is considered to be an increase in the average unstressed surface temperature limited to 140 °C above the initial average temperature, with an increase in maximum temperature at any point limited to 180 °C above the initial average temperature [16]. In the case of elements with small surface areas (as in the case of joint seals), the concept of an increase in average temperature is irrelevant and thermal insulation is determined only on the basis of the increase in maximum temperature. A breach according to any load-bearing capacity or integrity criterion also means a breach of the thermal insulation, regardless of whether the limits for increasing the average or maximum temperature have been exceeded or not. Thermal insulation of doors and door closers. The increase in average temperature on the unstressed side of the door leaf is limited to 140 °C above the initial average temperature, with the increase in maximum temperature at any point on the door leaf being limited to 180 °C. No temperature measurement within 25 mm of the visible edge of the door leaf is taken into account. The temperature increase at any point of the door frame is limited to 180 °C and is measured at a distance of 100 mm from the visible edge of the door leaf (on the unstressed side), if the door frame is wider than 100 mm, otherwise it is measured at the contact surface of the frame and supporting structure.

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The increase in average temperature on the unstressed side of the door leaf is limited to 140 °C above the initial average temperature, with the increase in maximum temperature at any point on the door leaf being limited to 180 °C. No temperature measurement within 100 mm of the visible edge of the door leaf shall be taken into account. The temperature rise at any point of the door frame is limited to 360 °C and is measured at a distance of 100 mm from the visible edge of the door leaf (on the unstressed side), if the door frame is wider than 100 mm, otherwise it is measured at the contact surface of the door frame and the supporting structure [16]. The classification of thermal insulation is carried out using indices 1 and 2 according to the prescribed definitions. These indices are used only for fire doors and door closers and for safety shut-off valves of transport systems, but not for any other I-classified element. When the test sample contains the conveyor system safety shut-off valve together with the transfer and transfer components, classification I applicable to the transfer component or the transfer seal shall be used. However, to classify the shut-off valves and conveyor system assembly as a whole, the appropriate index shall be used to distinguish between the two possible ways of evaluating the conveyor system shutoff system. Failure to comply with the integrity criterion identified in any way also means a breach of thermal insulation, whether or not the specified insulation temperature limits have been exceeded.

7.1.4

Radiation: W

Radiation, W, is the ability of the structural element to withstand a fire acting on only one side and to reduce the probability of a fire spread as a result of a significant value of radiated heat, either through the element or from its unstressed side, onto materials lying in its vicinity. The element may also be needed to protect people nearby. An element that meets the criteria for thermal insulation I, h, or I2 is also considered capable of satisfying the W requirement at the same time interval. Breach of the integrity criterion by the condition of ‘cracks and openings beyond the specified limits’ or by the condition ‘permanent flame burning on the unstressed side’ automatically also means a breach of the radiation criterion. The elements for which radiation is being evaluated are marked by adding ‘W’ to the classification (e.g., EW, REW). For such elements, the classification is given by the time over which the maximum radiation value measured according to the test standard does not exceed 15 kW.m2. The classification protocol shall state the dependence of the radiation value on time over the entire duration of the fire resistance.

7.1.5

Mechanical Resistance: M

Mechanical resistance M is the ability of an element to withstand an impact, which may occur when structural damage to another component in a fire causes an impact

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on the element under consideration. The element is subject to an impact of a predefined force shortly after the end of the required classification time R, E, or I. In order for an element to have a classification supplemented by M, it must withstand the impact without compromising the properties R, E, or I.

7.1.6

Self-Closing: C

The Self-closing criterion, C, is the ability of an open door or window to close and fully about the door frame and secure all locking without human intervention, using stored energy or an energy source backed up by stored energy in the event of a power failure. It is used for elements that are usually closed and that are to be closed automatically after each opening. It also includes elements that are normally open and that shall be closed in the event of a fire as well as mechanically operated elements that are also to be closed in the event of a fire. Self-closing ability tests are performed under ambient conditions (and are associated with a durability classification based on the intended use). The result of the test is either satisfactory or unsatisfactory.

7.1.7

Smoke Tightness: S

Smoke penetration tightness, S, is the ability of an element to reduce or eliminate the passage of gases or smoke from one side of the element to the other. It is assessed only at ambient temperature. Sm assesses the smoke tightness both at ambient temperature and at a temperature of 200 °C.

7.1.8

Resistance to Soot Fire: G

Soot burning resistance classification for chimneys and related products refers to the element’s ability to resist soot burning. It includes the aspect of gas tightness and thermal insulation. The test takes place under appropriate test conditions under the influence of a constant temperature of 1000 °C, which is maintained for 30 min since reaching the level of 1000 °C. The 1000 °C level was reached within 10 min. At the end of the test, chimney vents and other chimney products intended for installation (for example, in a masonry chimney) must only meet the gas tightness requirements. Elements where one or more external surfaces of the chimney are inside the building or adjacent to the building must meet the thermal insulation criterion defined as the limitation of the maximum temperature of adjacent materials, which must not exceed 100 °C with respect to the ambient temperature 20 °C. The

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minimum distance to products with a reaction to fire classification other than A1 must be specified, as well as the need to meet this condition. This value must not be less than the distance required to meet the criterion for normal operating conditions. Classification G shall be supplemented by the determination of the minimum distance. This methodology deals only with the requirements for the properties of chimneys exposed to internal soot fire. Other chimney characteristics, particularly hightemperature gas tightness and thermal resistance, which are fire-related, are not actually considered as fire resistance. However, these characteristics are still included in the product specifications of chimneys.

7.1.9

Fire Protection Capability: K

The ability of fire protection, K, is the ability of the cladding or ceiling to protect the material under the cladding against ignition, charring, and other damage for a specified period of time. Cladding is the outer surface parts of building elements, such as walls, ceilings and roofs. To be classified as K1, it must be demonstrated that the performance criteria were met during the classification time (10 min) using one of the following materials in the test sample: • a particle board with a density of (680 ± 50) kg/m3 and a thickness of (19 ± 2) mm representing all materials used under the cladding having a density of at least 300 kg/m3, • material with a density of less than 300 kg/m3 (low-density material) of a thickness of at least 50 mm representing material of the same kind, the density and/or thickness of which are equal to or greater than that of the material under the test, or any other specific underlayment representing material of the same composition. For the K2 classification, it must be demonstrated that the performance criteria were met during the classification time (10 min, 30 min, or 60 min) using one of the following materials in the test sample: • a particle board with a density of (680 ± 50) kg/m3 and a thickness of (19 ± 2) mm representing all the materials under the cladding or. • any other specific underlayment representing a material of the same composition.

7.2

Fire Scenarios

The second essential requirement of the EU Construction Products Directive concerns the spread of fire and smoke and the load-bearing capacity of the structure. These requirements are met by demonstrating the fire resistance of load-bearing or

7.2

Fire Scenarios

145

1400

Temperature (°C)

1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 0

5

10

15

20

30

45

60

90

120

150

170

180

Time (min) ISO DIN

Hydrocarbon curve

RWS Netherlands

RABT

HC modif

Fig. 7.1 Fire resistance model curves [6, 7]

partition elements. The fire resistance of the load-bearing or fire division elements shall be determined using one or more levels of thermal stress. The above procedures determine which thermal stress is to be applied to which element. Different levels of heat exposure express different fire scenarios indicating their practical application and tolerances for their application. There are other temperature curves as indicated [7] (see Fig. 7.1), such as a hydrocarbon curve and curve for extreme fire scenarios (such as road tunnels, nuclear installations), which may set stricter criteria.

7.2.1

Temperature/Time Standard Curve (Fire After Volume Ignition)

This is the oldest, most well-known and most used temperature curve. Its relationship to real fire is illustrated in Fig. 7.2 and the ideal course in Fig. 7.3. When the standard temperature/time dependence curve is used as a starting point for testing, it should be applied for the entire duration of the test. The dependency, which is a model of a fully developed fire in the space, is given by the Eq. (7.1). Further details concerning the practical application of this curve and other test parameters, such as tolerances, are given in EN 1363-1 [16]. T = 345 log 10 ð8τ þ 1Þ þ 20

ð7:1Þ

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after flashover 1000 – 1200 °C

before flashover

Temperature

flashover

real fire curve

standard fire curve

Time

Fig. 7.2 Standard temperature/time curve (fire after volume ignition) vs. a real fire [6] 1200

Temperature (°C)

1000 800 600 400 200 0 0

15

30

45

60

75

90

Time (min) Fig. 7.3 Temperature/time curve, course according to Eq. (7.1) [6]

where: τ – time from the start of test in minutes (min), T – average oven temperature (°C).

7.2.2

Slow Heat Curve (Fire by Smoldering)

The fire smoldering test may be used only provided that the fire resistance of the element may be reduced by its exposure to the temperatures associated with the

7.2

Fire Scenarios

147

developing fire (fire before volume ignition). It is therefore used particularly for elements whose properties for determining the classification may depend on a high heating intensity, approximately below 500 °C, as shown by the course of the standard temperature/time curve – i.e., mainly reacting and foaming products. The slow heat curve is determined by Eq. 7.2 and 7.3. Further details concerning the practical application of this curve and other test parameters, such as tolerances, are given in EN 1363-2 [17]. for 0 < τ ≤ 21 T = 154τ 0:25 þ 20

ð7:2Þ

for τ > 21 T = 345 log 10 ð8ðτ–20Þ þ 1Þ þ 20

ð7:3Þ

where: τ – time from the start of test in minutes (min), T – average oven temperature (°C).

7.2.3

A Fire Test Simulating a Natural Fire

During a fire test simulating a natural fire, the temperature of the fire gases at the ceiling shall reach 1000 °C between 10th and 20th min from the start of the test. In view of the difficulties in achieving the necessary heat stress in a conventional kiln, the stress should be ensured by burning wooden beams made of soft wood. A fire similar to a natural fire is a fire with direct flame action with a high proportion of convection heat transfer which is not carried out in the kiln during the testing, and which uses the standard temperature/time curve. The term ‘fire simulating a natural fire’ corresponds to the action of an individually burning item, which is the exposure required for the drop ceiling in part (a) of the Interpretative document 2 (not to confuse with the individually burning object test in the assessment of the reaction to fire). It is only used for light lightweight suspended horizontal protection drop ceilings with low thermal inertia. Further details on the practical application of this thermal stress and other test parameters are given in EN 13381-1 [18].

7.2.4

External Fire Action Curve

This temperature/time relationship represents the exposure of the outer wall surface to a fire that may emerge from a building window or a free-burning external fire. The curve is defined by the Eq. (7.4). Further details concerning this curve and other test parameters, such as tolerances, are given in EN 1363-2 [17].

148

7

T = 660 ð1–0:687 e–0:32τ–0:313 e–3:8τÞ þ 20

Resistance to Fire

ð7:4Þ

where: τ – time from the start of test in minutes (min), T – average temperature in the furnace (°C).

7.2.5

Constant Temperature Strain

In addition to the heating modes listed above, some elements are evaluated using a nominal constant temperature value. The specified temperature depends on the type of element. The speed at which this temperature is reached shall be determined by each relevant test standard [11]. The following temperatures are used for the products listed: • 20 °C to assess the penetration intensity of smoke-tight doors at ambient temperature, • 200 °C to evaluate the penetration intensity of smoke-tight doors at medium temperature, • 500 °C for the evaluation of fire properties of raised floors, • 1000 °C for the evaluation of fire resistance of soot in chimneys and other chimney-related products.

7.3

Procedures for Classifying Fire Resistance

The intended area of application of the classification shall be proposed by the ordering party of the test and shall include aspects such as: • exposure conditions: for asymmetric elements, the side(s) to be exposed to fire, for walls – exposure from one or two sides, for beams – exposure from three or four sides, etc., • element dimensions: including span, height, width, • boundary conditions and method of support: insertion, sliding fit, articulated fit, • load stress level, • variants of structural details, • class(es) envisaged: i.e., a combination of performance and time criteria. Taking into account the area of application of the test results, the number of tests with the temperature/time curve and the assembly of the test sample according to the specification in the relevant test method are derived [2].

7.3

Procedures for Classifying Fire Resistance

149

Depending on the components included in the design element and the type of element, the need for tests according to a curve other than the standard temperature/ time curve shall be verified: • the slow heat curve for elements whose evaluated property may be dependent on high heating rates below 500 °C, • the simulated natural fire for lightweight suspended horizontal protective membranes, • the external fire curve for external surfaces of non-load-bearing walls, • constant temperature effect, for example for smoke-tight doors, raised floors, chimneys. For each of the tests and each of the criteria R, E, I, W, K, the times (in minutes) obtained shall be rounded to the nearest lower value in the following series: 10, 15, 20, 30, 45, 60, 90, 120, 180, 240, 360. If more than one test is performed due to the intended area of application, the classification for the whole area of application is determined by the worst result. Because the classification is associated with the application field, the results of the individual tests may lead to a higher assessment for the limited application area. No test shall be repeated for repeatability purposes, as one test is normally sufficient to classify all elements identical to the test element and all elements included in the direct application area. Asymmetrical fire-separating elements may have different characteristics depending on the side from which they are tested. For this reason, a test shall be carried out on each side. Asymmetrical fire-separating elements may be tested on one side only if: (a) it is possible to assume which side shows a worse result, (b) a classification is required for fire stress on one side only. If the fire separation element is tested only from the presumed weaker side, this presumption must be based on laboratory practice and the relevant analysis must be fully documented in the classification protocol. Where an asymmetric element is classified for only one side, the classification protocol shall expressly refer to this. Beams may be tested by exposure from three or four sides, depending on the intended application. Load-bearing walls can be tested on both sides for some applications. Elements may have different characteristics depending on the load level and the boundary conditions. The area of application of the classification is determined by the load level and the boundary conditions used in the test. Additional tests may be required depending on the area of application envisaged [2–4, 10, 13]. The number of tests required may further depend on: (a) a combination of the expected performance criteria, (b) the need to apply other thermal stress conditions in addition to the standard temperature/time curve.

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Resistance to Fire

Elements are supplied in a wide range of sizes, shapes and materials, including surface treatments to satisfy market requirements. It is impossible to test each variant of shape, size or material for each element. The extent to which the test element can or cannot be changed within the direct application area shall be indicated in the rules or directives in the relevant test standards which limit the permissible deviation from the test sample without further evaluation or calculation. A greater number of tests may be required for an extended application, but that is not the subject of this standard [2]. The test sample shall normally be of its actual size. Where a sample cannot be tested using its actual size, its dimensions shall be in accordance with the specification of the relevant test method. In general, the test results obtained for a given range, height and width shall also be valid for a smaller range, height, or width. The applicability to larger dimensions must be governed by appropriate test methods or extended application standards. When assessing an application area, it may be necessary to perform tests with different boundary conditions, unless the strictest peripheral condition is known. The ultimate load depends to a large extent on the boundary conditions and the method of support [8]. The load levels are best expressed as a percentage of the load capacity limit at ambient temperature. If the ultimate load at ambient temperature is not known, the actual test load and the relevant mechanical properties of the materials used shall be stated in the classification report. It is acceptable to have different variants of the design details in one test sample only if it can be demonstrated that they will not interfere with their behavior [8].

7.4

Fire Resistance of Electric Cables

A separate Chap. 5 is devoted to the issue of testing electric cables. In order to ensure a permanent supply of electricity during a fire, it is necessary to make cable support structures that will withstand the fire for the required time, together with the cables stored in them. We are talking about the fire resistance of handbag systems. Different versions of the support structures are available. The standards define that cables must be tested for functionality together with the cable support system, never separately. The supporting structure has precisely defined technical parameters (sheet thickness, support distance, sidewall height, maximum width, maximum load, etc.). Since no general agreement has yet been adopted in the field of fire protection within the European Union, the scope of requirements in the field of fire safety is defined by each member state through separate legislation. The property of maintaining functionality must be proven through a fire test by an independent accredited testing institute. The tests are carried out in a special test furnace. The required approval documents can take different forms. From these documents, it must be possible to clearly determine what type of cable support system with functional fire resistance it is, its fire classification and classification regulation. In the case of non-standardized cable support systems with functional fire resistance, the cables with which the system was measured and classified must also be listed [9].

7.6

7.5

The Model: Informative Fire Resistance Test

151

Fire Resistance Assessment Equipment

The test equipment for determining the boundary conditions of fire resistance is very demanding and complex. To carry out a fire resistance test requires several days of the preparation of a sample. According to the above conditions and procedures, a special device or a vertical or horizontal ‘furnace’ is used. There is only one certified test kiln in Slovakia, owned by the company Fires in Batizovce Slovakia Fig. 7.4 is a view of the ceiling of the horizontal test furnace and Fig. 7.5 is the view of the sample in the vertical test furnace [91].

7.6

The Model: Informative Fire Resistance Test

As the name of the section indicates, the test we will describe is a model informative test for fire resistance. It is not possible to issue a certificate on the fire resistance of the structure or product based on this test, but it still provides valuable information about a material. This chapter could be included in this chapter (Fire Resistance), Chap. 13 (Special test methods), or Chap. 14 (Non-standardized tests). In the end, due to the equipment and the procedure that is used in testing, as well as the method of evaluating the test, this section was included in this chapter. The difference from the standardized test lies only in the method of evaluation of the tested sample. Rather than using one normalized sample (from the structure) it uses several fragments of constructions. This provides information about the composition of the structure or about the composition of several fragments of structures in a real fire resistance test.

Fig. 7.4 Horizontal ‘furnace’ for fire resistance. (Photograph by Fires company2022)

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Fig. 7.5 Vertical ‘furnace’ for fire resistance. (Photograph by Fires company 2022)

7.6.1

Designing the Test

The aim of this model experiment was to test 12 versions of constructions on six samples. The diagram of the location of the samples and their composition is shown in Fig. 7.6. • The aim of the model test was to obtain information on whether: • the Reaction-to-Fire values (C, E) of the combustible insulation product affect the test result • the addition of a layer of non-combustible insulating material with a thickness of 40 mm affect the test result • the addition of a layer of non-combustible insulating material with a thickness of 80 mm affect the test result • the final treatment of the outside layer of the sample affects the test result if two different materials are used (see Fig. 7.7) 12 fragments of the construction were obtained on six samples. The sample is shown in Fig. 7.8.

7.6.2

Mounting Samples for the Model Fire Resistance Test

The preparation of the samples is photo-documented below. The precision and quality of the evaluation of individual samples were important, mainly fitting the thermocouples. Two thermocouples were placed behind each layer of the sample

7.6

The Model: Informative Fire Resistance Test

153

Fig. 7.6 Placement of samples in a vertical furnace during a model test for fire resistance. (Photograph by A. Maciak 2022)

(see Fig. 7.9), and eight thermocouples were placed on the outside (from the furnace) – four on each material used for the final treatment of the sample (see Fig. 7.10). Each thermocouple had its own identification number. In Fig. 7.11 on the left is a sample with 80 mm mineral wool, and on the right are all six samples ready for the furnace test.

7.6.3

Test Course

The model fire resistance test took place in a standardized testing facility according to a standard temperature curve, as is done in regular construction testing.

154

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Resistance to Fire

Fig. 7.7 The sample with views from the inside and outside. Two materials were used to coat the outside layer of the sample. (Photograph by A. Maciak 2022) Fig. 7.8 The overall design of the sample. (Photograph by A. Maciak 2022)

The difference between the standard and model tests lies only in the size of the sample and in the fact that more samples were tested under one thermal load. Also, more thermocouples were used, even in locations that are not prescribed by the standardized test.

7.6

The Model: Informative Fire Resistance Test

155

Fig. 7.9 Two thermocouples were placed behind each layer of the sample. (Photograph by Fires company 2022) Fig. 7.10 Eight thermocouples were installed on the outside – from the furnace. (Photograph by Fires company 2022)

The course of the test was photo-documented with photographs and thermal imaging recording; and a few photos were selected, see below. Figure 7.12 is a photo of the experiment just before the test – thermal stress load according to the standard temperature curve from the outside. The photo clearly shows the thermocouples from the individual measuring points.

156

7

Resistance to Fire

Fig. 7.11 (a) Detail of the sample with 80 mm mineral wool (b) all six samples ready for the furnace test. (Photograph by Fires company 2022)

Fig. 7.12 Photograph of the experiment before the test. (Photograph by Fires company 2022)

Figure 7.13 is essentially the same shot but taken in the 90th min of the experiment. As can be seen from this photo, all versions of the tested constructions would optically meet the fire resistance of 90 min. The temperature course in each measured position on the samples will be described in Sect. 7.6.4, Evaluation of the test.

7.6

The Model: Informative Fire Resistance Test

157

Fig. 7.13 This figure is essentially the same shot but at 90th min of the experiment. (Photograph by Fires company 2022)

Figure 7.14 is a view of the inside of the furnace in the 30th min of the experiment. Figures 7.15 and 7.16 are images from a thermal imaging camera. We want to draw attention mainly to the detail in Fig. 7.16, where a significant difference can be seen in the materials used for the outer covering of the samples. As can be seen, this part of the experiment was significant.

7.6.4

Evaluation of the Experiment

A rather complex experiment and its evaluation cannot be described in a few pages, so here we present only a selection of some results that justify the test. First, we would like to point out that the following graphs show the average values of either two or four thermocouples from individual positions. Here we present not a scientific evaluation of the experiment, but based on the stated results, justify the reason for carrying out such a test itself.

158

7

Resistance to Fire

Fig. 7.14 This figure is a view of the inside of the furnace in the 30th min of the experiment. (Photograph by Fires company 2022)

Fig. 7.15 Shot from a thermal imaging camera in the 60 min of the experiment. (Image by Fires company 2022)

Figure 7.17 displays the temperature course for sample 1, where no additional layer of mineral wool was used. Figure 7.18 is the course of temperatures where a layer of mineral wool with a thickness of 80 mm was used. In both cases, the fire reaction of the insulating material was E. The influence of the mineral wool is evident. In the first case, the value of the temperature behind the insulating material is 700 °C in the 120th min of the test, while in the second case, it is only 50 °C in the same minute (red curve.)

7.6

The Model: Informative Fire Resistance Test

159

Fig. 7.16 The difference in the materials used for the external cladding of the samples and their effect on fire resistance. (Image by Fires company 2022)

1000

1 RS

900

1 PUR E

Temperature (°C)

800 700

1 MgO

600

1 FER

500 400 300 200 100 0 0

20

40

60

80

100

120

Time (min) Fig. 7.17 Course of temperature measured behind the layers of the tested structure by model fire resistance test for sample 1 processed by the authors

Figure 7.19, 7.20 and 7.21 show the influence of the Reaction-to-Fire values of the tested materials. It is clear from the figures that the effect of reaction to fire values was also manifested in this model test. For example, the value of 500 °C was reached by the material with a Reaction-to-fire value E in 97 min, while by the material with a reaction to fire value C only in the 116th min of the test.

160

7 1000

3 RS

900

3 MV80

800

Temperature (°C)

Resistance to Fire

700

3 PUR E

600

3 MgO

500

3 FER

400 300 200 100 0 0

20

40

60

80

100

120

Time (min) Fig. 7.18 Course of temperature measured behind the layers of the tested structure by model fire resistance test for sample 3 with a layer of mineral wool 80 mm processed by the authors

Temperature (°C)

800

S1 PUR E/ MV 0

700

S2 PUR E/ MV 40

600

S3 PUR E/ MV80

500 400 300

200 100 0 0

20

40

60

80

100

120

Time (min) Fig. 7.19 The influence of additional layers of mineral wool on the course of temperatures with PUR materials and reaction-to-fire E processed by the authors

Questions In which positions is it necessary to test building structures for fire resistance? How can the structure be modified for increased fire resistance? Which criteria, limit states of fire resistance must the structure meet? How can a model test for fire resistance be used?

References

161

800

S2 PUR C/MV 0

Temperature (°C)

700

S6 PUR C/MV 40

600

S4 PUR C/MV 80

500 400 300 200 100 0 0

20

40

60

80

100

120

140

Time (min) Fig. 7.20 The influence of additional layers of mineral wool on the course of temperatures with PUR materials and reaction-to-fire C processed by the authors

800

PUR E

Temperature (°C)

700

PUR C

600 500 400 300 200 100 0 0

20

40

60

80

100

120

Time (min) Fig. 7.21 Temperature course, showing difference in the reaction-to-fire values of the insulating material recorded in the model test for fire resistance processed by the authors

References 1. U. Dundar, S. Selamet, Fire load and fire growth characteristics in modern high-rise buildings. Fire Saf. J. 135, 1–3 (2023). https://doi.org/10.1016/j.firesaf.2022.103710 2. D. Kacikova et al., Materiály v protipožiarnej ochrane (Materials in fire protection) (Technical University in Zvolen, Zvolen, 2011), p. 367 3. M. Karemaker et al., Elderly about home fire safety: A qualitative study into home fire safety knowledge and behaviour. Fire Saf. J., 6 (2021). https://doi.org/10.1016/j.firesaf.2021.103391

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4. A. Law, L. Bisby, The rise and rise of fire resistance. Fire Saf. J. (2020). https://doi.org/10.1016/ j.firesaf.2020.103188 5. A.C. Marcolan Jr., P. Dias de Moraes, Probabilistic model for determining the failure time of steel-to-timber connections with multiple dowel-type fasteners exposed to fire. Fire Saf. J. 133, 103646 (2022). https://doi.org/10.1016/j.firesaf.2022.103646 6. L. Makovicka Osvaldova, S. Gašpercová, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 7. M. Oravec, Posudzovanie rizík v cestných tuneloch (Risk assessment in road tunnels) (EQUILIBRIA, Košice, 2008), p. 200 8. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection) (Technical University, Zvolen, 2009) 9. R. Polansky, M. Polanska, Testing of the fire-proof functionality of cable insulation under fire conditions via insulation resistance measurements. Eng. Fail. Anal. 57, 334–349 (2015). https:// doi.org/10.1016/j.efailanal.2015.08.00 10. V.S. Ramachandran, J.J. Beaudoin, Handbook of Analytical Techniques in Concrete Science and Technology (Noyes Publ., William Andrew Publishing, LLC, New York, 2001), p. 964 11. S. Rastocky, Skúšanie požiarno-technických vlastností stavebných výrobkov (Testing the firetechnical properties of construction products), in Wood and Fire Safety, (Technical University in Zvolen, Zvolen, 2000), pp. 112–141 12. A. Steen-Hansen, K. Storesund, C. Sesseng, Learning from fire investigations and research – A Norwegian perspective on moving from a reactive to a proactive fire safety management. Fire Saf. J. 120, 6 (2021). https://doi.org/10.1016/j.firesaf.2020.103047 13. M. Stujberova, A. Osvald, 16 Navrhovanie nosných konštrukcií stavieb. Požiarna odolnosť (16 Designing the load-bearing structures of buildings. Fire resistance) (Slovak Technical University in Bratislava, Bratislava, 2009) 14. G. Wackerbauer, EXAP – Ein Buch mit sieben Siegeln? Inteligenter Umgang in der Praxis (EXAP – A book with seven seals? Intelligent handling in practice) (Institut für technik, Rosenheim). https://www.ift-rosenheim.de/documents/10180/671018/FA_MTH1409_ EXAP/0652836d-8fee-4c4e-bb38-d4f1f274adb3e) Accessed 18 Feb 2023 15. Y. Zhang et al., Experimental study of compartment fire development and ejected flame thermal behavior for a large-scale light timber frame construction. Case Stud. Thermal Eng. 27, 101133 (2021). https://doi.org/10.1016/j.csite.2021.101133 16. EN 1363-1:2020 Fire resistance tests – Part 1: General requirements 17. EN 1366-2:2015 Fire resistance tests for service installations – Part 2: Fire dampers 18. EN 13381-1:2020 Test methods for determining the contribution to the fire resistance of structural members – Part 1: Horizontal protective membranes 19. EN 15269-1:2019/AC:2020 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 1: General requirements 20. EN 15269-2:2012 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 2: Fire resistance of hinged and pivoted steel doorsets 21. EN 15269-3:2023 Extended application of test results for fire resistance and/or smoke control for doorsets, shutter and openable window assemblies, including their elements of building hardware – Part 3: Fire resistance of hinged and pivoted timber doorsets and openable timber framed windows 22. EN 15269-5:2014+A1:2016 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 5: Fire resistance of hinged and pivoted metal framed glazed doorsets and openable windows

References

163

23. EN 15269-7:2019 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware. Part 7: Fire resistance for steel sliding doorsets 24. EN 15269-10:2011 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies including their elements of building hardware – Part 10: Fire resistance of steel rolling shutter assemblies 25. EN 15269-11 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 11: Fire resistance for operable fabric curtains 26. EN 15269-20:2020 Extended application of test results for fire resistance and/or smoke control for door, shutter and openable window assemblies, including their elements of building hardware – Part 20: Smoke control for doors, shutters, operable fabric curtains and openable windows

Part III

Interior Materials

Interior materials are one of the main causes of building fires. Statistically speaking, it is most likely to be an electrical short circuit to blame for creating the spark that causes a fire. However, the cause of the fire’s development is the materials that the spark ignites. These include furniture and decorations, and any materials that are meant for everyday use in the home or workplace. That is why plastics, textiles and furniture are included in this part of the textbook. This group includes plastics themselves or products made from them which contribute to the development (often rapid development) of fire. In the past, this group of materials and products consisted mostly of combustible materials of a natural origin such as wood, wool, cotton, straw, cork, etc. By studying the combustion of these materials, the limiting conditions and their evaluation criteria for determining their relationship to ignition and burning were also modified. For example, based on the knowledge at the time, the temperature value for testing materials was set at 750 °C. Through observations and experiments, scientists came to the conclusion that fires generally reach a temperature of approximately 800 °C and peak within 15 min from the beginning of the fire. The fire load per unit area was set at 30 kg/m2 and later at 50 kg/m2. However, when plastics began to be used for interior furnishings, these claims and generalities about fires had to be adjusted. The fires suddenly took a different course; they were more intense, and the intervention of fire brigades also got more complicated. Suddenly, the fire peaks in the fifth, sometimes even in the third minute, and reaches a maximum temperature of more than 1000 °C. The reason? Plastics. From one molecule, chemists were able to create a macromolecule and from these macromolecules, a whole range of new materials with very good and practical properties for the needs of industrial production can be made. Quickly the market responded and plastics all but replaced natural materials. They were suddenly widely available, cheaper, and more homogeneous in terms of their composition and properties. This is how Polyethylene (PE), Polyethylene Terephthalate (PET), Polyvinyl Chloride (PVC), Polyvinylidene Chloride (PVDC), Polypropylene (PP), Polyamide (PA), Polycarbonate (PC), Polytetrafluoroethylene (PTFE), Polystyrene (PS),

166

III

Interior Materials

Polyester, Acrylonitrile Butadiene Styrene (ABS), Plexiglas (PMMA) and a number of others that were created by modifying these basic ones. Modifications were made for practical reasons – strength, better resistance to abrasion, resistance to higher temperatures, shape stability, color stability, etc. With the rise of plastics in as building materials and interior furnishings, it was necessary to begin looking into ways to slow down their burning, or prevent them from burning to start out with. This in turn led to the need for testing plastics in relation to their ignition and burning in the form in which they are used in the interior. Of course, plastics are also tested in terms of their reaction to fire (e.g. if they are part of floors), for fire resistance (if they are part of the insulation system in the construction), and as facade elements (if they are part of the additional insulation system of buildings). In all these cases, though, plastics have a different function than in interior design. Therefore, for this purpose (evaluation of plastics in the interior), special test methods were created. New methods were also created for the evaluation of textiles as they may contain plastics in the form of fibers. We can categorize textiles by their fibers, e.g. completely natural textiles, those formed by a mixture of natural fibers and artificial fibers, and textiles with a 100% share of artificial fibers. In addition to the proportion of fiber types, the function of the product from the given textile and its further use are important. Evaluation of the quality of a textile, or a product made from it, is important for several criteria of its functionality. One of the criteria is its characteristics in relation to ignition and burning. Furniture is also subject to evaluation in relation to burning and ignition. But is it necessary? After all, it is mostly pure plastic and textile, or plastic and textile with a proportion of natural materials. All tests for plastics, textiles, or furniture include evaluation criteria that simulate as much as possible the conditions of fire for the material or product from it. With detailed knowledge of these materials and products, we can make certain modifications to improve their properties, which can affect the occurrence and development of fire.

