Scuba Regulator Maintenance and Repair [1 ed.] 0967887305

Citation preview

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Vance Harlow's

SCUBA Regulator Maintenance and Repair

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SCUBA Regulator Maintenance and Repair Vance Harlow

AIRSPEED PRESS

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CONTENTS

Page

Introduction Chapter 1

How A Regulator Works

1

Demand Regulators - Am bient Compens::ition - Some Nomenclature - Upsu·eam or Dovvnstream - Diaphragm vs Pi ston - Second Stages - Bal::tncing - Ventu ri Assist avy and CEN Tests - Gim micks -Subtleties

Chapter 2

Getting Started

27

Overview - Warnings - More Nomencl::iture - Overhauls and U nderhauls

Chapter 3

First Stage Overhaul

35

Non-Balanced Pistons - Balanced Pistons - Balanced D iaphragms

Chapter 4

Second Stage Overhaul

51

Downsu-eams - Barrel Poppers - Others

Chapter 5

Tuning The Regulator

65

O ver view - Single Adjustment - Two Adjustment - First Stages - Fine Points

Chapter 6

Procedures and Techniques

81

Pre-Servicing C hecks - Loosening Stuck Parts - Cleaning -Inspection - Lubrication - Tightening T hings Intermediate Pressure - Cold Water Kits - C racking Pressure - Flow Testing -Final Testing - Routine Maintenance

Chapter 7

Servicing Regulator Components

103

Inlet Filters -Snap and Lock Rings - HP and LP Seats Orifice Blocks - B::ilance Cham bers - Purge Asse mblies Exhaust Valves - Safi: Parts - Cold Water Kits - Plastic Hoses - Yoke and Din Connectors - Dust Caps

Chapter 8

0-rings And Other Seals

121

Static or Dynamic? - Care and Handling - Lubrication Material Specifications - Buying 0-rings - Sizing 0-rings - 0 -rings for Oxygen Service - Packing Seals and Gaskets

Chapter 9

Tools

134

Tools - Test Equipmenr - Chemicals

Chapter 10 Diagnosis Diagnosis Charrs - None O f The Above

155

Chapter 11

Valves , Tanks And Gauges

167

Removing Valves - Diagnosis - Overhaul Procedure Burst Disks - Tanks - Visual Inspection - Neck Cracks Hydrotesting and Tumbling - Gauges

Chapter 12 Servicing Regulators In A Non-Shop Environment 187 Obtaining Parts - Service Literature - Other Sources of In formation - Recalls - .Manufacturers Tech Courses

Chapter 13 Regulators By Make

195

Apeks - Dacor - O ceanic - Mares - Poseido n - Scubapro Sherwood - Spiro - Zeagle - Torque Specifications

Appendices

213 1 2 3 4 5

-

Glossary Sources SCUBA Regulator Manufacturers Buying A Regulator N PT to SCUBA Straight Th read Adaptors

Schematics

225 First Stages 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

15

Apeks Atomic Dacor 960 Genesis DAD Modular Dacor (in Chapter 3) Mares MR 22 Oceanic Sport NBP Oceanic BD Poseidon Poseido n Xstream Seaquest Mirage NBP Sherwood Scubapro Mk 5, Oceanic BP and Copies Scubapro Mk 20/25 Scubapro Mk l4/ 16/18

16.

Spiro SEA

11 . 12 . 13. 14.

Second Stages 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Apeks Atomic Mares Ruby/Abyss/Voltrex Oceanic Delta2 Poseidon Jetstream/Odin Scubapro Gl 90 Scubapro S600 , S600T, S5 50 Scubapro G2 50, G200, BA and 109 Sherwood Spiro Basic Downstreams USD/Aqualung Miera/Miera Adj.

Other "K" Non-Reserve Valve & "J" Reserve Valve

DISCLAIMER The information in this book is complete and true to the best of our knowledge. However, all recommendations are made without any guarantee on the part of the author or publisher, who also disclaim any liabili ty incurred in connection with the use of the information in this book.

The names of SCUBA gear manufacturers used in this book such as Seaquest, Scubapro, Dacor, Mares, Aqualung/ US Divers. Oceanic, Poseidon. Apeks, Zeagle, Prosub, Apollo are the property of the copyright holders, as are many of the names of design features and models such as VIVA, Dry Air Bleed, Omega and Cyklon. They are used here for identification purposes only and do not imply the endorsement or approval of those copyright holders. This book is not an official publication of any SCUBA gear manufacturer.

Both auth or and publisher gratefully acknowledge True Kelley's invaluable editorial assistance. We welcome any feedback. Please address any comments, complaints, inquiries and especially corrections to: Airspeed Press 79 Old Denny Hill Rd Warner NH 03278 Email: [email protected] \.vww.airspeedpress.com Any updates and corrections to this book wi ll be posted on our website. Additional copies of this book are available direct from publisher - check our web page for current price and ordering information. Due to the changeable nature of the Internet, it is possible that we may be changing our addresses in the future. Should this happen, doing a net search for "Airspeed Press", ''The Oxygen Hacker's Companion" or the name of this book should find us. ISBN 0-9678873-0-5 Copyright 1999-2002 by Airspeed Press With the exception of brief quotes for the purpose of a review, no portion of this publication may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photcopying, recording or otherwise, without prior written permission from the publisher.

SCUBA REGULATOR MAINTENANCE AND REPAIR

INTRODUCTION This book is intended for the novice professional SCUBA tech who wishes to gain a broader understanding of the field than is usually taught in the regulator manufacturers' sin gle-make tech courses, and for the individual diver who wishes to acquaint him or herself with the servicing of dive gear. The notion of a book on regulator servicing for sale to the general public may be alarming to some, but anyone professionally involved in servicing dive gear knows it really isn't very hard. T hat's not to say it is something to be approached lightly - a SCUBA regulator is prime life support equipment! If your motivation in learning how is to save money, you'll be better off q uitting smoking or switching to a cheaper beer - or hobby. However, if your motive is that you like to fix things, are good at it, and feel safer diving with gear that you have serviced yourself, then you are the sort of person for who m this book is intended. If you wouldn't hesitate to rebuild the brakes - right down to the calipers - on your car, or the carburetor, then you'll find regulators easy. The only reason it is isn't more commonly done is that the dive industry has done a very effective job of restricting consumer access to the parts and technical information necessary to do it right. As someone who feels safer diving, flying and driving gear I have serviced

myself, I have no patience with this. Besides, I've seen enough regulators come back from a "professional" shop overhaul in worse condition than they went in, to believe that a conscientious owner, working cautiously with the knowledge that he (or she) will be trusting his life to the quality of his work, can do at least as good a job as a bored shop tech trying to knock out a few more regulators before quitting time, even though the shop tech may know a hell of a lot more about what he or she is doing. Hopefully, this book will be a step towards opening up the game, the way the OXYGEN HACKER'S COMPANION blew the mixing game wide open, and cut through the selfserving myth and misinformation with which the tech industry was trying to surround it. T his book takes a different approach than most of the manufacturers' tech literature. They can cover one regulator at a time , and can devote as much space as necessary to each one, and tell the tech each move to make. All the tech has to do is follow directions. It doesn't really matter if the tech understands why as long as he follows them. I can't do it that way - there just isn 't enough space or time. So instead, I've tried to give a thorough background on how regulators work, and why things are done the way they are, so the reader will have the understanding and background necessary to v

