Reg Failures

[Teller]

Other than a free flow is there anything else that can stop a reg from working properly on a dive?

[Fishpie]

Water in a tank making it wet (and nasty) to breathe from.
Rust from tank clogging filter.
Faceplate falling off.
Mouthpiece comming off.
Exhaust valve not sealing properly.
Inhilation valve not sealing properly.
Demand lever breaking or dislodged.
Spring breaking in either 1st or 2nd stage.
Cracked/damaged 2nd stage.
Poor swage comes away from hose.
2nd stage comes unscrewed from hose.
J valve knocked down by mistake.
Tank valve not fully open.
.......these will not cause a ff.
Most other problems will result in ff.

[Teller]

Thanks

[Max Speed]

Debris in tank blocks dip tube.

Sent from my SPH-P100 using Tapatalk 2

[dumpsterDiver]

Regulator hose fails...
O-ring extrudes.
Shop monkey forgot to screw the hose in tight enough to the first stage.
The second stage is cracked and causes major leakage of water on inhalation.
First Stage seat fails and causes freeflow.


I've personally seen all of these happen.. as well as others..

[awap]

Misassembly resulting in parts changing position or falling apart due to improperly torqued connections.

[j yaeger]

everything fishpie said...and operator error:shocked2:
generally thats the one that gets ya
have fun
yaeg

[CPH]

Water in a tank making it wet (and nasty) to breathe from.
Rust from tank clogging filter.
Faceplate falling off.
Mouthpiece comming off.
Poor swage comes away from hose.
2nd stage comes unscrewed from hose.
J valve knocked down by mistake.
Tank valve not fully open.
Misassembly resulting in parts changing position or falling apart due to improperly torqued connections.
O-ring extrudes.
Shop monkey forgot to screw the hose in tight enough to the first stage.

All these items are under the tittle of poor maintainence/operator error.

[Wookie]

Misassembly resulting in parts changing position or falling apart due to improperly torqued connections.

I seem to remember a improperly installed poppet on a trip you were on that resulted in a complete failure to deliver air.... MK10B/G250 if I remember right. Unit just had come from service and the owner hadn't tested it in the dog water bowl (or anywhere else except at 95 feet deep.....).

[Teller]

Water in a tank making it wet (and nasty) to breathe from.
Rust from tank clogging filter.
Faceplate falling off.
Mouthpiece comming off.
Poor swage comes away from hose.
2nd stage comes unscrewed from hose.
J valve knocked down by mistake.
Tank valve not fully open.
Misassembly resulting in parts changing position or falling apart due to improperly torqued connections.
O-ring extrudes.
Shop monkey forgot to screw the hose in tight enough to the first stage.

All these items are under the tittle of poor maintainence/operator error.

To be more specific I am trying to understand how a reg can fail and not free flow. Many people say that a drawback to SM is that if one reg fails you just lost half of your gas however it is very easy to feather the valve on a cylinder in SM configuration if the reg free flows. So what I want to understand is how can my reg fail and not free flow with proper maintenance?

[LeadTurn_SD]

Teller,

Are you asking how can a catastrophic failure occur, or how likely this type of failure is with a correctly serviced, inspected, tested and maintained regulator?

The answers given earlier in the thread describe how a total catastrophic failure can occur (I define a total catastrophic failure as sudden loss of the ability to breath from the reg.... not a freeflow).

You'll note that all of the failures listed are 100% preventable, they are not random failures. They are caused by a lapse by the tech during service, failure to test and inspect by the diver, etc.

A correctly serviced, tested, inspected and maintained reg is not very likely to suffer this type of failure.

The more likely type of failure is a freeflow or other "leak", caused by seats or o-rings failing, which would result in loss of air and cause you to cancel or abort the dive, but should not be a catastrophic event.

Best wishes.

[Teller]

Teller,

Are you asking how can a catastrophic failure occur, or how likely this type of failure is with a correctly serviced, inspected, tested and maintained regulator?

The answers given earlier in the thread describe how a total catastrophic failure can occur (I define a total catastrophic failure as sudden loss of the ability to breath from the reg.... not a freeflow).