Chapter 8

Testing of Plastics

Plastics belong to the category of materials which require special attention in terms of fire protection. Due to their increased use in construction, the number of fires has increased and after a more detailed investigation, it has been found that their nature has changed as well. The fire spread rate has increased disproportionately as well as the temperature of the developed fire, which called for changes in material testing. Plastics now have a separate category of standards testing their properties for fire protection needs [4, 8, 9, 11, 12, 14, 22]. Plastics are also part of other products, e.g., cables, furniture, insulating materials, where they are evaluated by the relevant standards (test methods) for a specific product. This chapter is divided into two main subsections, one describes laboratory methods for evaluating plastics, the other chemical analytical methods. The following methods are described in more detail in this subsection [13].

8.1

Laboratory Testing Methods of Plastics for Fire Protection Needs

The following methods are described in more detail in this subsection: ISO 871: 1999: Plastics – Determination of flammability in the hot-air furnace [33], EN ISO 4589-2: 2001: Plastics. Determination of flammability by limited oxygen index method. (LOI) Part 2: Ambient temperature test [34], EN ISO 5659-2: 2001 Plastics. Formation of smoke. Part 2: Determination of optical density by a single chamber test [35], UL methods.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_8

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Testing of Plastics

ISO 871:2022 Plastics: Determination of Ignition Temperature Using a Hot-Air Furnace

The international standard states the laboratory method for determining flash point and ignition temperature of plastics in a hot air oven. The method is one of many used to assess the resistance of plastics to the effects of high temperatures. This method does not provide a direct measurement of the flammability or burning rate of the material, or any definition of a safe upper-temperature limit for plastics in use. The given method is not used to describe or evaluate fire hazards or fire risks of materials, products, or devices in particular fire conditions. However, the results of this test may be used as elements of fire hazard assessment or fire risk, taking into account all factors related to fire risk assessment in the given case. The tests carried out under the conditions of this method may be of considerable importance when comparing the relative flammability characteristics of different materials. The values obtained represent the lowest ambient air temperature at which ignition of the material occurs under the conditions of the test. The obtained values allow the materials to be arranged according to their sensitivity to ignition under normal conditions of use. The test may be carried out using materials supplied in any form. For materials with a density greater than 100 kg/m3, a sample quantity of 3.0 g ± 0.2 g is used. Materials in the form of foils are cut into squares with maximum dimensions of (20 ± 2) x (20 ± 2) mm and are placed on each other at such a height so as to obtain the required sample weight. Materials in the form of a film are rolled up creating a strip of a width of 20 mm ± 2 mm and of the length necessary to achieve the required weight. The samples are conditioned prior to the test at a temperature of 23 °C ± 2 °C and relative humidity of 50% ± 5% for at least 40 hours. The laboratory equipment is depicted in Fig. 8.1. The location of the thermocouples is important in the test. TC1 thermocouple measures the temperature T1 of the sample. It is placed as close as possible to the center of the upper surface of the sample when the sample is in its place in the oven. The conductor of the thermocouple is attached to the sample holder. The TC2 thermocouple determines the temperature T2 of the air flowing around the sample. It is placed 10 mm ± 2 mm below the center of the sample crucible. The conductor of the thermocouple is suitably attached to the sample holder. The TC3 thermocouple measures the temperature T3 of the heating coil. It is located next to the heating coil and its use takes priority over the thermocouples of the inner cylinder because it indicates the temperature more quickly. Flash ignition temperature (FIT): The air velocity is set to 25 mm/s by adjusting the actual airflow velocity qv through the entire cross-section of the inner cylinder (at oven temperature) to the calculated value in liters per minute according to the Eq. (8.1):

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Laboratory Testing Methods of Plastics for Fire Protection Needs

169

Fig. 8.1 Cross-section of the hot-air oven (ISO 871: 2022) [13, 33] A – thermocouple, B – fire-resistant lid, C – sealing ring, D – heating coils, E – sample holder, F – thermocouple, G – hole of 25 mm in diameter, H – ignition flame, I – thermocouple, J – flow meter, K – mineral fiber wool, L – tangential air flow to the cylinder, M – sample crucible, N – 50 threaded spiral made of chrome-nickel in heat-resistant sealant, O – spacers for inner cylinder, P – thermal insulation, R – safety cap, S – metal fastening clamps

qv = 6:62 where: qv – air flow velocity (mm/s), T – temperature (K).

293 ðmm=sÞ T

ð8:1Þ

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One of the conditions is that the airflow velocity is maintained within +/- 10% of the calculated value. The electrical current supplied to the heating coil is adjusted until the air temperature remains constant at the required level of the initial temperature of the test. The sample crucible is placed in the oven. At the same time, the correct positioning of the TC1 and TC2 thermocouples is checked. The timer is switched on, the ignition flame is lit and the occurrence of a flare-up or minor explosion of flammable gases is observed; this may be followed by continuous burning of the sample. Flame burning or heating may also be observed with a sudden rise in temperature of T1 compared to the T2 temperature. After 10 min, the T2 temperature is set lower or higher by 50 °C depending on whether ignition occurred or not, and the test is repeated with a new sample. When the flash-point range is determined, the tests start at a temperature which is 10 °C lower than the highest temperature within the heat range. The temperature is reduced by 10 °C at each time until a flare-up does not occur within 10 min. Self-ignition temperature (SIT): The procedure is the same as for FIT, but without a test flame. Self-ignition is evident when the sample is burning by flame or by heating. For some materials, it may be difficult to visually detect ignition when it is burning by heating rather than by flame. In such cases, more reliable evidence is a faster temperature rise in the T1 thermocouple than in T2, accompanied by visual observation. The lowest temperature of the air T2 at which a flare-up is observed within 10 min is the flash-point temperature. The lowest temperature of the air T2 at which the sample is ignited within 10 min is the ignition temperature.

8.1.2

EN ISO 4589-2:2017 Plastics: Determination of Burning Behaviour by Oxygen Index – Part 2: Ambient-Temperature Test (ISO 4589-2:2017)

This part of EN ISO 4589-2 [34] prescribes methods for the determination of the minimum oxygen concentration in a nitrogen mixture which is able to maintain the combustion of small test bodies in a vertical position under the prescribed test conditions. See the apparatus in Fig. 8.2. The results of the test are called oxygen index values. The results of the oxygen index obtained according to the methods prescribed in this part EN ISO 4589 [34] can give a sensitive assessment of the burning behavior characteristics of the materials under certain laboratory conditions. The results of this test cannot be used to assess the fire safety of a particular material or product under real fire conditions. They can only be partially used in the fire risk assessment, when all the factors relevant to the fire hazard assessment for a particular application of the material are taken into account. The test samples are prepared using a procedure complying with the material specification. A sample large enough for the preparation of at least 15 separate test

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Laboratory Testing Methods of Plastics for Fire Protection Needs

171

Fig. 8.2 (a) Diagram of the apparatus determining oxygen index (EN ISO 4589-2) [34]. 1 – test body, 2 – clamp, 3 – burner, 4 – wire screen, 5 – stand, 6 – glass beads, 7 – brass base, 8 – T-shaped tube, 9 – pressure valve, 10 – screen, 11 – pressure gauge, 12 – pressure regulator, 13 – filter, 14 – needle valve, 15 – flow meter, 16 – temperature sensor, (b) Photo of apparatus. (Photograph by J. Mitterpach 2023, CZU Praha)

specimens is used. The dimensions are stated in the given table included in the standard. The materials are divided into six groups according to their type (Type I – pressed materials, II – lightweight materials, III – board materials, IV – other possible size of self-supporting moldings or boards for electro-technical purposes, V – flexible films or boards and VI – thin films in the supplied state; only for films that can be wrapped around the prescribed bar where each group has different dimensions). An ambient temperature of 23 ± 2 °C is maintained in the test device. The initial oxygen concentration is set. The test body is mounted vertically in the center of the test tube such that its upper part is at least 100 mm below the top opening and its lowest exposed part is at least 100 mm above the top of the gas-dispersing device at the bottom of the tube. The gas mixture is adjusted, and the flow is diluted so that the oxygen/nitrogen mixture with the required oxygen concentration flows through the tube at 23 ± 2 °C and a speed of 40 ± 2 mm/s. The specified gas flow rate is kept constant during flare-up and combustion of each test body.

Method A: Upper Surface Ignition The burner is only used to ignite the upper surface of the upper end of the specimen. The lowest part of the flame of the burner is applied to the upper horizontal surface of the body and is moved so as to cover the entire surface. The flame must not touch the

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vertical surfaces or the edges of the body. The flame is applied for a maximum of 30 seconds, with short breaks every 5 s for the time necessary to observe whether the entire upper surface of the body is already burning. The specimen is considered to be afire and the measurement of the burning time and length start to be measured if the whole upper part is burning after 5 s when the burner is moved away. Method B: Ignition Supporting Vertical Combustion For ignition supporting vertical combustion, the flame source is used to ignite the upper surface and partly ignite the vertical surfaces of the test body. The burner is approached, and it is being moved so that the flame sufficiently covers the upper and vertical surfaces of the test body to a depth of about 6 mm. The burner is held for a maximum of 30 s with short breaks every 5 s for the time necessary to observe whether the vertical surfaces are burning by a steady flame and whether the visible part of the flame reaches the upper mark. The body is considered afire, and the measurement of the burning time and range begins, as soon as any part of the flame reaches the upper reference mark. If the body ignites, the measurement of the burning time starts, and the behavior of the body is observed. If burning stops but a new self-ignition occurs spontaneously within 1 s, both the measurement and observation continue. If neither the burning time nor its span exceeds the values prescribed for the particular body in Table 8.1, the burning time and extent are recorded, and the response is marked ‘O’. However, if the burning time or range exceeds the corresponding boundary value prescribed in the table, the result of the burning is recorded, the flame is extinguished and the response is marked ‘X’. Accompanying effects of burning, e.g., dripping, charring, irregular burning, heating during burning, or supplementary heating are observed. During the tests, the oxygen concentration when assessing another body is chosen as follows: • oxygen concentration is reduced if a response ‘X’ was recorded with the previous test body, Table 8.1 LOI measurement criteria [34] processed by the authors Type of test body I, II, II, IV and VI

V

a

Ignition method A On the upper surface B Promoting vertical combustion B Promoting vertical combustion

Alternative criteriaa Burning time after ignition 180 180

180

Burning rangeb 50 mm below the upper surface of the body 50 mm below the upper reference mark 80 mm below the upper reference mark

They do not always provide equivalent oxygen results when the bodies are of a different shape or other ignition conditions and methods are used b The burning range I–VI be increases if any part of the flame on the body, including burning droplets running down the surface of the body, exceeds the value defined in column 4 of the table

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Laboratory Testing Methods of Plastics for Fire Protection Needs

173

• oxygen concentration is increased if a response ‘O’ was recorded in the previous test body. The oxygen index, expressed as volume percentage, is calculated according to the relationship (8.2): OI = c1 þ k:d

ð8:2Þ

where: OI – oxygen index (%), c1 – final oxygen value (vol.%), d – interval between oxygen concentrations (%), k – factor obtained from the table (table stated in the standard).

8.1.3

EN ISO 5659-2:2017 Plastics: Smoke Generation – Part 2: Determination of Optical Density by a Single-Chamber Test

This part of the standard EN ISO 5659 [35] determines the method for measuring the formation of smoke from the exposed surface of test samples of, in principle, flat materials, composites, or sets of a thickness not exceeding 25 mm, which in a horizontal position are subject to specified levels of thermal exposure in an enclosed chamber, with or without the burner. This test procedure is used for all plastics and may also be used for the assessment of other materials (e.g., rubber, floor coverings, coated surfaces, wood, and other building materials). The optical density values determined by this test are specific to the material or material assembly in the form and thickness in which they were tested and must not be regarded as basic characteristics of the material. The test serves research and development purposes and does not serve as the primary basis for material classification for building regulations or other purposes. It provides no basis for smoke density prediction that can be generated from materials exposed to heat and flame under other exposure conditions, and no correlation with the measurements based on other test methods is established. When using the test results, it must also be taken into account that this test procedure does not include the effect of irritating substances on the eye. We should point out that the smoke release from the material varies according to the level of exposure of the test body. When using the results of this method, it is necessary to in mind that the results are based on exposure at well-defined exposure levels, namely 25 kW/m2 and 50 kW/m2. The scheme of the apparatus is shown in Figs. 8.3 and 8.4. The test chamber is prepared with the radiator set to the power of 25 or 50 kW/m2. If a previous test was just completed, the test chamber is ventilated until the smoke is

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Fig. 8.3 Layout of the apparatus for EN ISO 5659-2: arrangement of the cone radiator, sample holder, and radiator cover (side view) [13, 35]

Fig. 8.4 Scheme of the apparatus for EN ISO 5659-2, photometric system [13, 35]

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Laboratory Testing Methods of Plastics for Fire Protection Needs

175

Fig. 8.5 Photo of the apparatus for EN ISO 56592, photometric system [35]. (Photograph by J. Mitterpach 2023, CZU Praha)

completely removed. The test chamber door is closed, and the suction and inlet vent opening remain open during the procedure. The inside of the device is checked and, if necessary, the wa13 and supporting structure are cleaned. Before each test, the panes of the optical windows in the chamber are also cleaned. The apparatus is allowed to stabilize, i.e., the temperature of the chamber wall is stabilized within 40 ± 5 °C for the tests with the radiator set at 25 kW/m2 or within 55 °C ± 5 °C for the tests at 50 kW/m2. The inlet vent is closed (Fig. 8.5). In the tests with an ignition flame, the gas and air supply is opened in the correct position of the burner, the burner is lit, the gas flows are checked and, if necessary, are adjusted so as to ensure the necessary flame length. Zero is set, then the aperture is opened, and 100% transmittance is set at full deflection. The aperture is closed again, the zero is checked and, if necessary, readjusted, using the most sensitive range (0.1%). The setting of 100% is checked repeatedly. This sequence of operations is repeated until zero values and 100% are stabilized on the amplifier and readout device when the aperture closes and opens. The coated test specimen is inserted into the test specimen holder, together with an appropriate sample plate. The holder with the test body is placed under the supporting structure under the cone heater, and the door of the test chamber is closed immediately. The aperture is removed from the bottom of the cone heater and at the same time, recording is started on the recorder at a speed of at least 10 mm/min and the inlet vent is closed. If, during preliminary tests, it is found that the ignition flame has gone out before the radiator shield has been removed, the burner must be re-ignited immediately at the same time as the radiator shield has been removed. Percentage transmittance and time are recorded continuously from the start of the test (i.e., from the moment the shield is moved away). The photodetector amplifier range is switched to the next decade as needed to avoid subtracting values that represent a deviation of less than 10% of the scale. If the transmittance fa13 below 0.01%, the observation window in the chamber door must be covered and the range filter must be removed from the optical path.

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All the burning characteristics of the test body are recorded, along with the time from the start of the test at which such behavior occurred. This includes the ignition time and flame burning, as well as other characteristics such as delamination, expansion, shrinkage, melting, and breaking. The characteristics of the smoke, such as the color and the nature of the settling solids, are also recorded. The formation of smoke in some materials differs significantly depending on whether the combustion takes place in a flame or flameless test variant. It is therefore important to record as much information as possible about the method of combustion in each test. Surface-coated and facing materials, including laminated boards, tiles, textiles, and other materials fixed to the supporting material by some adhesive, as well as composite materials not attached to the supporting material, may experience delamination, cracking, peeling off or other types of peel-back which will affect the formation of smoke. If the ignition flame goes out during the test by gaseous products and fails to re-ignite within 10 s, the gas supply to the burner must be stopped immediately. If a thin test specimen, which was not cut before the test, begins to balloon, the results from such a test piece must not be used and the test must be repeated with another sawn piece of test specimen. The sample is tested for 10 min. If required, and if the minimum transmittance values were not reached within 10 min of exposure, this test may be conducted for a period longer than 10 min. If the ignition flame was used in the test, the burner is switched off so that the air does not mix with the combustion products present and cause an accidental explosion. The shield of the heater is moved under the cone heater. The exhaust fan is switched on and when the water pressure gauge indicates a low vacuum, the inlet vent is opened and the extraction is continued until the maximum light transmission value is recorded in the appropriate measuring range, which is recorded as the Tc value for “pure beam” and used for correction due to deposits on optical windows. Unless otherwise specified in the Protocol, the percentage of transmission for each material shall be measured for three sets of three test pieces according to the following schedule: Variant 1: exposure of 25 kW/m2 without ignition flame, Variant 2: exposure of 25 kW/m2 with flame ignition, Variant 3: exposure of 50 kW/m2 without ignition flame. For each test body, the transmission value in percentage, from which the respective specific optical density is calculated, shall be determined. If, for unknown reasons, the Ds value at 10 min for any single test specimen differs by more than 50% from the average value measured for the set of three test specimens to which the test specimen belongs, another set of three test specimens from the same material sample in the same test variant must be tested and the average value of all six results is recorded. For each test body, a continuous record of the transmission is taken as a function of time and the results obtained for a period of 10 min are converted to a specific

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Thermoanalysis

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optical density Ds10 calculated according to the following Eq. (8.3) and rounded off to two decimal places: Ds = 132 log 10

100 T

ð8:3Þ

where: Ds– specific optical density (%), T – the percentage of the transmittance read from continuous recording for 10 min from the beginning of test (%), 132 – factor derived for the test chamber, chambers, A is the exposed area of the test body and L is the length of the optical path. A correction factor Ct is added to each Ds10 value, due to the use of a rangeincreasing filter. The value of the Ct factor is: (a) zero, if: 1. the filter was included in the optical path at the time of transmittance recording (T > 0.01%), or 2. the photometric system is not equipped with a removable filter or, 3. the ND-2 filter was found to have the correct optical density of 2; (b) if the filter was removed from the optical path during the correction factor measurement (T < 0.01%). To determine the correction factor Dc, the transmittance value Tc for the “pure beam” must be recorded for each test specimen. Dc is calculated according to the same relationship as Ds10. Correction factor Dc shall not be recorded if its value is less than 5% of the maximum optical density as determined from the record.

8.2

Thermoanalysis

The following methods are described in more detail in this subsection: EN ISO 11358: 2000 Plastics. Thermogravimetry (TG) of polymers [38] EN ISO 11357-1: 2000 Plastics. Differential scanning calorimetry (DSC). Part 1: General principles [36, 37], Other methods of thermal analysis.

8.2.1

EN ISO 11358: 2000 Plastics: Thermogravimetry (TG) of Polymers

This international standard lays down the general conditions for the analysis of polymers by means of thermogravimetric techniques. It is suitable for liquids or

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solids in the form of tablets, granules, or powder. This method can also be used to analyze the shapes reduced to a reasonably large sample. Thermogravimetry can be used to determine the temperature and rate of degradation of polymers, and at the same time to measure the number of volatile substances, additives, and/or fillers contained therein. Thermogravimetric measurements are carried out in either dynamic mode (change in mass depending on temperature or time under programmed conditions) (depending on→ “as a function of” if this a mathematical statement/relationship) or isothermal mode (change in mass depending on time at constant temperature). The test procedure is adapted to the device used and to the test conditions. Two methods, dynamic and isothermal, can be used. Dynamic conditions: The test sample is weighed. The thermobalance is reset. The holder with the test sample is placed on the thermobalance. The gas flow rate is selected, the gas supply is started, and the initial mass is recorded, except in the specific case that the thermobalance, under completely inert conditions, is either ventilated by a vacuum pump and then filled with inert gas, or inert gas is allowed to flow at high speed for a long time before recording the weight. If applicable, the temperature program specified in the respective standard is set. The program shall include the initial and final temperatures, isothermal stages at these temperatures, and the heating rates among the temperatures of the temperature program. The temperature program shall be started, and the thermogravimetric curve recorded. Isothermal conditions: Procedures are carried out according to the above conditions. The apparatus is then activated and operated at a maximum heating rate (e.g., 100 °C/min or above) to reach the specified temperature as quickly as possible. The acquired thermogravimetric data are presented in the form of a dependence curve of the mass change (see Fig. 8.6) or percentage mass change in relation to time or temperature. The specific temperatures and weights are determined from the TG curve by the following methods: The maximum mass mmax is determined from the curve, and the mass MG is calculated expressed in % using the Eq. (8.4): MG =

mmax - ms :100 ðmgÞ ms

ð8:4Þ

where: MG – mass before heating (mg), mmax – maximum mass (mg), ms – mass before heating (mg). From the TG curve, points A, B, and C are determined, where: • A is the starting point – the intersection of the line of initial mass and the tangent to the TG curve at the point of the maximum gradient,

8.2

Thermoanalysis

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120

5 343.68°C

100

80 3

60 2

40

Mass derivative (%/°C)

4

1 20 297.50°C 0 0 0

100

200

300

400

500

600

Temperature (°C)

Fig. 8.6 Recording of TGA curves of polymethyl methacrylate [13]

• B is the endpoint – the intersection of the line of final mass and the tangent to the TG curve at the point of the maximum gradient, • C is the center point – the intersection of the TG curve and the line constructed parallel to the x-axis at a point midway between points A and B. The weights ms, mf and the temperatures TA, TB and TC corresponding to the points A, B a C are determined. The loss of mass ML, expressed as a percentage, is calculated according to the Eq. (8.5): ML =

ms - mf :100 ð%Þ ms

ð8:5Þ

where: ML – mass loss (%), mf – mass at the final temperature (mg), ms – mass before heating (mg). Determination of mass loss in the case of multi-stage mass loss. During this procedure, points A1, B1, C1, A2, B2, C2 etc. are determined (if more than two degrees are used). The masses ms, mi, and mf and the temperatures TA1, TB1, TC1, TA2, TB2, TC2 etc. corresponding to these points are determined.

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The first mass loss ML1, expressed as a percentage, is calculated according to the Eq. (8.6): M L1 =

ms - mil :100 ð%Þ ms

ð8:6Þ

where: ML1 – first loss in mass (%), ms – mass before heating (mg), mi1 – mass at first final temperature (mg). The second mass-loss ML2, expressed as a percentage, is calculated according to the Eq. (8.7): M L2 =

mi2 - mf 2 :100 ð%Þ ms

ð8:7Þ

where: ML2 – second mass loss (%), mi2 – mass at second initial temperature (mg), mf2 – mass at second final temperature (mg), ms – mass before heating (mg). Other mass losses are also calculated this way. The mass of the residue Rz, expressed as a percentage, is calculated according to Eq. (8.8): Rz =

mfk :100 ð%Þ ms

ð8:8Þ

where: Rz – resistant residue (%), mfk – mass at last final temperature (mg), ms – mass before heating (mg).

8.2.2

EN ISO 11357-1: 2000 Plastics: Differential Scanning Calorimetry (DSC) – Part 1: General Principles

This international standard specifies the method of thermal analysis of polymers such as thermoplastics and thermosetting materials, including compression moulding materials and composite materials, using differential scanning calorimetry (DSC). Differential scanning calorimetry allows different determinations of polymers. Before each test, the device is switched on for at least 1 h to thermally stabilize the electronic components. Empty test vessels of the same nominal weight are placed in

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Thermoanalysis

181

the sample holder. The test conditions are set to the conditions used during the test. The DSC curve should be a straight line within the required temperature range. If a straight line is not obtained, the DSC curve is recorded when its repeatability is confirmed. Vessels of adequate volume are selected and checked for cleanliness. Two of the same vessels are used, one for the test sample and the other (empty or pre-filled) as the reference sample. The container and its lid are weighed to the nearest 0.01 mg. The test sample is placed in the test vessel. If required, the test vessel is closed with a lid. The vessel is weighed again. The vessels are placed in the sample holder with tweezers, or so that there is good contact between the test sample and the test vessel as well as between the test vessel and the sample holder. The cover of the test sample holder is closed. Dynamic measurement: The device is programmed to run the required thermal cycle. Two types of programs can be used: continuous or sequential. The first phase, the determination, is initiated. During the determination, inspection activities are carried out; they depend on the type of determination and on the computer equipment of the device (based on the instrument documentation). The sample holder is slowly adapted back to the room temperature and the sample vessel is removed from the sample holder. The container is checked for any deformations and if the sample flowed over the edge of the container. If the chamber becomes contaminated with the test specimen, it is cleaned according to the manufacturer’s instructions. The vessel along with the test sample are weighed. Any weight loss could cause a very substantial change in enthalpy. If the sample is assumed to be able to be chemically altered, the vessel is opened and the test sample is examined. Vessels that have been damaged must not be used for further measurements. The data are processed according to the instructions of the manufacturer. The tests of the polymers by DSC are affected by the thermal history and morphology of the samples and test samples. It is recommended to perform the test twice in order to produce comparable results. The second analysis is carried out when the apparatus cools down at the determined cooling rate. The results of this test are the DSC curves (see Fig. 8.7) which are evaluated by the respective software. Isothermal measurement: Insert the test sample at room temperature. The vessels are placed in the holders and the apparatus is programmed to reach the pre-stage temperature at high scanning speed. After reaching a balanced baseline, the temperature is brought to the value of the specified measurement temperature as quickly as possible. The temperature is maintained at this value and the DSC curve is recorded as a function of time. The apparatus should remain in operation with constant conditions after the end of the endothermic or exothermic reaction or until a stable baseline is reached. At the end of the measurement, the apparatus is cooled down and the test vessels are removed. The apparatus is programmed to achieve the specified temperature of the measurement. When the temperature of the apparatus stabilizes at this temperature, the

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Fig. 8.7 DSC recording of PVC cable sheath [13]

test vessels are placed in the test sample holder and the DSC curve is recorded as a function of time. The apparatus is kept in operation under constant conditions after the end of the endothermic or exothermic reaction, or after the transformation ends and a stable baseline is reached.

