CSA B149.3-15 update no. 1 - Code for the field approval of fuel-related components on appliances and equipment 9781771397605

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B149.3-15

Code for the field approval of fuel-related components on appliances and equipment

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Update No. 1 B149.3-15 December 2017 Note: For information about the Standards Update Service, go to shop.csa.ca or e-mail [email protected]. Title: Code for the field approval of fuel-related components on appliances and equipment — originally published August 2015 The following revisions have been formally approved and are marked by the symbol double delta (ΔΔ) in the margin on the attached replacement pages: Revised

Clause 9.4.1

New

None

Deleted

None

• Update your copy by inserting these revised pages. • Keep the pages you remove for reference.

© 2017 CSA Group

Code for the field approval of fuel-related components on appliances and equipment

9.2.2 Components used to establish purge periods shall be of a fixed-timer type or shall be designed to prevent field tampering.

9.2.3 Purge requirements shall take into consideration the safety of processes such as the purging of substoichiometric atmospheres or special atmosphere appliances. See also Clause 13.1.1.2.

9.3 Low fire start A proven low fire start shall be provided on a variable input appliance that has an input in excess of 1 000 000 Btuh (300 kW), unless otherwise approved. On a multiple-burner appliance, when the burners are firing inside a common combustion chamber, the low-fire requirement is considered accomplished when the first burner has been ignited.

9.4 Temperature and pressure safety limit controls ΔΔ Δ

9.4.1 An appliance that heats a liquid or vapor shall be equipped with all of the following applicable approved safety devices and shall include a manual-reset feature or shall require operator attention before resuming operation, the sole function of which shall be to shut off the fuel supply in the event of any of the following: (a) low liquid level in an appliance with a minimum liquid level that requires continuous immersion in a liquid for safe operation; (b) low liquid or vapor flow in an appliance that requires flow for safe operation; (c) high fluid temperature for an appliance where the temperature can exceed a safe operating limit. Where portions of the appliance are sufficiently independent, multiple temperature sensors might be required; (d) high pressure for vaporizing appliances which are pressure controlled and pressure is a function of temperature; or (e) low water in a water boiler located above the hot-water circulating system.

9.4.2 When two or more liquid boilers of the coil- or finned-tube type, each with an input rating of 400 000 Btuh (120 kW) or less, are installed in one system, a low liquid fuel cut-off device shall not be required on each boiler, provided that (a) a low liquid fuel cut-off device is installed in the main liquid outlet header; (b) a flow switch is installed in the outlet piping of each boiler, which will cut off the fuel supply to the burner in the event of no liquid flow; and (c) the devices in Items (a) and (b) are installed so that they cannot be rendered inoperative.

9.4.3 Every automatically controlled space-heating furnace shall be equipped with an approved high temperature limit control, the maximum setting of which shall be 350°F (175 °C) for a gravity space-heating furnace or 250°F (120 °C) for a forced-air space-heating furnace.

9.4.4 Flame detectors that can fail in a flame-proving mode shall be of the self-checking type when the burner firing cycle can last longer than 24 h without cycling, unless they are used on equipment that operates above 1400°F (760 °C) and is equipped with a 1400°F (760 °C) bypass controller and on which the ramp up cycle time to reach 1400°F (760 °C) is less than 24 h. When cooling with the burners firing, verification of the flame detectors shall be accomplished before the temperature drops below 1400°F (760 °C).

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9.5 Gas pressure safety limit control 9.5.1 Where the failure or an outlet pressure adjustment of the pressure regulator results in unsafe operation and/or operation does not comply with Clause 5.6.4, a high gas pressure safety device shall be installed downstream of the pressure regulator and shall initiate shut-off of the supply of gas when the gas pressure at the high gas pressure safety device exceeds the setpoint. In the absence of the burner manufacturer's requirements, the setpoint shall be set to not more than 125% of the normal operating pressure at the maximum firing rate. Notes: (1) When installed upstream of the safety shut-off valve(s), the high gas pressure safety device may be by-passed into the combustion safety control until the burner trial for ignition begins. (2) On multiple burner appliances, compliance to Clause 9.5.1 does not exclude the potential need to have an additional high gas pressure safety device downstream of a flow control valve in order to detect excessive pressure at individual burner(s) as other burner(s) turn off.

9.5.2 For appliances with inputs in excess of 400 000 Btuh (120 kW), or where the design outlet pressure of the appliance pressure regulator is in excess of 0.5 psig (3.5 kPa), a low gas pressure safety device shall be installed and shall initiate shut off of the supply of gas if the pressure at the point of connection drops below 50% of the lowest normal operating pressure. The device shall be installed (a) downstream of the pressure regulator where used and upstream of the safety shut-off valve or valves and upstream of the flow control valve; and (b) downstream of the multifunctional control where used. The low gas pressure safety device shall be bypassed into the combustion safety control until the burner has started.

9.5.3 When a gas pilot is used on a multi-fuel appliance, a low gas pressure safety device shall be installed in the gas pilot supply immediately upstream of the first safety shut-off valve. When the pilot is firing, the low gas pressure safety device shall be in service and shall (a) shut down the pilot in a low gas condition; or (b) shut down the main burner in a low gas condition if the pilot is required for stable main burner flame. If the pilot is an interrupted pilot, this device may be removed from service at the completion of the pilot run time.

9.5.4 On burner start-up, electrical delay of the low gas pressure safety device as required in Clause 9.5.2(b) shall only be done either within a programmable controller or with a safety timer. The delay time shall not exceed 5 seconds.

9.6 Auxiliary fans and dampers 9.6.1 When air-supply fans, compressors, or blowers for supply air or instrument and control air are required for use with an appliance combustion system, airflow proving devices of the differential type, or an approved equivalent, shall be provided and shall be interlocked to prevent the flow of fuel to the burners on failure of this air supply.

9.6.2 When adjustable or motorized dampers are used in conjunction with the auxiliary fans specified in Clause 9.6.1, they shall be cut away or equipped with mechanical stops or limit switches interlocked into the safety circuitry to ensure that they are incapable of being moved to a position that might contribute to or result in an unsafe condition.

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Standards Update Service B149.3-15 August 2015 Title: Code for the field approval of fuel-related components on appliances and equipment Pagination: 80 pages (ix preliminary and 71 text), each dated August 2015 To register for e-mail notification about any updates to this publication •

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B149.3-15 Code for the field approval of fuel-related components on appliances and equipment

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ISBN 978-1-77139-760-5 © 2015 CSA Group All rights reserved. No part of this publication may be reproduced in any form whatsoever without the prior permission of the publisher.

© 2015 CSA Group

Code for the field approval of fuel-related components on appliances and equipment

Contents Technical Committee on the Code for the Field Approval of Fuel-Related Components on Appliances and Equipment vi Interprovincial Gas Advisory Council (IGAC) ix Preface xi 1 Scope 1 2 Reference publications 2 3 Definitions 4 4 Pilot gas valve train 9 4.1 Pilot supply 9 4.2 Manual shut-off valves 10 4.3 Pressure regulators 10 4.4 Overpressure protection devices 11 4.5 Safety shut-off valves 11 4.6 Test firing valves 12 4.7 Pilot burners 13 4.8 Safety flare pilots 14 5 Main gas valve train 14 5.1 Manual isolation valves 14 5.2 Pressure regulators 14 5.3 Safety shut-off valves 14 5.4 Input flow control systems 17 5.5 Test firing valves 17 5.6 Main burner 18 5.7 Overpressure protection devices 20 6 Additional requirements for liquid propane valve trains 20 7 Applications 21 7.1 Installation 21 7.2 Unions and flanges 22 7.3 Pressure test points 22 7.4 Pressure ratings 22 7.5 Multi-purpose components 22 7.6 Bleed vents for valves, combination controls, pressure regulators, relief valves, and other control devices 22 Observation of main burner flame and ignition source 24 7.7 7.8 Pneumatic control systems 24 7.9 Supplementary requirements for controls and valves subjected to low ambient temperatures 24 7.10 Hoses and hose fittings 24 8 Ignition systems 24 8.1 General 24 Electric ignition systems 25 8.2 8.3 Manual ignition systems 25

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9 Safety controls 25 9.1 Combustion safety control systems 25 9.2 Prepurge 26 9.3 Low fire start 27 9.4 Temperature and pressure safety limit controls 27 9.5 Gas pressure safety limit control 28 9.6 Auxiliary fans and dampers 28 9.7 Programmable controllers 29 9.7.1 General 29 9.7.2 Programmable controllers 29 10 Electrical requirements 31 10.1 Supply 31 10.2 Appliance circuits 31 11 Rating plate 32 12 Initial start-up procedure 32 13 Additional requirements for process ovens, process furnaces, and atmosphere generators 32 13.1 General requirements 32 13.1.1 Design and installation 32 13.1.2 Location 33 13.1.3 Accessibility and mounting of controls 33 13.1.4 Explosion relief 33 13.1.5 Auxiliary fans and dampers 34 Gas safety devices 34 13.2 13.2.1 General 34 13.2.2 Combustion safeguards 34 13.2.3 Temperature bypass controllers and their temperature-sensing elements 34 13.3 Ignition systems 35 13.4 High temperature limit control 35 13.5 Purge cycle 35 13.6 Gas/air mixers 35 13.6.1 Gas/air mixture piping 35 13.6.2 Mixer adjustments 36 13.6.3 Mixing blowers 36 13.6.4 Mechanical gas/air mixers 36 13.6.5 Automatic fire-checks 37 13.7 Radiant-tube heating systems 37 13.8 Atmosphere generators 37 13.8.1 Exothermic generators 37 13.8.2 Endothermic generators 39 Annexes A (informative) — Recommended procedure for initial start-up of high input equipment [over 400 000 Btuh (120 kW)] 42 B (informative) — Valve diagrams 44 C (informative) — Abbreviations 61 D (informative) — Guidelines for electronic-type fuel air-ratio control (FARC) systems 62 E (informative) — Guidelines for flare pilot systems 65 F (informative) — Guidelines for valve proving systems (VPS) 67 G (informative) — Requirements for use of oxygen in combustion systems 72

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H (informative) — Liquid fuels 74 I (informative) — Solid fuels 76 Tables 5.1—Valve and vent line pipe sizing 17

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Technical Committee on the Code for the Field Approval of Fuel-Related Components on Appliances and Equipment K. Carlisle

Karl Dungs Inc., Blaine, Minnesota, USA

Chair

S. Carron

Combustion Solutions Inc., Calgary, Alberta

Vice-Chair

P. Baker

Maxitrol Company, Port Dover, Ontario

Associate

R. Brousseau

Régie du Bâtiment du Québec, Montréal, Québec

Associate

C. Bale

Weishaupt Corporation, Mississauga, Ontario

P. Barhydt

AerBurn Engineering and Consulting, Burlington, Ontario

P. Bégin

Pierre Bégin, ing., Consultant-Combustion, Sainte-Thérèse, Québec

G. Bradley

Maxon, a Honeywell Company, Mississauga, Ontario

R. Chapman

Firebridge Inc., Burlington, Ontario

Associate

P. Christensen

Yukon Government, Whitehorse, Yukon Territories

Associate

N. Croskerry

ArcelorMittal Dofasco, Hamilton, Ontario

D. Curry

Selas Heat Technology Company, Inc., Streetsboro, Ohio, USA

S. Davey

Bacon Engineering Ltd., Toronto, Ontario

M. Davidson

Province of New Brunswick Dept. of Public Safety, Fredericton, New Brunswick

Associate

W. Dell

Sector Technology Inc., Burlington, Ontario

Associate

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J. Domuracki

Fives North American Combustion Canada Inc., Bolton, Ontario

F. Drndarevic

Technical Standards & Safety Authority (TSSA), Toronto, Ontario

D. Eastman

Service NL, Newfoundland & Labrador, St. John’s, Newfoundland & Labrador

D. Evans

Bruce Sutherland Associates Ltd., Dartmouth, Nova Scotia

N. Farahani

Intertek Testing Services NA Ltd., Coquitlam, BC

Associate

P. Fowler

Nova Scotia Department of Labour Advanced Education, Halifax, Nova Scotia

Associate

Z. Fraczkowski

Technical Standards & Safety Authority (TSSA), Toronto, Ontario

Associate

D. Hird

SaskPower, Regina, Saskatchewan

R. Hutchinson

Dow Chemical Canada ULC Western Canada Operations, Fort Saskatchewan, Alberta

C. Ireland

Fuel Applications Ltd., Hamilton, Ontario

Associate

M. Ishikawa

Miura Boiler Company Limited, Brantford, Ontario

Associate

J. Jachniak

ENEFEN Energy Efficiency Engineering Ltd., Leduc, Alberta

Associate

C. Jorgenson

British Columbia Safety Authority (BCSA), New Westminster, British Columbia

C. Lashek

Manitoba, Office of the Fire Commissioner, Winnipeg, Manitoba

Associate

M. LeBlanc

Province of New Brunswick Dept. of Public Safety, Grand Falls, New Brunswick

Associate

W. Lock

British Columbia Safety Authority (BCSA), New Westminister, British Columbia

Associate

S. Manning

Alberta Municipal Affairs Safety Services, Edmonton, Alberta

Associate

J. Marshall

Technical Standards & Safety Authority (TSSA), Toronto, Ontario

Associate

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Associate

Associate

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R. McRae

Government of the NWT Public Works & Services, Yellowknife, Northwest Territories

Associate

G. Prociw

Union Gas Limited, Chatham, Ontario

Associate

V. Quiring

Engineered Air, Division of Airtex Manufacturing Partnership, Calgary, Alberta

Associate

B. Reid

Department of Environment, Energy and Forestry, Charlottetown, Prince Edward Island

Associate

J. Renaud

Régie du bâtiment du Québec, Montréal, Québec

W. Simpson

North American Standards Assesment Corp., Sherwood Park, Alberta

T. Siteman

Fossil Power Systems Inc., Dartmouth, Nova Scotia

T. Stroud

Hearth Patio & Barbecue Association, Seattle, Washington, USA

R. Sumabat

Technical Standards & Safety Authority (TSSA), Toronto, Ontario

Associate

P. Terkovics

Advanced Combustion Inc., Concord, Ontario

Associate

P. Tervit

PT Energy Solutions, MIssissauga, Ontario

G. Tremblett

Service NL, Newfoundland & Labrador, St. John’s, Newfoundland & Labrador

Associate

C. Valliere

Alberta Municipal Affairs Safety Services, Edmonton, Alberta

Associate

P. Voortman

JV Energy Solutions Inc., Kingsville, Ontario

Associate

G. Williams

Regina, Saskatchewan

Associate

K. Penn

CSA Group, Mississauga, Ontario

Project Manager

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Interprovincial Gas Advisory Council (IGAC) J. Marshall

Technical Standards & Safety Authority (TSSA), Toronto, Ontario

Chair

M. Davidson

Province of New Brunswick Dept. of Public Safety, Fredericton, New Brunswick

Vice-Chair

J. Renaud

Régie du bâtiment du Québec, Montréal, Québec

Vice-Chair

A. Ali

SaskPower, Regina, Saskatchewan

R. Brousseau

Régie du Bâtiment du Québec, Montréal, Québec

P. Christensen

Yukon Government, Whitehorse, Yukon

P. Fowler

Nova Scotia Department of Labour Advanced Education, Dartmouth, Nova Scotia

Z. Fraczkowski

Technical Standards & Safety Authority (TSSA), Toronto, Ontario

Alternate

D. Hird

SaskPower Regina, Saskatchewan

Alternate

C. Lashek

Office of the Fire Commissioner, Province of Manitoba, Winnipeg, Manitoba

W. Lock

British Columbia Safety Authority (BCSA), New Westminster, British Columbia

S. Manning

Alberta Municipal Affairs Safety Services, Edmonton, Alberta

R. McRae

Government of the NWT, Yellowknife, Northwest Territories

B. Reid

Department of Environment, Energy and Forestry, Charlottetown, Prince Edward Island

G. Slingerland

Standards Council of Canada (SCC), Ottawa, Ontario

G. Tremblett

Service NL, Newfoundland & Labrador, St. John’s, Newfoundland and Labrador

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Alternate

Alternate

Associate

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C. Valliere

Alberta Municipal Affairs Safety Services, Edmonton, Alberta

M. Wani

Government of Nunavut Dept. of Community & Government Services, Iqaluit, Nunavut

B. Zinn

British Columbia Safety Authority (BCSA), Coquitlam, British Columbia

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Code for the field approval of fuel-related components on appliances and equipment

Preface This is the fifth edition of CSA B149.3, Code for the field approval of fuel-related components on appliances and equipment. It supersedes the previous editions published in 2010, 2005, and 2000 by the Canadian Standards Association (CSA) as CSA B149.3, and in 1989 by the Canadian Gas Association (CGA) as CAN/CGA-B149.3. This Code brings together for the convenience of users the applicable requirements for appliances and equipment, originally published as part of the CSA B149.1 and CSA B149.2 Codes. In this 2015 edition, where a major change or addition to the previous edition of the Code has been made, the clause, table, or figure affected is identified by the symbol delta (Δ) in the margin. Users of the Code are advised that the change markers in the text are not intended to be all-inclusive and are provided as a convenience only; such markers cannot constitute a comprehensive guide to the revisions made to the Code. Care must therefore be taken not to rely on the change markers to determine the current requirements of the Code. As always, users of the Code must consider the entire Code and any local amendments. The CSA B149.3 Code Committee, which is responsible for preparing this Code, consists of members of the provincial gas inspection authorities, natural gas utilities, propane distributors, appliance, equipment, and accessory manufacturers, certification organizations, and representatives from the Heating, Refrigeration and Air Conditioning Institute of Canada, the Mechanical Contractors Association of Canada, and federal government departments. This Code has been formally approved by the CSA B149.3 Technical Committee on the Code for the Field Approval of Fuel-Related Components on Appliances and Equipment and by the Interprovincial Gas Advisory Council. Notes: (1) Use of the singular does not exclude the plural (and vice versa) when the sense allows. (2) Although the intended primary application of this Code is stated in its Scope, it is important to note that it remains the responsibility of the users of the Code to judge its suitability for their particular purpose. (3) This Code was developed by consensus, which is defined by CSA Policy governing standardization — Code of good practice for standardization as “substantial agreement. Consensus implies much more than a simple majority, but not necessarily unanimity”. It is consistent with this definition that a member may be included in the Technical Committee list and yet not be in full agreement with all clauses of this Code. (4) To submit a request for interpretation of this Code, please send the following information to [email protected] and include “Request for interpretation” in the subject line: (a) define the problem, making reference to the specific clause, and, where appropriate, include an illustrative sketch; (b) provide an explanation of circumstances surrounding the actual field condition; and (c) where possible, phrase the request in such a way that a specific “yes” or “no” answer will address the issue. Committee interpretations are processed in accordance with the CSA Directives and guidelines governing standardization and are available on the Current Standards Activities page at standardsactivities.csa.ca. (5) This Code is subject to review five years from the date of publication. Suggestions for its improvement will be referred to the appropriate committee. To submit a proposal for change, please send the following information to [email protected] and include “Proposal for change” in the subject line: (a) Standard designation (number); (b) relevant clause, table, and/or figure number; (c) wording of the proposed change; and (d) rationale for the change.

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B149.3-15 Code for the field approval of fuel-related components on appliances and equipment 1 Scope Δ

1.1 This Code contains the requirements for fuel-related components and accessories and their assembly on an appliance utilizing gas, downstream of the manual shut-off valve specified in Clause 6.18.2 of CSA B149.1. Clause 13 of this Code contains additional requirements for process ovens, including bakery ovens, process furnaces, and atmosphere generators operating at approximately atmospheric pressure and used by industry for the processing of materials. Recommended requirements for liquid and solid fuel-burning appliances are located in Annex H (liquids) and Annex I (solids).