SCUBA REGULATOR MAINTENANCE AND REPAIR

puzzle o ut an unfamiliar regulator. The reader will also notice some repetition in this book. T hat's intentional. Rather than trying to put everything about h ow to service a regulator in one king-hell narrative, the book uses a parallel structure. The key chapters cover the actual overhaul and repair procedures, but assume the reader knows the basic procedures and tools. If the reader doesn't, there's a parall el chapter that goes into the common procedures in depth, and another that discusses tools in depth, and so on. There's a certain amount of overlap this way, and much info that could just as logically go in any of several places. Rather than risking that the reader who skims and skips through the book might miss any of the more critical points, I repeat them , to pound them in. The Nevil Norway Mystic Mechanic Method O ne of the best things ever written about servicing of critical machinery is in Nevil Norway's novel ROUND THE BEND. Nevil Norway was a very good aircraft engineer, pilot and novelist wh o d id most of his writing in the 40's and SO's under the pseudonym of Nevil Shute. T he book is about an aircraft mechanic in the middle east just after WW2 who inadvertently founds a cult of super-mechanics when he tries to teach the locals to be better mechanics by incorporating their religion into their work. In this scene, he is speaking to his flock while he works on an engine:

" I inspect some of the work you do upon these engines and these aeroplanes," he said. "God the All-Seeing and All-Knowing, He inspects it all. You come to me and say, "I have replaced tl-iis manifold and the job is finished." I come to look at it to see if t11ere is an y fault, and I see everything Vl

in place. I look at the nuts, and I see the locking wires correctly turned the right way to preven t the nuts unscrewing, and that is all I can see. I cannot see if the nuts are on ly finger tight. I can not see if you h ave put a lever on the spanner and strained them up so tight that the bolts are just about to fail in tension. Th ese things are hidden from me, but nothing is hidden from the All-Seeing Eye of God." He paused. "God the All Knowing knows if you have done well or ill." he said quietly. "If you ask Him humbly in prayer to tell you, He will tell you if you have done well or ill; in that way you will h ave a chance to do the job again, and to try to do it better. Or you can come to me and say, Help me to do this work, because I cannot do it right". God is All-Merciful, and He will not h old bad work against you if He sees you strivi ng to do right. So I say this to you ." He paused again. "With each piece of work you do, witl1 every nu t you tighten down, with every filter that you clean or every tappet that you set, pause at each stage and turn to Mecca, and fold your hands, and humb ly ask the All-Seein g God to p ut into your heart the knowledge whetl1er the work that you have done has been good or ill. Then you are to stand for half a minute with your eyes cast down, thinking of God and of the job and God will put into your head th e knowledge of good or ill. So if the work is good you may proceed at peace, and if it is ill you may do it over again, or come to me and I will help you to do it well before God". While that puts it in a religious context, any good tech will recogn ize the process as being that which any really competent

SCUBA REGULATOR MAINTENANCE AND REPAIR

mechanic naturally fo llows, whether by appealing to God or his/her own judgement or subconsciOL1s - that is to say, thinking about each step as it is performed, and actively pausing to ask yourself whether you have truely done it as well as it can be done. If the answer is yes, then you can proceed. If no, then you go back and do it over right. If the answer is " I just don't know" then don't guess - stop right there and seek o ut the information, tools or parts necessary in order to be able to answer "yes" without reservation. Anyone working on their own regulator has a special impetus in this regard - his/her question is not just "Have I done this right?" but rather "Have I just done something that could kill me?"

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What if you don't want to work on your regulator? It's likely that a certain nu mber of you who will read this book will have no interest in actually working on your regulators, but rather, be reading it just to gain a more intimate understanding of how a regulator works, and what the advantages and disadvantages of the different configurations are. Nothing wrong with that. But I'd like to encourage you to go a little further. Without taking a single tool to your regulator, or doing anything that could in any way effect its operation, it is possible, by fo llowi ng some of the simpler procedures in this book, to do a fairly complete check on the tune and performance of your regulator. For example, the post-service checks listed at the end of Chapter 7 can be easily done by anyone with a minimum of tools, and without opening the regulator. They are well worth doing anytime a regulator comes back from servicing, both to confirm that the shop tech didn't forget something, and as a way of getting a handle on how well that shop is doing it's job. We all lrnow stories of friends who headed

A LoJV Tech Cracliing Pressure Test

off for that big dive trip with a freshly shopserviced regulator only to end up doing the dive-of-a-lifetime trying to suck air from some junkbox rental when it turned out the shop back home had screwed up. A few simple checks done before leaving home might avoid all that. The same checks are also useful in the field, when minor problems arise, to determine how serious they are, and whether the regulator needs a full service or just the immediate problem fixed. Two particularly useful tests for the non-

Field Checking The Intermediate Pressure Vll

SCUBA REGULATOR MAINTENANCE AND REPAIR

tech are the IP check and the water test. The former requires an intermediate pressure gauge, which snaps onto the BC inflation hose and can be made for under $10. The latter just a sink, bucket or ocean of water in which to immerse the regulator. But the two of them together can give a very accurate picture of the regulator's internal state of health. A Warning If you are not a certified SCUBA tech, be careful about messing with other people's gear, especially if you are imbued with the enthusiasm of someone who has newly and imperfectly come into knowledge of an arcane subject. It's fun to come to the rescue and save some poor fool's dive, but offering to "try and help" with someone's gear when you do not dearly understand the problem or the cure, is as likely to lose friends as to make them, and maybe in the worst sense possible. We had an incident on a local d ive boat recently that nicely illustrates the point. An instructor who was acting as divemaster noticed that one of the divers was wearing a rented BC equipped with a C02 backup inflator. The instructor, who was not trained as a tech, had no experience with C02 inflators, and knew nothing about them except some tired old dive shop gossip, took it upon himself to tell her that C02 inflators were extremely dangerous and that he wou ld not allow her to dive with one. He then removed the cartridges and told her she could now dive in safety. She (overweighted as novice divers usually are) exited the boat in a giant step, hit the water and plummeted straight to the bottom, a torrent of air bubbles streaming from the unplugged holes where the cartridges had been. She had enough sense to keep pumping air into her BC and managed to regain the V III