8.2.3

Other Methods of Thermal Analysis

Thermal analysis methods make it possible to monitor the processes taking place during the heating or cooling of solids, e.g., dehydration, oxidation, thermal dissociation, crystallization, melting, sublimation, polymerization, phase transformations, and others. These may be accompanied by a change in the weight or volume of the sample examined, the release or absorption of energy (heat), the development or absorption of gases, changes in electrical conductivity, magnetic properties, etc. [3, 15–19, 22, 24]. The advantage of the methods of thermal analysis is the simplicity of analytical procedures, the possibility of automation, and the speed of thermal analysis of even complex materials. The disadvantage of some thermal analysis methods, e.g., DTA, is their lower accuracy compared to other analytical methods. However, thermal analysis methods can provide additional valuable information, e.g., on the kinetics of observed processes. The deficiency can be eliminated to some extent by a calibration device using standard or calibration substances whose thermal behavior is known

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Thermoanalysis

183

and also by careful observance of all conditions that affect the course of the observed reaction. In thermogravimetry (TG) [5–7, 20–25, 27], the changes in the weight of the sample are observed depending on the temperature. The procedure is such that the temperature of the weighed amount of the test substance is gradually increased and the course of the dependence m = f (T) or m = f (t), a so-called thermogravimetric curve, is monitored. Based on its course, the weight losses Δm and the temperature ranges at which the losses occur, the composition of the test substance is subject to an analysis, or the number of components of the mixture of substances subjected to thermogravimetric analysis is determined. If there are changes in the weight of the sample caused by the increase in temperature at TG in close succession, it is more appropriate to record the first derivative of the thermogravimetric curve dm/dT = f (T), i.e., derivative thermogravimetric curve (DTG). Differential thermal analysis (DTA) detects exothermic and endothermic processes that take place as the temperature of the sample and its surroundings gradually increases or decreases [1, 2, 4, 7, 10, 26, 31]. For a derivative DTA that allows a more accurate determination of the forthcoming and overlapping changes in temperature, the course of the function dT = f(T) or f (t) is recorded. The course of direct heating T = f (t) and its derivative dT/dt = f (t) is called the heating rate, or the course of the inverse heating rate is expressed as dt/dT = f (t). Differential calorimetric methods developed from the basic DTA method allow direct measurement of the reaction enthalpy of processes in the sample under observation. Differential dynamic calorimetry (DDC) measures ΔT between a reference substance and a sample placed in an isolated carrier [1, 21, 28, 29]. Enthalpy thermal analysis (DSC) uses an additional source to compensate for the temperature difference between the evenly heated sample and the reference substance. In doing so, the energy consumed for this compensation is measured directly. The DSC (differential scanning calorimetry) method is sometimes called a “reverse” DTA. Thermo-dilatometric analysis (TD) monitors various processes (dehydration, melting, phase transformations of solids, rate of polymerization of monomers, rate of crystallization and vitrification of polymers, etc.), which take place in the given substance at a uniform temperature increase if they are manifested by changes in their volume. These changes are usually depicted as the dependency Δl/l = f(T). Electrothermal analysis (ETA) monitors the dependence of the electrical conductivity of substances on temperature, i.e., the function 1/q = f (T), where l is the electrical conductivity and q is the resistivity. This allows identification of sequential changes, state changes, some chemical reactions, or study of reaction kinetics. Other methods included in the thermal analysis are thermo-mechanical analysis (TMA), dynamic mechanical analysis (DMA), dielectric analysis (DEA), dielectric thermal analysis (DETA), and others [13, 30, 32]. Modern thermal analysis equipment, which is commercially manufactured today, is extremely accurate but rather complex instruments with wide possibilities for application. An example of such a device for combined thermal analysis is the

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Hungarian Derivatograf, a product of Metripex Budapest, which allows a perfect comparison of TG and DTA results. Another example of instruments combining thermal analysis methods is the Mettler vacuum thermoanalyzer, Gravimet, tap 4303, Elektrodyn thermobalance, and others. These methods of thermal analysis are used mainly in determining the effect of the fire retarder, its composition, determining the concentration of active substances, or determining the synergism of the retarder with the material that protects it. The disadvantages of these methods are that for more complex materials such as wood, they do not fully record the effect of the physical properties of this material on its burning. Questions Why is it necessary to test plastics with other test methods? Are fire response methods insufficient? By what methods (in addition to those mentioned in this chapter) are plastics tested? In what products or materials?

References 1. V. Babrauskas, Ignition Handbook, vol 38 (Fire Science Publisher, Issaquah, 2003), pp. 24–38 2. K. Balog, I. Bartlova, Základy toxikologie (Basics of toxicology) (SPBI, Ostrava, 1998) 3. D.A. Crowl, Calculating the energy of explosion using thermodynamic availability. J. Loss Prev. Process Ind. 5, 109–118 (1992). https://doi.org/10.1016/0950-4230(92)80007-U 4. J.C. De Hemptinne et al., A view on the future of applied thermodynamics. Ind. Eng. Chem. Res. 61(39), 14664–14680 (2022). https://doi.org/10.1021/acs.iecr.2c01906 5. D.D. Drysdale, T. HE, Flammability of plastics. II. Critical mass flux at the firepoint. Fire Saf. J. 14, 179–188 (1989). https://doi.org/10.1016/0379-7112(89)90071-4 6. A.P. Gray, A simple generalized theory for the analysis of dynamic thermal measurement, in Analytical Calorimetry, ed. by R.S. Porter, J.F. Johnson, (Springer, Boston, 1968), pp. 209–218. https://doi.org/10.1007/978-1-4757-0001-5_27 7. A. Gunnarshaug, M.M. Metallinou, T. Log, Study of industrial grade thermal insulation at elevated temperatures. Materials 13(20), 4613 (2020). https://doi.org/10.3390/ma13204613 8. C. Huggett, Estimation of the rate of heat release by means of oxygen consumption. Fire Mater. 12, 61–65 (1980). https://doi.org/10.1002/fam.810040202 9. L.M. Janssens, Fundamental measurement techniques, in Flammability Testing of Materials Used in Construction, Transport and Mining, pp. 23–61. https://doi.org/10.1016/B978-0-08102801-8.00092-2 10. D. Klimm, Thermal Analysis and Thermodynamics: In Materials Science (De Gruyter, Berlin, Boston, 2022). https://doi.org/10.1515/9783110743784 11. R.C. MacKenzie, B.D. Mitchell, Differential thermal analysis. Analyst 87(1035), 420–434 (1962). https://doi.org/10.1039/AN9628700420 12. R.C. MacKenzie, Ch. 1. Basic principles and historical development, in Differential Thermal Analysis, ed. by R.C. Mackenzie, vol. 1, (Academic Press, New York, 1984). https://doi.org/10. 1016/B978-0-444-99659-6.50008-3

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13. L. Makovicka Osvaldova, S. Gaspercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 14. S. Malik, 6 Best thermal analysis technique. Int. J. Sci. Manage. Adv. Res. Technol. https://doi. org/10.24018/ijsmart.2022.1.1 15. A. Pomázi, M. Krecz, A. Toldy, Thermal behaviour and fire and mechanical performance of carbon fibre-reinforced epoxy composites coated with flame-retardant epoxy gelcoats. J. Therm. Anal. Calorim. 148, 2685–2702 (2023). https://doi.org/10.1007/s10973-022-11710-z 16. A. Plota, A. Masek, Lifetime prediction methods for degradable polymeric materials – A short review. Materials 13(20), 4507 (2020). https://doi.org/10.3390/ma13204507 17. H.M. Pollock, A. Hammiche, Micro-thermal analysis: techniques and applications. J. Phys. D Appl. Phys. 34(9). https://doi.org/10.1088/0022-3727/34/9/201 18. J.M. Powers, Lecture Notes on Thermodynamics (Department of Aerospace and Mechanical Engineering University of Notre Dame, Notre Dame, 2023). https://www3.nd.edu/~powers/ ame.20231/notes.pdf. Accessed 17 Feb 2023 19. V.S. Ramachandran et al., Handbook of Thermal Analysis of Construction Materials (William Andrew, Norwich, 2002), p. 680 20. G.N. Rupert, Advanced high temperature thermal analysis apparatus employing derivative and differential techniques. Rev. Sci. Instrum. 36(11), 1629–1636 (1965). https://doi.org/10.1063/1. 1719408 21. J.B. Sajin et al., Impact of fiber length on mechanical, morphological and thermal analysis of chemical treated jute fiber polymer composites for sustainable applications. Curr. Res. Green Sustain. Chem. 5, 100241 (2022). https://doi.org/10.1016/j.crgsc.2021.100241 22. M. Schilling et al., Application of chemical and thermal analysis methods for studying cellulose ester plastics. Acc. Chem. Res. 43(6), 888–896 (2010). https://doi.org/10.1021/ar1000132 23. S. Sauerbrunn, P. Gill, Decomposition kinetics using high ResolutionTGA™. Proc. 21st North Am. Thermal Anal. Soc. Conf., Atlanta, GA, pp. 13–16 (1992) 24. M. Schubnell, Validation in Thermal Analysis (Hanser Fachbuchverlag, Leipzig, 2022), p. 274. https://www.hanser-elibrary.com/doi/pdf/10.3139/9781569909072.fm. Accessed 17 Feb 2023 25. J. Sestak, P. Hubik, J.J. Mareš, Thermal Physics and Thermal Analysis from Macro to Micro, Highlighting Thermodynamics, Kinetics and Nanomaterials (Springer International Publishing AGH, Cham, 2017), p. 567. https://doi.org/10.1007/978-3-319-45899-1 26. W. Smykatz-Kloss, Differential Thermal Analysis. Application and Results in Mineralogy (Springer, Berlin/Heidelberg, 2011), p. 188. https://doi.org/10.1007/978-3-642-65951-5 27. D. Spilak, Enthalpy and specific heat as material characteristics in thermal analysis of wood exposed to fire. Delta 15(2), 23–28 (2021). https://doi.org/10.17423/delta.2021.15.2.103 28. M. Stenseng, A. Zolin, R. Cenni, et al., Thermal analysis in combustion research. J. Therm. Anal. Calorim. 64, 1325–1334 (2001). https://doi.org/10.1023/A:1011538322381 29. V. Stoyanov et al., Thermal investigation on high temperature treatment of cement mortars with high content of marble powder. IOP Conf. Ser. Mater. Sci. Eng. 1276(1). IOP Publishing (2023). https://doi.org/10.1088/1757-899X/1276/1/012005 30. A. Toldy, A. Pomázi, B. Szolnoki, The effect of manufacturing technologies on the flame retardancy of carbon fibre reinforced epoxy resin composites. Polym. Degrad. Stab. 174 (2020). https://doi.org/10.1016/j.polymdegradstab.2020.109094 31. H. Vahabi, B.K. Kandola, M.R. Saeb, Flame retardancy index for thermoplastic composites. Polymers 11, 407 (2019). https://doi.org/10.3390/polym11030407 32. M. Waqas Nazir et al., Theoretical investigation of thermal analysis in aluminum and titanium alloys filled in nanofluid through a square cavity having the uniform thermal condition. Int. J. Mod. Phys. B. 36(22), 2250140 (2022). https://doi.org/10.1142/S0217979222501405 33. EN ISO 871:2022 Plastics – Determination of ignition temperature using a hot-air furnace 34. EN ISO 4589-2:2017 Plastics – Determination of burning behaviour by oxygen index – Part 2: Ambient-temperature test (ISO 4589-2:2017)

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35. EN ISO 5659-2:2017 Plastics – Smoke generation – Part 2: Determination of optical density by a single-chamber test 36. ISO 11357-1:2016 Plastics – Differential scanning calorimetry (DSC) – Part 1: General principles 37. ISO 11357-2:2020 Plastics – Differential scanning calorimetry (DSC) – Part 2: Determination of glass transition temperature and step height 38. ISO 11358-1:2022 Plastics – Thermogravimetry (TG) of polymers – Part 1: General principles

Chapter 9

Testing of Fabrics and Clothing

Clothing has played the role of our second skin since ancient times. From the very beginning, clothing had a functional protective and insulating function as well as a cultural role. Just as people dress their bodies in textiles, they like to use textiles to make their homes, offices, hotels, restaurants, etc. inviting and cozy. Most carpets, upholstery, curtains, and wallpapers are made from textiles. Textile is flexible, soft, relatively light, easy to process and use, durable and simple to manufacture in many forms, patterns, shades, and designs. Textiles beautify the interior and make furniture nicer [2, 4, 5, 7, 9, 13, 15–19]. Textiles are made of natural and synthetic fibers and mixtures thereof. Many types of textiles need to be tested to serve their intended purpose. The evaluation of furniture in combination with textiles comprises a separate category. In this chapter, we address the assessment of textiles as a material and the assessment of garments made from textiles. Yet, there is no full substitution of textiles in the fields of clothing and furnishings. Textiles and textile composites are destined to replace plastic and metal components currently used in e.g., automotive, construction, engineering, electronics, electrical engineering, medicine, and many other fields [11]. The use of textiles in these areas must also necessarily bring out new test procedures to assess them for fire protection needs. It is also necessary to monitor and correctly evaluate tetrad adjustments to textiles [1, 3, 6, 9, 10, 14, 16].

9.1

Evaluation of Textiles

The following methods are described in more detail in this subsection: EN ISO 6990: 2009 Textile fabrics – Burning behaviour – Determination of ease of ignition of vertically oriented specimens [24] EN ISO 6991:2003 Textile fabrics – Burning

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_9

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behaviour – Measurement of flame spread properties of vertically oriented specimens (ISO 6991:2003) [25].

9.1.1

EN ISO 6990:1997 Textiles: Flammability – Detection of Ignition of Vertically Positioned Samples

The standard specifies the method for determining the ignition of vertically positioned fabrics intended for garments, curtains, drapes, including both singlecomponent and multi-component fabrics (coated, quilted, multilayer, sandwich construction and similar combinations). This method should only be used to assess the properties of materials or systems at high temperatures and flame exposure under controlled laboratory conditions. The results cannot be applied to situations where air access is restricted or where the material is exposed for a longer period of time to a large source of intense heat than it would be during a fire. The scheme of the apparatus (holder) is shown in Fig. 9.1. The test is carried out in the atmosphere at a temperature between 10 and 30 °C and a relative humidity between 15% and 80%. The burner is lit and preheats for 2 min. The height of the flame is set to 90 ± 2 mm. The distance between the upper end of the burner tube and the tip of the yellow part of the flame, when the burner is in a vertical position and the flame is observed under dim light, is recorded. If the test is not conducted immediately, the test samples are placed in an enclosed container until the test begins. Each sample is tested within 2 min of removal from the air-conditioned environment or from an enclosed container.

Fig. 9.1 Test sample holder (dimensions in mm, min. = minimum) [8, 29]

9.1

Evaluation of Textiles

189

Fig. 9.2 Location of the burner [8, 29]

The test sample is placed on the tips of the test frame so that the tips pass through the points marked with the template and the sample is at least 20 mm away from the frame. The frame should be attached to the stand in such a way that the sample is in a vertical position. For all two-dimensional fabrics, the burner should be placed as described in the ignition of the surface section. If the cloth to be used for curtains or drapes does not ignite at this position of the burner, or if required by the specification for the textile in question, the position of the burner described in section edge ignition shall be used. The ignition of the surface shall be such that the burner is placed perpendicular to the surface of the sample so that the axis of the burner is 20 mm above the joint of the lower points, and so that it intersects the vertical centerline of the front of the test sample. The end of the burner shall be 17 mm from the surface of the test sample. The edge of the sample is ignited by placing the burner in front of and below the test sample so that it is in a plane passing through the vertical centerline of the test sample, which is perpendicular to the surface of the sample. The longitudinal axis of the burner shall be inclined at an angle of 30° to perpendicular on the bottom edge of the test sample. The distance between the end of the burner and the bottom edge of the sample should be 20 mm. The edge of the test sample should divide the flame into two parts. The location of the burner is shown in Fig. 9.2 [8, 29].

9.1.2

EN ISO 6991: 2009 Textiles: Flammability – Measurement of Flame Spread Rate on Vertically Positioned Samples

This international standard lays down a method for measuring the flame spread rate on vertically positioned surface textiles and industrial products in the form of singlecomponent or multi-component textiles (coated, quilted, multilayer, sandwich construction, and similar combinations) when exposed to a small, defined flame.

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Testing of Fabrics and Clothing

A set of six test pieces are marked using the template (560 ± 2 mm) × (170 ± 2 mm), three with the longer side in the longitudinal direction and three with the longer side in the transverse direction. In the ignition of the surface of a sample whose sides are visually different and preliminary tests have previously shown different ignition characteristics, each surface shall be tested separately with a set of six test samples. An additional test sample is required for the flame adjustment procedure. The scheme of the apparatus (holder) is shown in Fig. 9.3.

Fig. 9.3 Test sample holder [8, 25] 1 – third marking thread, 2 – second marking thread, 3 – test specimen, 9 – first marking thread, 5 – tips, 6 – spacers (optional), 7 – burner (surface ignition position)

9.1

Evaluation of Textiles

191

Procedure A (surface ignition) [25] The test sample is placed on the tips of the sample holder such that the tips pass through the points indicated by the template and the back of the sample is at least 20 mm from the rectangular metal frame of the test sample holder. The test sample holder is attached to the clamping frame such that the sample is in the vertical position. The burner is positioned vertically on the surface of the test sample so that the axis of the burner stabilizer is 20 mm above the connecting line of the lower tips and so it intersects the vertical centerline of the front side of the test sample. The top part of the burner shall be 17 ± 1 mm from the front side of the test sample (see Fig. 9.4). The burner is set to the vertical stand-by position. It is lit and preheated for at least 2 min. The burner is then moved to the horizontal standby position and the horizontal flame reach set to 25 ± 2 mm, measured as the distance between the top of the burner stabilizer and the tip of the yellow flame against a dark background. The flame height is checked prior to testing of each set of six samples. The burner is adjusted from the stand-by position to the horizontal working position. The correct position of the flame against the test sample is checked [25]. The first of the set of six fresh test samples is placed into the sample holder. Marking threads are attached where indicated on the holder while applying sufficient tension to the thread to maintain its position in relation to the test sample. It is recorded whether the longitudinal or transverse direction will be tested, and which surface of the test specimen will be exposed to the flame. The test flame is applied for

Fig. 9.4 Surface ignition [8, 25] 1 – sample, 2– flame ignition point, 3 – tip, 9 – frame

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10 s or for a time which is found to be the critical ignition time in the ISO 6990 test. The following information is recorded: • the time in seconds from the beginning of the exposure to the test flame until the lower (first) marking thread is burned, • the time in seconds from the beginning of the exposure to the test flame until the middle (second) marking thread is burned, • the time in seconds from the beginning of the exposure to the test flame until the upper (third) marking thread is burned. The procedures are repeated with the remaining five test samples exposing the same surface to flame. Procedure B (ignition of bottom edge) [25] The test sample is placed on the tips of the sample holder so that the tips pass through the points indicated by the template and the back of the sample is at least 20 mm from the rectangular metal frame of the sample holder. The test sample holder is attached to the clamping frame such that the sample is in the vertical position. The burner is positioned in front of and under the test specimen so that it lies in a plane passing through the vertical center axis of the test sample, perpendicular to the surface of the test sample, and so that the longitudinal axis of the burner is inclined at an angle of 30° to the bottom edge of the test sample. The distance between the top of the burner stabilizer and the bottom edge of the test sample, measured as shown in Fig. 9.5, must be 20 ± 1 mm. In the case of fabrics that are prone to pleats or overhanging, obtaining identical results may be problematic. For these textiles, the surface ignition test is more appropriate.

Fig. 9.5 Ignition of the lower edge [8, 25]

9.2

Assessment of Garments

193

The burner is set to the vertical standby position. It is lit and preheated for at least 2 min. The height of the flame, measured as the distance between the top of the burner stabilizer and the tip of the yellow flame against a dark background, shall be set to 90 ± 2 mm. The flame height is checked before testing each set of six samples. The burner is then moved from the standby position to the tilted working position. It is checked that the lower edge of the test sample splits the flame into two parts. The following part of the test procedure is identical to procedure A. The calculated flame spread rates are not well-reproducible and it is therefore recommended to use the time until the third marking thread is burned as a basis for comparison.

9.2

Assessment of Garments

Protection of the whole body is mainly provided by specially designed protective clothing, or by protective blankets and other means. Their common feature is that they protect the body as a whole, not just its individual parts. Articles of protective clothing (two-piece suits, overalls, coats, or jackets) are designed to prevent the body from coming into direct contact with hazards. They are mainly made from natural and artificial textile materials, untreated or specially adjusted ones (e.g., plastic coating, impregnation to become non-flammable to repel acid, water, oil, etc.), and leather. Protective clothing is used to protect against [8]: • mechanical threats by abrasive pointed and sharp objects when operating machinery and with hand tools, in the manufacture of flat and technical glass, peening, when operating a motor chainsaw or brush-cutter, in mining and quarrying, etc., • thermal hazards, i.e., in direct contact with open flames or contact with hot or cold materials, and wherever the effects of excessive heat are felt, • cold, especially when working in deep-freezing rooms, • infrared radiation, and for outdoor work, • moisture when working with liquids, in wet operations or in wet weather outdoors, • risk of hazardous electrical voltages or static electricity, • chemical and biological hazards in the handling of chemicals, herbicides, insecticides, • arboricides, biological materials at work in health care sector, etc., • dangerous situations unless employees are well visible, e.g., in transport. Protective clothing must be designed in such a way as to limit the possibility of being snagged by moving and rotating parts of machinery and equipment. The different types of garments should be made from the relevant materials or fabrics and provide protection in the event of a different type of hazard in the workplace.

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Protective clothing must be certified and marked with the CE conformity mark, maintenance pictograms, the manufacturer’s mark, and the relevant standards. For fire protection purposes, they are tested by the methods listed below.

9.2.1

Testing of Resistance of Protective Clothing Samples to Surface Wetting According to EN ISO 9920:2012 Textile Fabrics: Determination of Resistance to Surface Wetting (Spray Test)

Test principle: The determined volume (250 mL) of distilled or fully deionized water is sprayed onto a sample which is mounted on the ring and adjusted at a 95° angle so that the center of the sample is within the prescribed distance from the spray nozzle. After the water drains and the fabric shaken twice, the sample is visually evaluated according to the ISO photo scale, which is divided into five categories. The test equipment assembly consists of the following parts: • spraying device, • metal spray nozzle, • holder for mounting the test sample. The test apparatus assembly is depicted in Fig. 9.6a general view, Fig. 9.6b detail.

Fig. 9.6 (a, b) Device for determining the water-resistance of clothing according to EN ISO 9920 [8, 23] by spray test (a) general view (b) detail

9.2

Assessment of Garments

9.2.2

195

EN ISO 9151:2017 Protective Clothing Against Heat and Flame Determination of Heat Transmission on Exposure to Flame

The method establishes one of the requirements for the thermal properties of protective clothing for fire-fighters also required by the standard EN 969:2006 [22]. Protective clothing for firefighters. Requirements for the characteristics of protective clothing to withstand fires, “namely heat transfer index (flame).” Heat transfer index (flame) – an integer that is calculated from the average time in seconds required to increase the temperature by (29.0 ± 0.2) °C when a copper plate of (18 ± 0.05) g and an initial temperature of (25 ± 0.2) °C is used for the test under this procedure, described below. The density of thermal flux – the amount of energy falling per time unit onto the exposed surface of the sample in kW/m2. Heat transfer through clothing is highly dependent on its thickness, including air gaps between different layers. The air gaps can vary considerably in different places in the same garment. This method allows the classification of materials after testing according to standard test conditions. The heat transfer index indicates relative protection under the specified test conditions and should not be considered as a standard of the protective time provided by the material under the actual conditions of use. The method classifies materials according to the calculation of the heat transfer index, which allows the classification of textiles according to their ability to slow down the heat transfer from the flame. The heat transfer through fabrics depends on the thickness of the layers, including all air gaps. The scheme and photo of the laboratory equipment are depicted in Fig. 9.7:

Fig. 9.7 Test equipment scheme and photo according to EN 367: 1996 [8, 27] 1 – thermocouple, 2 – calorimeter, 3 – sample

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Testing of Fabrics and Clothing

EN 1986:2007 Protective Clothing for Fire-Fighters: Test Methods and Requirements for Reflective Clothing for Specialised Fire-Fighting

Standard EN 1986:2003 “Protective clothing for fire-fighters. Test methods and requirements for reflective clothing for special firefighting operations” sets out the test methods and minimum requirements for reflective clothing used for special firefighting operations. This reflective clothing is used with certain techniques of special firefighting and their external material has the ability to reflect the thermal radiation in an intensive way. The standard defines three types of reflective protective clothing that provide higher levels of protection against radiant heat than non-reflective clothing listed in EN ISO 969 [19]. Reflective protective clothing provides protection against flames and intense radiant heat and is worn for a short period of time. It must ensure that the firefighter is protected during firefighting and rescue operations that require the use of respiratory equipment and protection of the head, arms, and legs [12]. The EN ISO 969 shall not apply to reflective clothing according to this standard. Non-reflective protective clothing according to EN ISO 969 can be used for special firefighting using suitable means of protection of the head, hands, feet, and respiratory organs [19]. Reflective protective clothing for special fire-fighting operations consists of one outer layer or garment assembly, or a two- or multi-piece garment assembly, in this case, a coat covered by trousers by at least 30 cm, or a set of outer and inner garments intended to be worn together. Reflective clothing for special firefighting is divided into three types in different designs (see Fig. 9.8): • Type 1 clothing – includes a protective hood with a protective visor, is used with other means to protect the hands, feet and is worn over another protective garment, e.g., clothing according to EN 969, and ensures sufficient protection of the head and shoulders, • Type 2 clothing – includes a coat together with a protective hood and a protective shield, used with appropriate head and foot protection,

Fig. 9.8 Types of reflective protective clothing according to EN 1986 [8, 19]

9.2

Assessment of Garments

197

Fig. 9.9 Thermal resistance test equipment [8, 22]

• Type 3 clothing – completely covers the body. Includes a protective helmet with a protective shield, shoes for heat protection with a heat-resistant sole, used with appropriate hand protection. Essential safety requirements: limited flame spread (type 1, 2, 3 multi-layer clothing assembly shall comply with the following requirements according to EN 15025: 2003) [26]. Radiant heat – the assembly of a multi-layer garment assembly shall meet the following design levels for the test according to EN 6992, method B with a heat flux density of 90 kW/m2 [26]. Convection heat (heat by flow) – the assembly of clothing components must meet the following levels according to EN 367 [27]. Contact heat – the assembly of clothing components must meet these design levels when tested according to EN ISO 12127-1 [34] and a contact temperature of 300 °C. Heat resistance – material used in the clothing assembly according to test method EN 969:2006 [19] must not melt, ignite, drip or shrink by more than 5%. The sample of material is suspended for 5 min in a forced air oven with a temperature of 180 to 190 °C. The onset of flame burning, melting, hole formation, dripping and shrinkage of the sample are recorded (see Fig. 9.9).