Δ

1.2 This Code does not apply to (a) installations in marine pipeline terminals; (b) gas where used as a feedstock in petroleum refineries or chemical plants; (c) gas designated for storage or handling, or both, at liquefied petroleum gas bulk plants; (d) gas where used for natural gas for vehicles; (e) a new appliance for which there is an approved Standard; (f) a manually operated appliance with an input not exceeding 20 000 Btuh (6 kW) used for industrial applications; and (g) other fuels not covered in this Code and used in combination with gas.

Δ

1.3 When another fuel is used in the installation and in combination with gas, the safe operation of that fuel shall be approved.

1.4 Requirements contained herein apply only to that portion of an appliance using gas as defined in Clause 1.7, atmosphere gas, and reaction gas.

1.5 The requirements contained in this Code apply (a) to new non-certified appliances and equipment of all inputs for which there is no approved Standard; (b) when the upgrading of an existing certified or non-certified appliance is required; and (c) to programmable logic controllers or microprocessor-based controls used for flame safety.

1.6 The requirements contained in this Code may be used to replace or supplement an approved Standard with the permission of the authority having jurisdiction.

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1.7 When the term “gas” is used, the requirements of this Code include, and apply equally to, any of the following gases or mixtures of them: natural gas, manufactured gas, propane, propane air, propylene, butane (normal butane or isobutane), and butylene.

1.8 The values given in yard/pound units are the standard. The values given in parentheses are for information only.

1.9 In this Code, unless approved otherwise by the authority having jurisdiction, “shall” indicates a mandatory requirement; “should” indicates a recommendation or that which is advised but not mandatory; and “may” indicates an advisory or optional statement. Notes to the text do not include mandatory or alternative requirements. The purpose of a note is to separate from the text explanatory or informative material that is not properly a part of this Code. Notes to figures and tables, however, are considered part of the figure or table and may be written as mandatory requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

2 Reference publications This Code refers to the following publications, and where such reference is made, it shall be to the edition listed below, including all amendments published thereto. CSA Group Note: CGA Standards, Recommended Practices, and Codes are now published by CSA.

CAN1-6.4-M79 (R2011) Automatic gas ignition systems and components ANSI Z21.21-2012/CSA 6.5-2012 Automatic valves for gas appliances ANSI Z21.78-2010/CSA 6.20-2010 Combination gas controls for gas appliances ANSI Z21.15-2009/CSA 9.1-2009 (R2014) Manually operated gas valves for appliances, appliance connector valves and hose end valves CGA 3.11-M88 (R2014) Lever Operated Pressure Lubricated Plug Type Gas Shut-Off Valves CGA 3.16-M88 (R2014) Lever Operated Non-Lubricated Gas Shut-Off Valves CAN/CGA-8.1-M86 (R2011) Elastomeric Composite Hose and Hose Couplings for Conducting Propane and Natural Gas CAN1-8.3-77 (R2011) Thermoplastic Hose and Hose Couplings for Conducting Propane and Natural Gas B139 Series-15 Installation code for oil-burning equipment B140 Series of Standards

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B149.1-15 Natural gas and propane installation code B149.2-15 Propane storage and handling code B365-10 Installation code for solid-fuel-burning appliances and equipment B366.1-11 Solid-fuel-fired central heating appliances C22.1-15 Canadian Electrical Code, Part I C22.2 No. 0.8-12 Safety functions incorporating electronic technology C22.2 No. 13-13 Transformers for oil- or gas-burner ignition equipment CGA CR96-001 Flexible metallic hose ANSI Z21.20-2014/CAN/CSA-C22.2 No. 60730-2-5-14 Automatic electrical controls for household and similar use — Part 2-5: Particular requirements for automatic electrical burner control systems API (American Petroleum Institute) 537-2008 Flare Details for General Refinery and Petrochemical Service, Second Edition BSI (British Standards Institution) BS EN 1643:2014 Safety and control devices for gas burners and gas burning appliances: Valve proving systems for automatic shut-off valves Compressed Gas Association G-4.1-2009 Cleaning Equipment for Oxygen Service IEC (International Electrotechnical Commission) 61508 series of Standards (Parts 1–7) Functional safety of electrical/electronic/programmable electronic safety-related systems 61511 series of Standards (Parts 1–3) Functional safety — Safety instrumented systems for the process industry sector ISO (International Organization for Standardization) 23552-1:2007 Safety and control devices for gas and/or oil burners and gas and/or oil appliances — Particular requirements — Part 1: Fuel/air ratio controls, electronic type NFPA (National Fire Protection Association) 85-2015 Boiler and Combustion Systems Hazards Code 86-2015 Standard for Ovens and Furnaces

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3 Definitions Note: Throughout this Code, certain terms appear in bold italic type. These terms have been defined in this Clause to ensure understanding of their intended meaning in this Code. Defined terms have been highlighted in bold italic type only in certain key contexts. It is the responsibility of the user to ensure that the defined terms are understood in accordance with this Clause, whether or not they appear in bold italic type.

The following definitions shall apply in this Code: Accessory — a part capable of performing an independent function and contributing to the operation of the appliance that it serves. Appliance — a device to convert gas into energy; the term includes any component, control wiring, piping, or tubing required to be part of the device. Appliance control system — a combination, as applicable, of a primary safety control, safety limit control, or operating control that is used to control a burner or an appliance. It includes automatic, manual, and semi-automatic appliance control systems. Automatic appliance control system — an appliance control system in which the burner, when started, will continue an unlimited number of operating cycles without manual attention unless shut down by the combustion safety control. Manual appliance control system — an appliance control system in which the burner, when manually started, will complete only one cycle of operation without manual attention. Semi-automatic appliance control system — an appliance control system in which the burner, when started, will continue an unlimited number of operating cycles without manual attention unless shut down by the combustion safety control or safety limit control. Appliance rated input — total maximum input in Btuh of all fuels, as defined in this Code, that can be fired simultaneously in an appliance, based on their respective Higher (Gross) Heating Values (HHV). Approved — acceptable to the authority having jurisdiction. Authority having jurisdiction — the governmental body responsible for the enforcement of any part of this Code, or the official or agency designated by that body to exercise such a function. Automatic fire-check — a device for stopping the progress of a flame front in burner mixture lines (flashback) and for automatically shutting off the fuel/air mixture. Bleed vent — a vent where the expiration or inspiration of air or gas occurs from, or to one side of, a diaphragm of any accessory, component, or equipment such as a valve, pressure regulator, or switch. Burner — a device or group of devices that forms an integral unit for the introduction of gas, with or without air or oxygen, into the combustion zone for ignition. Fan-assisted burner — a burner in which the combustion air is supplied by a mechanical device, such as a fan or blower, at sufficient pressure to overcome the resistance of the burner only. Forced-draft burner — a burner in which the combustion air is supplied by a mechanical device, such as a fan or blower, at sufficient pressure to overcome the resistance of the burner and the appliance. Multi-port burner — a burner having two or more separate discharge openings or ports. These ports may be either flush or raised. Natural-draft burner — a burner that is not equipped with a mechanical device for supplying combustion air.

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Certified (with respect to any appliance, component, accessory, or equipment) — investigated and identified by a designated testing organization as conforming to recognized standards, requirements, or accepted test reports. Combustion chamber — the portion of the appliance enclosure into which the fuel is fed, ignited, and burned. Combustion safety control (flame safeguard) — Common burner flame safeguard control — a safety control that senses the presence of flame on multiple burners and causes the fuel to be shut off to all the burners in the event of flame or ignition failure of one or more of them. Individual burner flame safeguard — a safety control that senses the presence of flame on a burner and causes the fuel to that burner to be shut off in the event of flame or ignition failure. Component — an essential part of an appliance or equipment. Control or instrument air — a dry air supply provided to a control or instrument by means of piping or tubing, where the air acts as the operating medium to energize or de-energize the control or instrument. Cut-off room — a room within a building, constructed of concrete walls bonded into the floor and ceiling, with at least one exterior wall, and accessible only from the outdoors. Δ

Direct-fired appliance — an appliance in which the combustion products or flue gases are intermixed with the medium being heated. Endothermic generator — an appliance used to convert, by the addition of heat, reaction gas and reaction air to a special atmosphere gas, and in which the special atmosphere gas is separated at all times from heating combustion products or other media. Equipment — a device, other than an appliance, accessory, or component, that is connected to a piping or tubing system. Exothermic generator — an appliance used to convert a gas to a special atmosphere gas by burning, either completely or partially, the gas with air in a controlled ratio. The combustion reaction is self-supporting and gives off heat; the combustion products become the atmosphere gas.

Δ

Flame failure response time — the time in seconds required for the combustion safety control to react upon flame failure (extinction).

Δ

Flare — Flare automatic ignition device — a high energy sparking igniter which is automatically energized when no flame is detected. A flare automatic ignition device may be used together with a flare pilot, or may be sufficiently sized to be used on its own as a sole ignition source for a flare. Process flare — a mechanical component intended for the discharge and combustion of combustible gases which can be shut down because it is not connected to any automatic relieving systems, included but not limited to pressure safety valves (PSVs) or emergency shutdown valves (ESDVs). Process flare pilot — a pilot on a process flare that is supplied by gas as defined in Clause 1.7. Safety flare — a critical mechanical component of a complete system design intended for the discharge and combustion of combustible gases which cannot be shut down for safety reasons, as it is required to ensure the mechanical integrity of upstream pressure equipment.

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Safety flare pilot — a pilot on a flare that is supplied by gas as defined in Clause 1.7. Igniter — a device that uses electrical energy to ignite gas at a main burner or pilot burner. The electrical energy may be produced by a direct spark transformer or spark generator. Ignition — the establishment of a flame. Ignition source — Continuous ignition source — an ignition source that, once placed in operation, is intended to remain ignited or energized continuously until manually interrupted. Intermittent/continuous ignition source — an ignition source that is ignited or energized upon the appliance user’s initiation of the operational cycle and that remains continuously ignited or energized during the appliance use cycle. The ignition source is extinguished or de-energized when the appliance use cycle is completed. Intermittent ignition source — an ignition source that is automatically ignited or energized when an appliance is called on to operate and that remains continuously ignited or energized during each period of main burner operation. The ignition source is automatically extinguished or de-energized when each main burner operating cycle is completed. Intermittent/interruptible ignition source — an ignition source that is ignited or energized upon the appliance user’s initiation of the operational cycle and that is extinguished or de-energized after the appliance use cycle has been initiated. Interrupted ignition source — an ignition source that is automatically ignited or energized when an appliance is called on to operate and that remains ignited or energized during the main burner flame-establishing period. The ignition source is automatically extinguished or de-energized when each main burner flame-establishing period is completed. Ignition system — a system designed to ignite and re-ignite an appliance burner. Such systems (a) automatically ignite gas at the main burner, or gas at the pilot burner so that the pilot can ignite the main burner; (b) prove the presence of either the ignition sources, the main burner flame, or both; and (c) automatically act to shut off the gas supply to the main burner, or to the pilot burner and the main burner, when the supervised flame or ignition source is not proved. Ignition system timings — Flame-establishing period — the period of time between the initiation of gas flow and the proof of the supervised flame, or between the proof of the supervised flame and the initiation of gas flow. This period of time can be applicable to proof of ignition source, proof of main burner flame, or both. Maximum time — the maximum allowable time for the specified function of any device built to this Code. Minimum time — the minimum allowable time for the specified function of any device built to this Code. Impedance — restrictive action on the flow of gas and pressure, caused by the internal resistance of the piping or tubing of a regulator vent system. Δ

Indirect-fired appliance — an appliance in which the combustion products or flue gases are not mixed within the appliance with the medium that is being heated. Low fire start — the initial ignition of the main flame at an input of 40% or less of the rated maximum input.

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Manifold — the piping between the burner and the last valve in the valve train. Manifold pressure — the pressure in the piping between the burner and the last valve in the valve train. Δ

Multifunctional control — an assembly of a safety shut-off valve in combination with a gas appliance pressure regulator without the use of a pipe nipple. Overpressure protection device — a device that under abnormal conditions will act to reduce, restrict, or shut off the supply of gas flowing into a system to prevent gas pressure in that system from exceeding the rated pressure of the system components.

Δ

Monitoring regulator — an overpressure protection device set in series with the primary gas pressure regulator, both sensing the same downstream pressure, and that functions as a second gas pressure regulator if the primary gas pressure regulator fails. Overpressure relief device — an overpressure protection device that functions by discharging gas from the downstream system. Overpressure shut-off device or overpressure cut-off (OPCO) device — an overpressure protection device that functions by completely shutting off the flow of gas into the downstream system.

Δ

Series regulator — an overpressure protection device that functions as a second gas pressure regulator in series with the primary gas pressure regulator. Pilot — flame that is used to ignite a gas/air mixture at the main burner or burners. Continuous pilot — a pilot that burns without turndown throughout the entire time the burner is in service, whether or not the main burner is firing. Expanding pilot — a pilot that burns at low turndown throughout the entire time the burner is in service, whether or not the main burner is firing, except that upon a call for heat, the fuel flow to the pilot is automatically increased to produce a flame that will reliably ignite the main burner fuel. Intermittent pilot — a pilot that is automatically lighted each time there is a call for heat and that burns during the entire period that the main burner is firing. Interrupted pilot — a pilot that is automatically lighted each time there is a call for heat and that is cut off automatically at the end of the flame-establishing period of the main burner. Proved pilot — a pilot flame supervised by a primary safety control that senses the presence of the pilot prior to gas being admitted to the main burner. Pressure drop — the loss in static pressure of the medium (air, gas, or water) due to friction or obstruction in pipes, valves, fittings, regulators, burners, and appliances and due to breaching. Pressure regulator — a device that maintains a constant outlet pressure at all rates of flow with variable inlet pressures. The device may be one of the following: Adjustable pressure regulator — Spring-type limited-adjustment pressure regulator — a regulator in which the regulating force acting upon the diaphragm is derived principally from a spring, the loading of which is adjustable over a range of not more than ±15% of the outlet pressure at the midpoint of the adjustment range. Spring-type standard-adjustment pressure regulator — a regulator in which the regulating force acting upon the diaphragm is derived principally from a spring, the loading of which is adjustable. The adjustment means are concealed.

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Balanced-type pressure regulator — a regulator designed to have the inlet pressure acting in two opposing directions on the orifice seat(s), thus producing a balancing effect that prevents an increase in set pressure through an increase in the inlet pressure. Lock-up (positive shut-off) pressure regulator — a pressure regulator that is capable of maintaining a reduced outlet pressure when the fuel flow condition is static. Δ

Pressure switch — High gas pressure safety device — a device used to protect a burner from excessive gas pressure. Low gas pressure safety device — a device used to protect a burner by preventing it from starting at a low pressure where delayed ignition can take place and during burner operation to prevent unstable flame or incomplete combustion. Proof of closure switch — a factory-sealed switch incorporated into a safety shut-off valve that includes at least one set of contacts, which close only after the valve port is closed and which open prior to the opening of the valve port. Reaction air — all of the air that, after reacting with gas in an endothermic generator due to the addition of heat, becomes the special atmosphere gas. Reaction gas — all of the gases that, after reacting with air in an endothermic generator due to the addition of heat, become the special atmosphere gas. Regulator suppressor assembly — a device or fabricated assembly installed in a piping or tubing vent system that provides a cushion effect to overcome impedance in the regulator vent line. Regulator vent — the opening in the atmospheric side of regulator housing permitting the in-and-out movement of air to compensate for the movement of the regulator diaphragm. Safety blowout — a protective device located in the discharge piping of large mixing machines and incorporating a bursting disc for excessive pressure release, a means for stopping a flame front, and an electric switch or other release mechanism for actuating a built-in or separate safety shut-off. A check valve or signaling means, or both, may also be incorporated. Trial-for-ignition period (flame-establishing period) — the interval of time permitted by the combustion safety control between the initiation of the opening and the initiation of the closing of the gas shut-off device if a flame has not been detected. Valve — a device by which the flow of a fluid can be started, stopped, or regulated by a movable part that opens or obstructs passage. Back check valve — a valve that is normally closed and allows flow in only one direction. Internal relief valve — a pressure relief valve that is built into the body of the diaphragm assembly of a pressure regulator to ensure that, in the event of a primary pressure regulator malfunction, the pressure downstream of the relieving point does not exceed that of the lowest-pressure-rated component in the system. Line relief valve — a relief valve installed in the piping or tubing system downstream of a final-stage pressure regulator that is not equipped with an internal relief valve to ensure that in the event of a primary pressure regulator malfunction, the pressure downstream of the relieving point does not exceed that of the lowest pressure rated component in the system. Lubricated-plug-type valve — a manually operated valve of the plug and barrel type that is (a) provided with means for maintaining a lubricant between its bearing surfaces; (b) so designed that the lapped bearing surfaces can be lubricated and the lubricant level maintained without removing the valve from service;

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Code for the field approval of fuel-related components on appliances and equipment

so constructed that the lubricant can be stored in a reservoir so as to be distributed evenly over the entire lapped bearing surfaces of the valve when the plug is rotated; and equipped with built-in stops to limit the rotation of the plug to one quarter turn when fully opening or fully closing the valve.

Manual shut-off valve — a manually operated valve in the gas line that is used to manually turn on or shut off the gas to the appliance. Marked C/I — a valve certified to applicable sections in ANSI Z21.21/CSA 6.5 pertaining to the C/I marking (commercial and industrial). Safety shut-off valve — a valve that automatically shuts off the supply of gas when de-energized by a combustion safety control, safety limit control, or loss of actuating medium. Slow-opening valve — an automatic valve that has an opening time of more than 5 s after being energized. Δ

Test firing valve (firing valve) — a quarter turn manual shut-off valve that is located downstream of all safety shut-off valves on the valve train and as close to the burner as is practicable.

Δ

Token relief valve — a small-capacity relief valve installed in the piping or tubing system downstream from or internal to a regulator to release the build-up of pressure due to sudden stop of fuel flow, due to an increase of temperature of the fuel gas in a no-flow condition, or due to an increase of leakage at the regulator disc and seat.

Δ

Valve proving system (VPS) — a system that proves the effective closure of safety shut-off valves by detecting leakage. It can consist of a programming unit, a measuring device, valves, and other functional assemblies. Valve train — the combination of valves, controls, piping, and tubing of an appliance upstream from the manifold through which gas is supplied to the appliance and by which gas is controlled. Zero governor — a regulating device that is adjusted to deliver gas at atmospheric pressure within its flow rating.

4 Pilot gas valve train Δ

4.1 Pilot supply 4.1.1 When the pilot supply is utilizing the same fuel source as the main fuel train, the takeoff shall be downstream of the appliance manual shut-off valve.

4.1.2 The piping or tubing shall be firmly secured, supported, and protected from physical damage and when the pilot utilizes the same fuel source as the main flame it shall be taken off (a) at the top or side of a horizontal fuel supply; or (b) at the side of a vertical fuel supply.

4.1.3 The piping or tubing when utilizing the same fuel source as the main train shall be taken off at a point that will supply adequate pressure for stable ignition of the pilot.

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4.1.4 When the fuel supply for the pilot is from an alternate fuel source it shall meet the requirements of Clause 4, with the exception of Clause 4.1.1.

4.2 Manual shut-off valves 4.2.1 A pilot shall be independently controlled by a manual shut-off valve located upstream of all other components of the pilot valve train. Δ

4.2.2 A pilot manual shut-off valve shall be of the quarter-turn, plug, ball, or eccentric type and it shall not be subjected to either a temperature or a pressure outside of its certified rated or approved rated range.