surface long enough for someone to help her drop her belt, and made it back to the boat OK but was too shaken to dive anymore that day. If she hadn't made it back up, he would have had a whole lot of explaining to do, and probably in court! That's a pretty dramatic example, but others are not hard to find. So think twice before offering to "take a shot at fixing it" . Bear in mind too, if you find yourself tempted to fiddle with other people's gear, that charging for it can, in the eyes of the law, make you a commercial entity, and greatly increase your li ability should you screw up. This goes doubly if you have any sort of professional dive qualifications; there have been recent suits against divermasters and instructors for not preventing accidents even when they were not along on a dive in a professional capacity! In the above story, the instructor would have bee n in a very bad situation if the diver had been hurt, since h e'd taken it upon himself to use his authority as an instructor to force upon her an unsafe modification, and one he was not qualified to perform. A cynical friend, who tends to carry a large stock of tools and parts, and hence be the one people come to for help, has come up with his own so lution: in addition to always telling people (loudly, so that others on the boat can hear) that he is not a qualified tech, and is only assisting them as a favor, when someone offers to pay him, says, quietly, "No, that's OK If you really want to, you can buy me a six pack after the dive." He figures if they're still alive d1en, it's safe to accept.

SCUBA REGULATOR MAINTENANCE AND REPAIR

Chapter 1 1st Stage

HOWA REGULATOR WORKS Most of us are pretty sure we know how a regulator works, but there are enough variations to make just about anything you can say that is true about one regulator untrue about another, and anyone who is going to presume to service them must be aware of all the different possibilities and ramifications. A compressed gas regulator, and that's what a SCUBA regulator is, is generically a device for automatically lowering the pressure of a compressed gas to a preset level. Automatically is the key word - a simple valve or orifice can lower the pressure, but the output pressure will vary wildly as the input pressure:: changes.

A regulator uses feedback to adjust the pressure automatically so that output will remain more or less constant regardless of input pressure. It does this by sensing the pressure on the output side, and using that pressure to turn a valve on and off as required. The regulators we use for diving need to be able to reduce the pressure from tank pressure - the pressure of the compressed air or mix in the tank, usually around 3000 psi with a full tank, to ambient - the pressure of the water or air surrounding the diver - so the diver can breathe it. Most compressed gas regulators work

.'lir 'la.n!(

pretty much the same way, regardless of their exact application or design. Somewhere inside there's a high pressure feed, a low pressure chamber, and a valve in between them. Then there's a spring loaded, pressureactivated movable barrier exposed to the pressure in the LP chamber, which opens and closes the valve depending on that pressure. The barrier may be a diaphragm - a flexible sheet of strong rubber-like material which is fixed and sealed around the edges but free to flex in the center - or a piston.

The Demand Regulator Just for example, here's a very simple imaginary regulator built using a shop air A Basic Demand Regulator Diaphragm

In from tank

-case

---.._,,.....~-1~

LP Chamber

1

SCUBA REGULATOR MAINTENANCE AND REPAIR

Ambient Compensation

blow gun for a valve mechanism. Normally the valve is closed and no air flows. Start sucking on the o utput hose, and the suction pulls the diaphragm inwards, pushing against the lever and opening the valve. This allows air to flow from the HP chamber to the LP chamber. Stop sucking, and the pressure in the LP chamber quickly builds to the point where there's no longer enough suction to ho ld the valve open, and the valve closes, shutting off the flow of air until you take another breath and the cycle repeats. At it's simplest, that's all a dive regulator is, a single diaphragm-activated valve. As long as the diver is inhaling, the pressure in the LP chamber remains low en ough to keep the valve open . When the diver stops inhaling the air pressure on the diaphragm closes the valve. A regu lator like this is called a "demand regulator", since it gives air on demand that is to say, it stays closed until the pressure in the LP chamber is lowered a certain amount below the ambient pressure (the pressure of the surro unding air or water) at which point it opens. There's another really neat trick that a reg ulator does, but it does it so undramatically thar it's easy to overlook.

2

Usually, it's desirable for a regulator to o utput not a si ngle fixed pressure, but rather to maintain a certain pressure in relation the ambient. This is especially the case with a SCUBA regulator which must perfor m over a wide range of depths and ambient pressures. Without ambient compensation, a SCUBA regulator that breathed fine on the surface wouldn't work at all a few feet down, since the ambient press ure outside the regulator would be greater than the ouput pressure of the regulator. Fortunately., compensating for changes in the ambient is very easily done, simply by exposing the "out" side of the piston or diaphragm to the ambient pressure o uts[de

Ambient Pressure

the regulator. Usually this is done by putting it in a chamber which is vented to the outside, and is called the "ambient chamber". In the basic dive regulato r shown above, depth compensation is automatic. The outside of the diaphragm is exposed ro rhe ambient pressure of the water, so as the depth increases, the more pressure is required inside the regulator to overcome the ambient pressure on the other side of the diaphragm, and shut the demand valve. So as the diver descends or ascends, the regulator

SCUBA REGULATOR MAINTENANCE AND REPAIR

The Rouquarol - Danayrouze Apparatus

'Ex._fi.a ust 'J/a(ve

automatica1ly increases o r decreases the output pressure to compensate for the changes in the ambient pressure. It's a wonderfully elegant and foolproof system. The Single Stage Regulator

The first functional SCUBA using these principles was patented by two Frenchmen, Benoist Rouquayrol, an engineer, and Auguste Danayrouze, a naval officer, in 1866. Unfortunately, the compressors and

cylinders available then were not highly developed enough to allow a useful suppl y of air to be carried, so the device was not really practical - though Jules Verne put o ne on Captain Nerno's back in 20,000 LEAGUES UNDER.THE SEA. Seventy- five years later high pressure techno logy had come a Jong way. Jacques Cousteau and Emile Gagnan revived Rouquayrol's idea of a demand reg ulator, updating it to take advantage of the much lighter, higher pressure tanks that were available by then, and came up, in 1943, with the first practical air SCUBA, which they called the "Aqualung". The Aqualung used a demand valve which

was mounted on the tank, behind the diver's back, and connected to a mouthpiece by two large diameter hoses, hence the name "double hoser". Since the air pressure was reduced from tank pressure to ambient in one giant step, these regulators are also called "single stage" regu lators. The second h ose, inc iden tally, was an

exhaust hose, which dumped the ex haled air

Aqualung ccMistral)) Regulator

SCUBA REGULATOR MAINTENANCE AND REPAIR

SINGLE STAGE "MISTRAL" REGULATOR

......._

One-way Valves Intake Hose Exhaust "flapper" Valve

:-:c

HP seat

)~ -- --

----

Compound Levers Case

--+---Tank Valve

back into the ambient chamber, from whence it was exhausted. There were two reasons fo r doing this. O ne is that it kept th e bubbles o ut of the diver's face - a nice refinement that kept many UW photographers using double hosers long after they became obsolete. But the main reason was that, if the air was exhausted at the mouthpiece, as it was on the first prototype Aqualung, then anytime the mouthpiece was higher than th e regulator the pressure differential between the diaphragm and the exhaust would be enough to create a free.flow out the exhaust, or, if the exhaust was much lower than the regulator, make the regulator breathe impossibly hard. Running the exhaust back down to the regulator made a balanced loop, th ough if the diver removed the mouthpiece and held it higher than the regulator, the loop would be broken, and the regulator