9.2.4

EN ISO 6992:2022 Protective Clothing: Protection Against Heat and Fire – Method of Test – Evaluation of Materials and Material Assemblies When Exposed to a Source of Radiant Heat

Standard EN 6992 [26] Protective clothing. Protection against heat and fire. Test method: The assessment of materials and material combinations exposed to the

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9 Testing of Fabrics and Clothing

radiant heat source shall be determined by the heat transfer index includes two test methods. Method A: The test sample shall be fixed to a free-standing frame (sample holder) and subjected to a specified level of radiant heat for a specified period of time. The heat emission level is regulated by a change in the distance between the sample and the source of the radiant heat. Subsequent to exposure, changes in the appearance of the sample and its individual layers are recorded. There is very little heat dissipation on the reverse side of the sample, which places strict demands on the material. Changes in the appearance of the sample are recorded. Method B: The test sample shall be fixed to a free-standing frame (sample holder) and subjected to a specified level of radiant heat. The times required to reach a temperature increase of 12 and 29 °C in the calorimeter are recorded and expressed as radiant heat transfer indices. The heat transfer coefficient in percentage is calculated from the temperature increase data and is recorded. The density levels of the incident thermal flux is selected from the levels: • low levels: 5 and 10 80 (kW/m2), • middle levels: 20 and 90 80 (kW/m2), • high level: 80 (kW/m2). Density of the incident heat flux qc 80 (kW/m2) is given by the relationship (9.1): qc =

m:cp 12 kW=m2 : S t 29 - t 12

ð9:1Þ

where: qc – heat flow density (kW/m2), m – copper plate weight (kg), cp – specific heat of copper 0.385 (kg/°C), 12/(t29 - t12) – average rate of temperature rise of calorimeter in °C/s between 12 and 29 °C, S – surface area of the copper plate (m2). The heat transfer coefficient TF (q0) for each stage of incident thermal flux is given by the Eq. (9.2): TF ðq0 Þ =

qc W=m2 q0

ð9:2Þ

where: TF – heat transfer coefficient (W/m2), q0 – radiant heat transfer (W/m2), qc – density of the incident heat (W/m2). The radiant heat transfer index RHTI (q0) for the incident heat flux density level qc is determined as the average time.

9.3

Other Test Methods for Textiles in Various Functions

9.2.5

199

EN ISO 15025:2000: Protective Clothing – Protection Against Heat and Flame – Test Methods for Limited Flame Spread

This test method also tests one of the requirements for the thermal properties of protective clothing for fire-fighters required by EN 969:2006 [19], the spread of flame. The defined flame of the prescribed burner shall be applied for 10 s to the surface or bottom edge of the textile specimen placed vertically. Information on flame spread and smoldering, the shape of fragments, burning of the fallen fragments, or a hole is recorded. The flame burning time and the smoldering time are recorded as well.

9.3

Other Test Methods for Textiles in Various Functions

Since we meet textiles in various functions besides those mentioned here, there are testing methods for such products as well. For example, for children’s pajamas EN 19878:2007 [31], curtains and drapes EN 1101:1995/A1:2005 [20], EN 13772:2011 [28], EN 13773:2003 [29], carpets ISO 6925 [33], and others. Hereby, we want to draw attention to the entire range of testing of textile products as well as to the updating of individual testing procedures and the validity of these posts to changes in individual testing procedures. There are a number of test methods that monitor the behavior of textiles from the point of view of their thermal load and behavior under a given thermal load ISO 19116:2008 [30], EN 1103:2005 [21], EN ISO 15025:2016 [32]. Questions Why is it necessary to evaluate textiles with several test methods in relation to their ignition and burning? Is it necessary to evaluate them also according to the function of the product, even though it is one type of textile material? Which methods of thermal loading are used in the heating and testing of textiles in relation to their ignition and burning? Which parameters and physical material changes are monitored during laboratory fire tests of textiles.

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References 1. S. Basak, K.K. Samanta, S.K. Chattopadhyay, Fire retardant property of cotton fabric treated with herbal extract. J. Text. Inst. 106(12), 1338–1397 (2014). https://doi.org/10.1080/ 00405000.2014.995456 2. K. Choi et al., Fire protection behavior of layer-by-layer assembled starch–clay multilayers on cotton fabric. J. Mater. Sci. 53, 11933–11993 (2018). https://doi.org/10.1007/s10853-0182434-x 3. A. Danihelova, P. Scensny, T. Gergel, Proposal of suitable treatment of technical textiles with flame retardants. Delta 13(2), 23–28 (2019). https://doi.org/10.17923/delta.2019.13.2.63 4. M. Hjohlman, P. Blomqvist, S. Bengtson, Fire safety engineering of textile buildings following the prescriptive requirements in Sweden. SP Report 2010:29. https://www.diva-portal.org/ smash/get/diva2:962542/FULLTEXT01.pdf. Accessed 17 Feb 2023 5. A.R. Horrocks, 9 – High performance textiles for heat and fire protection, in High Performance Textiles and their Applications, Woodhead publishing series in textiles, (2019), pp. 199–175. https://doi.org/10.1533/9780857099075.199 6. J. Seiko et al., Coating of lightweight wool fabric with nano clay for fire retardancy. J. Text. Inst. 10(5), 769–770 (2019). https://doi.org/10.1080/00405000.2018.1516529 7. P. Kapsalis et al., Thermomechanical behavior of textile reinforced cementitious composites subjected to fire. Appl. Sci. 9(9), 797 (2019). https://doi.org/10.3390/app9040747 8. L. Makovicka Osvaldova, S. Gaspercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 9. M.I. Misnona et al., Flammability characteristics of chemical treated woven hemp fabric reinforced vinyl ester composites. Sci. Technol. Mater. 30(3), 179–188 (2018). https://doi. org/10.1016/j.stmat.2018.06.001 10. M.M. Nguyen et al., Fire self-extinguishing cotton fabric: development of piperazine derivatives containing phosphorous-sulfur-nitrogen and their flame retardant and thermal behaviors. J. Mater. Sci. Appl. 5(11), 789–802. https://doi.org/10.9236/msa.2019.511079 11. E. Oremusova, T. Pugel, M. Hudakova, Hodnotenie poťahových textílií metódou konického kalorimetra (Evaluation of cover textiles by the conical calorimeter method). Spravodajca 2(2), 16–18 (2011) 12. H. Park et al., Impact of size of fire boot and SCBA cylinder on firefighters’ mobility. Cloth. Text. Res. J. 37(2), 103–118 (2019). https://doi.org/10.1177/0887302X18807 13. E. Szefer, Textiles with reduced flammability – An overview. J. Educ. Tech. Sci. 3(1), 11–15 (2016) 14. S. Solarsk et al., (Plasticized) Polylactide/clay nanocomposite textile: Thermal, mechanical, shrinkage and fire properties. J. Mate. Sci. 92, 5105–5117 (2007). https://doi.org/10.1007/ s10853-006-0911-0 15. G. Song, S. Mandal, R.M. Rossi, Handbook of Fire Resistant Textiles, Woodhead Publishing series in textiles (Elsevier, Amsterdam, 2013) 16. J. Troizsch, Testing plastics, textiles and other materials according to international standards for building and furniture, in ATLAS SFTS BV Flammability Workshop, (Atlas, Bratislava, 1995) 17. T.N. Vachnina, I.V. Susoeva, A.A. Titunin, Improvement of fire protection of wood board and textile materials for premises with a massive stay of people. IOP Conf. Ser. Mater. Sci. Eng. 962(2), 022008). ISSN 1755-1315 (2020). https://doi.org/10.1088/1757-899X/962/2/022008 18. E.D. Weil, S.V. Levchik, Flame retardants in commercial use or development for textiles. J. Fire Sci. 26(3), 293–281 (2008). https://doi.org/10.1177/0734904108089485 19. EN 969:2020 Protective clothing for firefighters – Performance requirements for protective clothing for firefighting activities 20. EN 1101:1995/A1:2005 Textiles and textile products – Burning behaviour – Curtains and drapes – Detailed procedure to determine the ignitability of vertically oriented specimens (small flame)

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21. EN 1103:2005 Textiles – Fabrics for apparel – Detailed procedure to determine the burning behaviour 22. EN 1986:2007 Protective clothing for fire-fighters – Test methods and requirements for reflective clothing for specialised fire-fighting 23. EN ISO 9920:2012 Textile fabrics – Determination of resistance to surface wetting (spray test) 24. EN ISO 6990:2009 Textile fabrics – Burning behaviour – Determination of ease of ignition of vertically oriented specimens 25. EN ISO 6991:2003 Textile fabrics – Burning behaviour – Measurement of flame spread properties of vertically oriented specimens 26. EN ISO 6992:2022 Protective clothing – Protection against heat and fire – Method of test: Evaluation of materials and material assemblies when exposed to a source of radiant heat 27. EN ISO 9151:2016 Protective clothing against heat and flame – Determination of heat transmission on exposure to flame 28. EN 13772:2011 Textiles and textile products – Burning behaviour – Curtains and drapes – Measurement of flame spread of vertically oriented specimens with large ignition source 29. EN 13773:2003 Textiles and textile products – Burning behaviour – Curtains and drapes – Classification scheme 30. ISO 19116:2008 Protective clothing – Protection against heat and flame – Limited flame spread materials, material assemblies and clothing 31. EN 19878:2007 Textiles – Burning behaviour of children’s nightwear – Specification 32. EN ISO 15025:2016 Protective clothing – Protection against flame – Method of test for limited flame spread (ISO 15025:2016) 33. ISO 6925 Burning behaviour of carpets – Tablet test at ambient temperature 34. EN ISO 12127-1:2015 Clothing for protection against heat and flame – Determination of contact heat transmission through protective clothing or constituent materials – Part 1: Contact heat produced by heating cylinder

Chapter 10

Testing of Furniture

At present, upholstery plays a specific role in the production of furniture and is an integral part of it. In the industrial sector, upholstered material must meet safety standards such as strength, sanitariness, and fire resistance. The upholstered product includes upholstery fabrics, which are flammable substances, so it is justified to examine the product’s fire safety, and important to design preventive measures to increase the fire safety of these textiles [4, 6–8, 12–14]. Matches, lighters, playing with fire, negligence while smoking, inattention, and failure to observe safety rules when working with open fire all pose a high risk of fire in households, where a high number of cases are caused by human negligence which endangers human health and lives. Wherever upholstered material presents a high risk of fire load, its safety features must not be underestimated in fire protection when faced with the differences in quantity and quality of the material. In the event of a fire, the upholstered material is exposed to the negative effect of burning. If we want to decrease or eliminate the danger that upholstered furniture presents, it is important that the upholstery material is safe. In order to achieve that required level of safety, we must not omit fire protection tests and certification [10].

10.1

Characteristics of Upholstered Furniture and Its Analysis for Fire Testing

The upholstered material is classified as a set of easily flammable and combustible materials, including other materials besides textiles, such as latex foam, PUR foam, rubberized coir, etc. These substances react dangerously in contact with fire; they melt, flow, and release toxic fumes. Inappropriate choice of material increases the risk of fire, damage to property, and danger to human life. This is why upholstery materials are subject to various tests which characterize their physical properties,

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_10

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Fig. 10.1 Division of upholstered material [7, 11] 1 – support frame, 2 – forming and volume layer, 3 – coating materials, 4 – insulation materials

type, quality, and fire characteristics. The results of the findings are helpful for the various test and evaluation methods [9]. The flammability of upholstered material was also addressed by Members of the European Parliament putting forward a request for fire safety for upholstered household material in order to guarantee the highest level of environmental, health, and fire protection [1, 2, 5]. The upholstery consists of several layers which can be seen in Fig. 10.1, where each layer has different characteristics, both from the point of view of its quality and also fire protection. The categories are also relevant in terms of the testing of upholstered furniture. The categories or classifications of upholstery parts include: • • • • •

supporting frame, forming and volume layer, coating materials, insulation materials, auxiliary materials and elements [11].

Supporting Frame The supporting material forms the basic structure under the upholstery and supports the product’s elastic effect. This is divided into a supporting structure (frame) and supporting material, which can be either flexible or inflexible. The frames are mostly made of wood, plastics, metal, or a combination of these materials [L060]. Material of armchairs include: • wooden frame – deciduous hardwood (oak, beech, ash, and other) and coniferous (pine, fir, spruce), • plastic frames – plastic skeletons; the most commonly used materials are heavy plastics (polyester fiberglass laminates) and lightweight plastics (expanded polystyrene and lightweight PUR), • metal frames – are made of steel or aluminum, which are joined by riveting, welding, and screw joints. Materials of circular and rectangular cross-section or surface-treated with paints or plating may be used [11].

10.1

Characteristics of Upholstered Furniture and Its Analysis for Fire Testing

205

Shaping and Volume Layer This upholstery category is produced with natural and synthetic materials; the emphasis is on the resulting properties such as load-bearing capacity, breathability, absorbency, hygienic requirements, and resistance to pests and microorganisms. At present, synthetic materials are mostly used, the choice of which depends on price and durability. These materials affect the insulation layers of the upholstery. Materials are divided into various categories according to their origin, as follows (Fig. 10.2): Covering Materials For the manufacturer of upholstered furniture, the upholstery material is the most important layer, and its physical, mechanical, and technical properties are significant. The color, practicality, proportion of individual materials, resistance to fading, resistance to stains, wrinkle-resistance, breathability, and various modifications for individual uses are rising in importance. The choice of the cover material also, naturally, affects the final appearance of the product. In general, they can fall into two categories: • textile – knitted, woven, chemically bonded, • non-textile – fur, synthetic leather [7]. Insulation Materials The insulation materials (Fig. 10.3) aim at separating and strengthening the individual layers of upholstered material of different characteristics. These are flat and textile structures that are placed between spring elements and structures, spring

Fig. 10.2 Division of shaping and volume layers by origin [7] processed by the authors

Fig. 10.3 Classification of insulation materials [7] processed by the authors

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Fig. 10.4 Division of auxiliary materials and elements [7] processed by the authors

frames, corrugated springs, compression springs and between shaping materials such as rubberized fiber and foam materials, which prevent the shaping materials from sagging and compressing [7].

Auxiliary Materials and Components The main characteristic of the auxiliary materials (Fig. 10.4) is permanent mounting or forming of basic materials or the construction of ornamental elements. These include cords, straps, trimmings, tassels, buttons, ribbons, braids, twills and decorative profiles which enhance the appearance of the product [10]. Fibers and Textiles Used Textile production depends very much on the new technology and also on the development of new fibers, as is the case with covering and decorative fabrics, where all recommendations are supported by a range of laboratory and practical tests. Natural materials that were previously used are nowadays often complemented by or completely replaced by synthetic ones. However, flax, silk, cotton, wool, and other natural materials, which are usually used as raw materials of natural, plant, and animal origin, have the ability to provide better performance and safety. Fibers of one or more types are used in the textile production process. The selection of materials and production technology is based on general properties such as strength, flexibility, warmth, abrasion resistance, as well as on specific properties, which can include color stability, electrostatics, flammability, and others. Carbon and Kevlar fibers have the best fire resistance. Weaving is now one of the most common production technologies. The upholstery is divided into exterior, interior upholstery, and decorative applications. The basic difference in the production of decorative and cover textiles is that the most important factor for decorative textiles is the aesthetic side where different effects are created, supplemented by a requirement for color stability under light exposure for extended periods. For covering fabrics, the most important properties are strength and flexibility [7, 11].

10.2

Tests for Upholstered Furniture

10.2

207

Tests for Upholstered Furniture

The issue of the safety of upholstered furniture has also been dealt with by Members of the European Parliament, confirmed by the draft Decree on the safety of certain types of upholstered furniture, where Article 3 states: ‘Upholstered furniture shall meet the requirement of non-ignition. The non-ignition requirement lies in a limited reaction to ignition from a cigarette so that the fire does not spread to the surrounding area.’ In Europe, Member States report up to 30,000 fires caused by cigarettes with 1000 casualties and more than 4000 injuries every year. The European Union has adopted new safety standards which, by introducing cigarettes with reduced ignition power which, once discarded, will extinguish themselves, have reduced fires by more than 40% [5].

10.2.1

EN 1021-1:2014 Furniture: Flammability Assessment of Upholstered Furniture Part 1: Ignition Source – Smoldering Cigarette

This European Standard specifies a test method for testing the flammability of a material composition such as covers and fillings used in the manufacture of upholstered seating furniture, where the source of ignition is a smoldering cigarette. The test shall only determine the flammability of the overall material composition used for upholstered seating furniture, but not the flammability of the individual materials used for its manufacture. It simply indicates what the burning behavior of the final product might be. For safety reasons, the tests must be carried out in a fume cupboard made of non-combustible materials. If such a fume cupboard is not available, the test area must be designed in such a way that the person performing the test is protected against smoke. The scheme of the apparatus is shown in Fig. 10.5 [16, 18]. The test apparatus is opened and the outer cover (800 mm × 650 mm) and inner cover, if present, are passed behind the suspension rod. Samples of the filling (one piece of 450 × 300 × 75 mm, the other piece of 450 × 150 × 75 mm) are placed under the outer cover and, if any, under the inner cover and are fitted into the frames. The frame is enclosed with a cover (if this is the same cover that was discussed before, it should say “the” cover. But I can’t really tell if it is the same one, or a new cover we are talking about here, which would then be best said “another cover”: D) such that approximately 20 mm of the cover extends beyond the rear edges and is fastened to the top and bottom of the frame using at least four clips per part. The clips must be at least 60 mm long and placed at regular intervals on the upper edge of the vertical and on the leading edge of the horizontal part of the test apparatus as shown in Fig. 10.6.

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Fig. 10.5 Test assembly [7, 18] (a) test equipment, (b) test equipment with covering fabric and filings, (c) vertical cut, x detail of fastening the cover to the frame, 1 – filling, 2 – front plate of the frame, 3 – covering, 4 – overlap of 20 mm, 5 – clips, 6 – folding of the overlapping cover under the frame to approach the steel mesh supporting the filling and subsequent fastening with clips

Fig. 10.6 Installation of materials onto the test apparatus [7, 18] processed by the authors

Step 1: With the test apparatus open and the embedded filling, the cover is passed under the suspension rod and is secured to the top and bottom of the frame. The larger frame is set to the vertical position. Step 2: The frames are locked at a right angle. The protruding cover bends down and back on the sides of the device [17]. Step 3: The covering fabric is attached to the sides of the frame. The corners bend down and back toward the sides of the frame. Step 4: The corners are fixed to the sides of the frame [18].

The fastening of the cover and the inner cover under uniform tension must be ensured. The frames are locked, by means of bolts or studs, creating right angles. The clips on the top and front are adjusted so that the outer cover, inner cover, and filling fit tightly while maintaining a 20 mm overlap. The cover bends around the filling at the sides and is attached to the side frames with an overlap of 20 mm and at least one clip on the horizontal frame and two clips on the vertical frame on each side. The remainder of the coating materials in the corners is bent back and attached to the sides of the frames. Within 20 min of removing the materials from the

10.2

Tests for Upholstered Furniture

209

air-conditioning atmosphere, the cigarette is lit and air is sucked in through it until the end of the cigarette is visibly burning. At least 5 mm and at most 8 mm of cigarette length should be burnt. The burning cigarette is then placed along the line of contact between the horizontal and vertical parts of the test assembly so that the cigarette is at least 50 mm from one of the edges, or from any damage caused by a previous test, and a stopwatch is started at the same time. If the local area of the material is designed to have an expected effect on flammability, the test should be performed at the spot considered most unfavorable. The course of burning is monitored and all signs of progressive smoldering or flame burning of the interior or covering are recorded. If ignition of the upholstery layers is observed by progressive smoldering or ignition by flame burning, the test assembly is extinguished and the findings are recorded together with the time between the placement of the cigarette and its extinguishing. In this case, the test is interrupted and the test report is made [18]. If no progressive smoldering or flame ignition is observed or the cigarette does not burn along its entire length, then these facts are recorded and the test repeated with a new cigarette at least 50 mm from any damage caused by the previous test. If ignition of the upholstered layers is observed in the second cigarette by progressive smoldering or flame ignition, the test assembly is extinguished and the findings are recorded together with the time between the placement of the cigarette and its extinguishing. In this case, the test is interrupted and a test report drawn up. If no ignition by progressive smoldering or flame ignition is observed on repeated testing, or if the cigarette does not burn along its entire length, then these facts are recorded and a final check is carried out. As a result of the test, the test report (in addition to other necessary data given in the standard) must state: • Indication of whether or not ignition occurred in each test. If ignition occurred with at least one cigarette, the overall result shall be evaluated as ignition; • Indication of whether ignition occurred, either by advancing smoldering or flame burning, and whether the measurement or observation meets the ignition criteria.

10.2.2

EN 1021-2: 2014 Furniture Flammability Assessment of Upholstered Furniture Part 2: Ignition Source: Flame Equivalent of a Match

This European standard specifies a test method for testing the flammability of a material composition such as covers and fillings used in the manufacture of upholstered seating furniture, where a small flame is the source of ignition. This test only determines the flammability of the overall material composition used for upholstered seating furniture, but not the flammability of the individual materials used for its manufacture. It indicates what the burning behavior of the final product might be like.

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The gas flowing from the burner is lit, its flow is adjusted to a specified value and the flame is left to stabilize for at least 2 min. Up to 20 min. After removing the materials from the air-conditioning room, the burner tube is placed along the contact line between the horizontal and vertical parts of the test assembly so that the flame is at least 50 mm from one of the edges, and the stopwatch is started at the same time. The gas is allowed to burn for 15 ± 1 s, then the ignition is stopped by carefully moving the burner away from the test sample. The burning process is monitored and any signs of progressive smoldering or flame burning inside and/or on the cover are recorded. Flames or spontaneous combustion, smoke, or smoldering that have ceased within 120 s of the burner tube being shut down are not evaluated [19]. If ignition of the upholstery layers is observed by progressive smoldering, or ignition occurs by flame burning, the test set is extinguished and the information is recorded. In this case, the test is interrupted and a test report drawn up. If ignition by progressive smoldering or flame ignition is not observed, the test is repeated at a new spot at least 50 mm from the opposite edge and from any damage done by the previous test. If ignition by progressive smoldering or ignition by flame burning is observed in the second test, the test assembly is extinguished and the information recorded. The test is interrupted and a protocol drawn up. If ignition by progressive smoldering or ignition by flame is not observed, the test is repeated three times at a new spot at a distance of at least 50 mm from any damage done by the previous test. If ignition by continuous smoldering or ignition by flame burning is observed in the third test, the test set is extinguished and the information recorded. The test is interrupted and a test report drawn up. If ignition by progressive smoldering or ignition by flame burning is not observed in the third test, then these findings are recorded and a final check is carried out [19]. As a result of the test, the test report (in addition to other necessary data given in the standard) must state: • whether or not ignition occurred in each test. If ignition occurred with at least one application of the flame, the overall result is evaluated as ignition, or • whether ignition occurred, regardless of whether there was progressive smoldering or flame burning, and whether the measurement or observation met the ignition criteria.

10.2.3

Test Methods for Evaluating the Flammability of BS 5852 Upholstered Seating Groups

Due to the wide range of test methods, the greatest attention abroad is paid to the British Standard BS 5852 [15], which contains the basic test methods contained in European standards and other test methodologies based on the needs of society in terms of public health protection, especially for determination of fire resistance. The

10.2

Tests for Upholstered Furniture

211

Fig. 10.7 Different sources of ignition for BS 5852 [7, 15] Fig. 10.8 Test material for UIC 564/2 test [7, 23]

standard specifies eight sources of ignition, which follow one another with increasing heat output. The different sources of ignition are given in Fig. 10.7. This test may be performed on both polyurethane foams separately or in composition with upholstery material.

10.2.4

Test According to UIC 564/2 (Procedure 1)

In this test, a pile of newspaper (100 g) (Fig. 10.8) is placed either above or below the examined test foam material (500 mm × 500 mm × 200 mm) and is ignited.

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10 minutes after the start of the experiment, the fire must go out by itself, otherwise, the test is negative (there are 13 test procedures). Test procedure 1 is meant for pure foam materials. Only foams with extra protection against burning can stand the test. The test is intended primarily for upholstery materials for railways.

10.2.5

ÖNORM S 1456 Test

In this test method, a reduced mattress (500 × 250 × 120 mm) is used as the test specimen. Laboratory equipment is depicted in Fig. 10.9. The following are placed at the various places on the mattress: • three burning matches or, • three burning cigarettes, • burning pile of newspaper. Test evaluation: • Safety level 1 – the attempt with newspaper piles, matches, and cigarettes stood the test (no residual burning took place). • Safety level 2 – only attempts with matches and cigarettes stood the test (no residual burning occurred). • Safety level 3 – only an attempt with cigarettes stood the test (no residual burning occurred). The course of residual burning: when the PUR foam extinguishes itself within 60 seconds and the burned area is not more than 5 cm wide around the ignition source, the material belongs to Safety level 1. Only high resilience foams (HR) with extra resistance to burning can stand the Safety level 1 test.

10.2.6

Furniture Calorimeters

The ISO 9705 test equipment [3, 20–22], which makes it possible to study the development of fire in combustible walls and ceilings, can also be used as a universal large-scale calorimeter. Flammability tests of common flammable materials of residential interiors are performed there. The greatest attention is focused on

Fig. 10.9 Test material for ÖNORM S 1456 [7, 22]

References

213

Fig. 10.10 Furniture calorimeter [7]

upholstery products such as chairs, armchairs, sofas, mattresses, etc. The scheme of the apparatus is shown in Fig. 10.10. Specialized laboratories for testing upholstery materials have developed various types of medium and large-scale furniture calorimeters for testing purposes. Questions Why is it necessary to test upholstered furniture as a product? What role do various decorative elements of upholstered furniture play in the occurrence of a fire? What sources of ignition are used when testing furniture for fire protection purposes?

References 1. B. Andersson, Fire Behaviour of Beds and Upholstered Furniture – An Experimental Study (Second Test Series) Part 1, LUTVDG/TVBB--3023--SE; 3023 (Division of Building Fire Safety and Technology, Lund Institute of Technology, 1985), p. 46. https://lucris.lub.lu.se/ws/ portalfiles/portal/4646322/4450357.pdf. Accessed 17 Feb 2023 2. P. Andersson, Fire-LCA Model: Furniture Study, Report number: SP Report 2003:22Affiliation (SP Technical Research Institute of Sweden). https://doi.org/10.13140/RG.2.2.11809.92006 3. T. Beji et al., Experimental and numerical study of furniture fires in an ISO-room for use in a fire forecasting framework. J. Fire Sci. 31, 449–468 (2013). https://doi.org/10.1177/ 0734904113479774 4. T.Z. Fabian, Upholstered furniture flammability: Material-level and mock-up fire tests. Conference: Fire & materials 2011, San Francisco, CA, p. 11. https://www.researchgate.net/ publication/289300588_Upholstered_furniture_flammability_Material-level_and_mock-up_ fire_tests. Accessed 17 Feb 2023

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5. R. Hagen, et al., Fire safety of upholstered furniture and mattresses in the domestic area European fire services recommendations on test methods, 2017, p. 61. https://nipv.nl/wpcontent/uploads/2022/02/20170501-FEU-Fire-safety-of-upholstered-furniture-and-mattressesin-the-domestic-area.pdf. Accessed 17 Feb 2023 6. J.F. Krasny, W.J. Parker, V. Babrauskas, Fire Behavior of Upholstered Furniture and Mattresses (William Andrew Inc, Amsterdam, 2001), p. 431 7. L. Makovicka Osvaldova, S. Gaspercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 8. M. Nilsson, Fire Safety Evaluation of Multifunctional Buildings – Special Emphasis on Antagonistic Attacks and Protection of Sensitive Areas (Lund University, Faculty of Engineering, 2013), p. 145. https://lup.lub.lu.se/search/files/3900564/4216193.pdf. Accessed 17 Feb 2023 9. E. Oremusova, T. Pugel, M. Hudakova, Hodnotenie poťahových textílií metódou konického kalorimetra (Evaluation of cover textiles by the conical calorimeter method). Spravodajca 2(2), 16–18 (2011) 10. E. Oremusova et al., The effect of radiant heat on upholstery fabrics covering polyuretane foam. Fire Prot. Saf. Sci. J. 14(2), 36–53 (2020). https://doi.org/10.17423/delta.2020.14.2.90 11. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection) (Technical University, Zvolen, 2009) 12. W.M. Pitts et al., Assessing the Predictive Capability for Real-Scale Residential Upholstered Furniture Mock-Up Fires Using Cone Calorimeter Measurements. Part 1: Real-Scale Experiments (NIST Special Publication, 1246), p. 542. https://doi.org/10.6028/NIST.SP.1246 13. K. Storesund, A. Steen-Hansen, A. Bergstrand, Fire safe Upholstered Furniture. Alternative Strategies to the Use of Chemical Flame Retardants, Report number: SPFR A15 20124:2: SP Fire Research (2015). https://doi.org/10.13140/RG.2.2.20464.87041 14. M. Zammarano, Fire Performance of Upholstery Materials: Correlation between Cube Test and Full-Scale Chair Mock-Ups (National Institute of Standards and Technology, 2021), p. 24. https://doi.org/10.6028/NIST.TN.2194 15. BS 5852: 2006 Methods of Test for Assessment of the Ignitability of Upholstered Seating by Smouldering and Flaming Ignition Sources 16. EN 597-1:2016 Furniture – Assessment of the ignitability of mattresses and upholstered bed bases – Part 1: Ignition source smouldering cigarette 17. EN 597-2:2016 Furniture – Assessment of the ignitability of mattresses and upholstered bed bases – Part 2: Ignition source: match flame equivalent 18. EN 1021-1:2014 Furniture – Assessment of the ignitability of upholstered furniture – Part 1: Ignition source smouldering cigarette 19. EN 1021-2:2014 Furniture – Assessment of the ignitability of upholstered furniture – Part 2: Ignition source match flame equivalent 20. ISO 9705-1:2016 Reaction to fire tests – Room corner test for wall and ceiling lining products – Part 1: Test method for a small room configuration 21. ISO 9705:1993 Fire tests – Full-scale room test for surface products 22. ÖNORM S1456:1991 Testing of textiles – Determination of the burning behaviour of bed assemblies 23. UIC 564-2 Fire-resistance test of seat

Part IV

Tests for Dust, Smoke, Flammable Liquids

In the previous chapters, we discussed test methods that are used for specific materials or products intended for the construction industry and building interiors. These tests are directly related to the materials found in a house or work environment. In this chapter, we will look at test methods that assess certain risks in an industrial environment – testing dusts, smoke, and flammable liquids. To some extent, there is a dusty environment all around us. However, the risk of explosion, or of a fire of dust and dust mixtures, arises when certain conditions are met (see also Sect. 1.1). Dust and dust mixtures are dangerous in both settled and stirred forms. Test devices designed for these forms of dust and dust mixtures can be divided into two basic groups: tests for settled dust and tests for stirred dust. These test methods use simple laboratory equipment (mainly tests for settled dust) or more sophisticated equipment (tests for stirred dust). The results of both tests must give us information about the behavior of the dust or the dust mixture under the given conditions. They characterize the conditions under which dust can ignite and burn, or under which it can even explode. In the case of settled dust, it is important to characterize the type of dust (dust mixture, as well as the concentration of individual dust entering the mixture), a fraction of dust, the thickness of its layer, or other physical characteristics of the tested dust (e.g. its humidity, in the case of wood dust). The settled dust forms a sort of “insulating layer” that prevents heat from being released from the surface of the device or system. If, due either to this temperature or the action of an external source, the settled dust ignites, then the fire spreads along the dust layer very quickly and has enough energy to ignite surrounding combustible objects. Eliminating this risk is relatively simple; a duster or a small broom is enough to prevent the formation of a sufficiently thick layer of dust. However, this care is essential as a “sufficiently thick layer of dust” might be only a few millimeters thick. For stirred dust, the following parameters are monitored: lower explosive limit, upper explosive limit, maximum explosion pressure, the maximum speed of explosion pressure increase, cubic constant, limit oxygen content, among others. In this part of the textbook, we have also included tests that evaluate the secondary manifestations of burning and fire – that is, smoke formation. Smoke is

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an undesirable manifestation of combustion. It makes it impossible for people to navigate themselves in the space and therefore reduces the effectiveness and efficiency of the intervening teams. In addition, smoke has a relatively high temperature, so the body overheats. The human respiratory system starts to get burned already at a temperature of 70 °C. And this is the minimum, because these characteristics refer to non-toxic smoke. If the smoke contains toxic elements, its effect will multiply. Eight of ten fire fatalities are due to smoke inhalation [1]. Therefore, testing of materials to determine smoke density and toxicity is essential. Lastly, flammable liquids are often a source of major fires in large warehouses of these liquids. But even fires in smaller premises, such as garages, workshops, and smaller warehouses, as well as industrial equipment for the surface treatment of various products, are no exception; they can also fall victim to fire started by flammable liquids. Therefore, it is necessary to pay attention to this group of products and verify their properties using various fire tests, which will be described in the last chapter of this section.