Δ

4.2.3 A pilot manual shut-off valve shall be certified to CGA 3.11, CGA 3.16, or ANSI Z21.15/CSA 9.1 or approved for use with gas, and it shall not be subjected to either a temperature or a pressure outside of its certified or approved rated range.

4.3 Pressure regulators 4.3.1 The gas supply to the pilot or group of pilots shall be regulated by a pressure regulator independent of the main burner gas supply.

4.3.2 A pilot pressure regulator shall be of the spring-loaded or pressure-balanced type.

4.3.3 A pilot pressure regulator shall maintain the pressure to the pilot supply piping, from the maximum to the minimum pilot firing rates, within 10% above or below the operating pressure.

4.3.4 A pilot pressure regulator shall not be bypassed. Δ

4.3.5 When the inlet supply pressure to the pilot pressure regulator is in excess of 0.5 psig (3.5 kPa), the pilot pressure regulator shall be a lock-up (positive shut-off) pressure regulator.

Δ

4.3.6 A pilot pressure regulator shall be equipped (a) for lighter-than-air gas, with a bleed vent leading outdoors in accordance with CSA B149.1, or into the combustion chamber adjacent to a continuous pilot, unless the pilot pressure regulator has an inlet pressure not in excess of 2 psig (14 kPa) and is constructed or equipped with a leak-limiting system that restricts the escape of gas to not more than 2.5 ft3 (0.0708 m3) per hour of a gas having a specific gravity of 0.6 and the fuel contains no more than 7 mg of hydrogen sulphide per cubic metre of gas at an absolute pressure of 101.325 kPa at 15 °C; or (b) for heavier-than-air gas, with a bleed vent leading outdoors in accordance with CSA B149.2, unless the pilot pressure regulator has an inlet pressure not in excess of 2 psig (14 kPa) and is constructed or equipped with a leak-limiting system that restricts the escape of gas to not more than 1 ft3

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(0.0283 m3) per hour of a gas having a specific gravity of 1.53 and the fuel containing no more than 7 mg of hydrogen sulphide per cubic metre of gas at an absolute pressure of 101.325 kPa at 15 °C. A pilot pressure regulator with vent-limiting system shall be installed in a ventilated space only.

4.3.7 A pilot pressure regulator that requires access to atmosphere for successful operation shall be vented to a safe location. When a regulator is constructed so as to limit the escape of gas in the event of diaphragm failure in accordance with Clauses 4.3.6 and 4.3.8, no external vent line from the regulator shall be required. This provision shall not apply to a zero governor used in connection with a gas/air proportioning and mixing system.

4.3.8 The vent line shall be of a size sufficient to prevent impedance upon the regulator or shall be equipped with a regulator suppressor assembly.

4.3.9 An outdoor bleed vent termination shall be equipped with a means to prevent the entry of water, insects, or foreign material.

4.4 Overpressure protection devices 4.4.1 When the inlet pressure to a pilot pressure regulator exceeds the pressure rating of any downstream component or accessory, an overpressure protection device shall be provided. If a relief valve is used, it shall be an integral part of the regulator, or a separate line relief valve shall be installed as close as possible downstream from the regulator. Such a device shall be set at a pressure such that the protected outlet pressure that can be generated will not exceed the pressure rating of the lowest-rated component.

4.4.2 The discharge from an internal relief or line relief valve shall terminate at a safe outdoor location. Δ

4.5 Safety shut-off valves

Δ

4.5.1 A safety shut-off valve shall (a) be certified; (b) when of the automatic type, open only when activated by the energizing medium; (c) when of the manual-reset type, open only by a manual-reset function in conjunction with the energizing medium; (d) be constructed so that the safety features cannot be bypassed; (e) not be bypassed except as required for operation of an approved valve proving system (VPS); and (f) except as required for operation of an approved valve proving system (VPS), when more than one valve is required, be wired in parallel.

Δ

4.5.2 A manual shut-off valve that can isolate an automatic vent valve shall not be installed in the automatic vent valve piping without the prior approval of the authority having jurisdiction.

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4.5.3 A pilot train with an input equal to or less than 20 000 Btuh (6 kW) shall (a) be equipped with a minimum of one safety shut-off valve certified in accordance with ANSI Z21.21/CSA 6.5 or CGA 3.9; or (b) be part of a circuit controlled by either a combination control certified to ANSI Z21.78/CSA 6.20 or by a thermocouple-type combustion safeguard certified to CSA CAN1-6.4 or ANSI Z21.20/CAN/CSA-C22.2 No. 60730-2-5 or both.

Δ

4.5.4 A pilot train with an input greater than 20 000 Btuh (6 kW) up to and including 400 000 Btuh (120 kW) shall be equipped with at least (a) two safety shut-off valves piped in series and wired in parallel and certified in accordance with ANSI Z21.21/CSA 6.5; or (b) one safety shut-off valve certified in accordance with ANSI Z21.21/CSA 6.5 and marked C/I or in accordance with CGA 3.9.

Δ

4.5.5 A pilot train with an input greater than of 400 000 Btuh (120 kW), up to and including 3 500 000 Btuh (1025 kW), shall (a) be equipped with two safety shut-off valves, both certified, one of which shall be certified in accordance with ANSI Z21.21/CSA 6.5 and marked C/I or certified in accordance with CGA 3.9; or (b) be equipped with one safety shut-off valve certified in accordance with ANSI Z21.21/CSA 6.5 and marked C/I or certified in accordance with CGA 3.9. The valve shall be equipped with a proof of closure switch that is interlocked in the starting circuit, and the holding circuit used in conjunction with the proof of closure shall not defeat the proof of closure switch. The valves specified in Items (a) and (b) shall not be bypassed.

4.5.6 A pilot train with an input greater than 3 500 000 Btuh (1025 kW) shall meet the requirements of a main fuel valve train. Δ

4.5.7 When a valve proving system (VPS) is used in a pilot train, it shall be approved by the authority having jurisdiction (see Annex F for guidelines on valve proving systems (VPS)).

Δ

4.6 Test firing valves 4.6.1 A pilot burner with input in excess of 20 000 Btuh (6 kW) shall be equipped with a test firing valve.

4.6.2 The test firing valve shall be located downstream of all safety shut-off valves and as close as practicable to the burner.

4.6.3 When a test firing valve is in the open position, the handle of the valve shall be parallel to the flow of gas, and the valve shall be capable of being turned to the ON and OFF positions without removal of the handle.

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4.6.4 The test firing valve shall be a quarter turn manual shut-off valve that (a) is rated for the temperature, fuel type, and pressure to which it is subject; (b) has stops in the OPEN and CLOSED positions; and (c) has an attached handle or loose-fitting key, or extended handle wrench.

4.6.5 The test firing valve shall be certified to CGA 3.11, CGA 3.16, or ANSI Z21.15/CSA 9.1, or approved for use with gas, and shall not be subjected to either a temperature or a pressure outside of its certified or approved rated range.

4.7 Pilot burners 4.7.1 A pilot burner and its components shall be installed according to the manufacturer’s instructions and shall be firmly secured in place to maintain correct alignment.

4.7.2 A pilot shall be designed and installed to ensure safe and reliable ignition of the main burner.

4.7.3 A pilot burner and its components, including the combustion safety control, shall be installed so as to be readily accessible.

4.7.4 A pilot burner shall be so installed and adjusted that there will be no injurious flame impingement on heating surfaces that can cause incomplete combustion or damage to these surfaces.

4.7.5 Provisions for observing the pilot burner flame shall be in accordance with Clause 7.7.1. Δ

4.7.6 Except when allowed in Clause 4.7.8, the input to a continuous pilot shall not exceed 3% of the maximum rated input to the main burner.

Δ

4.7.7 Except when allowed in Clause 4.7.8, the input to either an intermittent or interrupted pilot shall not exceed 5% of the maximum rated input to the main burner.

Δ

4.7.8 For appliances of 12 500 000 BTUh (3660 kW) or greater, the pilot should be sized to ensure reliable ignition of the main burner by an interrupted pilot or reliable ignition and support of the main burner by an intermittent pilot.

4.7.9 The trial-for-ignition period of an intermittent or an interrupted pilot flame shall not exceed 10s.

4.7.10 When two or more burners are supplied by a single manifold, the manifold shall be sized to provide equal pressure to all burners.

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4.8 Safety flare pilots Where required for reliable ignition and combustion of a safety flare or a process flare for the disposal of process gases, safety flare pilots and process flare pilots shall be approved (see Annex E for guidelines on flare pilot systems).

5 Main gas valve train 5.1 Manual isolation valves Δ

5.1.1 When gas and another fuel are used in a dual or combination burner, a manual isolation valve shall be provided upstream of the main gas valve train components but downstream of the pilot line connection.

Δ

5.1.2 The manual isolation valve shall be certified to CGA 3.11, CGA 3.16, or ANSI Z21.15/CSA 9.1, or approved for use with gas, and shall not be subjected to either a temperature or a pressure outside of its certified or approved rated range.

5.2 Pressure regulators 5.2.1 The fuel supply to the burner or group of burners shall be regulated by a pressure regulator.

5.2.2 The pressure regulator shall be of the spring-loaded or pressure-balanced type.

5.2.3 The pressure regulator shall be capable of maintaining an outlet pressure to within 10% above or below the regulator set pressure during burner operation from minimum to maximum firing rates.

5.2.4 The pressure regulator shall not be bypassed. Δ

5.2.5 When the inlet supply pressure to the pressure regulator is in excess of 0.5 psig (3.5 kPa), the pressure regulator shall be a lock-up (positive shut-off pressure regulator).

Δ

5.3 Safety shut-off valves 5.3.1 A safety shut-off valve shall (a) for capacities up to and including 200 000 Btuh (60 kW) and pressures not in excess of 0.5 psig (3.5 kPa), be certified in accordance with ANSI Z21.78/CSA 6.20, CGA 3.9, or ANSI Z21.21/CSA 6.5 or CSA CAN1-6.4 or ANSI Z21.20/CAN/CSA-C22.2 No. 60730-2-5; (b) for capacities in excess of 200 000 Btuh (60kW) or pressures in excess of 0.5 psig (3.5 kPa), be certified in accordance with CGA 3.9 or ANSI Z21.21/CSA 6.5; (c) when of the automatic type, open only when activated by the energizing medium; (d) when of the manual-reset type, open only by a manual-reset function in conjunction with the energizing medium; (e) be constructed so that the safety features cannot be bypassed;

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(f) not be bypassed except as required for operation of an approved valve proving system (VPS); and (g) when more than one valve is required, be wired in parallel except as required for operation of an approved valve proving system (VPS).

5.3.2 An appliance that has a maximum rated input in excess of 400 000 Btuh (120 kW) shall have main safety shut-off valves that are certified in accordance with CGA 3.9 or with ANSI Z21.21/CSA 6.5 and marked C/I and, where applicable, shall have pilot valves in accordance with Clause 4.5. Note: The downstream valve should be slow-opening, where practicably possible, to provide smooth and reliable lighting of the burners.

5.3.3 A holding circuit used in conjunction with any proof of closure shall not defeat the proof of closure switch.

5.3.4 A single burner appliance that has a rated input up to and including 200 000 Btuh (60 kW) and having an inlet pressure not in excess of 0.5 psig (3.5 kPa) shall (a) be equipped with two safety shut-off valves piped in series and wired in parallel and certified in accordance with ANSI Z21.21/CSA 6.5; (b) be equipped with one safety shut-off valve certified in accordance with ANSI Z21.21/CSA 6.5 and marked C/I, or certified in accordance with CGA 3.9; or (c) be part of a circuit controlled by either a combination control certified to ANSI Z21.78/CSA 6.20 or by a thermocouple-type combustion safeguard certified to CSA CAN1-6.4 or ANSI Z21.20/CAN/CSA-C22.2 No. 60730-2-5, or both. Δ

5.3.5 A single burner appliance that has a rated input in excess of 200 000 Btuh (60 kW) and up to and including 5 000 000 Btuh (1500 kW) or having an inlet pressure of greater than 0.5 psig (3.5 kPa) shall be equipped with at least (a) two safety shut-off valves in series; or (b) one safety shut-off valve equipped with a proof of closure switch that is connected into the start-up circuit of the combustion safety control.

5.3.6 A single burner appliance that has a maximum rated input in excess of 5 000 000 Btuh (1500 kW) and less than 12 500 000 Btuh (3660 kW) shall be equipped with at least two safety shut-off valves in series, one of which shall be equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control.

5.3.7 A single burner appliance that has a maximum rated input of 12 500 000 Btuh (3660 kW) or greater shall be equipped with at least two safety shut-off valves in series. Each safety shut-off valve shall be equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control.

5.3.8 A multiple burner appliance that has a total maximum rated input up to and including 5 000 000 Btuh (1500 kW) and uses a common burner flame safeguard shall be equipped with at least (a) two safety shut-off valves in series to each burner, where a main header safety shut-off valve, if installed, shall be considered one of the two safety shut-off valves in series to each burner; or (b) one safety shut-off valve equipped with a proof of closure switch at each burner. The proof of closure switch shall be integrated with the start-up circuit of the combustion safety control.

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5.3.9 A multiple burner appliance that has a total maximum rated input in excess of 5 000 000 Btuh (1500 kW) and less than 12 500 000 Btuh (3660 kW) and uses a common burner flame safeguard control shall be equipped with at least (a) one safety shut-off valve located on the main header and equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control, and a second safety shut-off valve located at each burner; or (b) two safety shut-off valves in series that shall be located at each burner, and one of the two safety shut-off valves shall be equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control.

Δ

5.3.10 A multiple burner appliance that has a total maximum rated input of 12 500 000 Btuh (3660 kW) or greater and uses a common burner flame safeguard control shall be equipped with at least (a) one safety shut-off valve located on the main header and equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control, and a second safety shut-off valve located at each burner and equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control; or (b) two safety shut-off valves in series at each burner, which shall each be equipped with a proof of closure switch that is integrated with the start-up circuit of the combustion safety control.

Δ

5.3.11 On a multiple burner appliance that incorporates individual burner flame safeguard controls, each burner shall be treated as a single burner appliance in accordance with Clause 5.3.4, 5.3.5, 5.3.6 or 5.3.7 based on individual burner rating. Vent valve and valve proving system (VPS) requirements shall be based on individual burner rating and shall comply with Clause 5.3.12.

Δ

5.3.12 An appliance that has a maximum rated input of 12 500 000 Btuh (3660 kW) or greater shall (a) have main burner safety shut-off valves supervised by an approved valve proving system (VPS), which is integrated into the start-up circuit of the combustion safety control and prevents main burner safety shut-off valves from opening when a leak is detected; or (b) be equipped with an automatic vent valve installed in a vent line that is connected into the burner valve train immediately downstream of the first automatic safety shut-off valve in the main burner valve train. There shall be no other valve or valves installed in the vent line.

5.3.13 A normally open valve used as an automatic vent valve shall (a) be certified to ANSI Z21.21/CSA 6.5; (b) close when electrically energized; (c) have the vent valve and vent line sized in accordance with Table 5.1; (d) have the outlet piping terminate in an approved outdoor location; and (e) be wired in parallel with the safety shut-off valves.

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Table 5.1 Valve and vent line pipe sizing (See Clause 5.3.13.)

Δ

Valve train pipe size at takeoff connection, NPS

Valve and vent lines pipe size, NPS

1-1/4 or less

1/2

1-1/2

3/4

2

1

2-1/2

1-1/4

3

1-1/4

3-1/2

1-1/2

4

2

5

2

6

2-1/2

8

3-1/2

Over 8

Not less than 15% of the cross-sectional area of the valve train pipe size at the takeoff connection

5.3.14 A manual shut-off valve that can isolate an automatic vent valve shall not be installed in the automatic vent valve piping without the prior approval of the authority having jurisdiction.

Δ

5.3.15 When a valve proving system (VPS) is used in the main burner train, it shall be approved by the authority having jurisdiction (see Annex F for guidelines on valve proving systems (VPS)).

5.4 Input flow control systems 5.4.1 An input flow control valve shall be provided on installations where the firing rate is automatically changed and shall maintain stable conditions at all firing rates without manual attention.

5.4.2 When an input flow control valve to a burner is operated automatically, it shall be (a) capable of any desired adjustment to provide sufficient gas for the combustion process; (b) provided with a means for preventing accidental change in settings; and (c) accessible for service and adjustment. Δ

5.4.3 When an electronic type fuel/air ratio control (FARC) system is used, it shall be in compliance with ISO 23552-1 or approved (see Annex D for guidelines on electronic type fuel/air ratio control systems).

5.5 Test firing valves 5.5.1 A test firing valve shall be installed on all burners and shall be located downstream of all safety shut-off valves and as close as practicable to the burner.

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5.5.2 When a test firing valve is in the open position, the handle of the valve shall be parallel to the flow of gas, and the valve shall be capable of being turned to the ON and OFF positions without removal of the handle. Δ

5.5.3 The test firing valve shall be a quarter turn manual shut-off valve that (a) is rated for the temperature, fuel type, and pressure to which it is subject; (b) has stops in the OPEN and CLOSED positions; and (c) has an attached handle or loose-fitting key, or extended handle wrench.

Δ

5.5.4 The test firing valve shall be certified to CGA 3.11, CGA 3.16, ANSI Z21.15/CSA 9.1, or approved, for use with natural gas, and shall not be subjected to either a temperature or a pressure outside of its certified rated range.

Δ

5.5.5 Except as noted in Clause 5.5.6, a test firing valve provided on a valve train to a burner with an input in excess of 12 500 000 Btuh (3660 kW) shall be equipped with an electric or pneumatic end switch connected within the safety limit control circuit of the flame safeguard system and interlocked to ensure that the valve remains closed until prepurge is completed and a pilot flame, if used, is proven.

Δ

5.5.6 The requirements of Clause 5.5.5 need not apply where the safety limit controls are of the manual-reset type or are wired into the non-recycling circuit of a flame safeguard system, or a combination thereof.

5.6 Main burner 5.6.1 Construction of a burner and any component parts shall be in accordance with reasonable concepts of safety, substantiality, and durability.

5.6.2 A burner shall be of a design that is compatible with the intended application and shall incorporate features that will ensure safe operation.

5.6.3 A burner shall be provided with a means to (a) be firmly secured in place to maintain its correct position; (b) prevent accidental movement of any adjustable part; and (c) maintain complete and stable combustion under all operating conditions.

5.6.4 A burner shall maintain stability of the designed flame shape, with neither flashback nor blow-off, over the entire range of turndown that will be encountered during operation, when supplied with combustion air and the designed fuels in the proper proportions and in the proper pressure ranges.

5.6.5 When a manually adjusted combustion airflow controlling device is provided on a burner, it shall be (a) capable of any desired adjustment to provide sufficient air for the combustion process; (b) provided with a means to prevent an unintentional change in setting; (c) constructed and mounted such that air leakage is minimized; and (d) accessible for service and adjustment.

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5.6.6 When a combustion airflow controlling device on a burner is operated automatically, it shall (a) comply with the requirements of Clause 5.6.5; and (b) be designed to provide maximum airflow upon failure of the operating mechanism.

5.6.7 When a burner combustion air supply is provided by mechanical means, fuel shall be prevented from entering the burner until the mechanically produced airflow to the burner is proven by means of an airflow proving device. In the event of failure of airflow to the burner, fuel shall be shut off.

5.6.8 When air from exhaust or recirculating fans, or both, is required for combustion of the gas, airflow shall be proven prior to the ignition attempt, and reduction of airflow to an unsafe level shall result in closure of the safety shut-off valve.