4

would freeflow vigorously - useful for filling li ftbags! It's worth understanding how a single stage "double hoser" worked, if o nly because they are such an important part of diving's past, an d because the best of th em had an admirable simplicity of design. The d efinitive double hoser, the classic Mistral, used a cl.ever system of compo und levers to operate an upstream poppet valve. Not surprisingly, these regulators breathed much harder than modern regulators. Since th e single stage had to dea l with the extremes of tank pressure, breathing effort also ch anged significantly as the air in the tank was used up and the supply pressure fell. The change in the inhalation effort as the tank pressure fell was not altogether a bad thing. An experienced diver could judge depth and remaining ai r simply by how the

SCUBA REGULATOR MAINTENANCE AND REPAIR

regulator breathed. Cousteau, who, as coinventor, may be excused for h aving an excessive fondness for this type of regulator, believed this made for better divers. His dive team was, last I heard, still using two hose regulators without BC's or consoles for much of their diving. Coustea u felt this stripped down configuration bought them closer to his ideal of the "manfish". The other problem with the double hose regulators was that it was very hard to make a demand valve responsive while it was mounted behind the diver's head and operated through a two foot long corrugated hose.

A Constant Output Regulator Flowing

-

Air From Tank-• ..----...---,-.."'l--

Locked Up

A SCUBA demand valve is basically just a vacuum operated valve that the diver actuates by sucking on the mouthpiece. That being the case, since air is very compressible and expandable, the more airspace there is between the diver and the diaphragm, the slower and less positive the valve action will be. It's kind of like trying to operate a faucet smoothly from across a room by tugging on it with bungee cords . The double hose regulator compensated for this by using a very large diaphragm. A large diaphragm will make a regulator more sensitive to small changes in pressure, but quickly reaches the point of diminishing returns since the larger the diaphragm, the greater the volume of air (though at a lower pressure differential) needed to actuate it. Constant Output Regulators A regulator can be made to deliver gas at ambient pressure whenever the pressure in the chamber falls below ambient, in which case it is a demand regulator, like the original Aqualung. It's also easy to make a regulator so it delivers its output at a more-orless constant pressure above ambient, in which case it is called a "constant output" regulator. All that's needed is to add a spring (or increase the tension of the existing spring) to "bias" the diaphragm. Now, instead of being normally closed (NC) the regulator will be be normally open (NO) since the spring will be holding the valve open when the regulator is at rest. When the regulator is pressurized, the valve will immediately begin to flow, and will continue flowing until the output from the LP chamber is blocked and the pressure on the diaprhagm from inside can build to the point where it overcomes the spring and closes the valve. Then the valve will remain shut until some of the pressure in the chamber is bled off - as when the diver takes a breath - at which point the pressure in the chamber is

5

SCUBA REGULATOR MAINTENANCE AND REPAIR

no longer enough to counter the spring. The valve reopens, and the cycle repeats. T he " lockup" point, or pressure at which the valve closes, is determined by how much pressure the spring is applying to th e diaphragm. The weaker the spring ho lding the valve shut, the lo wer the output pressure, and the stronger the spring, the hi gher the o utput pressure. If some method is included to allow adjusting the spring pressure, then the lockup point can be adjusted without having to change th e spring. Constant o utput regulators like this are by far the more common sort of regulators - the regulators you'll find on a gas grill, welding torch, or shop compressor are all constant output regulato rs. Two Stage Regulators It's desirable, when a very big jump in pressure regulation must be made, or a very even output is desired, to put n.vo regulator mech anisms in series, in which case each mechanism is referred to as a "stage", and the regulator as a ((two stage" regulato r. This was co mmon practice on welding and other industrial regulators, and was the next thing that the SCUBA manufacturers tried in order to make easier breathing regulators. A constant o utput stage was added

An Early Single Hoser 6

TWO STAGE REGULATOR between the tank and d emand regulator so that the tank pressure would already be substanti ally reduced before it reached the demand valve. That way the demand valve didn't have to cope with the fu ll range of extremes of tank pressure. The big diap hragm now controlled just the demand valve on the second stage, which saw a fairly constant " intermediate" or " interstage" pressure o f 100 psi (7 bar) or so, instead of anyth ing from 0-3000 (0-200 bar), the way a single stage demand valve wo uld. That made it possib le to use a much lighter spring on the d emand valve, so the regulator would breath much easier, and also " fl atter" - that is to say, for the inhalation effort to remain fai rly consistent regardless of the tank pressure. Some very good two stage d ouble hosers were built, like the R -series Dacors and the USD AquaMasters. There was even a do uble hoser that called itself a three stage - the Nemrod Snark - even tho ugh it wasn't (it was an upstream two stage with an overpressure relief valve) . · The catch was, tho ug h, that once the pressure reduction was being do ne in two steps, there was no reason to hang both stages on the tank. By separating the two stages the demand stage could be moved closer to the diver - in fact, put right into the diver's mouth . This eliminated all the extra air space between the diaphragm and the

SCUBA REGULATOR MAINTENANCE AND REPAIR

mouthpiece, which immensely improved the ease of breathing. This in turn allowed using a smaller, more responsive diaphragm, so that the entire demand stage didn't have to be much bigger than just the mouthpiece of a double hoser. Since the air going through the hose ben.vecn the two stages was still under pressure, the diameter of the hose coul d be quite small, which meant less drag in the water. And since the exhaust port and diaphragm were both on the mouthpiece, no return hose was necessary. T he new regulators were called "single hose" regulators, for obvious reasons. At first they were sold as bottom-of-the line regulators, on the assumption that real divers would still want the big chrome double bosers , but as the single hosers improved the inherent advantages of the design won out. Cousteau's team aside, just about all the regulators in use today are single hose, two stage regulators. OK, that's pretty much the standard dive book intro explanation, but if you are going to presume to work on the things you have to understand what's happening in a little more depth. What makes it confusing is that just about anything a reg ula tor docs can be

done in either of two ways. The valve can be an "upstream" valve, in which case the tank pressure will try to push it shut, or a "downstream" valve, in which case the tank pressure will try to push it open. It can be made NO (normally open) in which case the spring will hold the valve open and the pressure in the LP chamber will make it close, or NC (normally closed ) in which case tl1e spring will hold the valve shut and the pressure in the LP chamber will make it open. The valve can consist of a fixed seat and a movin g orifice or a moving orifice and a fixed seat. None of these differences really matter once yo LL understand what's happening, since