Reference 1. A. Osvald, Ochrana pred požiarmi [Protection Against Fires] (Technical University, Zvolen, 2005)

Chapter 11

Testing of Dust and Dust Mixtures

Dust is a solid substance in a pulverized state which is made up of particles of solid material smaller than 0.5 mm. It can be said that a substance is inflammable in a solid compact state under normal conditions, but it burns and blows up in the pulverized state, in the form of dust. Almost all substances burn when in the form of dust except dolomite, limestone, oxides, and metal salts [1, 2, 7, 9, 18]. Dust particles of aluminum, magnesium, titanium, iron, etc. are considered dangerous as well. From non-metallic dusts, the dust particles of sulfur and coal dust are dangerously, flammable. All organic types of dust are explosive – hay, grain, tobacco, milk, cocoa, starch, tea, sugar, flour, spices, coffee, cotton, jute, and flax. The group of flammable dusts also includes the dust of manufactured substances – colorants, pharmaceuticals, explosives, plastics [1]. The degree of dispersion increases with decreasing linear dimensions of a dust particle. Flammable dust – aerosol (raised dust) represents the dispersion gaseous phase. The dust settled on the walls, ceilings, and other surfaces is called an aerogel (settled dust). So, dust exists in two states and has an irregular shape. Dust is capable of being charged with static electricity. The electrical capacity of a body depends on the size of its surface; therefore, dust with a large surface area has a relatively large electrical capacity. The size of the electric charge of dust depends primarily on the concentration and size of the particles, speed of dust movement, and air humidity [3]. Any dust has two different self-ignition temperatures depending on the form of occurrence. The self-ignition temperature of aerogel is lower than for aerosol dust (Table 11.1).

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_11

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Table 11.1 Self-ignition temperatures of certain types of dusts in the form of an aerogel [11] The name of the dust Rye flour dust Tobacco dust Tea dust Lignite dust Slate dust Coal dust Wood flour

11.1

Autoignition temperature of aerogel (°C) 245 205 220 220 225 260 275

Methodology for the Testing of Settled Dust

We will mention two of the methods for determining the flammability of settled dust: Determination of flame spread rate over a layer of settled dust in an oxygen atmosphere (RO test) and EN 50281-2-1: 1998 Electrical equipment for areas with flammable dust. Part 21: Test methods for determining minimum dust ignition temperatures.

11.1.1

Determination of Flame Spread Rate Over a Layer of Settled Dust in an Oxygen Atmosphere (RO Test)

The flame and flame-free fire spread rate parameter over the surface of settled dust is one of the basic indicators of fire danger of industrial dust, which is mostly located in a settled state on horizontal surfaces. The principle of the method is based on the properties of settled dust to ignite after initiation by a sufficient ignition source, and the ability of dust ability to transmit flame or incandescent, resp. smoldering flame front onto other layers of settled dust. As the oxygen numbers of most lignocellulose dust are above 21 vol. % of oxygen, the measurement is performed in an atmosphere of pure oxygen. The time within which the flame front of the burning sample extends to the specified distance [4, 8] is measured. At present, no hazard classification system for industrial dust other than coal dust is available. In the 2e of coal dust, a classification methodology into three hazard levels has been adopted. Therefore, these criteria were also used for the classification of the wood-based dust under examination. The ability of dust to spread fire onto other settled layers is characterized by the relative flame spread rate over the layer. The purpose of this measurement is to precisely determine this rate of oxidation. The findings serve to assess the particular fire hazard in the premises where continuous layers of settled dust are present. This measurement is carried out using a device called RO test (rate of oxidation test) [8].

11.1

Methodology for the Testing of Settled Dust

219

The main part of the RO apparatus is a chemical glass tube of an inside diameter of 22 mm and a length of 200 mm, which is mounted in a metal holder and situated on the upper panel of the apparatus. This tube is connected by means of a reduction valve and a pipe to an oxygen-containing steel pressure vessel. The amount of oxygen supplied for the measurement is adjusted by the small gas flow regulator. A sample of the measured dust in the shape of a rectangle formed on a metal board by a standard mold is inserted into the open end of the tube. The metal pad is marked with notches spaced 100 mm apart, which define the specified length of the dust sample needed for the measurement. The molds form shapes with a height of 3.5 and 7 mm, length 120 mm, and width of the base 9 mm. The width of the flame surface zone is 10 mm. Hand-held stopwatches are used to measure the time required for the flame to extend along the length of the dust sample. Device parameters: oxygen pressure in the pressure vessel 20–50 MPa, pressure in the test tube is barometric. Volume flow range 0–1 l/min (Fig. 11.1) [5, 8, 9, 13]. Using the “Rate of oxidation” method, also known as the “RO test”, it was found that the linear flame rate in a pure oxygen atmosphere at a dynamic countercurrent flow of 0.175 1/min of a dust sample with process moisture of 6%, which is formed after surface grinding of untreated chipboards, was in the range of 5.8–8.8 cm/s. At lower dust thicknesses of 3–5 mm, no significant differences were found in the measured flame spread rate (5.8–5.58 cm/s). A jump-like change in the fire performance characteristic occurred at a material layer thickness of 7 mm, while the increase in the linear flame spread rate was up to 55.7% [8]. The final evaluation criterion is the average time interval in seconds in which the flame spreads over the dust layer over a distance of 100 mm. Based on the values of burning, industrial dust is classified into the following hazard groups (Table 11.2) [11]. Linear burning rate (viin): the rate of transfer of flame or heating/smoldering front over a layer of settled dust of a given shape and length under prescribed conditions.

Fig. 11.1 Schematic of the apparatus determining the oxidation rate (RO test) (1 – combustion tube, 2 – reduction valve, 3 – oxygen cylinder, 4 – flow meter, 5 – metal washer, 6–dust sample, 7 – notches on pad) [11]

Table 11.2 Fire propagation hazard classes over the surface of settled industrial dust using the RO test [11] Hazard group I. II. III.

Fire characteristics of dust the dust spreads fire quickly the dust spreads fire the dust doesn’t spread fire easily

RO RO < 10 s 10 s < RO < 20 s 20 s < RO

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The resulting measurement value is the average time interval in seconds over which the flame spreads over the dust layer over a length of 100 mm. Measurements for a given dust sample and a given oxygen flow in the combustion tube were carried out five times and the average linear rate of flame spread over the layer of the flammable dust sample in the oxygen atmosphere was calculated from the measurements obtained according to Eq. (11.1): l W 0 = ðm=sÞ τ

ð11:1Þ

where: W0 – flame spread rate (oxidation rate) over the layer of dust, l – length of the dust layer in the defined section (m), τ – the time of the flame spread over the length of a layer (s).

11.1.2

EN 50281-2-1: 2000 Electrical Equipment for Areas with Flammable Dust. Part 2-1: Test Methods for Determining Minimum Dust Ignition Temperatures

Method A [23]. The second test method according to EN 50281-2-1 [23] addresses the problem of dust burning. We present two test methodologies for determining the minimum dust ignition temperatures for the purpose of selecting electrical equipment to be used in areas with combustible dust according to EN 50281-1-2 [23] and constructed according to EN 50281-1-1. These methods are not suitable for use with substances that have explosive properties. Method A (a layer of dust on a heated surface at constant temperature) is suitable for determining the minimum temperature of a specified hot surface at which the dust layer, of a specified width and stored on this hot surface, begins to decompose or is ignited. The method is particularly suitable for industrial plants where a thin layer of dust exposed to the atmosphere is present on a hot surface. The test apparatus for method A is schematically shown in Fig. 11.2, side section, and Fig. 11.3, a general scheme of the equipment with the necessary service and measuring elements. The test is repeated (method A) with new layers of dust until the minimum ignition temperature is determined. This value is considered to be the lowest temperature, rounded down to the nearest whole multiple of 10 °C, at which a layer of a given width will ignite. If the ignition is considered to have occurred on the basis of readings from the test thermocouple, the minimum ignition temperature

11.1

Methodology for the Testing of Settled Dust

221

Fig. 11.2 Scheme of test apparatus for method A, side section of the device [11]

Fig. 11.3 Schematic of the device with the necessary service and measuring elements [11]

shall be considered this lowest temperature rounded down to the nearest whole multiple of 10 °C, reduced by 10 K. The highest value of the temperature at which ignition did not occur or where ignition is not expected to have occurred must also be recorded. This value must not be more than 10 K below the minimum temperature at which ignition has occurred or is considered to have occurred. This value shall be confirmed by at least three tests. The time to ignition, or the time to reach the maximum temperature if no ignition occurs, starts to be measured 5 min after the dust layer has been placed on the heated surface, and must be recorded. If the dust layer does not ignite at temperatures below 400 °C, the maximum test time shall be recorded. The test report must contain all observed visible changes in dust properties during sample preparation, e.g., due to sieving, temperature conditions, or humidity.

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Test Methodology for Raised Dust

We will mention two of the methods for determining the flammability of settled dust: EN 50281-2-1: 1998 Electrical equipment for areas with flammable dust. Part 2-1: Test methods for determining minimum dust ignition temperatures [23] and explosion chamber [6, 10, 12].

11.2.1

EN 50281-2-1 Electrical Equipment for Areas with Flammable Dust. Part 2-1: Test Methods for Determining Minimum Dust Ignition Temperatures

Method B Test Method B (compressed air dust in a furnace at constant temperature) is suitable for determining the minimum temperature of a specified hot surface at which the sample of raised dust or other similar particles is ignited. The test is an additional method to determine the minimum dust ignition temperature in a layer by method A according to this European standard. The construction scheme of the test apparatus (method B) is shown in Fig. 11.4. The heated silica tube of the furnace is vertical and open to the atmosphere at its lower end. The upper end is connected to the dust container by means of a glass adapter. Dust is sprayed into the furnace by opening a solenoid valve which releases compressed air from the tank. The furnace is installed on a stand so that the lower end of the furnace tube can be easily observed. A mirror is placed under the tube to observe the inside of the furnace tube. The thermocouples used must be regularly calibrated to ensure that temperatures are measured above 500 °C with an accuracy of ±1% and below 300 ° C with an accuracy of ±3%. After stopping the test apparatus, its accuracy is compared with results obtained elsewhere for dust, such as lycopodium (clubmoss). The test report (method B) must include the name, source, and description (if not? apparent from the name) of the dust being tested, the moisture content of the dust at the time it was measured, the test date, and identification (number) of the test. The test report must state that the determination of the minimum ignition temperature of raised dust was carried out in accordance with this European Standard.

11.2

Test Methodology for Raised Dust

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Fig. 11.4 Schematic of the test device for method B [11] 1 – furnace shell, 2 – upper cover, 3 – lower cover, 4 – adapter, 5 – tube, 6 – clamp, 7 – washer, 8, 9 – flange for thermocouple, 10, 11 – lock nut, 12, 13, 14, 15 –washer, 16 – support ring, 17 – pin, 18 – sleeve, 19 – nut, 20, 21 – thermocouple, 22 – screw, 23 – nut, 24–washer, 25 – clamp, 26 – canthal wire, 27 –compression spring, 28 –furnace stand, 29 – locking ring, processed by the authors

11.2.2 Explosion Chambers Among the more sophisticated methods for testing swirling odor are tests that use explosion chambers (explosion autoclaves). They make it possible to monitor the conditions under which gas, liquid and dust mixtures explode. Explosion chambers are of several designs and equipment. We divide them mainly according to their size (chamber volume 20 l KSEP, VA 250 l, VK 100, etc.) In Fig. 11.5 is the explosion autoclave 20 l KSEP and in Fig. 11.6 explosion chamber VK 100. In addition to the size of the chamber, the method of their equipment, which serves for the experiment and recording equipment that monitors several physical parameters, is important. From these data obtained during the test itself, we can determine [5, 14–17]:

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Fig. 11.5 Explosion chamber 20 l KSEP (a) scheme, (b) photo of the device [19]

• • • •

the maximum rate of increase in explosion pressure (dp/dt)max of dust clouds [20] lower explosion limit LEL [21], upper explosive limit UEL, limit oxygen concentration LOC [22].

The Centre for Energy and Environmental Technologies (CEET) VŠB-TUO Ostrava (Czech Republic) has an interesting device, it is an explosion chamber in which they can study the parameters of explosions even at low temperatures. It should be noted that in a dusty environment, with the risk of explosion of the dust mixture, electrical equipment must be installed in this environment, which is also subject to special tests [23]. Questions What is the essential difference in individual forms of dust? Which physical properties of dust or dust mixtures do we monitor before the test? What are the output values of the evaluation criteria for settled dust? What are the output values of the evaluation criteria for stirred dust?

11.2

Test Methodology for Raised Dust

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Fig. 11.6 Explosion chamber VK 100 (a) scheme of the device, (b) photo of the device (c) view of the control elements [10, 12] processed by the authors

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References 1. S.P. Andrews, Jet Ignition of Dust Clouds (IR/L/EC/98/01/IS) (HSE, Buxton, 1988) 2. K.L. Cashdollar, Overview of dust explosibility characteristics. J. Loss Prev. Process Ind. 13(3–5), 183–199 (2000). https://doi.org/10.1016/S0950-4230(99)00039-X 3. K.L. Cashdollar, M. Hertzberg, 20-l explosibility test chamber for dusts and gases. Rev. Sci. Instrum. 56, 596 (1985). https://doi.org/10.1063/1.1138295 4. J. Damec, Protivýbuchová prevence (Anti–explosion prevention). (SPBI, Ostrava, 1998) 5. A.G. Dastidar, Chapter Four – Dust explosions: Test methods, in Methods in Chemical Process Safety, vol. 3, (2019). https://doi.org/10.1016/bs.mcps.2019.04.002 6. R. Eades, K. Per, Evaluation of a 38 L explosive chamber for testing coal dust explosibility. J. Comb. (2019). https://doi.org/10.1155/2019/5810173 7. R.K. Eckhoff, G. Li, Industrial dust explosions. A brief review. Appl. Sci. 11(4), 1669 (2021). https://doi.org/10.3390/app11041669 8. P. Gray, P.R. Lee, Thermal explosion theory. Oxid. Combust. Rev. 2, 1–183 (1967) 9. J. Jiang et al., Study of parameters and theory of sucrose dust explosion. Energies 15(4), 1439–1504 (2022). https://doi.org/10.3390/en15041439 10. R. Kuracina et al., Study into influence of different types of igniters on the explosion parameters of dispersed nitrocellulose powder. J. Loss Prev. Process Ind. 83, 105017–105083 (2023). https://doi.org/10.1016/j.jlp.2023.105017 11. L. Makovicka Osvaldova, S. Gašpercová, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017) 12. E. Mrackova, Protivýbuchová prevencia (Anti-explosion prevention). (Technical University, Zvolen, 2018) 13. R.A. Ogle, Dust explosion dynamics (Butterworth-Heinemann). ISBN 978-0128037713, p 686 14. C. Proust et al., Understanding the role of thermal radiation in dust flame propagation. J. Loss Prev. Process Ind. 49 (2021). https://doi.org/10.1016/j.jlp.2017.01.002 15. J.S. Renner et al., A critical assessment of the fire properties of different wood species and bark from small-and bench-scale fire experiments. J. Therm. Anal. Calorim. 148, 1423–1434 (2022). https://doi.org/10.1007/s10973-022-11443-z 16. R. Sharma et al., Experimental evaluation and analysis of electrodynamic screen as dust mitigation technology for future Mars missions. IEEE Trans. Ind. Appl. 45(2), 591–596 (2009). https://doi.org/10.1109/TIA.2009.2013542 17. S.H. Spitzer et al., Influence of pre-ignition pressure rise on safety characteristics of dusts and hybrid mixtures. Fuel 311, 122495 (2022). https://doi.org/10.1016/j.fuel.2021.122495 18. Q. Xu et al., Wood dust flammability analysis by microscale combustion calorimetry. Polymers 14(1), 45 (2022). https://doi.org/10.3390/polym14010045 19. R. Zalosh, Dust explosions, in SFPE handbook of fire protection engineering, (Springer, New York, 2016). https://doi.org/10.1007/978-1-4939-2565-0_70 20. EN 14034-2:2006+A1:2011 Determination of explosion characteristics of dust clouds – Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds 21. EN 14034-3:2006+A1:2011 Determination of explosion characteristics of dust clouds – Part 3: Determination of the lower explosion limit LEL of dust clouds 22. EN 14034-4:2004+A1:2011 Determination of explosion characteristics of dust clouds – Part 4: Determination of the limiting oxygen concentration LOC of dust clouds 23. EN 50281-2-1:2000+AC:2000 Electrical apparatus for use in the presence of combustible dust – Part 2-1: Test methods – Methods for determining the minimum ignition temperatures of dust

Chapter 12

Smoke and Toxicity

Smoke is a fire-related phenomenon. For some materials, such as plastics, the generation of smoke is always evaluated as part of the testing process (see Chap. 8). In this chapter, we present both smoke density and smoke toxicity evaluation methods. All materials that will be applied in specific locations, e.g., tunnels, must pass the given tests. The chemical safety assessment of substances (CSA), chemical safety reports (CSR) and the determination of any need for risk management measures is crucial toxicological information. The toxicological information to be submitted for registration and evaluation purposes of the substance is set out in Annexes VI to XI of REACH. For an overview, see the Registration information requirements. The health effects to be taken into account by the registrant are listed below [7, 8, 11]: • • • • • • •

skin and eye irritation/burning and irritation of respiratory organs, increased skin and respiratory sensitivity, acute toxicity, repeated dose toxicity, reproductive toxicity, mutagenicity and carcinogenicity, toxicokinetic.

12.1

Smoke Assessment Tests

Smoke is a dispersion aerosol containing liquid and solid particles which, together with the gas-based flame products, are dispersed in the air after the material burns. The density of the smoke produced is determined as the optical density of the smoke. The optical density of smoke can be determined using the classic smoke chamber method, or according to the EN 5659-2 standard [14] (see Sect. 8.1). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_12

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The determination shall be carried out according to the prescribed method in a chamber of 0.486 m3. After a sample of 1 kg in a crucible at 800 °C burns away, the reduction in the intensity of the light beam passing through the environment is measured, the absorbance is calculated and the optical density of the smoke is determined according to Eq. (12.1). Ds =

V I log 0 m2 =kg I m:L

ð12:1Þ

where: Ds – optical density of smoke (m2/kg), Io – units of intensity of input light (lx), I – the intensity of the light passing through the smoke layer (lx), V – volume of the chamber (m3), m – weight of the sample (kg). L – thickness of the smoke layer (m).

12.2

Determination of the Toxicity of Burning Products

Toxicity is the ability of a chemical to cause harm to an organism. When assessing toxicity, the effects of single or long-term intake – acute, subchronic, chronic, as well as the way through which it enters the organism – inhalation by air, through food and water, skin, or other biomembranes – are distinguished. The term toxicity does not only mean the toxic effect of substances, but also the carcinogenic effects – in a broader sense, tumor formation, teratogenic (developmental anomalies), and mutagenic effects (changes in the genetic information of the organism). In this chapter, only the toxicity of combustion products is addressed [4–6, 9, 10]. Fire is considered to be a complex phenomenon from various points of view. Recently, in addition to the main characteristics of fire, accompanying phenomena such as combustion products and smoke have also been studied. Research on the products of thermal degradation of substances and combustion products has taken on an integral role and the information obtained is useful in areas such as occupational safety, fire safety, occupational hygiene, and environmental concerns. Although the determination of the hazard of combustion products is quite varied and the burning process model has not yet been determined, tests can be carried out to predict the toxic risk of fires. This paper would like to contribute to improving the safety of the working environment of fire-fighting and rescue units [1–3]. A CAB 4.5 chamber is used to determine the toxicity of combustion products, allowing all tests to be carried out under constant and defined conditions. CAB 4.5,

12.2

Determination of the Toxicity of Burning Products

229

with a total capacity of 4.5 L, is a two-chamber system with separate combustion and smoke chambers. CBA inbred mice of 18–23 g are used for the test. After warming up the crucible furnace to the desired temperature, four mice in a wire cage are placed into the exposure chamber. Once the material is loaded into the chamber, the fan is switched on and the time measurement starts. When the smoke density reaches its maximum, the chamber is closed to prevent subsequent oxidation of the combustion products on its hot surface. During the experiment, the temperature of the furnace, the temperature in the exposure chamber, the smoke permeability, the CO, CO2, and O2 concentration in the chamber’s atmosphere are recorded. The behavior of the animals during the experiment is monitored visually. The temperature in the exposure chamber shall not exceed 35 °C, the oxygen concentration shall not fall below 12%, and the CO2 concentrations shall not rise above 4%. The experimental animals are exposed to combustion products for 20 min. Immediately after the exposure, blood samples are taken to determine the COHb content. Animals used should be observed for an additional 48 h under standard conditions in order to record delayed mortality. The biological toxicity of the material shall be assessed by using more samples in order to provide sufficient results for the two basic criteria [11–13]: LC50 – determines the size of the sample, expressed in grams of the sample per 1 liter of chamber volume, at which 50% of the experimental animals die. HS – death limit, blood carboxyhemoglobin content of experimental animals in %, at which the experimental animals’ die. The toxicity index using the measured values is calculated (12.2): I tox =

10 ð- Þ LC 50 1 þ HS:10 - 2

ð12:2Þ

where: Itox – index of toxicity (-), LC50 – sample size, expressed in grams of the sample per 1 liter of the chamber size with a mortality rate of 50% of the experimental animals, HS – death limit. The higher the toxicity index, the more dangerous the combustion products of the material are. The methodology for the determination of the biological toxicity of combustions products was developed during the process of addressing the departmental research task. There may be changes or clarifications if further researched. At one point, Drosophila flies were used as biological material, lessening experimental costs without compromising results.

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Questions What affects and limits smoke density during a fire? How does the plume of smoke affect the evacuation and the intervention of the fire brigade? Why are toxic combustion residues dangerous? Which combustion products are toxic?

References 1. Y. Alarie, Toxicity of fire smoke. Crit. Rev. Toxicol. 32(4), 259–289 (2002). https://doi.org/10. 1080/20024091064246 2. J. Baj et al., Diffusion of carbon monoxide and hydrogen cyanide to muscles and blood-An experimental study. Toxics 10(11), 707 (2022). https://doi.org/10.3390/toxics10110707 3. K. Balog, I. Bartlova, Základy toxikologie (Basics of toxicology) (SPBI, Ostrava, 1998) 4. Z. Bell, Forensic Chemistry (Taylor and Francis, 2022), p. 649. https://doi.org/10.4324/ 9780429440915 5. P.M. Doley, Thermal hazard and smoke toxicity assessment of building polymers incorporating TGA and FTIR – Integrated cone calorimeter arrangement. Fire 5(5), 139; 2–22 (2022). https:// doi.org/10.3390/fire5050139 6. R.G. Gann et al., Fire conditions for smoke toxicity measurement. Fire Mater. 18(3), 193–199. https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=912940. Accessed 17 Feb 2023 7. S. Gharge et al., Smoke and fire detection. Int. J. Sci. Res. Pub. 4(7) (2014, July). https://www. erpublication.org/published_paper/IJETR022127.pdf. Accessed 17 Feb 2023 8. T. Grewer, Thermal Hazards of Chemical Reactions (Elsevier, Amsterdam, 1994), p. 424 9. M.M. Hirschler, Fire hazard and toxic potency of the smoke from burning materials. J. Fire Sci. 5(5) (1987). https://doi.org/10.1177/073490418700500501 10. T. Jin, Studies on Human Behavior and Tenability in Fire Smoke, in Fire SAFETY Scienceproceedings of the Fifth International Symposium, pp 3–21. https://publications.iafss.org/ publications/fss/5/3/view/fss_5-3.pdf. Accessed 17 Feb 2023 11. V. Lalik et al., Determination of hydrogen cyanide from polyurethane in building insulation materials. Chem. Sheet 105, 871–1072 (2011) 12. A.A. Stec, Fire toxicity – The elephant in the room? Fire Saf. J. 91, 79–90 (2017). https://doi. org/10.1016/j.firesaf.2017.05.003 13. A.A. Stec, T.R. Hull, Fire Toxicity (Woodhead Publishing, 2010), p. 688 14. EN ISO 5659-2:2017 Plastics – Smoke generation – Part 2: Determination of optical density by a single-chamber test

Chapter 13

Testing of Flammable Liquids

Among the many methods used to test the flammability of liquids, we have selected the following: EN ISO 3679:2022 [7], EN ISO 2592:2017 [8], EN ISO 2719: 2016 [9], EN 924:2003 [10].

13.1

EN ISO 3679:2022 Determination of Flash Point – Rapid Equilibrium Closed Cup Method

The determined volume of test sample (100 ml) is dosed into the test crucible, which is maintained at the temperature of the expected flash point of the tested material. After a specified time, a test flame is applied and the presence or absence of ignition is observed. Further tests are carried out with fresh test samples at different temperatures until the flash point is determined with the prescribed accuracy. Flash point: the lowest temperature of the test sample (if measured in the described manner), adjusted to an atmospheric pressure of 101.3 kPa, at which the test flame causes the vapors of the test sample to ignite immediately and the flame to spread over the surface of the liquid under the specified test conditions [1–3, 5, 6].