5.6.9 Whenever it is possible for combustion air pressure to exceed a maximum safe operating pressure, as can occur when compressed air is used, a pressure-reducing valve, high air pressure switch, and low air pressure switch shall be used.

5.6.10 When the means of providing secondary air is adjustable, it shall include a locking device to prevent an unintentional change in setting.

5.6.11 The trial-for-ignition period of a main burner flame from an intermittent or interrupted pilot flame shall not exceed 10 s.

5.6.12 When a burner has a flame width (or run length for duct burners) in excess of 3 ft (900 mm) from the source of burner ignition, (a) the main burner flame shall be proven at the furthest point(s) along its base from the source of ignition; (b) the source of ignition shall be located in the combustion zone adjacent to the entry of the fuel or fuel/air mixture to the burner; and (c) the main burner flame shall be proven at a location providing the most stable flame detection at all firing rates and not affected by the source of ignition.

5.6.13 When two or more burners are supplied by a single manifold, the manifold shall be sized to provide equal pressure to all burners.

5.6.14 Provisions for observing the main burner flame shall be in accordance with Clause 7.7.1.

5.6.15 Where a raw gas (nonaerated) burner is used, a differential airflow proving device shall be provided to measure differential pressure across the profile plates to ensure combustion air velocity is within the minimum and maximum limits specified by the burner manufacturer over the full range of turndown. The airflow proving device shall be (a) connected electrically in series in the safety limit control circuit; and (b) set to automatically shut down the burner where the limits specified by the burner manufacturer are exceeded.

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5.7 Overpressure protection devices 5.7.1 When either (a) the inlet pressure to a main pressure regulator exceeds the pressure rating of any downstream component or accessory; or (b) the failure of single upstream, line regulator or service pressure regulator results in pressure that exceeds the pressure rating of the pressure regulator or any downstream component or accessory. An overpressure protection device shall be provided, and set at a pressure such that the protected outlet pressure that can be generated will not exceed the pressure rating of the lowest-rated component or accessory.

5.7.2 Overpressure protection shall be provided by any one of the following: (a) monitoring regulator; (b) pressure relief valve; (c) series regulator; or (d) overpressure cutoff device.

5.7.3 If a relief valve is used, it shall be either an integral part of the regulator, or a separate line relief valve shall be installed as close as possible downstream from the regulator. A relief valve shall be capable of fully relieving the supply pressure so that the protected outlet pressure that can be generated will not exceed the pressure rating of the lowest-rated component or accessory. Note: A token relief valve should not be used as a full capacity relief valve.

5.7.4 When a monitoring or series regulator is used as an overpressure protection device, a device shall be installed and set to detect and notify the user of failure of the primary gas pressure regulator.

6 Additional requirements for liquid propane valve trains 6.1 All piping shall be Schedule 80 or heavier.

6.2 Valves, pipes, fittings, and components shall be approved for use with liquid propane.

6.3 A hydrostatic overpressure relief valve shall be installed wherever a liquid can be trapped between two components.

6.4 A fuel filter shall be installed on the inlet to the valve train.

6.5 Where dictated by the valve train design, the liquid propane regulator may be located immediately upstream of the test firing valve.

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Code for the field approval of fuel-related components on appliances and equipment

6.6 The requirements of Clause 5.3.12 do not apply to liquid propane valve trains.

7 Applications 7.1 Installation Δ

7.1.1 The installation of an appliance, the method of installing the components of the valve train, and the piping and tubing materials shall be in accordance with the requirements of CSA B149.1, except that threaded fittings and components may be used on gas trains up to and including NPS 4 (instead of the welded pipe joints for piping of NPS 2-1/2 or larger required by Clause 6.9.2 of CSA B149.1) and methods to ensure that records pertaining to design specifications, installation, operation and maintenance instructions are provided to the owner of the equipment. As a minimum the following documentation shall be provided: (a) Description of any hazardous condition which may affect this appliance or its installation. (b) Process and Instrumentation Diagram (P&ID). (c) Bill of Materials (BOM) or component data sheets showing the model number, manufacturer, construction, materials, ratings and certification of each relevant component and its tag number referenced on the other drawings and on the physical component. (d) Wiring diagram. (e) Burner management system specification. (f) Operating narrative, shutdown key/cause and effect diagram, ladder logic, installation, operation, and maintenance manual or other suitable description of appliance operation. (g) Specification of electrical area classification (in compliance with the authority having jurisdiction), appliance and instrument venting to a safe location, and overpressure protection of the fuel train. (h) Commissioning/combustion report with equipment/permissive set-points and stack readings at maximum fire. (i) For an appliance approved for use with different fuels, a switch-over procedure to be followed by the operator upon switching to another fuel without exceeding the maximum rating of the appliance.

7.1.2 Appliance clearances to combustible material shall be in accordance with the requirements of CSA B149.1. See also Clause 13.1.2.

7.1.3 The service clearance for an appliance shall be a minimum of 24 in (600 mm) to any side, top, or bottom where service is required to be performed. When this distance is not sufficient for the removal, replacement, or repair of a component, an accessory, or any equipment forming an integral part of, or connected to, the appliance, a service clearance shall be provided that is adequate to effect such removal, replacement, or repair.

7.1.4 Except as specified in Clause 7.6.1, neither aluminum nor plastic piping or tubing shall be used for the construction of an appliance valve train.

7.1.5 A means of access shall be provided to permit inspection and maintenance of the appliance and auxiliary equipment.

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7.1.6 Special measures shall be taken when installing vent lines such as those from vent valves, regulator vents, pressure limit sensors, or other controls when fuel gas contains poisonous compounds, such as those found in sour gas supplies containing hydrogen sulphide. Leak limiters shall not be used on those fuel gas trains, which contain poisonous fuel gases.

7.1.7 When a filter is used on a gas valve train, a low-pressure or high differential pressure indicator shall be installed directly downstream of the filter.

7.2 Unions and flanges Unions or flanges shall be installed on valve trains for maintenance and replacement of components.

7.3 Pressure test points 7.3.1 Pressure test points not exceeding NPS 1/4 shall be provided to allow testing of the valve train components and the set-up of the burner. Δ

7.3.2 A pressure test point connection shall be closed in a manner that cannot be accidentally opened when not in use, and shall (a) be provided as an integral part of a valve train component; or (b) consist of a threaded or welded pipe fitting.

7.4 Pressure ratings A valve train component shall have a pressure rating not less than the protected inlet pressure to the component.

7.5 Multi-purpose components A component incorporating one or more functions may be used if the required functions and operating characteristics are provided.

7.6 Bleed vents for valves, combination controls, pressure regulators, relief valves, and other control devices 7.6.1 Except as specified in Clauses 7.6.2 to 7.6.4 and 7.6.9, when an automatic valve, diaphragm valve, combination control, pressure regulator without internal relief, or other control device (excluding a gas overpressure relief valve) that requires venting is installed, it shall be vented separately to a safe location outdoors by a vent line (a) of seamless aluminum or steel tubing, or copper tubing that complies with Clause 6.2.4 of CSA B149.1, or of steel pipe; and (b) of a size at least equal to the nominal pipe size of the vent outlet of the valve, combination control, pressure regulator, or control device, but in no case less than 0.25 in (6 mm). Δ

7.6.2 When an appliance pressure regulator without internal relief having an inlet pressure not in excess of 2 psig (14 kPa) is installed on an appliance, it shall be vented to the outdoors unless it is constructed or equipped with a leak limiting system, which restricts the escape of gas to not more than 2.5 ft3/h (0.0708 m3/h) of a gas having a specific gravity of 0.6 and 1.0 ft3/h (0.0283 m3/h) of a gas having a

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specific gravity of 1.53 and the fuel contains no more than 7 mg of hydrogen sulphide per cubic metre of gas at an absolute pressure of 101.325 kPa at 15 °C. A regulator with vent-limiting system shall be installed in a ventilated space only.

7.6.3 When a diaphragm valve or combination control is installed on an appliance with an inlet supply pressure not in excess of 0.5 psig (3.5 kPa) and using a gas lighter-than-air, it may be vented into the appliance combustion chamber adjacent to the continuous pilot, provided that the terminus of the bleed vent is in a burner tip having a melting point in excess of 1450°F (790 °C), securely held in a fixed position relative to the pilot flame, and does not adversely affect the operation of the thermal element.

7.6.4 When two or more, or any combination of, automatic valves, diaphragm valves, pressure regulators without internal relief, combination controls, or other control devices (excluding gas overpressure relief valves) that require venting are installed, they may be connected into a single vent, provided that (a) there is compliance with Clause 7.6.1 for inlet pressure not in excess of 0.5 psig (3.5 kPa); or (b) there is compliance with Clause 7.6.5 for inlet pressure in excess of 0.5 psig (3.5 kPa). The single vent line shall have an area of not less than twice the total area of the connected bleed vents.

7.6.5 Except as specified in Clause 7.6.6, when a pressure regulator with internal relief or a gas overpressure relief valve is installed, it shall be vented separately to a safe location outdoors by a vent line (a) of seamless steel tubing, or copper tubing that complies with Clause 6.2.4 of CSA B149.1, or of steel pipe; and (b) of a size (i) at least equal to the nominal pipe size of the vent outlet of the valve or regulator, increased as specified by the manufacturer’s instructions; or (ii) in the absence of manufacturer’s instructions, increased by one pipe size diameter for every 50 ft (15 m) or part thereof that the vent line extends beyond the initial 50 ft (15 m). This increase shall be made at the connection on the device.

7.6.6 When two or more gas overpressure relief valves are installed, they may be connected into a single vent line, provided that (a) there is compliance with Clause 7.6.5; (b) the single vent line has an area equal to the largest relief valve opening plus 50% of the total area of the other relief valve openings; and (c) the variance between the inlet pressures and the variance between the outlet pressures of the relief valves do not exceed 10%.

7.6.7 The outdoor vent termination shall be equipped with a means to prevent the entry of water, insects, or foreign material.

7.6.8 The vent line shall be of a size sufficient to prevent impedance upon a regulator or shall be equipped with a regulator suppressor assembly.

7.6.9 A pressure regulator, line relief valve, or hydrostatic relief valve on an appliance using gas heavier-than-air shall be equipped with a vent line (a) in accordance with Clause 7.6.5; and (b) that terminates outdoors in accordance with Clause 5.8.1 of CSA B149.2.

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7.6.10 A safety limit or a safety relief device shall not be isolated, bypassed, or in any way made ineffective by a valve or other device.

7.7 Observation of main burner flame and ignition source 7.7.1 Means shall be provided to enable an operator to observe from the start-up location (a) the pilot burner flame or other ignition source; and (b) the main burner flame at the point of ignition.

7.7.2 When observation ports are not practicable, other approved means for verifying lighting of individual burners shall be provided.

7.8 Pneumatic control systems Where pneumatic control systems utilize compressed flammable gasses instead of instrument air, all components shall be suitable for operation with such gases. In addition, venting requirements relevant to the use of flammable gases shall be followed. See also Clause 7.1.6. Δ

7.9 Supplementary requirements for controls and valves subjected to low ambient temperatures 7.9.1 Controls and valves not rated for the ambient temperatures to which they are to be subjected shall be enclosed in a heated compartment as described in Clause 7.9.2 or the appliance shall be provided with a low limit temperature control that will prevent the appliance from operating at a temperature less than the highest minimum (low) ambient rating of any control within the appliance.

7.9.2 An electrically-heated compartment intended to house controls and valves in accordance with Clause 7.9.1 shall be of non-combustible construction and shall be heated to maintain a temperature within the compartment of at least 18°F (10 °C) higher than the highest minimum (low) ambient rating of any control within the compartment, taking into account the possible effects of wind, snow and ice, if the equipment is intended for use outdoors. Note: Electrically heated compartments may be thermally insulated.

Δ

7.10 Hoses and hose fittings Every hose and hose fitting shall comply with: (a) CAN/CGA-8.1; (b) CAN1-8.3; or (c) CGA CR96.

8 Ignition systems 8.1 General An ignition source shall be located in a position that will permit smooth and reliable ignition of the pilot/main flame at the burner manufacturer’s specified ignition conditions.

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8.2 Electric ignition systems 8.2.1 Electric ignition systems shall be certified (in accordance with ANSI Z21.20/CAN/CSA-C22.2 No. 60730-2-5 or CSA C22.2 No. 13) for use in the intended application.

8.2.2 Direct spark ignition shall not be used to ignite pilot gas unless the pilot is proved.

8.2.3 Direct spark ignition shall not be used to ignite main burner gas, unless (a) the main burner input is not in excess of 3 500 000 Btuh (1025 kW) at the time of ignition; (b) the main burner is proved; (c) the spark is of the interrupted type; (d) the ignition transformer secondary is rated at not less than 6000 V and 20 mA, or at an approved voltage and amperage to ensure reliable and smooth ignition; (e) the location and setting of the electrodes are secure and provide reliable and smooth ignition; and (f) the trial-for-ignition period of a burner with an input (i) not in excess of 400 000 Btuh (120 kW) does not exceed 10 s; or (ii) in excess of 400 000 Btuh (120 kW) does not exceed 5 s.

8.3 Manual ignition systems Δ

8.3.1 A non-proven manual ignition system shall not be used to ignite a main burner, unless approved.

8.3.2 A manually ignited proven pilot shall (a) be firmly secured in place to maintain correct alignment and positioned to ensure safe and reliable ignition of the main burner; (b) be positioned to allow for observation by an operator during start-up; (c) have an input not exceeding 3% of the maximum rated input to the main burner; and (d) have a flame failure response time not exceeding (i) 90 s for lighter-than-air gases and 20 s for heavier-than-air gases when used on an appliance that has an input up to and including 400 000 Btuh (120 kW); or (ii) 4 s when used on an appliance that has an input exceeding 400 000 Btuh (120 kW) except as specified in Clause 9.1.1(c)(iii).

9 Safety controls 9.1 Combustion safety control systems Δ

9.1.1 A combustion safety control system shall (a) be provided on every appliance with an automatic or semi-automatic control system; (b) be certified and provide the functions required for the intended application; (c) de-energize the main burner fuel safety shut-off valve(s) in the event of flame failure, with a flame failure response time of (i) 90 s or less for an appliance that has an input of 400 000 Btuh (120 kW) or less; (ii) 4 s or less for an appliance that has an input in excess of 400 000 Btuh (120 kW); or

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(iii) 90 s or less for gases lighter-than-air and 20 s or less for gases heavier-than-air used in an atmospherically fired appliance with an unrestricted vertical flow of combustion products where the maximum input of each burner or burner unit is 1 000 000 Btuh (300 kW), provided that there is a supervised pilot for each burner unit wired in series with the main burner fuel safety shut-off valve(s); (d) supervise the main burner flame at the end of the main trial-for-ignition period for (i) burners using mechanical means to supply combustion air or exhaust gas removal; (ii) all types of burners with modulating or high-low firing; (iii) natural draft atmospheric gas burners having inputs greater than 2 500 000 Btuh (733 kW); and (e) be provided with a trial-for-ignition period in accordance with Clauses 4.7.9, 5.6.11, and 8.2.3(f).

9.1.2 When control or instrument air or gas is required for use with an appliance combustion system, a pressureproving device, or an approved equivalent, shall be provided and shall be interlocked to prevent the flow of fuel to the burners on failure of such air supply, unless the appliance fails safe on loss of instrument air or gas.

9.1.3 Except as specified in Clause 9.1.4, where intermediate relays are used in the limit circuit, a safety relay or circuit that provides redundancy and a self-monitoring function shall be used.

9.1.4 Intermediate relays may be used in the limit circuits, provided that each intermediate relay serves only one safety interlock.

9.2 Prepurge Δ

9.2.1 When either an intermittent or an interrupted pilot or a direct transformer spark igniter is used to light the main burner and the combustion air supply is by mechanical means, the appliance control system shall provide a proven purge period prior to the ignition cycle. This purge period shall provide at least four air changes of the combustion zone and flue passages. The airflow rate during purge shall be not less than 60% of that required at maximum input, unless a lower airflow rate is required to prevent hazardous conditions. See also Clause 13.5. After a burner shutdown or flame failure, there shall be a proven purge period unless (a) the appliance combustion chamber is at or above 1400°F (760 °C) and a bypass controller is used for this purpose; or (b) when multiple burners are firing inside a common combustion chamber and do not operate at or above 1400°F (760 °C) (i) at least one of the burners remains ignited in the common combustion chamber; and (ii) the burner(s) remaining in operation shall provide ignition of any unintended release of fuel through other burners that are not in operation without explosion. (c) assuming that all safety shut-off valves fail in the full open position, it can be demonstrated that the combustible concentration in the combustion chamber and all other passages that handle the recirculation and exhaust of products of combustion cannot exceed 25% of the lower explosive limit (LEL).

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9.2.2 Components used to establish purge periods shall be of a fixed-timer type or shall be designed to prevent field tampering.

9.2.3 Purge requirements shall take into consideration the safety of processes such as the purging of substoichiometric atmospheres or special atmosphere appliances. See also Clause 13.1.1.2.

9.3 Low fire start A proven low fire start shall be provided on a variable input appliance that has an input in excess of 1 000 000 Btuh (300 kW), unless otherwise approved. On a multiple-burner appliance, when the burners are firing inside a common combustion chamber, the low-fire requirement is considered accomplished when the first burner has been ignited.

9.4 Temperature and pressure safety limit controls Δ

9.4.1 An appliance that heats a liquid or vapor shall be equipped with approved safety devices provided with a manual-reset feature or shall require operator attention before resuming operation, the sole function of which shall be to shut off the fuel supply in the event of (a) low liquid level in an appliance with a minimum liquid level that requires continuous immersion in a liquid for safe operation; (b) low liquid or vapor flow in an appliance that requires flow for safe operation; (c) high fluid temperature for an appliance where the temperature can exceed a safe operating limit. Where portions of the appliance are sufficiently independent, multiple temperature sensors might be required; (d) high pressure for vaporizing appliances which are pressure controlled and pressure is a function of temperature; or (e) low water in a water boiler located above the hot-water circulating system.

9.4.2 When two or more liquid boilers of the coil- or finned-tube type, each with an input rating of 400 000 Btuh (120 kW) or less, are installed in one system, a low liquid fuel cut-off device shall not be required on each boiler, provided that (a) a low liquid fuel cut-off device is installed in the main liquid outlet header; (b) a flow switch is installed in the outlet piping of each boiler, which will cut off the fuel supply to the burner in the event of no liquid flow; and (c) the devices in Items (a) and (b) are installed so that they cannot be rendered inoperative.

9.4.3 Every automatically controlled space-heating furnace shall be equipped with an approved high temperature limit control, the maximum setting of which shall be 350°F (175 °C) for a gravity space-heating furnace or 250°F (120 °C) for a forced-air space-heating furnace.

9.4.4 Flame detectors that can fail in a flame-proving mode shall be of the self-checking type when the burner firing cycle can last longer than 24 h without cycling, unless they are used on equipment that operates above 1400°F (760 °C) and is equipped with a 1400°F (760 °C) bypass controller and on which the ramp up cycle time to reach 1400°F (760 °C) is less than 24 h. When cooling with the burners firing, verification of the flame detectors shall be accomplished before the temperature drops below 1400°F (760 °C).