the principles remain the same regardless of how the app lication of them varies, but it is important to understand them in o rder to be able to puzzle out just how a particu lar regulator works. Some Nomenclature But before we get any deeper, it mi ght be good to nail down a bit of nomenclature. The actual valve mechanism on a SCUBA regulator almost always consist of l:\.vo components, a metal orifice with a raised sharp edge around it called the "crown" "cone" or " hard seat" and a plastic or rubber piece that covers it to block the flow, wh ich is call ed, depending on which stage it is on, either the "HP seat" or "LP seat", and also sometimes, the "soft seat". Either tl1e seat or th e orifice may be fixed, depending on the regulator design, and the oth er one moving. In practice, tho ugh, diaphragm and non-balanced piston reguJators tend to have movin g scats and fixed orifices, and balanced piston regulators tend to have fixed seats and moving orifices. When l:\.vo stages are used , tl1e pressure benveen the l:\.vo stages, that is to say, the output pressure from the 1st stage, is call ed the "intermediate pressure", usually abbreviated to " IP ", or sometimes the " interstage pressure" which is, fo rtunately, abbreviated the same way. Each stage has two chambers, a high pressure chamber and a low pressure chamber. The pressure in the low pressure chamber of the 1st stage is the same thing as tl1e intermediate pressure, which is also the pressure in the high pressure chamber of the 2nd stage. On 1st stages, the HP chamber and related parts is often referred to collectively as the "HP side" and the low pressure chamber and related hardware as the "LP side". First stages, being constant output regulators, are always Normally Open (NO), which means that the valve is open when the )

)

7

-

SCUBA REGULATOR MAINTENANCE AND REPAIR

UPSTREAM AND DOWNSTREAM VALVES DOWNSTREAM

UPSTREAM

Crown/Orifice

Crown/Orifice Valve seat IN

regulator is not pressurized, and doesn,t close until the pressure inside gets high enough to overcome the spring and close the valve. 2nds, being demand valves are usually Normally Closed (NC) in that they are closed when at rest, and don ' t open until the pressure in the IP chamber drops low enough to suck the diaphragm in and open the valve. Oh, and some people get confused because they can't find a low pressure chamber on the 2nd stage. The entire inside of the regulator body, including the mo uthpiece and the divers mouth is the LP chamber. Upstream and Downstream The valve seats used on SCUBA regulators come in two flavors; upstream and downstream, depending o n where the movable side of the valve seat is in relation to the flow. If it's on the HP side, then it's an upstream valve, because the valve action takes place upstream of the seat. If it's on the LP side then it's a downstream valve. It's a significant difference, because the two kinds o f valves behave very differently. Think of them as being like the door o n a crowded room full of people clamoring to

8

IN

get out. If the door opens inward - upstream - it will be very hard to open it with the people pressing against it, and tend to keep getting pushed shut by the fl ow. If it opens outward -downstream - it will be easy to open but very hard to close in the same siniation. On an upstream valve th e pressure of the gas o n the HP sid e, or downstream pressure (DSP) as some W--+ Hlll!!--t--Cl -= --nmnj) ------·

~T~Y~Y? ~

i--

J------ --- -------- ---- --------------------------------- --- -- ------- -- -------------- -- ---------- ---------

-

I

Trim excess off stem after installing a new diaphragm in th e plunger

(Cover components shown in reduced scale)

Inlet Tube

Wave Spring

13 14 15 16

0-Ring

17

Poppet

6

Orifice Sleeve

7 8 9 10 11 12

0-Ring

18 19 20 21 22 23 24

Jam Nut

2 3 4 5

0-Ring Orifice

Case AFC Plunger AFC Diaphragm AFC Cover 0 -Ring

Lever Sleeve Lever LP Seat 0 -Ring Poppet Spring Balance Chamber 0 -Ring Spring Pad 0 -Ring Split Washer

25 26 27 28 29 30 31 32 33 34 35 36

Knob Stem 0-Rin Ad 'ust Sleeve Knob Knob Retainer Exhaust Valve Exhaust Cover Dia hra m Thrust Washer Front Cover Cover Ring

239

SCUBA REGULATOR MAINTENANCE AND REPAIR

Mares Ruby/Abyss/Voltrex

Downstream Second

--@

,' ,' ,' ,'

e "Must Replace" parts listed in bold type 21

27 28

29 30 31 32 33 34

240

Poppet Seat 0-ring Seat Connector 0-ring Poppet Body Poppet Spring Case Locknut, Demand Lever Washer, Demand Lever

See "About the Schematics" note on page XX 35 36 37 38 39 40 41 47

Demand Lever Diaphragm Clamp Ring Screw Cover Assembly Exhaust Valve Exhaust Tee Poppet Seat, Rubber

SCUBA REGULATOR MAINTENANCE AND REPAIR

OCEANIC DELTA II

External Adjustment Downstream 2nd

?~? ~®

=-·-~-@+------------------------;

Gpcp> o/2 ~~ ~ ~

•-~m]D-~o~~

0--*

,

:

:

~

:'

'--- - - -~- --0-~-bl>-

@@@~

0

--[llWND-=l:PI+{]-~-

/

@@@ @@@)(@)@

©-© ©-. '

---arrmO --

"®

cb

~-----K "tD "Must Replace" parts listed in bold type

1 2 3 4 5 6 7 10

11 12 13

Front Cover Washer - Diaphragm Diaphragm Housing Assembly (case) Cover - exhaust tee Exhaust Valve Screw - Adj. Knob 0-ring - Orifice Orifice Coupling 0 -ring - Coupling

See "About the Schematics" note on page 30

14

15 16 17 18

19 20 21 22

et Lever Arm Washer

S acer Lock Nut - N Ion Shaft - Balance

23

24

25 26 27 28 29 30

31 32 33 34

0-ring - Adj . Tube Pad - Sprin Spring - adjustment Follower - Piston Spring Stem 0-ring - Stem Washer - Thrust Nut - Packing Knob - adjustment Button - Purge

Tube - ad"ustment

241

SCUBA REGULATOR MAINTENANCE AND REPAIR

POSEIDON JETSTREAM I ODIN

Servo Valve Second

----- -- - - --------- --------- --------------- ------------------ ----------------------------~

.. . ..

_,.