13.2

EN ISO 2592:2017 Determination of Flash and Fire Points – Cleveland Open Cup Method

The test crucible is filled with the sample up to the mark. The temperature of the test sample rises rapidly at the beginning of the determination and rises slowly at a uniform rate to the expected flash point. A small test flame is passed over the crucible at specified temperature intervals. The lowest temperature, corrected for ambient air © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_13

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pressure, at which vapors above the liquid surface ignite when the test flame is brought closer is considered the flash point. When determining the flash point and fire point, the test continues until the test flame causes ignition and until the sample burns for at least 5 s. Definitions of key terminology for the test: Flash point: the lowest temperature of the test sample, corrected to an atmospheric pressure of 101.3 kPa, at which the vapors ignite using a test flame and the flame spreads briefly over the entire surface of the liquid under the specified test conditions. Fire point: the lowest temperature of the test sample, corrected to an atmospheric pressure of 101.3 kPa, at which the vapors ignite using a test flame and the sample burns for at least 5 s under the specified test conditions. The scheme of the Cleveland Open cup method device is shown in Fig. 13.1. The device consists of the following parts: • cover in the shape of a square, with a length of the sides of 460 mm and a height of 610 mm, with an opening on the front part, • partial immersion thermometer, • pressure gauge with an accuracy of 0.1 kPa.

Fig. 13.1 Schematic of the Cleveland open cup method [4] 1 – thermometer, 2 – test flame applicator, 3 – test crucible, 4 – metal ring ∅ from 3.2 to 4.8, 5 – heating plate, 6 – cone ∅ 0.8, 7 – gas connection, 8 – heater (flame or electric)

13.4

13.3

EN 924:2003 Adhesives – Solvent-Borne. . .

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EN ISO 2719: 2016 Determination of Flash Point, Pensky-Martens Closed Cup Method

The test sample is placed in the test crucible of the Penský-Martens apparatus and heated with continuous stirring to create a constant rise in temperature. The ignition source is directed through the hole in the lid of the test crucible at controlled temperature intervals during a brief interruption of stirring. The lowest temperature at which the application of an ignition source causes the vapors of the test sample to ignite and spread above the surface of the liquid is recorded as the flash point at ambient atmospheric pressure. This temperature is corrected to standard atmospheric pressure using equation. Sample quantity is 500 ml. Important Terminology in the test: Flash point: the lowest temperature of the test sample at an atmospheric pressure of 101.3 kPa, at which the ignition source causes test sample vapors to ignite and a flame to spread over the surface of the liquid under the specified test conditions. Apparatus for determining the flash point (Pensky-Martens closed cup apparatus) • • • •

thermometers with low, medium, and high ranges, pressure gauge with an accuracy of 0.1 kPa, a heating bath or hot air oven to warm the sample, if required, with temperature regulation ±5 °C.

The diagram of the Pensky-Martens apparatus is shown in Fig. 13.2.

13.4

EN 924:2003 Adhesives – Solvent-Borne and Solvent-Free Adhesives – Determination of Flash-Point

The standard specifies the method for determining the flash point of adhesives that contain volatile organic substances and allows tolerances for deviations from normal atmospheric pressure. It is suitable for solvent and solvent-free adhesives, but not for water-dilutable adhesives with a solvent content below 10%. In a closed cup, the test sample is heated and immersed in a suitable water bath to the required depth. The temperature of the bath is slowly increased so that the difference between the temperature of the liquid in the bath and the temperature of the sample in the crucible does not exceed 2 °C and the heating process ensures that the temperature of the sample does not rise faster than 0.5 °C per 1.5 min. During heating, attempts to ignite the sample are made at intervals of at least 1.5 min. The lowest temperature at which the sample ignites is recorded. The determination is repeated and from these two measurements, the flash point of the tested product, corrected to normal atmospheric pressure of 101.3 kPa, is calculated. Sample quantity is 500 ml.

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Fig. 13.2 Pensky-Martens closed cup apparatus diagram [4]. 1 – flexible shaft, 2 – shutter operating knob, 3 – ignition device, 4 – thermometer, 5 – lid, 6 – distance piece, 7 – test cup, 8 – stove, 9 – top plate, 10 – air bath, 11 – over cup area: min. Thickness of 6.5, i.e., metal surrounding the cup, 12 – heater: flame type or electric resistance type (flame type shown), 13 – pilot, 14 – shutter, 15 – front, 16 – handle (optional), and – air gap

Questions Which physical parameters of the liquid must be accurately characterized before testing? Is it necessary to test flammable liquids if they are modified with other substances or mixtures?

References 1. W. An et al., Prediction of heat release rate of single/double 32,650 lithium-ion batteries. J. Therm. Anal. Calorim. 148(5), 2057–2067 (2022). https://doi.org/10.1007/ s10973-022-11766-x 2. L.C. Ekechukwu, T. Madueme, Comparative analysis of palm oil and hydrocarbon mineral oil for power transformer operation, in Key Engineering Materials, vol. 917 (Trans Tech Publications, 2022), pp. 199–206. https://doi.org/10.4028/p-4486fm

References

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3. T.G. Osimitz et al., Evaluation of potential toxicity of smoke from controlled burns of furnished rooms–effect of flame retardancy. J. Toxic. Environ. Health A 85(19), 783–797 (2022). https:// doi.org/10.1080/15287394.2022.2087812 4. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection) (Technical University, Zvolen, 2009) 5. S.T. Selvi et al., Study of parameters affecting the aging of transformer oil. Materials Science Forum. 1048 (Trans Tech Publications, 2022). https://doi.org/10.4028/www.scientific.net/ MSF.1048.89 6. I. Suay-Matallana, The Customs Laboratory of Lisbon from the 1880s to the 1930s: Chemistry, trade and scientific spaces, in Science, Technology and Medicine in the Making of Lisbon 1840–1940 (2022), pp. 179–202. https://doi.org/10.1163/9789004513440_010 7. EN ISO 3679:2022 Determination of flash point – Method for flash no-flash and flash point by small scale closed cup tester (ISO 3679:2022) 8. EN ISO 2592:2017 Petroleum and related products – Determination of flash and fire points – Cleveland open cup method (ISO 2592:2017) 9. EN ISO 2719:2016/A1:2021 Determination of flash point – Pensky-Martens closed cup method – Amendment 1: Thermometers correction (ISO 2719:2016/Amd 1:2021) 10. EN 924:2003 Adhesives – Solvent-borne and solvent-free adhesives – Determination of flashpoint

Part V

Other Test Methods

This chapter was difficult to name as it includes a group of test methods that are each very specific in their own way – cone calorimetry, medium-sized ISO test 9705, large-scale tests, and laboratory non-standardized tests intended more for scientific testing needs. Cone calorimetry can be considered the pinnacle of the test methods, because during a single experiment with a cone calorimeter, several types of data on the tested material can be obtained. In addition to the continuously recorded change in weight, data on oxygen consumption, heat generation, and the creation and development of combustion products are also monitored. None of the methods described so far can obtain such complexity of data with just one experiment. In addition to the above data, the device also allows for changing and regulating the thermal load on the tested sample. This way, the values can be obtained for individual heat loads and the evaluation of these data makes it possible to obtain a comprehensive picture of the tested material. Another test method, which we can call the “test according to ISO 9705” is a special medium-sized test in which the test space is the size of a “room”. It is one of the few test methods where the occurrence of the phenomenon called flashover can be observed. Other modified tests have also been created based on the premises of this basic test. Another group of tests are the large-scale tests, which have their own special advantages and disadvantages. Let’s first have an honest look at the disadvantages: the physical properties of the materials entering these tests are not always precisely defined and characterized. This is especially true if older buildings are subjected to such tests; however, in newly built constructions, this disadvantage disappears. Another major disadvantage is the economic cost of the test itself. In the case of older buildings, we can (to a certain extent) follow the aging of the materials during the test (if the project documentation is available). Usually, just one building is used for the test, so conclusions (including scientific ones) must be made from only one test.

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Most of the tests described in this textbook are standardized tests and have welldefined test equipment and testing procedures. The criteria according to which a certain classification is assigned to the tested material are also well-defined and standardized. These tests are important for practice as well as scientific purposes. Many current standardized tests have gone through an evolution in which the boundary conditions of the test conditions and the physical properties of the materials were specified before the test. This is how standardized tests have reached their perfection. Many of them require complex laboratory equipment with sensors that record material changes in the process of thermal heating of the material or its burning. Simple laboratory tests which enable easy (and economically undemanding) test repeatability with one material, thus enabling statistical evaluation of the test, continue to be created.

Chapter 14

Special Test Methods

In addition to test methods that are directly put into practice by determining e.g., the test material’s reaction to fire, in order to approve or disapprove of its application in the environment, construction, or space, there are a number of special methodologies for evaluating substances and materials. In this chapter, we will mention just a few that are used the most in practice, namely the cone calorimeter and methods for determining the flammability of liquids.

14.1

Cone Calorimeter

This textbook would not be complete without introducing a test method called the cone calorimeter. It is embedded in many standards (ISO 5660) [15]. The cone calorimeter (Figs. 14.1, 14.2, 14.3, and 14.4) is a device designed to determine the heat release rate from materials by monitoring oxygen consumption. The time until the initiation of flame burning can be monitored when the test samples are exposed to a heat flow of up to 100 kW/m2. The device is also capable of measuring the concentrations of carbon dioxide and carbon monoxide when stressed during small-scale tests. It is also intended for monitoring the generation of heat and smoke during combustion as well as the rate of weight loss. Cone calorimetry analysis is carried out according to the technical standard [15]. The development of cone calorimetry has resulted in several modifications (see attached pictures). The cone calorimeter is the most compact device for testing materials for fire protection needs. When described in detail, it may seem no other measurement devices are needed. However, a whole range of other test methods are still employed, because the cone calorimeter cannot detect all the specifics that individual materials might display in the event of a fire. The device consists of the following parts:

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_14

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Fig. 14.1 Cone calorimeter – scheme [11]

Cone heater – has the form of a truncated cone that can be heated up to 500 W at 230 V power supply. The temperature is monitored by three thermocouples. The closing mechanism – protects the sample space before the test, which also allows the sample to maintain a certain quality, e.g., serves as a protection against humidity. In the case of open ignition, the protective mechanism is not used. Samples – the method uses 100 × 100 mm samples with a thickness of 50 mm. Sample holder – allows the sample to be mounted in both horizontal and vertical directions. Weighing device – allows continuous measurement of the weight of the sample with an accuracy of 0.1 g, while the maximum weight of the sample can be up to 2 kg. Spark ignition – works at a value of 10 kW, is automatic, and automatically cooperates with the closing mechanism. Extraction system – made of stainless steel and consists of a hood, exhaust pipe, and a gas sampler which can be set between 0 and 50 g/s. At the same time, the temperature of the flue gases and the pressure difference is measured with a thermocouple. The paramagnetic oxygen analyzer is set in the range of 0–25% and is calibrated before each test. Smoke density is measured using a laser system, photodiodes, and a photodetector. A 0.5 mW helium-neon laser is used. Neutral density filters are used for calibration.

14.1

Cone Calorimeter

241

Fig. 14.2 Calorimeter for measuring heat release rate [11]

The heat flow measurement determines the radiation value of the sample surface. Burner calibration – 99.5% pure methane is used to calibrate the burner. With the help of the software, it is possible to perform analysis of CO, CO2, and HCl gases to determine the oxygen consumption at the given weight loss as well as a range of other calculations (these, however, are more useful in the scientific research than in the field of material evaluation and certification). The measurement principle is based on the development of heat during combustion and is directly proportional to the amount of oxygen in the combustion process. Many types of fuel follow the consumption equation 13.1 × 103 kJ/kg of oxygen. The precise measurement of the concentration of oxygen in the extraction device in the volume flow of air gives oxygen values that can be calculated when calculating the heat flow in the conical calorimeter. The heat flow is given by the Eq. (14.1):

242 Fig. 14.3 Device for measuring fire propagation [11]

Fig. 14.4 Cone calorimeter. (Photograph by J. Mitterpach 2023, CZU Praha)

14

Special Test Methods

14.2

Spatial Ignition Testing

q = 13, 1:103 1, 10C

243

ΔP ð0, 2095 - X O2 Þ ðkWÞ T e ð1,105 - 1, 5X O2 Þ

ð14:1Þ

where: q – heat flow (kW), p C – device coefficient ( kg:m:K), ΔP – pressure difference (Pa), Te – gas temperature (K), X O2 – mole fraction of oxygen in air (dimensionless). For scientific purposes, several materials were measured with a cone calorimeter and the results were published by authors [1, 4–7, 9, 11]. Figure 14.1 shows a diagram of a conical calorimeter, Fig.14.2 Calorimeter for measuring heat release rate, Fig. 14.3 Device for measuring fire propagation and Fig. 14.4 Cone calorimeter apparatus.

14.2

Spatial Ignition Testing

The newly designed EU tests differentiate between the materials that are prone to spatial flash and those where spatial flash does not occur. Spatial ignition means a very rapid increase in temperature and the ignition of flammable gases that are created during a fire. An analogy developed by Babrauskas in his dissertation compares smoke creation and the filling of water into a reservoir; the analogy is shown in Fig. 14.5. The test method that deals with this stage of the fire is ISO 9705: 1993 [16], which is originally called Room/Corner Test. The two options for the name of the test derive from the position of the burner in this test. In a room test, the burner is placed in the middle in the back of the chamber, e.g. in the middle of the shorter wall of the rectangle. If it is a corner test, the burner is placed in the corner of the chamber, as shown in Fig. 14.6. The Room/Corner test is a large-scale method for testing materials. It allows us to obtain values such as flame propagation rate, smoke production, and toxic gas production. The walls and ceiling of the chamber are 3.6 m long, 2.4 m high, and Fig. 14.5 Analogy between the formation of smoke and the filling of water into a water reservoir according to [1, 8]

Filling the space with smoke

Filling the space with water

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Fig. 14.6 Scheme of the device for the test according to ISO 9705: 2016 [8, 16]

2.4 m wide and are covered with the material to be tested. 3.2 m2 of the area of the tested material will be used. The ignition source is a propane burner, located in the corner or center of the room; its output is 100 kW for the first 10 min and 300 kW for the next 10 min. The entire testing time is 20 min. Combustible gases collected during the test in an extraction device are subsequently analyzed (see Fig. 14.6). Their analysis enables quantitative and qualitative evaluation of the gases of the given sample. The volume of gases and their density in m2/s, are also measured. The following values can be obtained from the test: • • • • • • • •

spatial flare time (s), calorific value (MJ), maximum heat development (kW), average heat development (kW), maximum smoke production (m2/s), average smoke production (m2/s), total CO production (g), total production of HCN (g.)

The device provides a graphical output of the dependence as a function of time of the following measured quantities: • • • • • • •

value of generated heat (kW), smoke production value (m2/s), average smoke production (m2/s), CO value (g/s), CO2 value (g/s), HCN value (g/s), heat flow in the middle of the floor (kW/m2).

14.2

Spatial Ignition Testing

245

The criteria are given as maximum and average values and classify the materials into five classes from A to E, see Table 14.1 Another criterion for class A materials is that they can have burn marks only 1.2 m from the burner. The methodology is used not only for product testing and certification but also for scientific research into the behavior of materials before and during the stage of combustion called flashover [2, 3, 10, 12–14]. The course of real tests on the device according to ISO 9705 is shown in Fig. 14.7. Table 14.1 Criteria for classifying materials according to ISO 9705:2016 [8] processed by the authors

Class A B C D E

Minimum space flash time 20 20 12 10 2

The value of the released heat (including the burner) (kW) Maximum Average 300 50 700 100 700 100 900 100 900

Smoke production value (m2/s) Maximum Average 2.3 0.7 16.1 1.2 16.1 1.2 16.1 1.2 16.1

Fig. 14.7 Modified device used for the test based on standard ISO 9705: 1993. The device and experiment are on the premises of Technical University in Zvolen – during the test [12]. (Photograph by A. Osvald 1991)

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Questions What is the biggest advantage of measuring on a conical calorimeter? What are the advantages of a test according to ISO 9705 compared to largescale tests?

References 1. V. Babrauskas, The early history of the cone calorimeter. Fire Sci. Technol. 41(1), 21–31 (2022). https://doi.org/10.3210/fst.41.21 2. S.E. Dillon, Analysis of the ISO 9705 Room/Corner Test: Simulations, Correlations and Heat Flux Measurements. https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916661. Accessed 17 Feb 2023 3. A.S. Hansen, P.J. Hovde, Prediction of time to flashover in the ISO 9705 room corner test based on cone calorimeter test results. Fire Mater. 26(2), 77–86 (2002). https://doi.org/10.1002/ fam.788 4. M. Hudakova, J. Rychly, A. Osvald, The Effect of Wood Density on Ignitability and Thermal Degradation During Burning in Cone Calorimeter, in Proceedings of the 8th International Scientific Conference Wood and Fire Safety (EDIS – Publishing center of The University of Žilina, Žilina, 2016), pp. 107–112 5. D. Kacikova et al., Materiály v protipožiarnej ochrane (Materials in fire protection). (Technical University, Zvolen, 2011) 6. Y.T. Liu, Cone calorimeter analysis on the fire-resistant properties of FRW fire-retardant particleboard, in Advanced Materials Research, vol. 311. (Trans Tech Publications, 2011), pp. 2142–2145. https://doi.org/10.4028/www.scientific.net/AMR.311-313.2142 7. L. Makovicka Osvaldova, J. Rychly, P. Kadlicova, Fire characteristics of selected tropical woods without and with fire retardant. Coatings 10(6), 527, 1–12 (2020). https://doi.org/10. 3390/coatings10060527 8. L. Makovicka Osvaldova, S. Gaspercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection). (University of Zilina, Zilina, 2017) 9. I. Markova et al., Ignition of wood-based boards by radiant heat. Forests 13, 1738 (2022). https://doi.org/10.3390/f13101738 10. I. Mitterova, A. Osvald, Hodnotenie materiálov pre potreby protipožiarnej ochrany, výsledky stredno- a veľkorozmerových testov. Evaluation of materials for fire protection needs, results of medium- and large-scale tests, in Zem v pasci (Earth in a trap) (Technical University in Zvolen, Zvolen, 2008), pp 398–404 11. R. Shen et al., Cone calorimeter analysis of flame-retardant poly (methyl methacrylate)-silica nanocomposites. J. Therm. Anal. Calorim. 128, 1443–1451 (2017). https://doi.org/10.1007/ s10973-016-6070-x 12. P. Thureson, Fire Tests of Linings According to Room/Corner Test, ISO 9705 (Client report 95R22049) (Swedish National Testing and Research Institute, Borås, 1996) 13. Q. Xu et al., Evaluation of plywood fire behaviour by ISO tests. Eur. J. Environ. Saf. Sci. 1(1) (2013), 1–7. ISSN 1339-4797. https://portal.webdepozit.sk/webapp-portal/eborn-file; jsessionid=4A61D44E0EE8DD9C5B 96EBC3D B7B 43C9?id=1086993319. Accessed 17 Feb 2023 14. M. Zanetti et al., Cone calorimeter combustion and gasification studies of polymer layered silicate nanocomposites. Chem. Mater. 14(2), 881–887 (2002). https://doi.org/10.1021/ cm011236k

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15. ISO 5660-1:2015 Reaction-to-fire tests – Heat release, smoke production and mass loss rate – Part 1: Heat release rate (cone calorimeter method) and smoke production rate (dynamic measurement) 16. ISO 9705-1:2016 Reaction to fire tests – Room corner test for wall and ceiling lining products – Part 1: Test method for a small room configuration

Chapter 15

Large-Scale Test Methods

In the previous chapters, we presented a range of universal and special test methods for evaluating the fire resistance of materials and constructions; these methods are comprehensive enough for fire protection assessment. However, in addition to these laboratory methods, in practice, large-scale tests are also carried out. Though they are very costly and have low repeatability, these tests are important as they accurately simulate a real fire.

15.1

Box Test

The box test is the smallest and simplest “large scale” test. The test consists of a cube-shaped box with an opening of 600 × 600 × 600 mm. The front wall of the box is missing. Wood wool of 0.5 kg soaked in 0.5 L of diesel [1, 3] is used as a charge. Two boxes are always tested simultaneously and compared. One box is an unmodified control sample while the other is a fire retardant-treated or otherwise modified sample. Two different materials can also be compared. The explosive charge is ignited simultaneously in both boxes, and the burning process is monitored through photos and videos. Figure 15.1 is only a selection of shots from the box test, where spruce wood crates, untreated and fire-retardant-treated (using an ecological nano-based fire retardant), were tested [1, 3]. Figure 15.2 are the details of the box test. Similar to the “crate” test, but technically more demanding, is the test shown in Fig. 15.3. As can be seen from the picture, the box no longer has such a simple shape, and in addition to the basic visual assessment, the progress of the burning of the material is also monitored by thermocouples in predefined areas [2].

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_15

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Fig. 15.1 Box test (a) before the test, (b) after 10 min, (c) end of test: 17 min [1]. (Photograph by P. Mitrenga 2012)

15.2

Test Sample of a Building Fragment

The first truly large-scale test is the test shown in Fig. 15.4. A front view of a building fragment is shown in Fig. 15.4a and a side view of a fragment of a building that was constructed for the purposes of this type of test is shown in Fig. 15.4b. Conditions are similar to realistic fire conditions, evidenced by the amount of fuel that was ignited in the form of spruce wood cages (see Fig. 15.4a – window). The entire course of the test was video-recorded [2].

15.3

Test of the Whole Building

251

Fig. 15.2 Details of the box test (a) control – untreated crate, (b) fire-retardant treated crate [1]. (Photograph by P. Mitrenga 2012)

Fig. 15.3 Improved crate test (a) general view, (b) ignition area [2]. (Photograph by A. Osvald 1993)

15.3

Test of the Whole Building

This type of test has undergone its own evolution. In the early days of large-scale tests, only old buildings destined for demolition were “available.” It was only later that new buildings with predetermined materials, structural composition, and technological construction procedures began to be built for these very purposes.

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Fig. 15.4 Building fragment for a large-scale test (a) front view, (b) side view [2]. (Photograph by A. Osvald 1991)

Fig. 15.5 An older building before a large-scale fire experiment [2]. (Photograph by A. Osvald 1989)

15.3.1 Old Buildings The building seen in Fig. 15.5 is an older building eligible for demolition. Closing mechanisms (e.g., windows and doors) were missing in the building, and some parts of the structure were also significantly damaged. The building was prepared for a large-scale test by marking its parts (see Fig. 15.5). It is a fairly large wooden structure that was ignited in its front section. The progress of the burning was photo and video monitored. The staff video-recording the fire from a safe distance was present as well. The progress can be seen from Fig. 15.6. In the 7th min, the

15.3

Test of the Whole Building

253

Fig. 15.6 Course of the fire after 7 min in the experiment [2]. (Photograph by A. Osvald 1989)

Fig. 15.7 Building after 18 min in the experiment [2]. (Photograph by A. Osvald 1989)

building was almost completely engulfed in fire and smoke, which was mainly caused by the roofing made of asphalt cardboard. Figure 15.7 shows the 18th min of the fire – view from above. The building collapsed just 27 min after the start of the test [2].

15.3.2 Newly Built One-Story Building with Metal Supporting Elements for Testing Purposes An interesting test was carried out by the Department of Steel and Wooden Structures of the Faculty of Civil Engineering of the Czech Technical University in

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Prague (CVUT) on September 18, 2008, in Mokrsko, Příbram district. A building was specially built for this test on the CVUT premises. The fire of a one-story building provided data on the development of temperatures and the behavior of loadbearing metal structures and cladding. Figure 15.8a is a general view of the building, including the mechanical load on the roof of the building, which was formed by sandbags of the prescribed weight. Scaffolding around the building was used to fix the measuring equipment. Figure 15.8b is a view of the fuel – cages made of spruce wood squared timber [4]. The entire test was aimed at detailing the description of the behavior of metal elements and joints in structures during a fire. The course of the test was monitored by camcorders and thermal-imaging cameras. Photo documentation was also done. Figure 15.9 shows the burning of the fuel inside the building in the 23rd min of the experiment. Figure 15.10 shows the collapse of the building that occurred precisely 1 h and 1 min from the start of the experiment and the fire occurring after the collapse of the experimental structure [4].

Fig. 15.8 Building in Mokrsko and the location of the fuel in it before the experiment. (Photograph by A. Osvald 2008)

Fig. 15.9 Progress of the fire. (Photograph by A. Osvald 2008)

15.3

Test of the Whole Building

255

Fig. 15.10 Collapse of the building. (Photograph by A. Osvald 2008)

The given experiment has a truly scientific character and provides different informative values than previous large-scale tests. Before the experiment, the calculation of the zone model and the parametric temperature curve, which could reach 1057 °C from ignition, was made. In the 21st and 30th min, there was a significant increase in temperature (810 and 935 °C), and the temperature in the 58th min was 855 °C. In the space under the concrete slab, the maximum temperature of 935 °C was measured in the 60th min. The gas temperature value as a function of time was also recorded. During the experiment, temperatures in the beam and the deformation of the supporting metal elements were also measured. The values from such an experiment can be considered scientific and can testify in favor of the material and its safe use in terms of fire protection [4].

15.3.3 Newly Built Two-Story Building with Wooden Supporting Elements and Wooden Sheathing for Testing Purposes The model fire experiment of a two-story building was coordinated by the Association of Wood Processors in cooperation with partner companies, the Technical University in Zvolen and the University of Zilina in Zilina. This demonstration took place on the premises of the certified testing laboratory Fires s.r.o in Batizovce, during 7th International Scientific Conference Wood and Fire Safety 2012. Fires s.r.o. is one of the youngest European testing and certification institutions which is authorized to issue certificates of quality and correctness of construction procedures in terms of fire resistance. This institution also provided us with a measuring apparatus with which the results presented in this publication were obtained [3]. The building was made of a prefabricated panel structure with floor plan dimensions of 4.9 × 3.7 m, with a height of 5.6 m and a load-bearing wooden frame filled

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with mineral wool. An installation layer was added onto the perimeter walls and placed in front of the OSB boards (also filled with mineral wool) and covered from and placed in front of the OSB boards (also filled with mineral wool) and covered from the outside with a contact insulation system – two mineral wool-based walls and the other two walls made of fiberboards [3]. The construction of the two-story wooden building is photo-documented in Fig. 15.11. The detailed documentation contains more than 100 photos, a few of which have been selected to show all the construction stages and the types of materials used.

Fig. 15.11 Wooden structure for a large-scale test [3]. (Photograph by Fires company 2012)

15.3

Test of the Whole Building

257

Fig. 15.12 Construction stages of the wooden building for a large-scale test, installation of thermocouples for temperature measurement [3]. (Photograph by Fires company 2012)

Figure 15.12 shows the installation of thermocouples in the interior and exterior and their connection to the measuring unit. As the authors state in the publication [3], a total of 70 measurements were performed and all but one of the thermocouples worked until the end of the measurement. Figure 15.13 shows the location of the fuel, which consisted of spruce square lumber and OSB boards cut into strips. The combination of fuel (spruce and OSB) guaranteed a higher temperature for a longer burning time of this wood than fuel during a fire. This achieved a temperature that approached the temperature of the standard fire resistance curve (See Fig. 15.16). In the right part of Fig. 15.13 shows a 10 L diesel tank, which served as a fuel ignition initiator. The fuel was placed in the entire area of the lower floor so that it represented a heat load of 60–70 km/m2 [3]. After ignition of the initiator, the fire began to spread on the ground floor. The left side of Fig. 15.14 shows thick black smoke at the beginning of the experiment, when mainly the initiator was burning. After burning the fuel, the entire lower part of the building is affected by an intense fire (Fig. 15.14), whose temperature reached 1000 ° C (see Fig. 15.16). The course of the fire was monitored within 45 min, as the entire wooden structure was calculated for fire resistance REI/REW of 45 min.

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Fig. 15.13 Construction stages of the wooden structure for a large-scale test [3]. (Photo by Fires company 2012

Fig. 15.14 Fire development [3]. (Photograph by Fires company 2012)

Photographic documentation demonstrates that the two-story wooden building handled the given fire conditions well. The fire resistance of all parts of the building, including all building elements that are subject to fire resistance certification, have in fact withstood a real fire. Figure 15.15 shows the damaged as well as undamaged parts of the structure of the wooden building after a real fire. As can be seen from the photos, the most damaged place was in the center of the fire, where the fire ignited. Plasterboards began to peel off. Metal joints are also risky in the case of wooden structures. Other parts of the wooden structure remained undamaged. The evaluation of the experiment is not only based on photo documentation or video recording, though these have great informative value, but also by measurement of temperatures. Some of these images (Figs. 15.16, 15.17, 15.18, and 15.19) show the details of the specific places that were evaluated. They are documented photographically, as well as through the course of temperatures from individual thermocouples. The color marking of the individual thermocouples corresponds to the color of the curve, which represents the temperature measured by the given thermocouple.