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9.5 Gas pressure safety limit control 9.5.1 Where the failure or an outlet pressure adjustment of the pressure regulator results in unsafe operation and/or operation does not comply with 5.6.4, a high gas pressure safety device shall be installed downstream of the pressure regulator and shall initiate shut-off of the supply of gas when the gas pressure at the high gas pressure safety device exceeds the setpoint. In the absence of the burner manufacturer's requirements, the setpoint shall be set to not more than 125% of the normal operating pressure at the maximum firing rate. Notes: (1) When installed upstream of the safety shut-off valve(s), the high gas pressure safety device may be by-passed into the combustion safety control until the burner trial for ignition begins. (2) On multiple burner appliances, compliance to Clause 9.5.1 does not exclude the potential need to have an additional high gas pressure safety device downstream of a flow control valve in order to detect excessive pressure at individual burner(s) as other burner(s) turn off.

9.5.2 For appliances with inputs in excess of 400 000 Btuh (120 kW), or where the design outlet pressure of the appliance pressure regulator is in excess of 0.5 psig (3.5 kPa), a low gas pressure safety device shall be installed and shall initiate shut off of the supply of gas if the pressure at the point of connection drops below 50% of the lowest normal operating pressure. The device shall be installed (a) downstream of the pressure regulator where used and upstream of the safety shut-off valve or valves and upstream of the flow control valve; and (b) downstream of the multifunctional control where used. The low gas pressure safety device shall be bypassed into the combustion safety control until the burner has started.

9.5.3 When a gas pilot is used on a multi-fuel appliance, a low gas pressure safety device shall be installed in the gas pilot supply immediately upstream of the first safety shut-off valve. When the pilot is firing, the low gas pressure safety device shall be in service and shall (a) shut down the pilot in a low gas condition; or (b) shut down the main burner in a low gas condition if the pilot is required for stable main burner flame. If the pilot is an interrupted pilot, this device may be removed from service at the completion of the pilot run time.

9.5.4 On burner start-up, electrical delay of the low gas pressure safety device as required in Clause 9.5.2(b) shall only be done either within a programmable controller or with a safety timer. The delay time shall not exceed 5 seconds.

9.6 Auxiliary fans and dampers 9.6.1 When air-supply fans, compressors, or blowers for supply air or instrument and control air are required for use with an appliance combustion system, airflow proving devices of the differential type, or an approved equivalent, shall be provided and shall be interlocked to prevent the flow of fuel to the burners on failure of this air supply.

9.6.2 When adjustable or motorized dampers are used in conjunction with the auxiliary fans specified in Clause 9.6.1, they shall be cut away or equipped with mechanical stops or limit switches interlocked into the safety circuitry to ensure that they are incapable of being moved to a position that might contribute to or result in an unsafe condition.

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9.7 Programmable controllers Δ

9.7.1 General When programmable microprocessors are used as a primary safeguard device, they shall conform to CSA C22.2 No. 0.8, or to the requirements of Clause 9.7.2, or be certified to IEC 61508. Where IEC 61508 is used, a functional safety assessment shall be performed by competent personnel other than the designer, to verify full compliance with the IEC 61511 standard. Note: Programmable microprocessor systems include all controllers where the application software allows the user full flexibility in creating the sequence of operation and adjusting critical timing. These systems are often named Programmable logic controllers (PLCs), Programmable Automation Controllers (PAC) or more generally Logic Solvers. It does not include Flame Safeguard Systems certified to ANSI Z21.20/CAN/CSA-C22.2 No. 60730-2-5 which provided very limited user programming more commonly referred to as configuration. Assessment should be performed by a competent third party to verify full compliance with the IEC 61511 standard. The authority having jurisdiction may require that the burner management systems (BMS) be designed in accordance with internationally recognized safety standards such as the IEC 61511 series of Standards, NFPA 85, or NFPA 86.

9.7.2 Programmable controllers 9.7.2.1 Programmable controllers may be used for the monitoring, sequencing, and control of all aspects of burner or process, or both, subject to Clause 9.7.2.2. The system designer shall be experienced in the design and implementation of microprocessor-based systems hardware and have proven background in the design of burner management systems. The designer shall be solely responsible for both logic development and logic software conversion. The designer shall be completely familiar with the specific features and weaknesses of the particular hardware being used, its failure modes, and any potential impact that a failure in any part of the BMS would have on its operation, equipment, personnel, and the environment. No single point of failure in any part of the BMS shall result in an uncontrollable condition, render the system inoperative, or place the system in a condition that would cause the operator to unknowingly create a hazardous situation. Δ

9.7.2.2 The microprocessor-based system shall be solely dedicated to the BMS. Logic for functions other than the BMS applications shall not be part of the I/O structure, memory, or software program. The following requirements shall apply: (a) The software program for the BMS shall reside in some form of non-volatile memory storage. Acceptable memory storage devices shall be EEPROM, Flash ROM, battery-backed RAM, or EAPROM. Processors using battery-backed RAM shall automatically monitor battery voltage, activating and maintaining an alarm on impending low-battery voltage. A fully expired battery shall have no effect on memory storage as long as the processor is being supplied from the main power source. (b) A watchdog timer internal to the BMS processor shall monitor the program scan time. In the event of an occurrence of a non-deterministic condition, all outputs shall de-energize, resulting in an immediate master fuel trip. The time allowed for a single processor scan shall not exceed three times the predefined scan time. In addition to the internal watchdog timer, an external watchdog timer featuring timed-on and timed-off delays shall be incorporated into the system design. This device shall monitor a dedicated output channel controlled by the processor at a frequency directly related to the processor scan time. The watchdog circuit shall be hard-wired to the master fuel trip circuit to immediately de-energize the main trip valves and associated vent valves. (c) In the event of a power failure, the microprocessor-based system hardware and software shall not prevent the system from reverting to a safe condition. A safe condition shall be maintained upon restoration of power. (d) The BMS shall be equipped with a master fuel trip relay that shall de-energize when a master fuel trip command caused by operator intervention or by any of the critical system processes or component failures are present. It shall directly de-energize the main burner and main igniter header safety

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trip valves and associated vent valves; their operation shall result in a safe condition. No logic sequence, or device, that allows momentary closing and subsequent inadvertent re-opening of the main or igniter fuel valves shall be permitted. Once a master fuel trip is initiated, it shall require operator action before operation of the affected burners can resume. (e) Redundant processors with automatic transfer schemes shall be permitted. The designer shall be familiar with the conditions that would initiate a processor transfer and be fully satisfied that combustion safety is not compromised with the addition of redundancy hardware and/or the switching of processors. (f) The designer of the BMS and the software for system operation shall provide the end user and the authority having jurisdiction with the documentation needed to verify that all related devices and safety logic are functional before the BMS is placed in operation. Passwords and/or entry level privileges shall be provided before access to the processor’s memory shall be permitted. Inadvertent memory erasure shall be prevented by restricted access and high-level password-protected software. The system designer shall be responsible for the distribution of the BMS software program and may transfer the password for memory access to the end user when documentation control procedures are in place. The end user shall not make program alterations without written approval from the system designer or a qualified professional engineer in conjunction with the system designer. The end user shall keep the written approval on file until the equipment or appliance is decommissioned.

9.7.2.3 9.7.2.3.1 Critical input signals are process parameters that activate a BMS master fuel trip and shall be configured in the fail-safe mode. Input channels for all critical signals shall incorporate a continuous self-test feature that satisfies the requirements of Clause 9.7.2.3.2 or 9.7.2.3.3, or they shall be hard-wired to the master fuel trip relay. Bypass switches for critical field inputs shall not be permitted.

9.7.2.3.2 The interrogation voltage to all critical field devices shall be periodically removed. Any channel recognized as faulty shall be alarmed and a BMS trip shall be activated.

9.7.2.3.3 One of two or two of three voting schemes may be implemented. Inputs via communications between the BMS and other microprocessor-based systems shall be permitted. Signals that initiate a master fuel trip shall be hard-wired. When analogue input signals associated directly with the BMS are used, the following shall apply: (a) the analogue transmitter shall be dedicated to the BMS; and (b) out-of-range signals shall default to the safe condition.

9.7.2.4 BMS outputs shall be supervised for false triggering. Interposing relays shall only be used where the power demand exceeds the power rating of the output module or where the operating voltage for the field device is outside of the range offered by the output modules. Where interposing relays are used, the relay shall be sized to the voltage and current requirements of the equipment being controlled and shall be equipped with arc suppression devices designed for the application. Electronic output switches or dry relay contacts may be used in systems operating on AC voltages. They shall have a rating sufficient to control the application in both ON/OFF and continuous operations.

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9.7.2.5 Video interfaces shall be permitted but shall remain passive in their operation, providing only a window into the application and an ability to communicate operator write instructions to the BMS processor such as start/stop, open/close, or trip/reset commands. Video communication update times shall not compromise system safety. In the event of a communication failure, the video display shall default to a fail-safe condition, and there shall be an unambiguous text reference to the fact that the display is not current. Δ

9.7.2.6 Functional testing shall be performed and documented on the complete system prior to shipment to the end user. Functional testing shall include all aspects of the BMS, including the hard-wired tripping circuit, processor scan time, and I/O scan time. Where videographical display systems are involved in control selection and display, video response times shall be tested and recorded for all time-critical BMS control loops. Functional testing shall also be performed and documented after the system is installed at the user’s location. It shall include all aspects of the BMS, including the hard-wired tripping circuit.

9.7.2.7 The system designer shall develop complete system documentation, which shall include the following: (a) functional logic diagrams complete with timer and counter presets; (b) power distribution drawings; (c) a list of all error and alarm messages, their meaning, and suggested operator reactions; (d) a description of the microprocessor-based system and BMS operation; (e) a training manual; and (f) security procedures, privilege levels, and assignments. System documentation shall be supplied to the end user. A copy shall be retained by the system designer for at least 10 years. The end user shall keep the system documentation up-to-date and shall keep it on file until the equipment or appliance is decommissioned.

9.7.2.8 The end user shall ensure that training is provided to allow for safe operation and maintenance of the system.

10 Electrical requirements 10.1 Supply Electrical supply connections for an appliance shall comply with the provincial or territorial electrical code recognized by the authority having jurisdiction or, in the absence of such a code, with the Canadian Electrical Code, Part I.

10.2 Appliance circuits 10.2.1 Each electrical safety control circuit shall be connected into an isolated two-wire single-phase supply circuit of not more than 120 V nominal with one side grounded by a control circuit transformer, a 120 V branch circuit power supply, or their equivalent. All breaking contacts shall be in the ungrounded side.

10.2.2 An electrical circuit forming part of an appliance shall be in accordance with an approved wiring diagram.

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11 Rating plate An appliance shall have a clearly legible permanent rating plate that shall include the following information: (a) manufacturer’s or vendor’s name; (b) appliance type and identification number; (c) electrical specifications; (d) type of fuel(s); (e) maximum input rating in Btuh (kW) and design altitude in ft (m); (f) inlet pressure at the point of connection; and (g) maximum and minimum burner manifold fuel pressure.

12 Initial start-up procedure 12.1 The valve shall be tested to ensure gas-tightness of the valve seats when in the closed position.

12.2 A recommended initial start-up procedure for high-input gas-fired equipment is found in Annex A.

13 Additional requirements for process ovens, process furnaces, and atmosphere generators 13.1 General requirements 13.1.1 Design and installation 13.1.1.1 Furnaces, ovens, and related equipment shall be designed and installed with due regard to the fire hazard inherent in equipment operating at elevated temperatures. Δ

13.1.1.2 When a combustible atmosphere gas is to be introduced into an oven or furnace zone (a) the oven or furnace zone shall be proven to have an internal temperature of not less than 1400°F (760 °C); (b) a negative pressure inside the oven or furnace zone shall be avoided; (c) the atmosphere gas supply shall be provided with a low gas pressure safety device set at not less than 50% of the normal supply pressure, interlocked with a safety shut-off valve that requires a manual-reset function to open; and (d) an interlock shall be provided to prohibit the start-up of the oven or furnace zone unless an adequate supply of a non-reactive gas is available for use to purge the oven or furnace zone in an emergency.

Δ

13.1.1.3 An alarm interlock shall be provided that, after the oven or furnace zone is in operation, will alert the operator that the (a) non-reactive gas supply required by Clause 13.1.1.2(d) has been depleted; and (b) oven or furnace zone should not be shut down until the supply of non-reactive gas required by Clause 13.1.1.2(d) has been re-established.

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13.1.2 Location 13.1.2.1 Furnaces and ovens shall be located so as to be readily accessible, with adequate space above to permit installation of automatic sprinklers, the proper functioning of explosion vents, and inspection and maintenance. Roofs and floors of furnaces shall be insulated, and the space above and below ventilated, to keep temperatures at combustible ceilings and floors below 194°F (90 °C).

13.1.2.2 Furnaces and ovens may be installed on a floor constructed of combustible material, provided that (a) hollow tiles or steel tunnels are installed on top of the floor, extending to the furnace outline and laid to form continuous air channels (parallel with the short axis of the furnace, whenever possible), and are open at both ends for air movement; or (b) when the protection provided in Item (a) will not prevent the surface temperature of the combustible material from exceeding 194°F (90 °C), the air channels shall be connected to one end of a mechanical ventilation system sized so that the surface temperature of the combustible material will not exceed 194°F (90 °C), and the mechanical ventilation system shall discharge through a stack to the atmosphere.

13.1.2.3 When a furnace or an oven is installed in accordance with Clause 13.1.2.2, electrical wiring shall not be located between the combustible material and the bottom of the furnace or oven.

13.1.3 Accessibility and mounting of controls 13.1.3.1 Provision shall be made for the rigid attachment of control devices. Combustion safeguard mounts shall be arranged so that the electrode or other flame-detecting element is correctly positioned. Valves and control panels shall be located so that all necessary observations and adjustments can be readily made.

13.1.3.2 Mountings for auxiliary equipment shall provide for mounting of control instruments and safety devices to protect against damage by heat, vibration, and mechanical equipment.

13.1.4 Explosion relief Δ

13.1.4.1 Furnaces or ovens that can contain flammable liquids or gases shall be equipped with unobstructed relief vents for freely relieving internal explosion pressures.

13.1.4.2 When required, means for freely relieving internal explosion pressures shall be (a) provided in the ratio of 1.0 ft2 (0.0929 m2) of relief area to every 15.0 ft3 (0.4248 m3) of internal volume; (b) so arranged that, when open, the full vent opening shall be an effective relief area; (c) so located that, in the performance of their designed function, no potential hazard shall exist with regard to persons, fuel lines, controls, or firing equipment; (d) such that the firing equipment, controls, or fuel lines shall not be a part of nor attached to them; (e) so designed that, in the performance of their designed function, they shall remain attached to the fuel-fired equipment; and (f) reasonably distributed throughout the entire appliance length to allow uniform pressure relief.

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13.1.5 Auxiliary fans and dampers 13.1.5.1 When a fan is essential to the operation of a furnace, oven, or related equipment, an airflow proving device of the differential type, or an approved equivalent, shall be provided and shall be interlocked to prevent the flow of fuel to the burners on failure of this air supply.

13.1.5.2 When adjustable or motorized dampers are used in conjunction with the auxiliary fan specified in Clause 13.1.5.1, they shall be cut away or equipped with mechanical stops or limit switches interlocked into the safety circuit to ensure that they are incapable of being moved to a position that might contribute to or result in an unsafe condition.

13.2 Gas safety devices 13.2.1 General A manual-reset feature shall be provided on each safety device to prevent unintentional recycling of the safety system.

13.2.2 Combustion safeguards Each burner flame shall be supervised by an approved combustion safeguard that has a nominal flame failure response time of 4 s or less and is interlocked with the safety circuitry, except as follows: (a) A radiant-tube burner shall be supervised in accordance with Clause 13.7.4. (b) The flame supervision may be switched out of the combustion safety circuitry for a furnace zone when that zone temperature is at or above 1400°F (760 °C). When the zone temperature drops below 1400°F (760 °C), the burner shall be interlocked to allow its operation only if flame supervision has been re-established. A 1400°F (760 °C) bypass controller shall be used for this purpose. (c) Burners without flame supervision shall be permitted, provided that the burners are interlocked to prevent their operation when the zone temperature is less than 1400°F (760 °C). A 1400°F (760 °C) bypass controller shall be used for this purpose. The furnace shall be supervised until the furnace temperature is above 1400°F (760 °C). For guidance on valve train configurations, see Annex B. (d) Subject to the approval of the authority having jurisdiction, when combustion safeguards for each burner are too numerous to be practicable, multiple burners may use continuous line-burner-type pilots for groups of atmospheric multi-port burners, provided that an approved combustion safeguard is located at the far end of each line-burner-type pilot, away from the pilot fuel source, with the sensing element positioned at the junction of the pilot and last main burner flames. The pilot safety shut-off valve shall be initially opened by a manual momentary push button. (e) When two premix burners that will reliably ignite one from the other are used, a single approved combustion safeguard supervising one of the burners may be used. The supervised burner shall burn continuously at a firing rate sufficient to reliably ignite the unsupervised burner at all times. (f) Burners for direct-fired heating systems that supply a furnace at a total fuel rate not exceeding 400 000 Btuh (120 kW) may be equipped with thermocouple-type combustion safeguards or safety pilots. For small equipment under constant attendance, combustion safeguards may be omitted subject to the approval of the authority having jurisdiction. Δ

13.2.3 Temperature bypass controllers and their temperature-sensing elements 13.2.3.1 Failure of the temperature-sensing element shall cause the same response as an operating temperature less than 1400°F (760 °C).

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13.2.3.2 The 1400°F (760 °C) bypass controller set point shall not be set below 1400°F (760 °C), and the set point shall be displayed clearly or marked in units of temperature (°F or °C).

13.2.3.3 The operating temperature controller and its temperature-sensing element shall not be used as the 1400°F (760 °C) bypass controller.

13.3 Ignition systems Burners shall be ignited by a manual torch, by a continuous, intermittent, or interrupted pilot burner, or by direct electrical means.

13.4 High temperature limit control 13.4.1 A high temperature limit controller shall be used on any appliance where it is possible for the controlled temperature to exceed a safe limit.

13.4.2 A high temperature limit controller shall be interlocked with the safety circuitry to cut off the source of heat when safe temperature is exceeded and shall require operator attention before start-up of the furnace or oven, or affected furnace or oven zone.

13.4.3 The operating temperature controller and its sensing element shall not be used as the high temperature limit controller.

13.5 Purge cycle Except as permitted by Clause 13.7.1, when flammable vapours from a process can accumulate during a shutdown period in a direct-fired furnace or oven, a timed pre-ignition purge cycle of the furnace or oven volume shall be provided in accordance with the furnace or oven manufacturer’s recommendations.

13.6 Gas/air mixers 13.6.1 Gas/air mixture piping 13.6.1.1 In the design, fabrication, and use of mixture piping, special attention shall be given to the fact that the mixture is in the flammable range.

13.6.1.2 Piping shall be sized to prevent excessive pressure losses (and attendant capacity reduction) and to provide essentially uniform mixture pressures at multiple nozzles.

13.6.1.3 The total length of mixture piping shall be as short as practicable within the limits of established good practice.

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13.6.1.4 Devices that can result in pressure loss or can adversely affect the flow velocity pattern shall not be installed in the mixture piping. Fixed balancing orifices shall be installed in mixture piping only under the direction of the manufacturer.

13.6.1.5 Flow control valves shall not be used in gas/air mixture piping except as provided in Clause 5.4.1.

13.6.2 Mixer adjustments If any field-adjustable device (e.g., gas orifice, air orifice, air shutter, etc.) is built into the mixer, an appropriate locking device shall be provided to prevent unintentional changes in the setting.

13.6.3 Mixing blowers 13.6.3.1 Mixing blowers shall not be used to function as gas-mixing machines.

13.6.3.2 Gas/air piping and gas/air control adjustments for mixing blowers shall comply with Clauses 13.6.1 and 13.6.2, respectively.