~

@

,®

fi)

,®

L@-ee--e-- ~

Nut Jam Unif 0-ring Orifice 0-ring Case 0 -ring Flow Vane 0 -ring Housing Lever Retaining Knob Clip 0-ring Seat Poppet 0-ring (2) Spring 0-ring (2) Knob Spring Pad 0-ring Ba lance Chamber 0-ring Piston, Balance Chamber 0-ring (2) 0 -ring Plug, Knob Decal Pin, Case Exhaust Valve Pin Cover, exhaust Diaphragm Washer, Anti-friction Ring Purge Cover Frame Ring Assy

SCUBAPRO G190 1

2 3 6 7 8 9 10

11 12 13 14

15 16

17 18 20 21

22 23

24 ' '

'

0---0---

--1--~-----­ ®®

25

26 27

29 30 31

Pin , Exhaust Cover Cover, Exhaust Valve, Exhaust Case, 190 Flow Reducer Retaining Clip, Fl ow vane Flow Vane 0 -ring, Flow Vane, Red Plug 0-ring, Plug, Red Diaphragm Diaphragm Disk Spacer Ring Cover, 190 Pure Spring Purge Button

Nut, Demand Valve Washer, Lever Lever Housing Spring, Demand Valve Stern, Demand Valve

Seat, Demand Valve Pin, Cover Retaining Demand Valve Body 0-ring, Orifice, Blue Orifice

243

SCUBA REGULATOR MAINTENANCE AND REPAIR

SCUBAPRO G250, G200, G2008, 109 and BA

: -~--------j

®-6® (Cover components shown in reduced scale) Metal cased barrel poppets like the 109 and BA use the same valve and adjuster parts, but the air tube is an integral part of the case and is not removable. The G200B is essentially identical, minus the external adjuster. A shorter air tube is used, with an 0-ring sealed adjuster plug. Otherwise, all the components, including the case, are the same. Non-balanced versions, like the metal 109 and the G200 use the "Duro" poppet, which has a replaceable seat, along with a longer spring and a spring seat. These parts interchange directly with the bal anced versions, and vv.

~~ ~~

.---=-m-fllJINJM -0---See "About the Schematics" note on page 30

"Must Replace" parts listed in bold type

26

0-ring, stem, Black Stem, Poppet

Cover, Exhaust

12 16

Valve, Exhaust

17

Flow Vane

27 28

Case

18

0-rin , flow vane, Red

29

Balanced Chamber

Nut, Jam

19

0-rin , Orifice

0-ring, Adj Knob, Blue

Orifice

10

Cover, front

20 21 22 23 24

Retain in

11

Spring , purge

25

Poppet Assy, Balanced

30 31 32 33 34 35 36

Screw Ca Socket Head

2 3 4 5

6 7

8 9

244

rin , flow VIVA

0-rin , Inlet Tube, Red Inlet Tube,

G250

Lever Pin

Spring, Balanced Poppet

Adjustment Knob Inlet Tube,

G200

Plug, Adjustment

Seat, Duro Poppet Spring Spring Seat

SCUBA REGULATOR MAINTENANCE AND REPAIR

SHERWOOD

Downstream Second Stage

~~ ~ ~

~

er (---------nbP-~-C@··--@==>rn!CE----.

J-------- --- -- --- --- ---------------------- --- ------ --- --------- -- --

)

(

- ----~------­

-.. ---.. -... ---·-

~

.. -... --------·

'

®---(!!)

'

'

'

®---!

!

NOTE: While the outside appearance of Sherwood 2nds changes dramatically from time to time, the inner workings change very little and most are internally very similar to the one shown. Some models have "moisturizing" fins in the mouthpiece passage which screw onto the lever support, and cold.water versions have a second set of fins over the exhaust valve which attach between the orifice housing and lever support.

"Must Replace" parts listed in bold type 2 3 4

5 6 7

8 9 10

Stet Cover Diaphragm Retaining Ring Diaphragm Screw (#10 Tone/slot) Lever Lever Support Spring Stem (poppet) Poppet Seat Insert

See "About the Schematics" note on page 30 11 12 13 14 16 17 18 19 20

Exhaust Valve Exhaust Tee Screw (#10T/slot) Mouthpiece Case Orifice Housing 0-ring Adjusting Orifice Hose Assembly

245

SCUBA REGULATOR MAINTENANCE AND REPAIR

SPIRO BASIC DOWNSTREAM

o

-.

...

11 1 11 1 1 11 111 1 1 , 11 11 11 1 ;

~r

C? cp ~~

iii ii rr 111 1111 L! ~ '. ~ ~ ~ ~ ~:. ..

-----.'.r·-------------a-~o-o--c;v Cip ··-l-· fill()--··--·--· --·

,,

,,

,,

,'

NOTES: Many mid-line Spiro models are very similar but are fitted with an adjustable orifice. Parts marked "*" are not fitted to all models. "Must Replace" parts listed in bold type

2 3 4 5 6 7 8

9

246

Inlet Fitting 0-ring Disk (LP seat) Retainer Spring Washer Lever Spacer Locknut

10 11 12 13 14 15 16 17 18

See "About the Schematics" note on page 30 Port Plug* O·ring * Box Bottom (case) Clamp Mouthpiece Exhalation Valve Exhaust Tee Diaphragm Thrust Washer

19 20 21 22

SCUBA REGULATOR MAINTENANCE AND REPAIR

USO MICRA, MICRA ADJ

:

Barrel Poppet Second

Nonadjustable Version

:

-

-

"Must Replace" parts listed in bold type 15

1 2

11 12 13 14

23

0-ring Vane Adj. Switch C-clip 0-ring Valve Body Pin LP Seat

31 32 33

Lever Retaining Sleeve Adj. Screw 0-ring 0-ring Cap Nut Adj. Knob Pin

24

Poppet

34

Exhaust Cover

25 26

Spring Washer

34

End Cap

16 19

3 4 5 6

20 Lever Exhaust Valve 2 0-ring Ad"ustable Crown Hex Nut 3/4" Box Bottom case

See "About the Schematics" note on page 30

21 22

27 28

29 30

247

SCUBA REGULATOR MAINTENANCE AND REPAIR

VALVES - "K" and "J " (Reserve)

TT T ~ Tr TTTI I ·--(S)-W--@ -

~

-©-{)-- 0-@-o--©--~-c:@Ilill}----

..

~--- - ------- - - - ---- - - - - ----- - -- -- - -- - ---------------------- - --

1 2 3 4 5 6 7 8 9

10 11

12 13

Body Dip Tube Locknut Spring Washer (2) Handwheel (knob) Bonnet 0-ring or sealing washer Backup ring 0-ring Gasket Stem , actuating Valve Seat

.

--@

' '

. .... --.... ....

'

.

!----- --- --

O ····· @

NOTE: Considerable variation exists between make and year, especially regarding parts 8, 9, 10 and 11.