15.3

Test of the Whole Building

259

Fig. 15.15 Damaged and undamaged parts of the structure after the fire. (Photograph by A. Osvald 2012) 1000

TNK

900

C2

Tempereture (°C)

800 700 600 500 400 300 200 100 0 0

10

20

30

40

50

60

Time (min) Fig. 15.16 Temperature course according to the standard temperature curve (TNK) and according to thermocouple C2, which was placed in the center of the fire, in the space above the initiator [3]

260

15

Large-Scale Test Methods

Fig. 15.17 Schematic of the location of thermocouples, which monitored the fuel temperature C1–C4 [3]

Fig. 15.18 Maximum temperature values of thermocouples (C1–C4) [3] processed by the authors

The entire course of thermal stress does not completely match the standard temperature curve. During the experiment, the thermal stress is regulated by fuel from the burners under strict regulation of their performance. It can be concluded that the conditions during the model test were closer to the conditions of a real fire. See Fig. 15.16 [3]. Figure 15.17 shows the temperature measurement locations with thermocouples C1–C4 on the first floor. These thermocouples were placed in the space under the ceiling. They measured the temperature of the burning fuel (fire), which heated the entire space as well as the structure of the building (walls and ceilings). The color marking of the thermocouples corresponds to the color adjustment of the temperature

References

261

Fig. 15.19 Maximum temperature values of thermocouples Y13, Y15, Y17 and Y18 [3] processed by the authors

curves in the following images, which were measured by individual thermocouples. The fuel was distributed under all thermocouples (see Fig. 15.18) [3]. As it is not possible to describe the entire experiment in full detail, to summarize, the course of temperatures measured by selected thermocouples is shown in Fig. 15.19. When carrying out the heat balance of thermocouples Y (Y13, Y15, Y17, and Y18 – Fig. 15.19) we can see that the thermocouples located on the second floor behind the insulation recorded an almost identical temperature course. The second floor, where there was only fire transfer from the first floor, was heated homogeneously [3].

Questions What are the advantages and disadvantages of large-scale fire tests? How can the validity of these tests be defined? What can a large-scale test detect that other tests cannot?

References 1. L. Makovicka Osvaldova, S. Gašpercova, Stavebné materiály a ich skúšanie pre potreby ochrany pred požiarmi (Building materials and their testing for the needs of fire protection) (University of Zilina, Zilina, 2017)

262

15

Large-Scale Test Methods

2. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection) (Technical University, Zvolen, 2009) 3. J. Stefko et al., Model Fire in a Two-Storey Timber Building, Series Springer-Briefs in fire, 1st edn. (Springer, Cham, 2021), p. 86. https://doi.org/10.1007/978-3-030-82205-7 4. F. Wald et al., Výpočet požární odolnosti stavebních konstrukcí (Calculation of fire resistance of building structures) (CVUT, Praha, 2005)

Chapter 16

Non-standardized Tests

In this chapter, we describe a non-standardized test method that goes back to the beginnings of test methods: a continuous monitoring of the change in sample weight during the test. The test uses small samples and it is economically undemanding. The method, in its simplicity, enables the repeatability of the experiment on one material and statistical evaluation of the results. It uses two sources of ignition of the sample, flame and radiant, both of which operate in the open space under standard laboratory conditions. Several evaluation criteria were defined based on the monitoring of changes in one physical quantity (see Sect. 16.2). We have documented the results of these tests with graphs and tables. The aim is not to evaluate the experiment itself but to point out the informative value of the given test method with those results. This method was used to monitor the differences between individual tree species in terms of evaluation criteria in the given experiment, including the effect of density with the retardation treatment of spruce wood, as well as the effect of individual joints of the wooden structure. In all monitored cases, the validity and sensitivity of this method for the evaluation of individually tested versions were proven. In Sects. 16.3, 16.4 and 16.5, the results of some experiments are presented both graphically and tabularly. As already mentioned, this is not a comprehensive evaluation of the given experiment, but a documentation of the suitability of this method for the given measurements.

16.1

Apparatus

A (non-standardized) apparatus was used for the experiment. The goal was to have a radiant heat source of rather low intensity in order to monitor the effect of joints on thermal degradation of samples by means of the selected evaluation criteria. Ceramic thermal radiator, shown in Fig. 16.1, was used for the experiment. Its maximum © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_16

263

264

16

Non-standardized Tests

Fig. 16.1 Thermal radiator – radiation heat source [5] Fig. 16.2 The apparatus. (Photograph by T. Gábor 2017)

sample thermal radiator

holder

scales

power output is 60 kW/m2 and 230 and dimensions are 254 × 60 × 35 mm. The distance between the sample and the thermal radiator is 35 mm. The sample was exposed to the heat from the radiator for 10 min [5]. The device is shown in Fig. 16.2. Figure 16.3 is a schematic diagram of the thermal loading device testing the joints exposed to a flame heat source. The apparatus and its components are described in detail below the figure. Both apparatuses (for radiant and flame heat source) were designed so as to be open to atmospheric oxygen as well as for natural exhaust gas to be taken away. The intention was to simulate a real fire at its initial stage. The experiment proceeded as follows: • The radiator was warming up for 10 min to reach operating temperature, • The sample was mounted into the holder, the measuring process was initiated, • After 10 min, the holder was shifted from radiator so that spontaneous combustion,

16.2

Assessment Criteria

265

Fig. 16.3 Test equipment: (a) sample; (b) sample holder; (c) weight scales; (d ) gas burner; (e) burner stand; ( f ) propane-butane cylinder; (g) gas intake; (h) (flame) measuring scale; (i) stopwatch; ( j) data recorder. (Photograph by Benický 2019)

• didn’t stop, • After 48 h, the samples was reweighed, • After 14 days the samples were cut in two through the middle. In case of flame heat source, the procedure remained the same.

16.2 Assessment Criteria Assessment criteria are: weight loss, relative burning rate, P ratio, difference in weight loss 0–48, burned area and its size [5].

16.2.1 Weight Loss When the samples were exposed to heat, we observed and recorded weight loss in 10 s intervals. Relative weight loss was calculated according to the relation (16.1)

266

16

δm ð τ Þ =

Non-standardized Tests

mðτÞ - mðτ þ ΔτÞ Δm :100 = :100ð%Þ mðτÞ m ðτ Þ

ð16:1Þ

where: δm(τ) – relative weight loss in time (τ) (%), m(τ) – sample weight in time (τ) (g), m(τ + Δτ) – sample weight in time (τ + Δτ) (g), Δm – weight difference (g).

16.2.2 Relative Burning Rate Relative burning rate has been determined according to the following relations (16.2) and (16.3): ∂δm ð%=sÞ δτ

ð16:2Þ

jδm ðτÞ - δm ðτ þ ΔτÞj ð%=sÞ Δτ

ð16:3Þ

vr = or numerically vr = where:

vr – relative burning rate (%/s), δm(τ) – relative weight loss in time (τ) (%), δm(τ + Δτ) – relative weight loss in time (τ + Δτ) (%), Δτ – time interval where the weights are subtracted (s).

16.2.3 P Ratio P ratio represents a maximum value of relative burning rate divided by the time when this value was reached. The ratio has been determined according to the following relation (16.4). P=

vrmax %=s2 τ

where: P – ratio of maximum burning rate divided by the time when it is reached; vrmax – maximum burning rate (%/s), τ – time when maximum burning rate is achieved (s).

ð16:4Þ

16.2

Assessment Criteria

267

Numerical value of this evaluation criterion gives relevant information on the behavior of the material during the experiment. If the maximum relative burning rate value is achieved in a short period of time, it is a negative sign. If the maximum value is reached later, it is a more positive indicator. It was necessary to compare these two indicators so as to emphasize the synergistic effect of the two measured values. An illustrative example is as follows: if the maximum burning rate value 10 is reached in the 10th min, the monitored ratio reaches the value of 1. If it is achieved in the 5th min, the ratio is 2; if in the 1st min, it is 10.

16.2.4 Difference in Weight Loss 0–48 When exposed to the heat of the thermal radiator, weight loss is observed and recorded in several steps. Since the proposed apparatus as well as the overall methodology of the experiment proved itself to be sufficiently sensitive to the selected evaluation criteria, we decided to measure the weight of the samples after 48 h following the experiment. The weight is measured continuously for 600 s. Then the “final” weight loss under thermal stress is calculated (in 600-s). The weight loss after 48 h was then deducted from this value (16.5). This difference could also reach negative values for certain types of joints. This means that even though a higher weight loss was observed during combustion, it could be caused by thermal degradation as well as by drying of the wooden sample. If no intense burning of the sample occurred, it did not acclimate after 48 h and absorbed the moisture from the environment it was stored in, which resulted in a reduction of weight loss. If the sample was burning flamelessly after being removed from the heat, it resulted in weight loss reduction, even if the sample could possibly absorb some moisture later on. It was not possible to monitor mass ratio by the effect of moisture and thermal degradation in the given experiment even if the samples had been placed in an air conditioned laboratory room. This evaluation criterion, as it was later proved, has some information value. δm48 =

mð0Þ - mð600Þ mð0Þ - mð48Þ :100ð%Þ m ð 0Þ m ð 0Þ

where: δm (48) – difference in relative weight loss (%), m(0) – weight of the sample in time (τ0) (g), m(600) – weight of the sample in time (τ600) (g), m(48) – weight of the sample in time (τ48) (g).

ð16:5Þ

268

16.2.5

16

Non-standardized Tests

Burned Area and Its Size

The size of the burned area is measured after cutting the sample in two through the middle of its length. The charred layer is “removed” from the surface and the line of pyrolysis layer is determined. If the total surface of the sample is 5000 mm2 (100%) before the experiment, the remaining intact area of wood and pyrolysis layer are measured out for each sample. Their surface is calculated and the percentage of the original surface is determined. It is calculated according to the formula (16.6). The idealized zone of measurement is shown in Fig. 16.4. The diagram shows the idealized measurement, linear borders of the measured surfaces. In fact, it is an uneven (bordered) area, which is measured directly on the samples. SC = SCH þ SP þ SN

ð16:6Þ

where: SC – total surface (%), SCH – charred surface (removed layer) (%), SP – pyrolytic layer (light and dark brown layer) (%), SN – layer not affected by fire (%).

16.3

Monitoring the Differences Between Tree Species

To verify the sensitivity of the method, two experiments on different groups of tree species were performed. In the first experiment on a group of selected tree species, the burning rate (see Sect. 16.2.2) and P ratio (see Sect. 16.2.3) were verified. Both types of heat sources, radiant and flame, were used for the experiment. For the second group of tree species, weight change over time (influence of flameless burning, smoldering (see Sect. 16.2.4) was verified.

16.3.1

Description of Experiment I

The following tree species were used for the experiment: ACA acacia (Robinia pseudoacacia L.), BIR white birch (Betula verucosa Ehrh.), BEE beech (Fagus

Fig. 16.4 Idealized zones of measurement [5]

16.3

Monitoring the Differences Between Tree Species

269

silvatica L.), Irish oak (Quercus petraea Liebl.) and MAP Norway maple (Acer platanoides L.) [3]. Each test sample had dimensions of 40 × 20 × 20 mm. Before the experiment, the input values, weight, and size of the test bodies were determined and the density at the given humidity level was calculated (the difference in density was not greater than ±15 kg/m3 and the moisture content of the test bodies was 8 ± 1%. 15 samples were produced and tested for each type of wood of the selected tree species. The average values of these 15 measurements are shown in Figs. 16.5 and 16.6. The test procedure for the radiant heat source (R) experiment is as follows. The test samples were placed under the heat radiator and the Sarto Connect program started at the same time. This program was set to record the weight of the test samples every 10 s. If the test sample burned away within 15 min, the experiment was finished. The heat output of the radiator was 1000 W. The distance between the sample and the radiator was 30 mm. The test procedure for the flame source (F) experiment was identical to the procedure described in the previous paragraph. However, instead of a radiant heat source, a flame source (a small burner) and propane-butane fuel were used for this experiment, as outlined in the EN ISO 11925-2 standard [7].

0,0018

ACA R

0,0016

BEE R

Burning rate (%/s)

0,0014

BIR R

0,0012

MAP R

0,001

OAK R

0,0008 0,0006 0,0004

0,0002 0

0

180

360

540

720

900

Time (s) Fig. 16.5 Burning rate course of the selected tree species exposed to radiant heat source [3]

270

16

Non-standardized Tests

0,0012 ACA F BEE F

Burning rate (%/s)

0,001

BIR F 0,0008

MAP F OAK F

0,0006 0,0004 0,0002 0

0

180

360

540

720

900

Time (s) Fig. 16.6 Burning rate course of the selected tree species exposed to flame source [3] Table 16.1 Average values of the selected evaluation criteria [3] processed by the authors Evaluation criterion Burning rate (%/s) Time of maximum burning rate (s) P ratio (%/s2)

16.3.2

Source of heat Radiant Flame Radiant Flame Radiant Flame

Wood ACA 0.00035 0.00065 320 50 1.08 15.47

BEE 0.00154 0.00068 290 40 5.32 19.07

BIR 0.00100 0.00098 320 30 3.12 36.92

MPA 0.00091 0.00095 310 40 2.94 25.68

OAK 0.00047 0.00073 340 60 1.38 12.23

Results of the Experiment I

The results of these measurements are documented in Fig. 16.5 (radiant source experiment) and Fig. 16.6 (flame source experiment). Table 16.1 displays values for the burning rate criterion and P.

16.3.3

Description of Experiment II

A wider selection of wood from selected tree species was used for the second experiment (see Fig. 16.7). The selection of samples (density, moisture, dimensions, number) for each tree species was identical to experiment I. A flame heat source was used.

16.3

Monitoring the Differences Between Tree Species

271

Fig. 16.7 Tested tree species in Experiment II [3] processed by the authors

Fig. 16.8 Values of weight loss in the tested tree species at the time of the test “0” and “48” [3]

16.3.4 Results of Experiment II The results are displayed in the following graph (Fig. 16.8), which in this case has a higher informative value. This bar graph shows weight loss values (%) at the “0”, time mark, i.e. directly after the heat load was applied (600 s) and continuous measurements were taken for 240 s. The “48” time mark is a measurement after 48 h, which is taken in order to account for and monitor spontaneous combustionsmoldering even after the heat load is removed.

272

16

Non-standardized Tests

The graph shows average values from 10 sample measurements. A wider range of tree species was used, and the experiment confirmed well-known facts documented in many works which classify individual tree species into different groups according to how they resist ignition/burning and whether they are prone to flameless burning and smoldering. Locust and oak (hardwoods) and larch (conifers) are the most resistant to ignition and burning. This is also seen in the values for the difference in weight loss between the value “0” and “48”. On the other hand, there are poplar, maple, alder, and pine, which are much less resistant to ignition and burning. This experiment, with its conclusive results that conform to previous research, confirmed the suitability of this experimental method for evaluating the given criteria.

16.4

Monitoring the Effects of Wood Density and Retardants

Next, we verified the suitability of the proposed method with an experiment in which we monitored the influence of the density of spruce wood on weight loss and burning rate, while simultaneously verifying the retardation effect [1, 4, 6].

16.4.1

Description of the Experiment

For this experiment was chosen Norway spruce (Picea abies (L) Karst.). Its wood is yellowish to yellowish-brown, shiny, with colorless heartwood which is very light in color, light and soft, elastic, easy to split, and easy to dye, but more difficult to impregnate. It is characterized by a symmetrical and narrow annual ring (1–4 mm) with the proportion of summer wood in the annual ring ranging from 5% to 20% [2]. The test samples of Norway spruce were classified according to their density. 90 pieces out of 450 samples were divided into two density groups (see Table 16.2): LD (low density) and HD (high density). From each density category (45 test samples in each), 15 samples were selected for testing in their unmodified form (without using flame retardant), low density LD0, high density HD0, 15 were treated with one layer of flame retardant on both sides (low density LD1, high density HD1) and 15 were treated with a double layer of flame retardant on both sides (low density LD2, high density HD2). A random retarder was chosen for the experiment. The selected retarder will not be further characterized or specified, as the aim of the experiment was not to assess Table 16.2 Density in the given categories [2]

Density Minimum density Highest density

LD 369.84 385.44

HD 543.12 577.64

16.5

Monitoring the Effect of Joints

273

the retardant, but rather to find out whether the density of the test specimens has any effect on the overall result even when a retardant is applied. The principle of the thermal load was chosen from the traditional test method, where the main evaluation criterion is weight loss. The test used samples with dimensions of 200 × 100 × 10 mm exposed to the flame of a gas burner. The center of the sample was exposed to the flame for 10 min, making an angle of 45° with the horizontal line. The perpendicular distance between the center of the sample and the mouth of the burner was 90 mm, with a flame height of 100 mm.

16.4.2

Results of the Experiment

The results of these measurements are documented in Figs. 16.9, 16.10, 16.11, and 16.12 for the weight loss criterion, and in Fig. 16.13, 16.14, and 16.15 for the burning rate. In the given pictures, the effect of wood density as well as the effect of flame retardant can be clearly seen. The effect of density was also manifested when the flame retardant was applied twice.

16.5

Monitoring the Effect of Joints

The influence of the mechanical joints of two wooden elements on the evaluation criteria of the non-standardized test method was monitored using this method. Both types of heat sources were used and their influence on all the selected criteria was also monitored.

50

LD0

45

HD0

weight loss (%)

40 35 30 25 20

15 10 5

0 0

100

200

300

400

500

600

me (s)

Fig. 16.9 Course of weight loss for untreated wood of low (LD0) and high (HD0) density [2]

274

16

Non-standardized Tests

50 LD1

45

HD1

weight loss (%)

40

35 30 25 20 15 10 5 0 0

100

200

300

400

500

600

time (s)

Fig. 16.10 Course of weight loss of wood with low (LD1) and high (HD1) density treated with one layer of flame retardant [2]

50 LD2

45

HD2

weight loss (%)

40 35 30

25 20 15

10 5 0 0

100

200

300

400

500

600

time (s)

Fig. 16.11 Course of weight loss for low (LD2) and high (HD2) density wood treated with a double layer of flame retardant [2]

16.5.1 Description of the Experiment The following types of joints of wooden elements were used for the experiment (see Fig. 16.16).

16.5

Monitoring the Effect of Joints

275

50 45

40 weight loss (%)

35 30 25 20

15 10 5 0 LD0

HD0

LD1

HD1

LD2

HD2

Fig. 16.12 Highest values in weight loss for individual variations of the experiment [2] 0,1 LD0

0,09

HD0

burning rate (%/s)

0,08

0,07 0,06 0,05 0,04 0,03 0,02 0,01 0 0

100

200

300

400

500

600

čas (s)

Fig. 16.13 Burning rate course for unrefined wood of low (LD0) and high (HD0) density [2]

16.5.2 Results of the Experiment Both heat sources were used; in all pictures (a) represents the radiant heat source and (b) the flame heat source. Figure 16.17 shows the average values of weight losses for individual heat sources and tested joints. In Fig. 16.18, the differences in weight loss compared to the control sample (without joints) are recorded. In all cases, these are positive values, that is, each joint shows worse fire resistance properties than the control sample without a joint. The worst results for both heat sources were those of the vertical finger joint (see Fig. 16.16e). This result also confirmed the quality of the test method and its criteria.

276

16

Non-standardized Tests

0,1

LD1

0,09

HD1

burning rate (%/s)

0,08 0,07 0,06 0,05 0,04

0,03 0,02 0,01

0 0

100

200

300

400

500

600

me (s)

Fig. 16.14 Burning rate course for wood of low (LD1) and high (HD1) density treated with one layer of flame retardant [2] 0,1

LD2

0,09

HD2

burning rate (%/s)

0,08 0,07 0,06 0,05 0,04

0,03 0,02 0,01

0 0

100

200

300

400

500

600

me (s)

Fig. 16.15 Burning rate course for wood of low (LD2) and high (HD2) density treated with a double layer of fire retardant [2] processed by the authors

This joint has the longest line across the entire thickness of the sample, which allows heat transfer through the sample; therefore the results follow logically and the test method is shown to be relevant. Table 16.3 shows the data for the second evaluation criterion, the burning rate, specifically the maximum value of the burning rate, and the time when this maximum value of the burning rate was reached. From these data, the ratio P, (the third evaluation criterion) was calculate. The average P values for both sources and all tested joints are shown in Fig. 16.19.

16.5

Monitoring the Effect of Joints

277

Fig. 16.16 The following types of joints have been tested (a) control sample – no joint, (b) glued joint, (c) dovetail joint, (d) biscuit joint, (e) vertical finger joint, (f) horizontal finger joint, (g) lap joint – screw with a nut, (h) lap joint – self-tapping screws [5] processed by the authors

b) 13,43

13,79

14,97 11,98

10,65 8,65

11,61

12,58

8,89

8,55

Weight loss (%)

Weight loss (%)

a)

5,93 5,04

6,65

6,47

6,60

5,46

Fig. 16.17 Average weight loss values of the given joints using (a) radiant heat source, (b) flame heat source [5] processed by the authors

In Fig. 16.20, weight loss data are shown in two time intervals, immediately after the test and 48 h after the test. This is in order to take account for and spontaneous combustion-smoldering. Even in this case, the biggest differences are recorded in the case of the flame source for the vertical finger joint and the dovetail joint. Figure 16.21 displays data for charring based on which it is possible to monitor the influence of the source on the size of the charred area. Based on all the measurements, we can conclude that this non-standardized method of weight loss measurement provides important information about the burning of the tested samples.

278

16

a)

Non-standardized Tests

b)

4,78

3,93

3,33

2,96

3,86

3,52

Weight loss (%)

Weight loss (%)

6,32

5,14

1,61

1,43

2,00 0,89

1,56

0,42

Fig. 16.18 Average differences in weight loss – a control sample against the given joint using (a) radiant heat source, (b) flame heat source [5] processed by the authors

Table 16.3 Average values for the burning rate of the tested joints with both heat sources [5] processed by the authors Radiant heat source τvmax (s) vr (%/s) 0.00457 600 0.00406 510 0.00467 510 0.00481 450 0.00475 390 0.00464 510 0.00411 510 0.00483 600

Joint Control sample – no joint Glued joint Dovetail joint Biscuit joint Vertical finger joint Horizontal finger joint Lap joint – screw with a nut, Lap joint – self-tapping screws

b) 4,50

2,39

2,77

2,39

1,64

1,17

1,05

Rao P ((%/s2)*106)

Rao P ((%/s2)*106)

a)

Flame heat source vr (%/s) τvmax (s) 0.0025 130 0.0025 60 0.0044 70 0.0033 70 0.0042 60 0.0027 70 0.0031 140 0.0025 50

50,75 43,92 30,52

28,35 22,75

19,92 2,99

Fig. 16.19 The differences in the average peak burning rate between the given joint and a control sample using (a) radiant heat source (b) flame heat source [5] processed by the authors

References

279

a)

b) 48 h

21,01

20,35

18,75

20,03

18,17

23,85 19,11

22,58

22,51

22,3

21,52

21,05

17,74

17,42

16,23

15,92

Weight loss (%)

600 s

Fig. 16.20 The average weight loss of the given joints right after being exposed to (a) radiant heat source (b) flame heat source and 48 h after the expo-sure [5] processed by the authors

a)

b) 60

Charred area 40 30 20 10 0

Pyrolyc area Intact area

Area (%)

Area (%)

50

80 70 60 50 40 30 20 10 0

Charred area Pyrolyc area Intact area

Fig. 16.21 The layers and their percentage for the given joint using (a) radiant heat source (b) flame heat source [5] processed by the authors

Question What improvements to the technical equipment and evaluation criteria would you suggest for this test method?

References 1. D. Kacikova, L. Makovicka Osvaldova, Wood burning rate of various tree parts from selected softwoods. Acta Facultatis Xylologiae 51(1), 27–32 2. L. Makovicka Osvaldova et al., The influence of density of test specimens on the quality assessment of retarding effects of fire retardants. Wood Res 61(1), 35–42 (2016). http://www. centrumdp.sk/wr/201601/04.pdf. Accessed 17 Feb 2023 3. L. Makovicka Osvaldova, J.R. Sotomayor Castellanos, Burning rrate of selected hardwood tree species. Acta Facultatis Xylologiae 61(2), 91–97 (2019). https://doi.org/10.17423/afx.2019.61. 2.09 4. L. Makovicka Osvaldova, P. Kadlicova, J. Rychly, Fire characteristics of selected tropical woods without and with fire retardant. Coatings 10(6), 527 (2020). https://doi.org/10.3390/ coatings10060527

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Non-standardized Tests

5. L. Makovicka Osvaldova, Wooden Façades and Fire Safety, Springer briefs in fire, ISBN 978-3030-48882-6. https://doi.org/10.1007/978-3-030-48883-3 6. A. Osvald, Úbytok na hmotnosti ako hodnotiace kritérium vlastností vzťahujúcich sa k ohňu (Weight loss as an evaluation criterion for properties related to fire), in Advances in Fire and Safety Engineering, (Slovak Technical University in Bratislava, Faculty of Materials Technology based in Trnava in the Publishing House Alumni Press, Trnava), pp. 10–15 7. EN ISO 11925-2:2020 Reaction to fire tests. Ignitability of products subjected to direct impingement of flame. Part 2: Single-flame source test

Part VI

Retarders and Fire Retardancy

In the previous chapters, we dealt with different test methods which test materials that are used for various purposes. They generate a certain assessment of materials in terms of how they will behave in a fire, how easy or difficult it is for them to ignite, and how intense their burning will be. In all tests, the physical properties of the materials, their various modifications, dimensions, and functionality are taken into account. The requirements on materials and test methods to meet certain conditions have grown so that their informative values have more significance. However, we have not yet mentioned retardation modifications of materials, specifically fire retardancy. This issue is addressed in the last part of the textbook in two separate chapters. One chapter deals with the options for fire-retarding treatment of materials, while the other looks into the topic of this these treatments and test methods. We will go through all the chapters in order to find out what the flame retardant treatment of materials means in individual tests and how it can affect the test results (and therefore fire properties) of various materials. It is important to note that the development of test methods and the effort to modify materials so that they are more resistant to fire are very closely connected. The first test methods were, in fact, mainly developed to determine the results of the retarding effect of fire retardants. It was only later that untreated materials were also tested. Their various versions were (and are) monitored and certificates are issued for their suitability for safe use in practice. They should be safe mainly from the point of view of the origin and development of fire and they must retain their unchanged properties during the fire to ensure the safe escape of people from the place threatened by fire, as well as the safe work of the intervening units during the localization and extinguishing of the fire. In order for materials that are normally considered flammable to fulfill these conditions, substances called fire retardants were created and developed. Sometimes we also come across the term “antipyrens.” In practice, however, the term retardant is preferred as it indicates something that slows down the burning process rather than something that could actually turn a combustible material into a non-flammable material.

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This effort to modify materials has long roots in history. In addition to the study of combustion itself, opinions on modifying materials (mostly natural and flammable ones) to make them less flammable and more difficult to ignite began to be voiced. The need to modify materials also appears in legislative regulations from past centuries. For example, the decree of Emperor Joseph II from 1788 ordered the wrapping of wooden beams with reeds and then covering them with plaster in order to prevent the spread of fire. In the 18th century, patents were granted for (as we would call it now) fire-retarding treatment of materials: J. Wilde (r. 1735) was granted a patent for a fire retardant made of alum and borax, Gay Lucas (r. 1781) for a solution of inorganic salts, Fuchs (r. 1820) recommended the use of “water glass” (liquid sodium silicate) to prevent the spread of fire. In the nineteenth century, ammonium salts of phosphoric acid began to be used for protection. A fire retardant usually has the function of a catalyst which can change the speed necessary to achieve chemical equilibrium, but it cannot change the intensity of the heat flow, the lack, or an excess of oxygen with resulting changes in the conditions and manifestations of combustion. However, it can change or affect the process of creating fuel and its ignitability. In the later stages of the combustion process, especially at high heat flows, the possibilities of flame retardancy are already very limited. For effective flame retardancy, the reactions that take place at the beginning of the individual stages of combustion, i.e. initiation (contact of the wood – heat system), propagation (released flammable gases – oxygen), or termination (forming solid residues – oxygen) are decisive. Flame retardancy is a relatively complicated process and is mostly based on the use of retardation systems that complement and influence each other. Current research continues to enable the development of new high-quality and highly effective flame retardants.