13.6.3.3 Mixing blowers shall be equipped with a permanent but adjustable inlet air limit stop to ensure that a minimum mixture pressure can be field-established to suit the requirements of the burners, the manifold, and the combustion environment.

13.6.4 Mechanical gas/air mixers 13.6.4.1 A mechanical gas/air mixer supplying a mixture above the upper explosive limit (UEL) shall be installed (a) with a stop, or other means, that will prevent adjustment of the mixer within or near the explosive range; and (b) such that, when the mixer is located in a small detached building or cut-off room, the building or room shall be provided with explosion vents that are sized in the ratio of 1 ft2 (0.0929 m2) of vent area to every 20 ft3 (0.5663 m3) of room volume, unless otherwise sized in applicable provincial or territorial legislation.

13.6.4.2 A mechanical gas/air mixer supplying a mixture within the explosive range shall be installed (a) such that, when the mixer is located in a small detached building or cut-off room, the building or room shall be provided with explosion vents that are sized in the ratio of 1 ft2 (0.0929 m2) of vent area to every 20 ft3 (0.5663 m3) of room volume, unless otherwise sized in applicable provincial or territorial legislation; and (b) with an approved safety blowout device provided near the outlet of the mixer when the size of the mixture piping exceeds NPS 2-1/2.

13.6.4.3 Controls for a mechanical gas/air mixer shall include interlocks and safety shut-off valves in the gas supply connection arranged to automatically shut off the gas supply in the event of air or gas supply failure, or both.

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13.6.4.4 When a mechanical gas/air mixer is installed in a small detached building or cut-off room, the electrical equipment and wiring shall be installed either in accordance with the requirements for Class I, Division 2, hazardous locations of the provincial or territorial electrical code recognized by the authority having jurisdiction or, in the absence of such a code, in accordance with the Canadian Electrical Code, Part I.

13.6.5 Automatic fire-checks 13.6.5.1 An automatic fire-check shall be installed as close as practicable to the inlet of a burner supplied with a flammable mixture from a mechanical gas/air mixer, except that a single automatic fire-check may be used for a group of closely spaced burners with the permission of the authority having jurisdiction.

13.6.5.2 An automatic fire-check shall be located immediately downstream of the burner manual shut-off valve.

13.7 Radiant-tube heating systems 13.7.1 Pre-ignition purging of a radiant tube shall not be required.

13.7.2 A suitable collecting and venting system for radiant tubes shall be provided. The system shall be of sufficient capacity to render the total unburned capacity of the radiant tubes noncombustible.

13.7.3 A radiant-tube-fired burner system shall be equipped with at least one safety shut-off valve of the manual-reset type.

13.7.4 Flame supervision of a radiant-tube burner shall not be required, provided that (a) a supervisory valve system is used; (b) initial ignition is by manual or automatic means; and (c) subsequent ignition during the heating cycle is by an auxiliary pilot, a continuous self-piloted burner, or an approved direct spark ignition system.

13.8 Atmosphere generators 13.8.1 Exothermic generators 13.8.1.1 A gas pressure regulator meeting the requirements of Clause 5.2 shall be provided.

13.8.1.2 A low gas pressure safety device shall be provided that shall cause the safety shut-off valve to close and that shall shut off the air supply or mechanical mixer in the event of low fuel gas pressure. The switch shall be installed as close as practicable to the outlet of the regulator to shut off the gas to the burners if the pressure drops below 50% of the design operating pressure at the point of sensing.

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13.8.1.3 A manual-reset safety shut-off valve shall be provided that closes in the case of low fuel gas pressure, high fuel gas pressure, loss of air supply, power failure, or flame failure.

13.8.1.4 A manual shut-off valve shall be provided on the downstream side of the safety shut-off valve.

13.8.1.5 A high gas pressure safety device shall be provided when the design outlet pressure of the gas pressure regulator exceeds 0.5 psig (3.5 kPa). This device shall close the safety shut-off valve and shall shut off the air supply or mechanical mixer in the event of high fuel pressure. The switch shall be installed downstream of the safety shut-off valve to shut off the gas to the burners if the pressure exceeds the design operating pressure at the point of sensing by more than 25%.

13.8.1.6 The diaphragm vent opening need not be piped to the outdoors when a zero governor is used with a gas/air proportional mixer.

13.8.1.7 A low air pressure switch shall be provided in the air-supply piping coming from an air blower or compressed air line. This device shall close the safety shut-off valve and shall shut off the air supply in the event of low air pressure.

13.8.1.8 A combustion safeguard that has a flame failure response time not exceeding 4 s shall be provided to supervise the main burners. It shall close the safety shut-off valve and shall shut off the air supply or mechanical mixer when a flame failure occurs. Δ

13.8.1.9 Main burner ignition shall be provided by a supervised interrupted gas pilot unless otherwise approved.

13.8.1.10 The trial-for-ignition period of pilots of main burners shall not exceed 10 s. Δ

13.8.1.11 The use of a supervisory valve system in lieu of the combustion safeguard specified in Clause 13.8.1.8 shall be approved.

13.8.1.12 An automatic fire-check shall be provided in the gas/air mixture line as close as practicable to the generator burner inlet whenever a mechanical gas/air mixer is used. Actuation of the fire-check shall close the safety shut-off valve in the gas supply line and shall stop the mechanical mixer.

13.8.1.13 Provision shall be made to safely dispose of unwanted atmosphere gas at the point of discharge from the generator. Depending upon the specific local circumstances and the analysis of the atmosphere gas, this shall be accomplished by (a) providing a vent line, properly controlled by valves, to permit venting of the unwanted atmosphere gas to a safe place outside the building; or (b) arranging a suitable method of completely burning the atmosphere gas and properly disposing of combustion products.

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13.8.2 Endothermic generators Δ

13.8.2.1 The requirements of Clauses 13.8.2.2 to 13.8.2.13 shall apply only to the fuel gas supply to the burners of the endothermic generator.

13.8.2.2 A gas pressure regulator meeting the requirements of Clause 5.2 shall be provided.

13.8.2.3 A low gas pressure safety device shall be provided that shall cause the safety shut-off valve to close and shall shut off the air supply or mechanical mixer in the case of low fuel gas pressure. The switch shall be installed as close as practicable to the outlet of the regulator to shut off the gas to the burners if the pressure drops below 50% of the design operating pressure at the point of sensing.

13.8.2.4 A manual-reset safety shut-off valve shall be provided that shall close in the event of flame failure when a combustion safety control is provided, and in the event of low fuel gas pressure, high fuel gas pressure, loss of air supply, or power failure.

13.8.2.5 A manual shut-off valve shall be provided on the downstream side of the safety shut-off valve.

13.8.2.6 A high gas pressure safety device shall be provided when the design outlet pressure of the gas pressure regulator exceeds 0.5 psig (3.5 kPa). The switch shall cause the safety shut-off valve to close and shall shut off the air supply or mechanical mixer in the event of high fuel pressure. The switch shall be installed downstream of the safety shut-off valve to shut off the gas to the burners if the pressure exceeds the design operating pressure at the point of sensing by more than 25%.

13.8.2.7 The diaphragm vent opening need not be piped to the outdoors when a zero governor is used with a gas/air proportional mixer.

13.8.2.8 A low air pressure switch shall be provided in the air-supply piping coming from an air blower or compressed air line. The switch shall cause the safety shut-off valve to close and shut off the air supply in the event of low air pressure. Δ

13.8.2.9 An approved supervisory valve system or a combustion safeguard shall be provided.

Δ

13.8.2.10 When a supervisory valve system is used in accordance with Clause 13.8.2.9, a reliable means of main burner ignition shall be provided.

13.8.2.11 When a combustion safety control is used in accordance with Clause 13.8.2.9, a supervised interrupted gas pilot for main burner ignition shall be provided, and the trial-for-ignition period of the pilot or main burner shall not exceed 10 s.

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13.8.2.12 A high temperature limit control shall be provided that shall shut off the supply of fuel gas and reaction gas to the generator in the event that the temperature within the generator exceeds the maximum operating temperature specified by the generator manufacturer.

13.8.2.13 An automatic fire-check shall be provided in the gas/air mixture line, as close as practicable to the generator burner inlet, whenever a mechanical gas/air mixer is used. Actuation of the fire-check shall close the safety shut-off valve in the gas supply line and shall stop the mechanical mixer. Δ

13.8.2.14 When gas is used as the reaction gas, the requirements of Clauses 13.8.2.15 to 13.8.2.24 shall apply to the reaction gas supply to the generator. When gases other than “gas” as defined in this Code (see Clause 1.7) are used as the reaction gas supply, approved protective equipment shall be provided.

13.8.2.15 When required, a gas pressure regulator shall meet the requirements of Clause 5.2.

13.8.2.16 A low gas pressure safety device shall be provided that causes the reaction gas safety shut-off valve to close and that shuts off the reaction air supply in the case of low reaction gas pressure at the mixer. The switch shall be installed as close as practicable to the inlet of the safety shut-off valve to shut off the reaction gas if the reaction gas pressure drops below 50% of the design operating pressure at the point of sensing.

13.8.2.17 A manual-reset safety shut-off valve shall be provided in the reaction gas supply piping. The manual-reset safety shut-off valve shall close in the event of low reaction gas pressure, high reaction gas pressure, loss of reaction air supply, low generator temperature, high generator temperature, or power failure.

13.8.2.18 A manual shut-off valve shall be provided on the downstream side of the safety shut-off valve.

13.8.2.19 A high gas pressure safety device shall be provided that causes the reaction gas safety shut-off valve to close and that shuts off the reaction air supply in the event of high reaction gas pressure at the mixer. The switch shall be installed downstream of the safety shut-off valve to shut off the reaction gas if the reaction gas pressure exceeds the design operating pressure at the point of sensing by more than 25%.

13.8.2.20 A low air pressure switch shall be provided in the reaction air supply piping coming from an air blower or compressed air line. This device shall close the safety shut-off valve and shall shut off the reaction air supply in the event of low reaction gas pressure.

13.8.2.21 A device shall be provided to shut off the reaction air supply in the event of low or high reaction gas pressure at the mixer or in the event of a power failure.

13.8.2.22 A low generator temperature limit control shall be provided to prevent the flow of reaction air and reaction gas to the generator when the generator temperature is less than the minimum operating temperature specified by the generator manufacturer.

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13.8.2.23 An automatic fire-check shall be provided in the reaction gas/air mixture line, as close as practicable to the generator inlet, whenever a mechanical reaction gas/air mixer is used. Actuation of the fire-check shall close the reaction gas safety shut-off valve in the reaction gas supply line and shall stop the mechanical mixer.

13.8.2.24 Provision shall be made to safely dispose of unwanted atmosphere gas at the point of discharge from the generator. Depending upon the specific local circumstances and the analysis of the atmosphere gas, this shall be accomplished by one of the following means: (a) a vent line shall be provided, properly controlled by valves, to permit venting of the unwanted atmosphere gas to a safe place outside the building; or (b) a suitable method of burning the atmosphere gas and disposing of the combustion products shall be arranged.

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Annex A (informative) Recommended procedure for initial start-up of high input equipment [over 400 000 Btuh (120 kW)] Note: This Annex is not a mandatory part of this Code but is written in mandatory language to accommodate its adoption by anyone wishing to do so.

A.1 General This procedure has been developed to help ensure safe start-up of high input gas-fired equipment. Because of a large variation in the types of equipment and controls, some of the procedures as set out are not applicable to certain burners. On some equipment, other safety checks are required that may not be mentioned in this procedure. The commercial and industrial installer responsible for the installation shall be present during the initial start-up. This person will be required to demonstrate that the installation meets all relevant codes, including the testing of piping and the checking of safety controls and electrical connections, safety interlocks, and relief valve ratings. The installer shall ensure that all persons not directly involved in the start-up be cleared from the room in which the equipment is located before start-up is attempted. A dry run shall be carried out with all manual gas valves closed to determine that all controls are in a safe operating condition before gas is supplied to the burner or pilot. It is suggested that the dry run checks will take a minimum of four control cycles to perform. The dry run checks can be carried out as follows:

A.2 First cycle For the first cycle, perform the following checks: (a) Determine the movement or position of the air dampers during prepurge to ensure that the airflow is not less than 60% of that required for the maximum input to the unit during this period. (b) Check the volume of prepurge air to determine its conformance with Code standards (at least four air changes of the combustion chamber and flue passages). (c) At the end of the prepurge cycle, check the modulating gas valve and air damper to determine that they have returned to the low-fire position.

A.3 Second cycle During prepurge, simulate failure of the airflow or forced-fan operation and ensure that ignition spark does not occur. Failure may be simulated by failing a motor, closing a damper, removing a belt, removing a tubing connection from an air-proving device, or by other acceptable means.

A.4 Third cycle Connect a meter to measure the scanner or detector signal. Check this reading during the ignition period to ensure that it reads zero. If there is a reading, the scanner or detector is sensing a false signal due to spark, etc. Note: The meter should be connected according to the applicable specifications for the type and make of controls.

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A.5 Fourth cycle Subject the scanner or detector to a simulated flame and check that (a) the pilot proved (determined by Item (b)); (b) the main gas valve opens; (c) the pilot is interrupted (ignition spark ceases); (d) the trial for main flame is proven (the time between the opening of the main gas valve and the interruption of the spark); (e) the loss of flame signal is proven when the simulated flame is removed (and the main gas valve closes); and (f) the manual reset valve, when used in conjunction with a firing valve that incorporates an end switch interlock, cannot be opened with the firing valve in an open position (carried out by subjecting the scanner or detector to a simulated flame). The above procedure shall be carried out separately for each burner on a multi-burner unit.

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Annex B (informative) Valve diagrams Notes: (1) This informative Annex has been written in mandatory language to facilitate adoption where users of this Code or regulatory authorities wish to adopt it formally as additional requirements to this Code. (2) Where differences exist between the material found in this Annex and in the Code, the Code takes precedence.

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FUEL GAS 1.7

INPUT FLOW CONTROL VALVE 5.4

APPLIANCE MANUAL SHUT-OFF VALVE 1.1, CSA B149.1 6.18.2, 3. Definitions “Manual shut-off valve”

INPUT FLOW CONTROL VALVE WITH MECHANICAL STOP AND LOW FIRE START SWITCH 3. Definitions “Low Fire Start”, 5.4, 9.3

FUEL FILTER fuel gas filter or strainer 6.4, 7.1.7, E 1.5, G.1(2)

OPTIONAL MINIMUM FLOW BYPASS PRESSURE REGULATOR FOR LOW FIRE START 9.3

PRESSURE REGULATOR 3. Definitions “Pressure regulator”, main train: 5.2, 7.6, 13.8.1.1, 13.8.2.2, 13.8.2.15 pilot train: 4.3

HIGH GAS PRESSURE SAFETY DEVICE 3. Definitions “High gas pressure safety device”, 9.5.1, 13.8.1.5, 13.8.2.6, 13.8.2.19

OVERPRESSURE PROTECTION DEVICE 3. Definitions “Overpressure protection device”, main train: 5.7, pilot train: 4.4

MANUAL SHUT-OFF VALVE 3. Definitions “Manual shut-off valve”, main train: 5.1, 13.8.1.4, 13.8.2.5, 13.8.2.18 pilot train: 4.2

LOW GAS PRESSURE SAFETY DEVICE 3. Definitions “Low gas pressure safety device”, 9.5.2, 9.5.3, 9.5.4, 13.1.1.2, 13.8.1.2, 13.8.2.3, 13.8.2.16

TEST FIRING VALVE 3. Definitions “Test firing valve” main train: 5.5 pilot train: 4.6

THERMOCOUPLE-TYPE COMBUSTION SAFEGUARD SHUT-OFF VALVE CERTIFIED TO CAN1-6.4 main train 5.3.1, 5.3.4 pilot train 4.5.3

TEST FIRING VALVE WITH CLOSED POSITION END SWITCH 3. Definitions “Test firing valve” 5.5.5

DUAL COMBINATION CONTROL PRESSURE REGULATOR AND SHUT-OFF VALVE CERTIFIED TO CSA 6.20 main train 5.3.1, 5.3.4, 9.5.2b, 9.5.4 pilot train 4.5.3

BURNER 3. Definitions “Burner” 5.6

DUAL COMBINATION CONTROL SHUT-OFF VALVE AND INPUT FLOW CONTROL VALVE CERTIFIED TO CSA 6.20 main train 5.3.1, 5.3.4 pilot train 4.5.3

PRESSURE TEST POINT 7.3

TRIPLE COMBINATION CONTROLPRESSURE REGULATOR SHUT-OFF VALVE AND INPUT FLOW CONTROL VALVE CERTIFIED TO CSA 6.20 main train 5.3.1, 5.3.4, 9.5.2b, 9.5.4 pilot train 4.5.3

PILOT GAS 4.1

SAFETY SHUT-OFF VALVE CERTIFIED TO ANSI Z21.21/CSA 6.5 3 Definitions “Safety Shut-off Valve” main train: 5.3 pilot train: 4.5

PILOT BURNER 3. Definitions “Pilot” 4.7

SAFETY SHUT-OFF VALVE CERTIFIED TO ANSI Z21.21/CSA 6.5 AND MARKED C/I, or TO CGA 3.9 3 Definitions “Marked C/I” main train 5.3.1, 5.3.2, 5.3.4 pilot train 4.5.3, 4.5., 4.5.5

PIPING 4.1.2, 4.1.3, 6.1, 7.1.1, 7.1.4, 7.2, 13.6.1, 13.6.2

SAFETY SHUT-OFF VALVE WITH PROOF OF CLOSURE SWITCH CERTIFIED TO ANSI Z21.21/CSA 6.5 AND MARKED C/I, or TO CGA 3.9 3. Definitions “Proof of closure switch” main train 5.3.3, 5.3.5, 5.3.6, 5.3.7, 5.3.8, 5.3.9, 5.3.10; pilot train 4.5.5 SAFETY VENT VALVE CERTIFIED TO ANSI Z21.21/CSA 6.5 5.3.12(b), 5.3.13, 7.6

VENT LINES 4.3.7, 4.3.8, 5.3.12, 5.3.13, Table 5.1, 7.1.6, 7.6, 13.8.1.13, 13.8.2.24

VALVE PROVING SYSTEM 3. Definitions “Valve Proving System (VPS)” 4.5.1, 4.5.7, 5.3.1, 5.3.11, 5.3.12, 5.3.15, ANNEX F

Figure B.1 Symbol legend with CSA B149.3 references

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EQUAL TO OR LESS THAN 20 000 Btuh CSA B149.3 4.2, 4.3, 4.4, 4.5.3

OR

GREATER THAN 20 000 Btuh UP TO AND INCLUDING 400 000 Btuh CSA B149.3 4.2, 4.3, 4.4, 4.5.4, 4.6.1

OR

GREATER THAN 400 000 Btuh UP TO AND INCLUDING 3 500 000 Btuh CSA B149.3 4.2, 4.3, 4.4, 4.5.5

OR

Note: A pilot train with an input greater than 3 500 000 Btuh shall meet the requirements of a main fuel valve train (CSA B149.3 4.5.6).

Figure B.2 Pilot trains

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UP TO AND INCLUDING 200 000 Btuh and fuel inlet pressure not in excess of 0.5 psig — CSA B149.3 5.1, 5.2, 5.3.1(a), 5.3.4(c), 5.5, 5.7

OR

OR

OR

Note: These are examples of different configurations of combination controls.