~

L__ {J--0

~ -0

-0 ---

@@ @

1 ~ ~ rf f f ~ ~ er ~ ~ ·----·TI--~-~---o-@-oo---~- ®-cp

® W0----·

(These parts used only on "J" Valves )

HOWA "J" VALVE WORKS 1) Full tank - reserve ON. Tank pressure is strong enough to hold th e spring loaded seat open allowing full flow of air. 2) As tank pressure drops, the spring loaded seat closes, leaving only a tiny bypass open providing adequate air only if the diver immediately begins to ascend. 3) Opening the lever to the Open (Reserve Off) position lifts the seat fro m th e orifice, allowing full flow of air.

248

From Tank

To Regulator

-~

From ___. Tank ~::nl~

14 15 16 17 18 19 20

21 22 From Tank

23

Lever, reserve Reserve bonnet Backup ring Reserve mechanism

Burst plug, one piece Burst disk retainer Burst Disk Burst Disk washer 0-ring, valve-to-reg 0-ring, valve-to-tank

SCUBA REGULATOR MAINTENANCE AND REPAIR

INDEX 10% Overfill "Plus" Rating 181 635 1-T6 aluminum alloy 179 A-clamp 115 Abrasive stick 85, 141 Abysmal Diving 195 Acidic bath 83 Adjustable orifice/crown 67, 79 Adjustable Seconds 17 Air 153 Ambient chamber 35, 210 Ambient compensation 2 Ambient pressure 210 Anti-seize 86, 154 Antifreeze kits 61-62, llO Apeks 18, 48, 131, 195-7, 225, 238 Aqualung 3, 208 (See US Divers, Spiro) Argon regulators 24 Atomic 22, 197 -9, 226, 239 Backup rings 122-123 Backup washer 210 Balance chambers 20, 105, 107, 210 Balanced diaphragm 1st, diagram 11 Balanced diaphragm 1st, overhaul 43-48 Balanced piston 1st, diagram 10 Balanced piston 1st, overhaul 39, 43 Balancing 18-20 Barrel poppet 2nds 15, 58 -62, 68, 75-76 Barrel Poppet 2nd , tuning 68, 75 Beuchat VX 10 164 Brushes 141 Bullets 141 Burst disks 176-177 CEN standards 23 Classic Downstream 14, 55-56, 66-68, 74 Classic downstream 2nd, diagram 13 Cleaning 82 Cleaning solutions 151 C02 inflators viii Cold water kits 110 Collar wrenches 137 Compressed Gas Association ( CGA) 178 Cones 141 Constant output regulators 4, 6 Corrosion 160, 169 Cousteau, Jacques 3 Cracking Point 210 Cracking pressure 66, 77-79, 95 Creep 210 Crowfoot wrenches 87, 138 Crud 160

Dacor 48, 131, 198-9, 227 Dacor R Series 7 Dedicated first stage ports 22 Demand lever, bending 73 Demand regulator 1 Demand stage 210 Detergent bath 82 Detuning 74, 77 Diagnosis 155 Diaphragm 1st, overhaul 43-48 Diaphragm assisted piston 13 Diaphragm first overhaul 47 Diaphragm retainers 88 DIN connectors ll6 DIN valves 175 Dip tube 169 Dive Rite 199 DOT regulations 177-8 Double hosers 3, 5, 211 Dow lll 149 Dow 557 168 Dow No.7 149 Downstream 8 Downstream 2nd, tu ning 68, 74 Downstream pressure (DSP) 9 Drag link tool 138 Dry air bleed 205 Drying 84, 101 DSP 17,20,211 Durometer 127 Dust caps 114 Dynamic Flow Control 22 Dynamic 0 -rings 122 Environmental kit 211 Environmental sealing 90 , 92, llO, 212 Equipment Specialist courses 193 Exhaust valves 52, 108-9 External Adjustment 2nds 17, 76, 2 11 Extrusion 122 Face pin spanners 137 False cures 155 First stage holders 28, 134 First stage identification 35 First stage tuning 70 Flow benches 148 Flow testing 78, 97 Free flow 161, 163 Gauges 184 Generic 0 -rings 130 Genesis 199, 227 God the All-Seeing vi Green and yellow trim 26 Hand test 78 Hex keys 138

249

SCUBA REGULATOR MAINTENANCE AND REPAIR High Pressure Seats 34, 105-106 H ose protector installation tools 142 Hoses 112-113, 161 Hoses, oversized 25 Hot wrenching 81 HP seat failure 106 HP seats 34, 105 -106 HP-seat failure 106 H yd rotesting 181 H ydrotesting alter tumbling 183 H yperthane 126 In-Line tool 72, 144 Inlet filters 103, 160 Insertion tools 142 INSPECTING SCUBA CYLINDERS (book) 178 Inspection 85, 178 Incermedfate pressure 7, 65, 88, 89, 91, 160, 2 11 Intermediate pressure gauge I45 Intermediate Pressure, adjusting 65, 90 Interstage pressure 7 IP 7, 65 ,88,89,91,160,21 1 IP creep 89 IP, adjusting using cracking pressure 80 J valves 172, 248 K Valve 167, 247 Kludge 17, 87 La Spiroteclmique 208 Leak test 78 Leakage, regulator 161, 163 Leakage, valve 177 Lever height 65-66, 79, 155, 16 1 Linear flow 2nds 75 87, 154 Loctite Logging 79 Looseni ng 81 Low pressure seats 105 LP seats 105 Lubricants 149 Lubricants for 02 service 150 Lubricating 0 -rings 86 Lubrication 86 Luxfer 179-180 Magnahelic gauge 78, 80, 146 Maintenance, routine 100 Manfish 5 Mares 18, 201-2, 228, 240

Neutralizing bath 83 Nevil (Shu te) Norway v1 Ni.trogen 84, 153 Nitrox Din Connectors 118 Nitrox regulators 25, 132 Nomenclature 8, 31 Non-balanced piston 1st, diagram 12 Non- balanced piston 1st, overhaul 35-38 Normally closed (NC) 6 Normally open (NO ) 6 NPT to SCUBA adaptor 145, 153, 221 0-ring bullet tool 124 , 141 0-ring color 127 0-ring installation cones 141 0-ring lubrication 126, 149-50 0-ring picks 123, 140 0-ring size chart 129 0-rings 121 -134 0-rings for nitrox or oxygen service 132 0-rings, care and handling of 123 0-rings, generic 127 0-rings, metric 13 1 0-rings, sizing 128 0-rings. tank neck 175 Oceanic 88, 95, 200-1, 229-30, 241 Oceanic Alpha 18 164 Oceanic DX3 Oceanic Omega 17, 76, 199 Octopuses 77 OPVs 9, 24 Overlap cross effects 67 Overpressure Valve (OPVs) 9, 24 Oxygen clean 212 OXYGEN HACKER'S COMPANION v Ozone 109 Packing seals 121 , 132 Parts 194 Parts, fabricating 119 Parts, obtaining 188 Parts, reusing old ones 189 Piston 106 Plastic 111 Plastic boxes 29 Plastic cases 112 Pool use l 01 Poppet holders 143