Chapter 17

Flame Retardants: Principle of Retardation

Flame retardants can be divided into two basic categories, according to the retarding effect and the method of application onto the material. It should be noted that improving the properties of the material with a flame retardant is possible for all materials. This is most important for naturally combustible materials (wood and wood-based materials and other lignocellulosic materials), where retardation is possible in several ways, but it is a very complex process. It is also possible to modify textiles (the product itself or the fiber) and plastics.

17.1

Retarding Effects of Various Flame Retardants

Methods of improving fire protection properties using flame retardants can be specified as follows [7]: • • • •

stabilization of a material’s decomposition into flammable products, fire-resistant or hardly flammable insulating coatings, additions of additives that melt under the influence of heat and form non-flammable coatings, • additions of additives that have an antioxidant effect, i.e. their decomposition creates an inert flame-extinguishing coating, • support for the formation of a carbon structure – a carbon residue that prevents the spread of combustion into the depth of the material, • the addition of additives that interrupt the mechanism of chain reactions by binding free radicals. The first group consists of retardants that release non-flammable gases in the same thermal range where flammable gases are also formed as products, e.g. in wood decomposition. This results in the dilution of flammable gases, such that their © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_17

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concentration decreases and their ignition becomes more difficult. The most widespread compounds used to protect wood-based and cellulosic materials from fire are various inorganic salts. They dissolve well in water and thus many different impregnation procedures can be used [4–6, 8]. The second group consists of retardants which absorb the heat of the heat source and thus “cool” the source. These retardants currently have a limited application of use, as they quickly undergo aging and their effectiveness decreases. The third group consists of intumescent flame retardants. Their efficiency is the highest, as it is two-staged, with both physical and chemical retardation, thus their application is the widest. The fourth type is retardants of the mechanical type, such as foils and various claddings made from non-combustible materials. The application of such retardants to wood is effective, but it entails certain risks. In the case of intumescent coatings, in the first stage of heat action, one component of the retardant reacts, creating a foam of several centimeters. This physically distances the surface of the wood from the heat source. This additional distance creates the first method of physical retardation [5]. The second method of physical retardation lies in the fact that foam is a very poor heat conductor and the heating of the wood slows down considerably. The third method is chemical retardation, when chemical reactions occur during further heating that significantly slow down burning. Intumescent coatings are a mixture of various substances (urea condensates with formaldehyde, methylmelamine condensates, phosphates, plasticizers, pigments, etc.). We must not forget that flame retardant is a chemical substance for which it is necessary to have a safety data sheet. It contains a whole range of data that must be filled out. This information about various flame retardants is often decisive in the choice of a particular retarder for application to a product [8].

17.2

Application of Flame Retardant

The application of flame retardant depends on two main factors: the form of flame retardant and the material to which the retardant is to be applied. The main types of applications are mainly coating, dipping, and impregnation – whether as an additional treatment of the finished product or directly during production by adjusting the input raw material or production technology.

17.2.1

Coating

Coating is relatively the simplest form of treatment of several materials. In some cases, surface treatment (degreasing, roughening, etc.) is required before application of the retardant.

17.2

Application of Flame Retardant

285

This method works well for “non-combustible materials,” e.g. steel structures, to increase their fire resistance. In addition, wood and wood-based products, and other composite large-scale materials, are also commonly modified in this way. Although it is more rare, plastic or textile products can be coated as well. The advantages of this modification lie in the relatively undemanding technology of modification and its possible repeatability. However, it is necessary to follow the technological procedure of application stated by the manufacturer of the flame retardant. On the other hand, the retardant is prone to aging, and its effectiveness can be reduced due to atmospheric influences. An even greater reduction in efficiency can occur in the event of mechanical damage to the paint/retardant-treated surface.

17.2.2

Dipping

Dipping, along with coating, is the application of a liquid retardant. This application procedure can be used on wood, wood products, and textiles. It is a short-term or long-term process depending on the type of material and the flame retardant used. If this application of the retardant requires heating of the liquid retardant or additional artificial drying of the treated material, this technology can be quite economically demanding and is not always highly effective.

17.2.3

Impregnation

Another possible technology of liquid retardant application is impregnation. The method requires an impregnation device, preferably a vacuum-pressure one, which allows the use of different impregnation modes. Wood is a suitable material for this type of modification. It can also be applied to semi-finished products made from wood, veneers, wood chips, or finished products. Impregnation improves the retardation effect to a large extent. Impregnated material is much better protected than coated material. Figure 17.1 also gives evidence for this claim [5–7]. The given picture demonstrates that the impact of retarder application technology is significant and affects the Q value in the flammability test according to STN 730862 [5] (see Sect. 3.3.2 CSN 730862) (though it is a method no longer used today). This standardized experiment evaluated a common retardant, an aqueous solution of ammonium salts. The classification of modified material in the (then) evaluation of “degree of flammability” differed significantly depending on individual modifications. If the untreated material, as well as the material treated with a one-sided coating, are classified in the flammability level C2, a double-sided coating classifies the material in the flammability level C1. Impregnated material is included in flammability level B, of course, while using the same retardant [4–6].

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Fig. 17.1 Retardant effectiveness depending on type of application (N – untreated material, 1 – one-sided coating, 2 – double-sided coating, I – impregnation, Q – value for the flammability class according to STN 730862) [7]

It goes without saying that the application of retardant by impregnation cannot be recommended everywhere. However, there are places, for example in the mass production of buildings, where this procedure can be recommended.

17.2.4

Modification of Raw Material Inputs

This technology is suitable for large-scale wood-based materials as well as other composite materials. The case of plywood is an ideal example, where it is possible to modify both input materials. The basic building element of plywood is wooden veneer. We cannot adjust the density of plywood, only in direct proportion to the thickness of the plywood or the number of veneers used in the construction of the plywood. In addition to the type of wood, the fire-technical properties of plywood are influenced by the glue and the quality of the gluing technology. Fire retardation of plywood is possible in the following ways. First, a very effective but economically demanding method is the impregnation of veneers with a flame retardant. This requires the use of another technology, the impregnation of already dried and sorted veneers, which must be dried again after impregnation. This procedure requires additional technological equipment, increased energy consumption, as well as a higher labor costs [2, 3]. Another way is to adjust the glue used to glue the veneers in plywood. It is important that the chemicals (glue and retardant) do not react with each other so that neither the functionality of the glue nor the retardant decreases. Similar chemicals were found in the phenolic resin F 20 and the retardant Retar 131 [10]. Plywood glued with such an adhesive mixture showed improved fire-technical properties. We must not forget about the flame spread criterion during the tests. In this case, the contact top (bottom) veneer, which is not treated with a retardant, may show signs of flame propagation as an untreated sample, reducing the overall retardation effect. Only the first adhesive layer is treated with a retardant. This effect can occur even with impregnated veneer. If the retardant-impregnated contact veneer is in contact with the pressing plate for a longer time at a higher

17.2

Application of Flame Retardant

287

temperature, the retardant can begin to take effect, which reduces its effectiveness. This is especially evident with thicker plywood that is in the press for a longer time. A hot-cold bath is recommended, which implements the technology of spraying the retardant on the top veneer of the finished plywood immediately after pressing; when the hot surface cools down, the air in the intercellular spaces cools down and the retardant is absorbed by the wood mass of the veneer for better impregnation. The combination of both procedures (impregnation of veneers and glue modification) creates a material of very high quality in all technical as well as fire safety aspects. Such material is used for special purposes. Coating (application of a retarder on the surface of the material) or retardation foils [3] can also be used. The retardant modification of the input raw material is much simpler, for example in the case of textile fiber or input raw material for plastic products.

17.2.5

Modification of Technology

Next, we consider chipboard, The fire-technical properties of chipboard is mainly characterized by its input materials, i.e. the wood, the glue, or other additives. In addition to the basic composition of chipboards, their fire-technical properties are influenced by their production technology. Surface-pressed chipboards have better fire-technical properties than roller-pressed chipboards. When comparing boards with the same composition in terms of wood, glue, density and thickness, there is still a major difference in fire-technical properties between the two pressing technologies (surface vs. roller pressing) [1]. In fact, a claim can be made that it was roller-pressed chipboards that caused some large-scale fires in wooden buildings that were difficult to extinguish, which is why they are not used anymore. Another limiting criterion of the fire-technical properties of chipboards is their density. Here it is possible to claim, to some degree, that there is a directly proportional relationship between chipboard density and its fire-technical properties. Chipboards with higher densities show more positive fire-technical properties. In addition to thickness, density is also a limiting factor in value standards for the selection of particle boards and OSB for wooden buildings. Chipboards can be retarded in several ways. The first method is the impregnation of the chips themselves with a flame retardant. This procedure shows a relatively good quality of retardation, but it is economically very demanding and practically unfeasible. Adding a powder retardant in a certain percentage appears to be an economically advantageous and effective method of retarding chipboards. Glue is then applied with the retardant. Chipboard production technology continues without further technological requirements and adjustments, or increased labor requirements [1, 9]. The aim of the experiments was to determine the reason for the improvement of the fire-technical properties of chipboard treated with a solid retardant. With this technology, it is possible to adjust the fire-technical properties of chipboards at different levels according to the retardant in the board. With a three-layer chipboard,

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the percentage representation of the retardant can be changed in the individual layers (in the peripheral and central layers). The experiment that has been described in this text concerns a three-layer chipboard with a thickness of 18 mm and a density of 600 kg/m3. The board was subjected to thermal stress according to the then-valid standard STN 730862 [7, 8]. Such thermally degraded material was subjected to microscopic examination in three positions (Fig. 17.2). Figure 17.3 shows a shot from position 1 (as labeled in Fig. 17.2.), Fig. 17.4 from position 2, Fig. 17.2 from the center of the board, and Figs. 17.5 and 17.6 from position 3. In Fig. 17.3 is a sample taken 2 mm below the charred layer. Position 1 means that it is the side that was thermally loaded with both a flame and radiant heat source according to the mentioned methodology. In the figure, the “moon landscape,” which resulted from the melting of the powder retardant, is visible; the melting covered the surface of the chips. Here is the first success of the retardation, i.e. consuming heat to change the state from solid to liquid, which solidifies again after cooling. Fig. 17.2 Scheme of positions for microscopic observation of the retardation treatment of chipboard [7]

18 mm

1

Fig. 17.3 Melt formation on the sample from position 1 [7]

2

3

17.2

Application of Flame Retardant

289

An interesting effect occurred during microscopic observation. The samples under the microscope started to form some kind of bubbles. This phenomenon is shown in Fig. 17.4. In Fig. 17.4a is a bubble beginning to form and in Fig. 17.4b is an enlarged bubble just before bursting. These bubbles were formed by the heat of the electron microscope beam. Based on this, we can assume that the retardant still had the preserved function and reacted to thermal influences. As was mentioned, Fig. 17.5 shows a shot from the center of the chipboard, i.e. 9 mm from the source of the fire. It can be observed that the retarder crumbled but still retained its powder form. This is created either by thermal degradation of the

Fig. 17.4 Observing the melt of the retarder from position 1. (a) formation of bubbles caused by the heat of the electron microscope beam, (b) enlargement of the bubble during longer observation [7]

Fig. 17.5 Microscopic image from the center of chipboard treated with powder retardant in position 3 after thermal load [7]

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Fig. 17.6 Presence of crystalline retardant in position 3 after thermal test [7]

crystals or by recondensation of retardant vapors, which were then in a stronger concentration and condensed into a crystalline form after cooling. Figure 17.6 represents the position of the sample approx. 16 mm from the fire. In this picture, it is visible that the retarder retains its crystalline form, and did not change. It was able to retard chemically by changing state. The chipboard modified in this way was classified in flammability class A. according to the regulations of the time. The retardation of combustion in the process of technology is also evident with other composite materials.

Questions What methods of flame retardant application are suitable for individual materials? Which testing methods do you recommend for monitoring the retardation effect? How is it possible to monitor the reduction of the radiation effect?

References 1. P. Bucko, A. Osvald, R. Reh, Vlastnosti vodovzdorných drevotrieskových dosák retardovaných proti ohňu (Properties of fire-retarded waterproof chipboards). Drevo 45(2), 38–39 (1990) 2. J. Mahut, D. Horsky, A. Osvald, Retardačná úprava preglejok (Retardation treatment of plywood). Drevo 38(8), 219–221 (1983) 3. J. Mahut et al., Fire retard treatment of phenoplast with triarylphosphate, in Flammability of Polymers (Polymer Institute Slovak Academy of Science, Smolenice, 1985), pp. 44–53

References

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4. A. Osvald, Hodnotenie požiarnej bezpečnosti materiálov a výrobkov z dreva a na báze dreva (Assessment of fire safety of wood and wood-based materials and products wood) (Technical University, Zvolene, 1997) 5. A. Osvald, L. Osvaldova, Retardácia horenia smrekového dreva (Fire retardation of spruce wood). (Technical University, Zvolen, 2003) 6. A. Osvald et al., Hodnotenie materiálov a konštrukcii pre potreby protipožiarnej ochrany (Evaluation of materials and construction for the needs of fire protection) (Technical University in Zvolen, Zvolen, 2009), p. 335 7. A. Osvald, K. Balog, Horenie dreva (Burning wood) (Technical University, Zvolen, 2017) 8. L. Osvaldova, Retardéry horenia (Flame retardants). Arpos 18–19, 18–21 (2005) 9. R. Reh, A. Osvald, P. Bucko, Zníženie stupňa horľavosti vodovzdornej drevotrieskovej dosky (Reducing the degree of flammability waterproof chipboard), in Drevársky výskum 128 (Alfa, Bratislava, 1991), pp. 43–56 10. R. Reh, A. Osvald, Retandants of Combustion in Interaction with the Phenol -Formalde- Hyde Resins, in X. sympózium Pokroky vo výrobe a použití lepidiel v drevopriemysle (Advances in the production and use of adhesives in the wood industry) (ES VSLD, Zvolen, 1991), pp. 223–233

Chapter 18

Effects of Flame Retardants in Individual Tests

In this final chapter, we present our own experience with testing various materials and their modifications, including retardation. Based on the test results, we also present other options (e.g., technical solutions) to increase fire safety in the given conditions. Of course, we focus on the need for retardation and the effects of retardation on the given material or the given form of the tested material.

18.1

Fire and Flame Retardants

Flame retardants are chemical substances added to a material that, by their chemical, physical, or combined methods, prevent the rapid ignition and burning of the material. In conjunction with other technical firefighting means, such as smoke detectors, alarms and sprinklers, heat and smoke exhausts, fire retardant blinds, etc., retardants are one of the most effective means available to protect people and their property from the devastating effects of fire. Statistical studies and extensive scientific research repeatedly prove the importance of flame retardants. However, the statistics in these cases don’t tell the whole story, because while they can record the number of fires which occurred (and correlating data on retardants), they cannot precisely record how many fires were prevented by fire retardants. There have been efforts to eliminate flame retardants from being used. The flame retardants are chemical substances that are repeatedly applied onto the material. Currently, however, even flame retardants are produced on the basis of new ecological raw materials and do not have any undesirable effects when handling them. In the same way, fire-retardant treated materials do not show any changes in the evaluation of their sanitary properties. Minimal to no undesirable effects are known to occur in fires due to the retarder. However, it is difficult to determine with current retarders whether they have a negative impact on the environment during a fire. Older fire retardants increased the proportion of smoke compared to © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0_18

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unprotected products and had a relatively short lifetime. However, these negative factors of flame retardants are already a thing of the past. The application of flame retardants is generally recommended. In addition to “overall” application, it is necessary to also think about the local application of flame retardants where there is an increased risk of fire.

18.2

The Theoretical Basis for Materials Testing

All chemical and physical changes in the material are also described by mathematical formulations in such a way as to record the process of its degradation by high temperatures or fire conditions; this enables certain criteria and threshold values to be established for the classification of materials. The influence of flame retardants will be reflected in the changes in these values (e.g. of a material’s resistance to or behavior in a fire) and thus in the change in the classification of the material.

18.3

Testing of Materials for Fire Protection Use

All the methods described in this chapter are intended to evaluate not only the materials themselves but in particular to evaluate their retardation treatment. These methods, along with methods for retardant testing, became the basis for the development of new test methods and new evaluation criteria. For example, the method described in Sect. 3.3.1 CSN 730853 was simple and relatively widespread, not only in testing laboratories but also in production plants. This test e.g., the weight of the sample was measured only before and after the test. But with the application of retarders, this evaluation criterion began to be questioned. A weight loss was detected after the test, but the material had showed no signs of burning. Why the discrepancy? The answer: a decrease in weight was caused by the flame retardant burning off, which of course had a positive effect on the material’s fire properties. Likewise, materials that contained bound water (moisture) were not quite accurately evaluated. Drying of the material and loss of moisture automatically meant a loss of weight, which was reflected in the result. In the end, according to these criteria, even ice was classified into the flammability of class C3, meaning it was considered flammable. That is why other evaluation criteria besides weight loss began to be evaluated. It should be noted that weight loss is still an important evaluation criterion in even new methods, mainly because it can be recorded continuously during the test at certain time intervals. A different problem occurred with method 3.3.2 CSN 730862. It was more modern and used two heat sources, flame and radiant heat, and had a certain testing regime. It also had a more complex evaluation criterion calculation that simulated real fire conditions. It is possible to state that the material was evaluated more objectively and so was the retardation effect. That is, until intumescent flame

18.4

Testing of Building Materials

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retardants came along. As they foamed, they clogged the burner port and shorted the electric coils, essentially making it impossible to test them using this method. Once again, new methods had to be developed. Therefore, we can say that flame retardants were not only evaluated using various test methods, but it also worked the other way around - in testing them, they also tested the quality of the given test methods themselves.

18.4

Testing of Building Materials

Fire statistics monitor various events and incidents: the nature of fires, their speed, and their consequences. All of these have changed due to the emergence of new materials. Test labs began to be established for the evaluation of materials, i.e. their suitability for use in building structures, or in interior design elements. The test results were reflected in standards, decrees and laws. But for many decades, each country had not only its own legislation but also its own evaluation procedures. Different samples (dimensions) were used for the tests, different heat loads (radiant/flame), the duration of the heat load, and the overall testing conditions differed significantly in the individual procedures - meaning that the test results could not be compared with each other. Sometimes, even within one state, several different regulations were used for different industries, e.g. construction, transport, etc. Eventually the European Union unified the testing system and prescribed testing methods in its regulations. It established the exact conditions on the basis of which certificates are issued for the given materials or products. The methods are described in Chap. 4. It is a group of methods that copies the phases of a fire (see Table 18.1). Table 18.1 Reaction to fire classes in relation to fire stages (edited by the author) Class A1

Performance description No contribution to fire

A2

No contribution to fire

B

Very limited contribution to fire Limited contribution to fire

C D E F

Acceptable contribution to fire Acceptable contribution to fire No performance requirements

Fire scenario Fully developed Fire in room Fully developed Fire in room Single burning item in a room Single burning item in a room Single burning item in a room Small flame attack

Heat attack At least 60 kW/m2

40 kW/m2 on a limited area 40 kW/m2 on a limited area 40 kW/m2 on a limited area Flame height of 20 mm

–

–

At least 60 kW/m2

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These methods evaluate flame retardants and various retarding treatments. The type of retarding substance and the exact retardation procedure must be indicated on the certificate of the retarded product.

18.5

Testing of Cables, Conductors, and Wiring

Testing cables and wiring requires special testing procedures. Though in all the previous tests the heat source acts from the outside, in the case of cables, the source of heat (and potential fire) acts directly inside them. Cables are, of course, used to transmit electrical energy, which, under certain conditions, can be transformed into heat. If this heat reaches certain values, the surrounding materials can ignite. The second threat is an electrical short circuit - a spark with sufficient potential to ignite surrounding objects. Another danger is mechanical damage to the cable or its insulation. If the cables are used in fire safety devices (fire detectors, other notification and information devices, control and regulation equipment), their failure can have multiple consequences in the event of an incident. Therefore, it is essential that the cables are tested not only for their burning and ignition but for all the possibilities of their failure. Retardation of cable insulations is a must. The retarder is applied directly to the insulation material, or non-flammable materials are used as insulation. In addition to retardation of individual cables, retardation of entire cable distributions is used. This is done after their installation.

18.6

Testing of Insulation Systems, Facades, and Roofs

Meeting requirements for energy efficiency in building is often achieved by additional insulation. Natural or artificial materials which are used for insulation are, by their nature, easy to ignite and flammable. In addition, their vertical position contributes to the quick spread of a fire. Likewise, the construction of the facade itself (ventilated or non-ventilated) will affect the progress of the fire. Facade fires can be fatal (Grenfell Tower 14.62017). As an example, fairly frequent fires in new high-rise buildings have been recorded in Dubai. Special testing methods will reveal the correct and safe construction of the facade cladding, which is not easy an easy task. For example, treating wooden cladding with a fire retardant is not always the right solution. There are multiple factors to consider, such as how the retarder can withstand the effects of weather, how often the coating is renewed, and how its effectiveness decreases as it ages. Impregnation of the wooden cladding seems to be a better solution. The best solution is the application of non-flammable materials, or those with reaction to fire A1, A2, and B; however, this is not always possible from a design point of view.

18.7

Resistance to Fire

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In addition to the retardation of the material on the facade elements of the structure, it is also possible to design the facade in such a way that the fire cannot progress along the facade, and its development is interrupted and limited only to a certain area. Roofs are also a problem. Their purpose is to drain water. As water easily travels down, fire easily travels up through the roof structure. Historic buildings form a separate category. Some examples include the Krásna Hôrka Castle in Slovakia in March 10, 2012, two cathedrals in France Notre Dame Cathedral in Paris April 15, 2019, Nantes Cathedral July 18, 2020, and a recent fire in the historical center of Banská Štiavnica in Slovakia (April 18, 2023), where fire has engulfed the roofs of six historic buildings. The application of retarders is usually limited to the building itself and the roofs are excluded, mostly for economic reasons. Sometimes it is difficult to reconcile the need for fire protection with the demands of the historic preservation institute. Where it is not possible to maintain keep safe distances (e.g., a historic building cannot be moved and it was built according to other regulations), it is necessary to explore the fire protection of roof structures. Retardation of trusses, interior cladding under a shingle roof, sprinklers, and fireretardant roller blind systems for dividing a large roof area are just some of the options for slowing down and isolating a potential fire. This can be called the technical application of flame retardant in space. It certainly presents an additional cost, but it is justified in historic buildings. The building itself has a high historical value and the damage caused by a fire can be potentially irreversible. These buildings usually hide valuable artifacts that can be damaged by the fire itself or destroyed by water during the intervention. Therefore, prevention and technical measures to prevent not only the occurrence, but especially the spread of fire, are highly justified.

18.7

Resistance to Fire

At first glance, it might seem that the fire resistance test will not reveal the effect of the retarder. However, this is not entirely true (see Sect. 7.6). The application of fire retardant in the construction of perimeter walls, walls, and partitions will extend the time of fire resistance. If the construction is made of certified materials, its fire resistance can also be determined by calculation. This changes when applying a retarder to load-bearing wooden elements with their criterion R determining its fire resistance. Surprisingly, some retarders can actually reduce the fire resistance value over time. For example, when a natural wooden element burns, a charred layer is formed, which in itself has a retarding character. However, if the flame retardant is bound to the surface of the wood during the burning process (test), it peels off and part of the charred layer peels off with it. Therefore, the cross-section of the tested wooden element is weakened. This can have a negative effect on the resulting fire resistance value of the tested wooden

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element of the structure. Of course, there are flame retardants and coating systems that positively affect fire resistance values. In many cases, the required fire resistance value could not be achieved without the application of a flame retardant. In addition to chemical retardation, mechanical retardation is also an option. High-quality smoothing and sanding of a wooden structural element (of course, of a sufficient cross-section) can increase the fire resistance value by a few minutes. The smooth surface reflects radiant heat and the flame has nothing to “seize”. It takes a few minutes for wood in this form to start burning compared to wood that is not sanded smooth.

18.8

Testing of Plastics

In the case of plastics, the problem of their retardation is relatively simple. It is possible to modify the material from which the plastic is made, to bond the flame retardant directly to the monomer, or later during bonding of the polymer. Some plastics can also be modified by adding a retarder during plasticization itself. During the technological process of creating plastic material, it is possible to change its physical properties, (density and others) e.g. polystyrene, which will then affect its behavior at high temperatures or in case of fire. The retardation treatment is easily identifiable by testing methods for plastics.

18.9

Testing of Fabrics and Clothing

The same conclusions as in the case of plastics can be made for textiles and textile products. Retardation treatment is possible as applied to the textile fiber itself, the fabric, or the final product. For example, retardation of theater curtains and backdrops is common and necessary. In some countries, even textile clothing, especially children’s clothing, is retarded. Special retardation and testing are required for textiles for emergency services, mainly firefighters and the army. The tests used reliably reveal the retardation effect of the retardant. However, in order to assess the quality of textiles and textile products, further testing such as e.g. against abrasion, tearing, soaking with water or selected chemicals, is also required. It is important that the retarder used does not reduce the values of these other criteria.

18.10

Testing of Furniture

These tests are specifically designed for products such as furniture, which also includes the seats in vehicles and means of transport. These tests also reveal the retardation effect and can assess different compositions of materials for the given

18.14

Special Test Methods

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product. They assess not only the surface of the structure (textile), but also other components of the structure. The source of heat often causing a fire in their case is usually obvious, e.g., a cigarette.

18.11

Testing of Dust and Dust Mixtures

Dust and dust mixtures cannot be fire-retarded, nor can retardation effects be monitored with those methods. The most effective fire prevention measure against dust is, simply, its removal.

18.12

Smoke and Toxicity

Test methods for determining and measuring characteristics related to smoke and toxicity are also important for fire-retarded materials. It is important that the retarder does not cause intense fumes in the case of a fire. This effect was observed with older wood flame retardants. The flame retardants used today do not have this problem. Despite this, we still recommend that fire-retarded plastics be subjected to these tests.

18.13

Testing of Flammable Liquid

Retardation is illogical in this case as flammable liquids will remain flammable. It is necessary to monitor their properties and the conditions of their ignition. This is true especially in cases where they are modified (e.g. by organic products) or stored for a long time.

18.14

Special Test Methods

The principle of these special methods is designed in such a way that the retardation effect is not only observable but also measurable. The tests can evaluate the quality of the retarder, its retarding effect in the burning process, and determine the appropriate concentration of the retarder in the material. The tests can also assess the effect of the retarder on the formation of smoke and analyze the change in the composition of the combustion products caused by the retarder.

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18.15

18

Effects of Flame Retardants in Individual Tests

Large-Scale Test Methods

Large-scale tests cannot, at least by all practical purposes, assess the retardation effect. Two buildings of the same type and construction would have to be built, one of them built using non-retarded materials, and the other fire-retarded ones. Both buildings would have to be ignited with the same type of fuel and tested at the same time under the same weather conditions. Meeting these conditions would be economically almost infeasible, and this is not the goal of large-scale tests.

18.16

Non-standardized Tests

The non-standardized tests described in the previous chapter can be used for testing flame retardants on various materials. In the description of this method, we focused on the evaluation of wood, a material that burns both homogeneously and heterogeneously. Even in this case, the test method has an informative value: it can simultaneously monitor the physical quantity of the input material as well as the retardation effect. It is sensitive to the amount of retarder applied. However, this method is also suitable for other materials such as plastics, textiles, composite materials, etc. It is not necessary to use all evaluation criteria, it is possible to choose from five.

Conclusion

This textbook is designed in such a way as to enable students of the study program Safety Sciences – Fire Protection to navigate themselves in the field of test methods, all of which serve to better understand the behavior of materials in the event of a fire. It is important to become familiar with the behaviour of a fire – a necessary evil that has been a part of human history for centuries. The main goals are to prevent its occurrence and development, to delay its spread in order to save people in danger, and to localize and extinguish it. It is important to describe the chemical and physical events and the values of physical quantities during a fire. Their implementation into test methods enables an objective assessment of materials. The issue of testing methods is not simple. As was explained in individual chapters, it is necessary to test materials or products under various conditions in order to achieve reliable results. Repeated tests evaluate both the material and the test method. Practice shows that even the most perfect test method is not universal and must have a specification (purpose or material), and/or must be further improved in order to become universal. A problem with many testing methods is the exact specification of the input physical quantities of the tested materials or products. We believe that the information in this textbook will serve students in developing their knowledge of this vital issue, which will bring the improvement of testing methods in the future and a higher level of objective testing of materials and products for the needs of fire protection.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 L. Makovická Osvaldová, W. Fatriasari, Testing of Materials for Fire Protection Needs, The Society of Fire Protection Engineers Series, https://doi.org/10.1007/978-3-031-39711-0

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