UP TO AND INCLUDING 200 000 Btuh — CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.4(a), 5.3.4(b), 5.4, 5.5, 5.7

OR

UP TO AND INCLUDING 5 000 000 Btuh — CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.5, 5.4, 5.5, 5.7

OR

Note: ZSC and STP on IFCV only required in excess of 1 000 000 Btuh. Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.3 Single burner, flame safeguard, and input flow control valve (Continued)

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IN EXCESS OF 5 000 000 Btuh AND LESS THAN 12 500 000 Btuh — CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.6, 5.4, 5.5, 5.7

12 500 000 Btuh OR GREATER — CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.7, 5.3.12, 5.4, 5.5, 5.7

OR

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.3 (Concluded)

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UP TO AND INCLUDING 5 000 000 Btuh PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.8, 5.4, 5.5, 5.7

OR

Note: ZSC and STP on IFCV only required in excess of 1 000 000 Btuh.

IN EXCESS OF 5 000 000 Btuh AND LESS THAN 12 500 000 Btuh PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.9, 5.4, 5.5, 5.7

OR

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.4(a) Multi-burner, common flame safeguard, common input flow control valve

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12 500 000 Btuh OR GREATER PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7 with double block & bleed CSA B149.3 5.3.12(b)

OR

12 500 000 Btuh OR GREATER PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7 with approved valve proving system CSA B149.3 5.3.12(a)

OR

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.4(b) Multi-burner, common flame safeguard, common input flow control valve

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UP TO AND INCLUDING 5 000 000 Btuh PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.8, 5.4, 5.5, 5.7

OR

Note: ZSC and STP on IFCV only required in excess of 1 000 000 Btuh.

IN EXCESS OF 5 000 000 Btuh AND LESS THAN 12 500 000 Btuh PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.9, 5.4, 5.5, 5.7

OR

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.5(a) Multi-burner, common flame safeguard, individual input flow control valve

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12 500 000 Btuh OR GREATER PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7 with double block & bleed CSA B149.3 5.3.12(b)

OR

12 500 000 Btuh OR GREATER PER APPLIANCE CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7 with approved valve proving system CSA B149.3 5.3.12(a)

OR

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.5(b) Multi-burner, common flame safeguard, individual input flow control valve

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IN EXCESS OF 400 000 Btuh UP TO AND INCLUDING 5 000 000 Btuh PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.5, 5.3.11, 5.4, 5.5, 5.7

OR

Note: ZSC and STP on IFCV only required in excess of 1 000 000 Btuh.

IN EXCESS OF 5 000 000 Btuh AND LESS THAN 12 500 000 Btuh PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.6, 5.3.11, 5.4, 5.5, 5.7

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.6(a) Multi-burner, individual flame safeguard, common input flow control valve

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12 500 000 Btuh OR GREATER PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.7, 5.3.11, 5.4, 5.5, 5.7 with double block & bleed CSA B149.3 5.3.12(b)

12 500 000 Btuh OR GREATER PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.7, 5.3.11, 5.4, 5.5, 5.7 with approved valve proving system CSA B149.3 5.3.12(a)

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.6(b) Multi-burner, individual flame safeguard, common input flow control valve

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IN EXCESS 0F 400 000 Btuh UP TO AND INCLUDING 5 000 000 Btuh PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.5, 5.3.11, 5.4, 5.5, 5.7

OR

Note: ZSC and STP on IFCV only required in excess of 1 000 000 Btuh.

IN EXCESS OF 5 000 000 Btuh UP TO AND INCLUDING 12 500 000 Btuh PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.6, 5.3.11, 5.4, 5.5, 5.7

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.7(a) Multi-burner, individual flame safeguard, individual input flow control valve

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12 500 000 Btuh OR GREATER PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.7, 5.3.11, 5.4, 5.5, 5.7 with double block & bleed CSA 149.3 5.3.12(b)

12 500 000 Btuh OR GREATER PER BURNER CSA B149.3 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.7, 5.3.11, 5.4, 5.5, 5.7 with approved valve proving system CSA 149.3 5.3.12(a)

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures.

Figure B.7(b) Multi-burner, individual flame safeguard, individual input flow control valve

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Notes on alternative PSHH mounting configurations [Figures B.8(a) to B.8(d)]: Note A: Configuration acceptable for use in all applications. Note B: Configuration required when the safety shut-off valve or valves pressure drop is higher than 75% of the PSHH setting minus the droop of the PRV. See also Clause 9.5.1, Note 1. Note C: PSHH may only be located downstream of the IFCV on an appliance that utilizes full metering combustion control. The PSHH may be bypassed until the safety shut-off valve(s) are opened on the start of the first burner. Note D: Configuration acceptable when the upstream safety shut-off valve pressure drop is lower than 75% of the PSHH setting minus the droop of the PRV.

B8.1 Single burner, flame safeguard and input flow control valve, input up to and including 5 000 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.5, 5.4, 5.5, 5.7, 9.5.1, 9.5.2

*Note: ZSC and STP on IFCV only required for inputs equal to or larger than 1 000 000 Btuh

B8.2 Single burner, flame safeguard and input flow control valve, input greater than 5 000 000 Btuh and up to 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.6, 5.4, 5.5, 5.7, 9.5.1, 9.5.2

B8.3 Single burner, flame safeguard and input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.7, 5.3.12, 5.4, 5.5, 5.7, 9.5.1, 9.5.2

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures. The above examples show pressures without units as the problems with variable fuel pressures are equally present in systems operating in inches W.C. or psig. They are also present in multi-burner systems.

Figure B.8(a) Examples of fuel train designs with IFCV where safety of PSHH location should be considered

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B8.4 Multi burner, common flame safeguard and common input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7, 9.5.1, 9.5.2, with double block and bleed 5.3.12(b)

B8.5 Multi burner, common flame safeguard and common input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7, 9.5.1, 9.5.2, with approved valve proving system (VPS) 5.3.12(a)

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures. The above examples show pressures without units as the problems with variable fuel pressures are equally present in systems operating in inches W.C. or psig. They are also present in multi-burner systems.

Figure B.8(b) Examples of fuel train designs with IFCV where safety of PSHH location should be considered

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B8.6 Multi burner, common flame safeguard and individual input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7, 9.5.1, 9.5.2, with double block and bleed 5.3.12(b)

B8.7 Multi burner, common flame safeguard and individual input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.10, 5.4, 5.5, 5.7, 9.5.1, 9.5.2, with approved valve proving system (VPS) 5.3.12(a)

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures. The above examples show pressures without units as the problems with variable fuel pressures are equally present in systems operating in inches W.C. or psig. They are also present in multi-burner systems.

Figure B.8(c) Examples of fuel train designs with IFCV where safety of PSHH location should be considered

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B8.8 Multi burner, individual flame safeguard and common input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.11, 5.4, 5.5, 5.7, 9.5.1, 9.5.2, with double block and bleed 5.3.12(b)

B8.9 Multi burner, individual flame safeguard and individual input flow control valve, input equal to or greater than 12 500 000 Btuh — 5.1, 5.2, 5.3.1(b), 5.3.2, 5.3.11, 5.4, 5.5, 5.7, 9.5.1, 9.5.2, with double block and bleed 5.3.12(b)

Note: * PSHH high gas pressure safety device may be installed downstream of the PRV, downstream of the SSVs, or downstream of the IFCV as long as it protects the burner from excessive gas pressures. The above examples show pressures without units as the problems with variable fuel pressures are equally present in systems operating in inches W.C. or psig. They are also present in multi-burner systems.

Figure B.8(d) Examples of fuel train designs with IFCV where safety of PSHH location should be considered

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Annex C (informative) Abbreviations Note: This Annex is not a mandatory part of this Code.

The following abbreviations of words and phrases apply in this Code: BMS

— Burner management system

Btuh

— British thermal unit per hour

°C

— degree Celsius

°F

— degree Fahrenheit

FARC — Fuel/air ratio control ft

— foot

h

— hour

kPa

— kilopascal

kW

— kilowatt

LEL

— lower explosive limit

m

— metre

mA

— milliampere

mm

— millimetre

NPS

— nominal pipe size

psig

— pound per square inch gauge

s

— second

UEL

— upper explosive limit

V

— volt

w.c.

— water column

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Annex D (informative) Guidelines for electronic-type fuel air-ratio control (FARC) systems Note: This Annex is not a mandatory part of this Code. However, it is written in mandatory language to accommodate adoption by the authority having jurisdiction.

Δ

D.1 Definition Electronic-type fuel air ratio control (FARC) — both air and gas fuel-flow are independently controlled by separate, electrically operated devices.

Δ

D.2 Guidelines This Guideline provides a listing of some of the features that should be incorporated with typical electronic-type fuel-air ratio control (FARC) systems. Regardless of whether the provisions specified in this Guideline are satisfied, each application needs to be assessed to determine the suitability of the controller for the application. When a certified FARC system is used, it shall be in compliance with ISO 23552-1. If a non-certified engineered FARC system is used, it shall comply with the following: (a) The entire FARC system shall be evaluated as a complete closed-loop system. (b) Where the FARC system is of a positioning type, (i) it shall have provisions for continuous feedback of all valve/damper/actuator positions to ensure that the command position has been achieved; (ii) the inability of any of the valve/dampers or actuators to achieve the command position shall be detected and it shall prevent the associated valve/damper/actuator from traveling past the corresponding position; (iii) the error tolerance in valve/damper/actuator position shall be within the appliance’s safe operating range at all firing rates. It shall take into account factors that may affect fuel or air mass flows such as gas pressure, voltage fluctuations, or flue blockage. An operating curve shall be declared at the time of commissioning, programmed into the controller, and clearly identified within the operating and maintenance instructions of the appliance; (iv) fuel(s)/combustion air flow cross-limiting shall be incorporated in the control logic to ensure that the error tolerance in Subitem (iii) is not exceeded and that the burner does not operate in unsafe condition; (v) upon detection of a valve/damper/actuator position fault or of another unsafe condition, the system shall revert to a risk-addressed state or cause the flame safeguard system to safely trip the burner; (vi) assured sensing of valve/damper shaft position is required. Preferably this should be achieved through a shaft position sensor attached directly and securely to the shaft. If the sensor is attached to a linkage or an actuator, or is part of the actuator, all in-between connections shall be securely fastened to prevent slippage. Use of fastening methods that could become loose is not allowed; (vii) the valve/damper/actuator assembly shall incorporate an external indication of open/close position. In many applications that use quarter-turn dampers, a permanent method of marking the damper position on the visible end of shaft may be acceptable. In other applications, marking of open/close position and, in some cases, marking of intermediate positions may be required in another accessible location; (viii) valve/damper/actuator purge and ignition (low-fire or light-off) position interlocks shall be incorporated and interlocked with the flame safeguard system; and

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(c)

(d)

(e)

(f)

(g)

(h) (i) (j)

Code for the field approval of fuel-related components on appliances and equipment

(ix) where a variable speed drive is incorporated into the combustion control system and used as the primary air flow control method, secondary feedback from current, fan speed, or flow sensor shall be used. Where the FARC system is of a metering type, (i) it shall have provisions for continuous feedback of fuel(s) and combustion air flow(s) to ensure that the command air-to-fuel ratio is achieved; (ii) where combustion air or fuel(s) pressure or temperature can change, appropriate temperature and pressure compensation shall be used; (iii) where the calorific fuel value (Wobbe Index) can change, appropriate compensation shall be used; (iv) the inability of any of the flows to achieve the command setpoint shall be detected, and it shall prevent the associated flow from changing past the corresponding position; (v) the error tolerance in fuel(s) and combustion air flow readings shall be within the appliance’s safe operating limits at all firing rates. An operating curve shall be declared at the time of commissioning, programmed into the controller, and clearly identified within the operating and maintenance instructions of the appliance; (vi) fuel(s)/combustion air flow cross-limiting shall be incorporated in the control logic to ensure that the error tolerance in Subitem (v) is not exceeded and that the burner does not operate in an unsafe condition; (vii) for flow metering devices, the manufacturer shall declare the frequency of calibration, and this shall be documented within the service instructions; (viii) all connections between actuator and valve/damper shall be securely fastened to prevent slippage. Use of fastening methods that could become loose is not allowed; (ix) the valve/damper/actuator assembly shall incorporate an external indication of open/close position. In many applications that use quarter-turn dampers, a permanent method of marking the damper position on the visible end of shaft may be acceptable. In other applications, marking of open/close position and, in some cases, marking of intermediate positions may be required in another accessible location; and (x) if the air and fuel measurement system is not self-checking, valve/damper/actuator purge and ignition (low-fire or light-off) position interlocks shall be independent of the flow measurements and shall be incorporated and interlocked with the flame safeguard system. The FARC system may be also equipped with a checker device providing a redundant confirmation of valve/damper/actuator positions, fuel(s) or combustion air flow(s), pressures or temperatures, correct air-to-fuel ratio, or other system parameters that are important to safe FARC system operation. In some instances, special maintenance procedures may have to be included in order to test on a regular basis that both the primary sensing element and checker device function and calibration are correct. If a stack O2/CO/CO2 analyzer is used as a trim, the O2/CO/CO2 measurement shall not be used as the primary method of controlling combustion air flow. The O2/CO/CO2 trim control system shall be limited to ±10% correction of the combustion air flow or less as may be required by a specific application. The FARC system shall be interfaced and interlocked with the flame safeguard system to ensure that the required functionality is achieved. This includes an initial internal check to confirm that all components of the system are communicating, and confirmation of purge position, low-fire position, and fail-safe trip in the event that the FARC system detects a fault. The combustion control microprocessor may be independent from the burner management or incorporated into a PLC-based burner management system. Where applicable, the requirements of Clause 9.7 shall apply. If the air-to-fuel flow ratio, or air valve/damper-to-fuel valve position curves that are being stored in the controller, are field changeable, they shall be password protected. The FARC system/BMS shall provide an indication, alarm, or trip (appropriate to application) due to sensor fault, actuator fault, or FARC system fault condition. A shutdown shall be initiated should deviations in readings exceed a safe limit as declared by the burner manufacturer for that particular installation.

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(k) The FARC system shall be protected from RF interference sources such as VHF radios, cell phones, and variable-frequency drives. (l) The FARC system shall be calibrated/commissioned by a qualified technician, recalibrated/ re-commissioned after any component is replaced, and checked/maintained on a regular basis as required to ensure its safe operation and as recommended by the equipment manufacturer.

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Annex E (informative) Guidelines for flare pilot systems Note: This Annex is not a mandatory part of this Code. However, it is written in mandatory language to accommodate adoption by the authority having jurisdiction.

E.1 Background Safety flares are combustion devices used in industrial plants including petroleum refineries, petrochemical plants, natural gas processing plants in the downstream processing industry, as well as upstream oil and gas production facilities including oil wells, gas wells, offshore oil and gas rigs and landfills. Authorities having jurisdiction, including but not limited to environmental and energy regulations, define when a safety flare requires a safety flare pilot to ensure continuity and reliability of ignition and combustion of process gases. Once the need for a safety flare pilot has been established, this Code defines how that safety flare pilot must be installed. If a safety flare loses flame, it is often considered to be a facility emergency and every attempt will be made to relight the safety flare. Shutting down a running facility without a lit safety flare is a facility worst case environmental & safety scenario.

E.2 Safety flares E.2.1 Where the authority having jurisdiction, including but not limited to environmental or energy regulation, require reliable ignition and combustion for the disposal of process gases, the safety flare shall be provided with (a) at least one continuously burning safety flare pilot; or (b) a safety flare automatic ignition device.

E.2.2 The minimum number of safety flare pilots shall reliably ignite the safety flare burner per Clause E.2.5 or shall be in accordance with the following table: Minimum number of safety flare pilots

Safety flare burner outlet diameter (cm)

Safety flare burner outlet diameter (in)

1

Up to 20

Up to 8

2

> 20, up to 61

> 8, up to 24

3

> 61, up to 107

> 24, up to 42

4

> 107

> 42

Note: API 537 is a recognized standard by industry to determine the design, number and size of safety pilots for safety flares.

E.2.3 Each safety flare pilot shall be equipped with at least one dedicated means of ignition, which can be automated or manually initiated by the facility operator. Note: Commonly employed ignition systems include: spark ignition at pilot tip, spark ignition of a portion of the pilot gas/air mixture prior to the pilot tip, compressed-air flame-front generator, inspirating flame-front generator.

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E.2.4 Each safety flare pilot shall be equipped with (a) at least one dedicated means of flame detection, capable of distinguishing between the pilot and process burner flames; or (b) a safety flare automatic ignition device. Note: Commonly employed pilot-flame detection systems include: thermocouples, flame ionization detectors, optical systems (other than video cameras and monitors viewed by operators), and acoustic systems.

E.2.5 The safety flare pilots shall be capable of reliably lighting the safety flare burner and sustaining stable combustion of the pilot gas throughout the full range of process conditions, including severe weather conditions. Note: API 537 is a recognized standard by industry to determine the design, number and size of safety pilots for safety flares.

E.2.6 A safety flare pilot train shall have means to ensure gas is clean and free from liquid or solids such as a strainer, filter, settling chamber, or knockout pot installed in the fuel-supply line.

E.2.7 The fuel supply to safety flare pilots shall be pressure regulated and the safety flare pilot train shall be designed to ensure that the failure of any single component does not result in the interruption of fuel to all safety flare pilots.

E.2.8 The safety flare pilot system shall have critical measurements to allow for rapid diagnostics of safety flare operation, including but not limited to the following alarms: (a) fuel pressure; (b) loss of flame; (c) level of liquids or solids in devices indicated in Clause E.2.6.

E.3 Process flares E.3.1 Process flare pilots shall either meet the requirements of safety flare pilots (Clauses E.2.2 to E.2.8) or shall be ignited with an approved manual ignition procedure.

E.3.2 Capability to positively isolate process gases from a process flare shall be provided at a location where the operator will not be subjected to a radiation intensity of more than 500 Btu/hr/ft2 (1.6 kW/m2).

E.4 Management systems Management systems shall be in place for safety flares and process flares including, but not limited to: (a) written emergency procedures for re-ignition of pilots in the event of loss of flame on one pilot; (b) written emergency procedures for re-ignition of the safety flare or process flares in the event of a total loss of flame on all pilots; (c) written procedures for operator response to alarms generated by the safety flare or process flare system as required by Clause E.2.8. These procedures shall include an event log; (d) periodic operator training on safety flare or process flare operation and emergency procedures. Training record retention period shall be 5 years or in accordance with the authority having jurisdiction.

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Annex F (informative) Guidelines for valve proving systems (VPS) Note: This Annex is not a mandatory part of this Code. However, it is written in mandatory language to accommodate adoption by the authority having jurisdiction.

F.1 Relevant codes and standards Relevant codes and standards are as follows: (a) ANSI Z21.21/CSA 6.5; and (b) BS EN1643 (for general reference only).

F.2 Definitions BMS/FSG system — burner management system, or flame safeguard system. Burner rating — maximum fuel input into a burner expressed in Btuh HHV (Higher Heating Value). Where Btuh = BTU/hr. Detecting device — device for direct or inferential detection of leakage e.g., by measuring flow or pressure. Detection limit — leakage at which VPS gives a signal. Leakage testing time — time in which the VPS monitors a gas valve for leakage. Valve proving system (VPS) — system to check the effective closure of safety shut-off valves by detecting leakage. It may consist of a programming unit, a measuring device, valves and other functional assemblies. VPS operational time — time taken by VPS to perform its entire cycle of operation. VPS programming unit — unit which follows a predetermined sequence of valve proving actions. Minimum detection setting — lowest value for setting specified by the manufacturer at which VPS gives a signal. Minimum Detection Setting < Detection Limit.