Mares Ruby HP seats 200

Poppet spring pressure 65-66, 73, 161

Moaning I 63 Modular Dacor 1st, overhaul 48 Mushroom valve 15, 52, 108 Must Replace list 27, 189 Must Replace parts 31 Navy Class A standards 23 Nemrod Snark 7

250

Port plugs 142 Poseidon 12, 22, 34, 95, 109, 202-4, 231-2, 242 Poseidon HP Seats 34, 201 Poseidon Odin/Jetstream 76, 144 164 ' 201 229 242 Positive pressure breathing 24 Possessed regulators 165 )

)

)

SCUBA REGULATOR MAINTENANCE AND REPAIR

-

--

Post Valve 167 Pre-servicing tests 81 Pressure pot 148 Primary LP port 22 Professional Scuba Inspectors (PSI ) 178 Puck seats 57, 105 Purge assembly 52, 108 Purging 163 Push-pull 2nd 14 Reamer brush 141 Recalls 192 Regulator From Hell 84 Regulator, buyi ng 216 Retaining rings l 04 Rinsing 83, 100 Rodak's SCUBA DIVING 23, 104 ROUND THE BEND v1 Rouquayrol 3 Schematics 30, 49, 225-244 Scubapro 204, 236-7, 243-4 Scubapro D -series 17, 69, 205 Scubapro G-series 74 Scubapro Mk lO llO, 204, 235 Scubapro Mkl5 165, 204 Scubapro MIG 26, 204 Scubapro Mk20 26, 164, 203, 236 Seaquest 209, 231 Seats 7, 105-6 Second stage cover wrenches 138 Second stage tuning 71 Service literature 190 Servo valve 16, 54 Settling effect 74, 212 Sherwood 20, 26, 39 177, 208-9, 234-5, 245 Shimmin g 66, 70 Shims 38, 42, 119 Shuddering 163 Sidebreathers 109 Silicone spray 150 Single adjustment 2nds 66 Single stage regulators 3 Single-adjustment 2nds 2 13 Single hoser 213 Snap rings 104 Snoop 153 Soft parts, care and handling 62-63, 109 Solvents 84, 152 SPEC kit 93, 110 Spiro 210-11 , 233, 246 Spiro downstream tool 71, 144 Spools, gauge 185 Spring pressure 65-66, 73, 161 Stackup 47 Star rings 36, 104

Static 0 -rings 121-122, 165 Su-ap wrench 52, 139 Subtleties 26 Sunlight 101 Tank inspection 178 Tank, neck cracks 179 178-184 Tanks Tanks, painting 183 Tech courses 193 Testing, final 98 Three stage regulator 6, 16 Through-the-diaphragm exhausts Tightening du ngs 86 Tilt valves 15 T ilt valve 2nds, tuni ng 76 Torque wrench 87, 138 T umbling 182 T uning 65-80 Two-adjustment 2nds 67 U nderhauls 34 Upstream 8, 69 Upstream 2nd, tuning 69 US Navy Standards 23 USD 208, 247 USD AquaMaster 7 USO DX Mistral 22 USD Miera 69 , 86, 209, 246 USD Mistral 4 Vacuum test 78 Valve face 0 -Rings, stuck 175 Valve Face Seal 0 -Ring 174 Valve nut tool 139 Valve test block 146 Valve, overhaul 173 Valves, diagnosis 170 Valves 167-177, 248 Venturi assist 21, 65 -66 Venturi boost adjustment 77 VF - 23 151 VIP 178 Visual Plus 180 Viton 0-rings 132 Voit 80 Waisting 85, 213 Walking an 0 -ring 124 Water test viii, 96 Wet breathing 162 Whistling 164 Workstations 147 Yoke connector 115 Yoke nut wrenches 136 Zeaglc 211-2, 225, 238

109

251

-

OTHER AIRSPEED PRESS PUBLICATIONS Vance Harlow's THE OXYGEN HACKER'S COMPANION The tech diving classic, and ultimate guide to HP gas handling in the real world now in its 4th edition, THE OXYGEN HACKER'S COMPANION covers nitrox and trimixing, as well as oxygen handling for dive, emergency and aviation use. Also included are plans for building tank tumbers, mixing whips, samplers and the famous OXY HACKER under-$100 oxygen analyzer, as well as tips on buying gas, getting tanks hydroed for less, and more. $35

Vance ffarlow' s

Oxygen Hacker's Companion The. C.0..1111te..1 « Ww 1llhol'lttd 'loun:~buok on uioc tL.wtdlinq • Id U"'C of 0 ' ¥"- n 1om s.tld Trwnu. rot /)hr11;.

A,.~. -1 LttH"llJl'l ll)' ~

160 Pages

THE DIVELIGHT COMPANION If you want light - a lot of light - underwater, a canister light is the only way to go, and this book an essential guide to selecting, maintaining and building them. Plans for several different canister lights, including a cave-standard 12v/ 14 amp test tube light a MR16 "wrecklight", compact NiMH mini -canisters and several low-cost quick-build "instant divelights" . Cheap direct sources for bulbs, batteries and DIY parts, and battery charging secrets that can make your lights brighter and longer-lived INCLUDES HID, NiHM & Video! $30

140 Pages

LOW COST AND IMPROVISED GAS BOOSTERS Covers just that, showing several variations on a high pressure booster that can be made using low cost, readily available hydraulic components. Prospective buyers are cautioned that this is by no means a set of foo lproof plans. Rather, it is an idea and sourcebook for the mechanically adept and ven turesome individual with experience in HP gas han dling. $20

72 Pages

For more information on these books, or to order, visit our webpage at www.airspeedpress .com

252

Al RSl't:t:D l'RI:;SS

Vance lfarlow/s SCUBA REGULATOR MAINTENANCE AND REPAIR • l This is the real thing - not just another how-to-rinse-your-regulator-and-replace-a-mouthpiece book but a real, industrialstrength, hands-on guide to serious regulator servicing - how to take them apart, diagnose and overhaul them, and tune for maximum performance. Valves and tanks are also covered. Whether you are a professional SCUBA technician who wants to gain a broader unders tanding of the field than is usually taught in the SCUBA manufacturer' s tech courses, or an individual diver who wants a better understanding of your gear, this book will be an invaluable companion .

~--

Adiust1ng Nut

Vance Harlow is well known in tech diving circles as the author of THE OXYGEN HACKER'S COMPANION, the book that brought gas mixing and oxygen ...handling out of th e closet. Now he's done it again, writing, in his usual clear and comprehensive style, the definative book on the servicing of SCUBA regulators.

--

-

ISBN 0-9678873-0-5

9

SCUBA REGULATOR MAINTENANCE AND REPAIR

$ 50~ 00