F.3 Design concept (a) VPS may be used as an alternative to a double block and bleed system, or where additional protection from safety shut-off valve leakage is required. It is typically used in applications where gas venting is not practicable due to the length or location of vent lines (for example in a high-rise building), or where gas venting may create other safety hazards (such as venting of poisonous fuels). VPS may be also considered as a method aimed at reducing VOC emissions. (b) VPS shall be used (“exercised”) on a regular basis and used only as a method of maintaining relative valve tightness between tests. It shall not be used in lieu of periodic inspections and bubble testing (leak detection). The frequency of these activities shall be based on the type of service and quality of fuel gas, but shall not be more than: once per month for exercising, and once per 12 months for valve inspection and bubble testing. For continuous processes longer in duration than 12 months, which cannot be shut down for valve testing, alternative approved methods may be used. (c) VPS design shall be based on a direct measurement of leakage rates through safety shut-off valves. The system design shall take under consideration the upstream regulated pressure, the physical

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volume between the two valves being tested, the allowable leakage rate, as well as the accuracy of the detecting device. If the volume between the valves is too large, the accuracy of the detecting device too low, or the appliance regulated fuel gas pressure upstream of the VPS is low, the Minimum Detection Setting may not be registered or the VPS Operational time may be unreasonably long. (d) The Detection Limit used in the VPS design, shall be based on safety of the appliance with given amount of leaked fuel gas present, when ignition source is applied. This amount is subject to the appliance design, physical layout and size, and its ability to ventilate to prevent localized fuel accumulation. This is typically dependent on the method of motivating the combustion airflow. Hence, forced draft systems with proven combustion airflow, pre-purge, and post-purge functions shall be considered safer in this respect than natural draft systems, especially during cold startup when stack draft is not fully developed. There are also systems which cannot be air purged due to safety or process reasons. If the system is shut down for periods longer than 24 hrs, the manual block valve at the inlet shall be closed to prevent fuel accumulation inside the appliance. The VPS Detection Limit selection shall be based on industry standard safety limit for flammable gas present in air of 20% of their LEL (Lower Explosive Limit). For natural gas this corresponds to LEL of 5%*20% = 1% by volume, for propane to LEL of 2.2%*20% = 0.44%. (e) There are two types of VPS: Standard VPS and a Leak Detection VPS. The difference between these two types is the maximum allowable Detection Limit. Standard VPS may be used in appliances with proven ventilation or other approved method, which guarantees that a valve leak equal to the Detection Limit does not exceed the 20%LEL inside any part of the appliance. The Leak Detection VPS shall be used on all appliances with uncertain ventilation, or where additional protection from valve leak is required. (f) Standard VPS — Detection Limit shall not exceed fuel flow equivalent to 1760 Btuh HHV (50 dm3/hr of natural gas) or 0.1% of maximum burner or header capacity. Minimum Detection Setting shall be 50% of the Detection Limit. Both detection values can be converted from Btuh to flows based on their respective calorific HHV (for example: natural gas HHV = 1000 Btu/scf; propane HHV = 2500 Btu/scf) (g) Leak Detection VPS — Detection Limits shall be equal to the maximum allowable leakage rates specified in the safety shut-off valve standard ANSI Z21.21/CSA 6.5. Paragraph 2.4.2 of this standard defines these rates as follows: “Leakage of air through an automatic valve in the closed position assumed as a result of normal operation shall not exceed a rate, corrected to standard conditions of 30 inches mercury (101.3 kPa) and 60 deg F (15.5 deg C), of 0.0083 cubic feet per hour (235 cubic centimeters per hour) for automatic valves having a seal-off diameter of 1 inch (25.4 mm) or less, or of 0.0083 cubic feet per hour (235 cubic centimeters per hour) per inch of seal-off diameter for automatic valves having a seal-off diameter greater than 1 inch (25.4 mm)”.

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Valve seal-off diameter [in]

Detection Limit [scfh]

Minimum Detection Setting [scfh]

0.25

0.0083

0.00415

0.5

0.0083

0.00415

1.0

0.0083

0.00415

2.0

0.0166

0.0083

3.0

0.0249

0.01245

4.0

0.0332

0.0166

5.0

0.0415

0.02075

6.0

0.0498

0.0249

7.0

0.0581

0,02905

8.0

0.0664

0.0332

8.0 +

0.0083 * valve seal-off diameter

0.00415 * valve seal-off diameter

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The above nominal leakage rates apply to all fuel gas types, but are valve size and valve design specific. Valve seal-off diameter shall be as per valve manufacturer’s specification and is not equivalent to nominal valve body or pipe size (it is usually smaller). Manufacturer may also specify the maximum acceptable leakage rate at which valve should be replaced, in which case the lower of the two leakage rate values (ANSI Z21.21/CSA 6.5 standard, vs. manufacturer recommendation) shall be used. If both shut-off valves are not identical, their seal-off diameters and resulting Detection Settings may be different.

F.4 Functional requirements VENT SSVB3 VPS Vent valve

VOLUME “V” FUEL INLET TO VPS

FUEL OUTLET FROM VPS SSV1 Upstream shutoff valve

SSV2 Downstream shutoff valve

SSVB1 VPS upstream bypass valve

SSVB2 VPS downstream bypass valve

(a) The design of the VPS system shall be based on a direct measurement of the leakage rates in the volume (pipe, tubing or similar) between the two safety shut-off valves. This measurement shall be derived from the rate of change in pressure in this volume over a period of Leakage Testing Time. Other methods of measurement may be allowed if acceptable to the authority having jurisdiction. This specification is limited to the pressure change measurement method. (b) The following equation derived from the Ideal Gas Law shall be used to calculate Leakage Testing Time:

t=

V dP * * Tc * 3600 L 14.7

where t = Leakage Testing Time in seconds. Leakage testing time shall not be less than 10 seconds V = Total volume of cavity between two safety shut-off valves SSV1 and SSV2 in cu ft Note: Volume calculation to include the inside volume of piping spool piece connecting the valves, plus estimate of cavity volume in each valve’s body on the side of the tested spool piece, plus volumes of any other cavities connected to the tested volume (such as test point threadolet, piping, tubing, transmitter, pressure switch, pressure gauge, vent valve, etc.).

For example: two 6 in valves with 24 in long spool piece V = 0.39 + 2*0.05 + 0.01 = 0.5 cu ft (approximately) L = VPS Detection Limit Standard VPS detection limit shall be converted from Btuh to scfh based on the HHV (Higher Heating Value) of the fuel used. For example: on natural gas 1760 Btuh/1000 Btu/scf = 1.76 scfh; on propane 1760 Btuh/2500 Btu/scf = 0.704 scfh = L

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Leak Detection VPS table values shall be used directly or interpolated. For example: 6 in valve with a 4.5 in seal-off diameter L = 0.0083 * 4.5 = 0.03735 scfh dP = differential pressure change detectable by Detection Device such as a pressure transmitter, pressure switch, etc. dP shall not exceed 50% of or the regulated fuel gas pressure upstream of VPS. For example appliance pressure regulator setpoint = 10 psig; dP = 1 psid for Standard VPS or dP = 0.05 psid (1.38 in W.C.) for Leak Detection VPS 14.7 – conversion to STP (standard pressure = 14.7 psia) Tc – conversion to STP (standard temperature = 60 deg F) Tc =

460 + 60 460 + Tgas

where Tgas – fuel gas temperature, for example Tgas = 60 deg F; Tc = 1 3600 – conversion of Leakage Testing Time from hours to seconds Result in the above examples: For Standard VPS: For natural gas: t = 0.5 * 1 * 1* 3600 = 69.57 [ second] 1.76 14.7 For propane: t =

0.5 1 * * 1* 3600 = 173.93 [ second] 0.704 14.7

For Leak Detection VPS (both natural gas and propane): t =

0.5 0.05 * * 1* 3600 = 163.9 [ second] 0.03735 14.7

VPS system calculation based on the actual as-built valve configuration shall be documented and available for review by the authority having jurisdiction. (c) If the pressure change dP is detected in time shorter that calculated, the valve tested did not pass the test and the VPS shall prevent ignition and the opening of the burner valves. VPS may be wired into a non-recycling BMS/FSG as one of the safety permissives, may have its own valve logic lockout function, or may be part of a PLC based non-recycling BMS. (d) Following logic sequence shall be used (as a minimum) prior to the appliance purge sequence: 1. Ensure that the fuel line downstream of the VPS is open to the combustion chamber and that VPS test will not be affected by “line packing” (pressure increase due to blocked fuel line). 2. Open downstream safety shut-off valve SSV2, then close it. Alternately for systems using a separate VPS downstream bypass valve SSVB2, open it, then close it. For systems, which cannot be discharged into the combustion chamber, open a VPS vent valve SSVB3, then close it. Valve opening and closing time shall be considered in this logic. Pressure in the cavity between valves should be at this point equal to the downstream pressure and if the upstream valve is leaking it will increase after the downstream valve is closed. 3. After the downstream SSV2 (or SSVB2) closes, start the upstream Detection Limit timer set to Leakage Test Time value. 4. If the Detection Limit is not reached within the Leakage Test Time, the upstream valve SSV1 has passed the test and the test program shall continue to the next step. If the Detection Limit is reached or exceeded within the Leakage Time Test the upstream valve SSV1 has failed the test and the ignition and opening of safety shut-off valves shall be prevented through appropriate lockout. Lockout shall be initiated within 1 second after the valve failure is detected. 5. Open upstream safety shut-off valve SSV1 then close it. Alternately for systems using a separate VPS upstream bypass valve SSVB1, open it, then close it. Valve opening and closing time shall be considered in this logic. Pressure in the cavity between valves should be at this point equal to the regulated fuel gas pressure upstream of the VPS. If the downstream valve is leaking it will decrease after the upstream valve (or VPS upstream bypass valve is closed. 6. After upstream SSV1 (or SSVB1) closes, start the downstream Detection Limit timer set to Leakage Test Time value.

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7. If the Detection Limit is not reached within the Leakage Test Time, the downstream valve SSV2 has passed the test and the test program shall continue to the next step. If the Detection Limit is reached or exceeded within the Leakage Time Test the downstream valve SSV2 has failed the test and the ignition and opening of safety shut-off valves shall be prevented through appropriate lockout. Lockout shall be initiated within 1 second after the valve failure is detected. (e) Test program logic may include other elements such as valve open and closed position switches, upstream and downstream pressure monitoring, pressure change trending and alarms, etc. (f) Any gas necessary for the operation of the VPS may be discharged into the combustion chamber during the program sequence if this discharge does not exceed 20% LEL safety limit in the furnace as described above. If this cannot be assured, or if appliance cannot be purged prior to ignition due to safety reasons, or if it includes other safety shut-off valves or manual shut-off valves with closed position switches interlocked with the FSG, the gas shall be vented to atmosphere at a safe location. (g) If the VPS test sequence is interrupted (for example by power failure) it shall fail-safe by closing all valves, and resetting the entire VPS sequence. After system is restarted, VPS shall restart its sequence from the beginning. (h) Valves — VPS may be configured both for pilot or main burner safety shut-off valves using either these valves or external VPS bypass valves if acceptable to the authority having jurisdiction. Integrated or partially integrated VPS valve systems may also be used. Any configuration of safety shut-off valves used by the VPS shall be in compliance with the CSA B149.3 Code. In case gas from the VPS cannot be discharged into the combustion chamber, a separate safety shut-off valve SSVB3 may be necessary. This valve shall be certified to ANSI Z21.21/CSA 6.5 and marked C/I. (i) Measuring device — pressure change shall be measured either by pressure switches or pressure transmitter(s): PSHH – high activated on pressure increase referenced to the upstream pressure for upstream valve test, PSLL – low activated on pressure decrease referenced to the downstream pressure, for downstream valve test, Measuring devices shall be connected to VPS in a fail-safe configuration so that both system and loss of connection are detected. For example: pressure switch shall be wired NC (normally closed), pressure transmitter shall be monitored for lack of signal or lack of response to pressure changes. Accuracy and repeatability of measuring device shall ensure VPS operation below the Minimum Detection Setting. Pressure devices shall be rated for more than 250 000 cycles. (j) VPS programming unit — VPS system shall be controlled either by a certified dedicated VPS controller, or be a part of an approved BMS/FSG System. VPS shall be designed not to override other FSG or ESD (emergency shutdown) functions and shall be protected from unauthorized changes in the programming sequence and its timing. VPS sequence and timing calculation shall be documented. Time (t) and differential pressure change (dP) values (both upstream and downstream) shall be shown on the appliance rating plate.

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Annex G (informative) Requirements for use of oxygen in combustion systems Note: This Annex is not a mandatory part of this Code. However, it is written in mandatory language to accommodate adoption by the authority having jurisdiction.

G.1 Oxygen safety devices 1. Two oxygen safety shut-off valves in series shall be provided in the oxygen supply line. 2. A filter or fine-mesh strainer shall precede the upstream safety shut-off valve. 3. There shall be a high oxygen flow or pressure limit interlocked into the combustion safety control circuitry. The switch shall be located downstream of the final pressure regulator. 4. There shall be a low oxygen flow or pressure limit interlocked into the combustion safety control circuitry. This shall be located upstream of the first safety shut-off valve. 5. The oxygen safety shut-off valves shall shut automatically after interruption of the holding medium by any one of the interlocking safety devices. 6. An approved valve proving systems (VPS) shall be installed. Vent valves should not be permitted on oxygen gas piping systems. 7. Safety shut-off valves shall not be used as modulating control valves. 8. A permanent and ready means for making tightness checks of all oxygen safety shut-off valves shall be provided. 9. Local visual position indication shall be provided for each oxygen safety shut-off valve to burners or pilots in excess of 150 000 Btu/hr (44 kW). This indication shall directly indicate the physical position, closed and open, of the valve. Where lights are used for position indication, the absence of light shall not be used to indicate open or closed position. Indirect indication of valve position, such as by monitoring operator current voltage or pressure, shall not be permitted.

G.2 Materials of construction and cleaning 1. All safety shut-off valves shall be certified to ANSI Z21.21/CSA 6.5, and declared by the manufacturer as suitable for use in oxygen service. 2. All pressure switches, pressure regulators, or other devices shall be declared by the manufacturer as suitable for use in oxygen service. 3. All components in the oxygen piping shall be suitably cleaned for oxygen service and inspected with ultraviolet light or a similar device to ensure no contamination during the assembly process. Note: For guidelines for cleaning of piping and valves, see Compressed Gas Association G-4.1.

4. All piping assemblies shall be pressure tested with nitrogen prior to use. 5. Nitrogen shall be used to purge the line out of service and back in to service. 6. Extreme care should be taken in the design of the piping system to ensure that the velocities of oxygen in the pipe do not exceed those recommended for the materials used in the construction of piping and valves.

G.3 Oxygen-enriched burners 1. Where oxygen is added to a combustion air line, an interlock shall be provided to permit oxygen flow only when airflow is proven continuously. Airflow shall be proven in accordance with the requirements of Clause 9.1. 2. Care should be taken to ensure that the materials of construction of the oxygen enriched air line and burner are suitable for the concentration level of oxygen.

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3. Upon loss of oxygen flow, the flow of fuel shall be permitted to continue where there is no interruption in the flow of combustion air, provided the control system can revert automatically to a safe air-fuel ratio before a hazard due to a fuel-rich flame is created. 4. Burner systems employing water or other liquid coolants shall be equipped with a low coolant flow limit switch located downstream of the burner and interlocked into the combustion safety control circuitry. A time delay shall be permitted that allows the operator to take corrective action, provided an alarm is activated and it can be proved to the authority having jurisdiction that such a delay cannot create a hazard. 5. Coolant piping systems shall be protected from freezing and over pressurization.

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Annex H (informative) Liquid fuels Note: This Annex is not a mandatory part of this Code. However, it is written in mandatory language to accommodate adoption by the authority having jurisdiction.

H.1 Design and construction H.1.1 The design and construction of appliances intended to operate with liquid fuel shall meet or exceed the requirements of the Standard in CSA B140 series of documents appropriate to the type of appliance.

H.1.2 Appliances shall also meet the requirements of the liquid fuel Clauses of section 8 of NFPA 86 or the applicable sections in NFPA 85.

H.2 Installation and operation The installation of an appliance, the method of installing the components of the valve train, and the piping and tubing materials shall be in accordance with the requirements of CSA B139 Series. As a minimum the following documentation shall be provided: 1. Description of any hazardous condition which may affect this appliance or its installation. 2. Process and Instrumentation Diagram (P&ID). 3. Bill of Materials (BOM) or component data sheets showing the model number, manufacturer, construction, materials, ratings and certification of each relevant component and its tag number referenced on the other drawings and on the physical component. 4. Wiring diagram. 5. Burner management system specification. 6. Operating narrative, shutdown key/cause and effect diagram, ladder logic, installation, operation, and maintenance manual or other suitable description of appliance operation. 7. Specification of electrical area classification (in compliance with the authority having jurisdiction), appliance and instrument venting to a safe location, and overpressure protection of the fuel train. 8. Commissioning/combustion report with equipment/permissive set-points and stack readings at maximum fire. 9. For an appliance approved for use with different fuels, a switch-over procedure to be followed by the operator upon switching to another fuel without exceeding the maximum rating of the appliance.

H.3 Functional testing H.3.1 The burner shall be tested at the limits of its pressure envelop in order to verify flame stability without the ignition source present. Where multiple fuels or fuels with a changing composition are used, the burner shall be tested for all fuels and for all expected fuel compositions.

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H.3.2 During initial firing of the oil fired appliance, a combustion analyzer on an annual calibration cycle, shall be used to measure the emissions. The combustion equipment shall produce a smoke number less than 2 and the measured CO shall be less than 400 ppm through all firing rates. The NOx levels shall be checked to ensure they are below the current regulated threshold. All emissions shall be corrected to a 3% O2 basis.

H.3.3 Where there is sulphur in the fuel, the SOx shall be measured and verified to be below the current regulated threshold. The stack temperature shall be at least 122°F (50 °C) above the flue gas dewpoint. With sulphur in the fuel, the acid dewpoint shall be calculated and used instead of the flue gas water dewpoint.

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Annex I (informative) Solid fuels Note: This Annex is not a mandatory part of this Code. However, it is written in mandatory language to accommodate adoption by the authority having jurisdiction.

I.1 Design and construction I.1.1 Solid fuel burning appliances shall be designed in accordance with the CSA B366.1 standard and suitable for installation in accordance with the requirements of the CSA B365.

I.1.2 Solid fuel burning appliances and their accessories shall comply with the applicable sections of NFPA 85.

I.2 Installation and operation The installation of an appliance, the method of installing the components of the control system, and the materials shall be in accordance with the requirements of CSA B365. As a minimum the following documentation shall be provided: 1. Description of any hazardous condition which may affect this appliance or its installation. 2. Process and Instrumentation Diagram (P&ID). 3. Bill of Materials (BOM) or component data sheets showing the model number, manufacturer, construction, materials, ratings and certification of each relevant component and its tag number referenced on the other drawings and on the physical component. 4. Wiring diagram. 5. Burner management system specification. 6. Operating narrative, shutdown key/cause and effect diagram, ladder logic, installation, operation, and maintenance manual or other suitable description of appliance operation. 7. Specification of electrical area classification (in compliance with the authority having jurisdiction), appliance and instrument venting to a safe location, and overpressure protection of the fuel train. 8. Commissioning/combustion report with equipment/permissive set-points and stack readings at maximum fire. 9. For an appliance approved for use with different fuels, a switch-over procedure to be followed by the operator upon switching to another fuel without exceeding the maximum rating of the appliance.

I.3 Functional testing Appliances shall be tested in accordance with the requirements of Clause 10 of the CSA B365.

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