You'll note that all of the failures listed are 100% preventable, they are not random failures. They are caused by a lapse by the tech during service, failure to test and inspect by the diver, etc.

A correctly serviced, tested, inspected and maintained reg is not very likely to suffer this type of failure.

The more likely type of failure is a freeflow or other "leak", caused by seats or o-rings failing, which would result in loss of air and cause you to cancel or abort the dive, but should not be a catastrophic event.

Best wishes.


I am asking how a catastrophic failure can occur and my definition of catastrophic is the same, sudden and complete loss of the ability to breath from the reg (not a free flow). So then with a properly serviced regulator and the ability to feather the valve of the cylinder you should never loose the ability to access the gas inside of the cylinder?

[ianr33]

So then with a properly serviced regulator and the ability to feather the valve of the cylinder you should never loose the ability to access the gas inside of the cylinder?

A blown tank burst disc, or neck O ring, doesn't care if the reg is properly serviced or not.

[Teller]

A blown tank burst disc, or neck O ring, doesn't care if the reg is properly serviced or not.

I am trying to compare BM doubles to SM, so if the neck o-ring or the burst disk blew on a set of doubles you would still loose that gas. As I stated earlier I have heard many people say that a major draw back for SM is that if you have a reg fail you will loose half of your gas. The only mishaps I have ever seen with regs all resulted in free flow. I don't consider a free flow in SM configuration as loosing half the gas due to the fact that you have easy access to the valves allowing you to feather the valve and continue to use the cylinder during your ascent. Based on what LeadTurn stated above it would seem the only way a reg would have a catastrophic failure is if it was not maintained or reassembled correctly. If all of this is true I don't see how BM offers more redundancy then SM. Someone please correct me if I am wrong.

[dumpsterDiver]

well a hose can blow... unlikely... but it could happen, especaily if it was weak and was subject to some type of force or accident....

If this is a discussion about side mount loosing half your gas.... couldn't you just hold your breath long enough to switch the regulator from one tank to another? (Maybe 30 seconds?) That doesn't sound too hard... easier than making a free ascent from 100 feet..

you can never make sure that a reg will never fail, but you could train yourself to switch regs in order to yeild a good probablity that you could accomplish it in an emergency...Seems more useful that worrying about the details of a potential failure...

I know nothing about side mount diving other than the little i read on the internet,.

[Teller]

well a hose can blow... unlikely... but it could happen, especaily if it was weak and was subject to some type of force or accident....

If this is a discussion about side mount loosing half your gas.... couldn't you just hold your breath long enough to switch the regulator from one tank to another? (Maybe 30 seconds?) That doesn't sound too hard... easier than making a free ascent from 100 feet..

you can never make sure that a reg will never fail, but you could train yourself to switch regs in order to yeild a good probablity that you could accomplish it in an emergency...Seems more useful that worrying about the details of a potential failure...

I know nothing about side mount diving other than the little i read on the internet,.


I am not saying that I wouldn't switch regs but lets just say I need both cylinders to surface safely.

[Fishpie]

Swap regs as in detach bad reg from tank and put good reg in its place......

[ianr33]

I am not saying that I wouldn't switch regs but lets just say I need both cylinders to surface safely.

Then you have seriously messed up your gas planning!

My take on this is that,yes, with sidemount it is possible to lose half your gas. With proper planning that should not be a problem. (Even when solo.With a buddy it's even less of a problem)

With back mount you could lose ALL your gas if you don't fix a problem or take appropriate action pretty quickly. That is a problem!

Certainly possible to switch regs in sidemount if you have a spare reg to play with (stage,deco tank) Switching regs with only 2 regs (so you have nothing to breathe for a while) would be a real last ditch effort. Imagine unscrewing a reg on a breath hold and watching the DIN O ring fall into the abyss!

[Teller]

Then you have seriously messed up your gas planning!

My take on this is that,yes, with sidemount it is possible to lose half your gas. With proper planning that should not be a problem. (Even when solo.With a buddy it's even less of a problem)

With back mount you could lose ALL your gas if you don't fix a problem or take appropriate action pretty quickly. That is a problem!

Certainly possible to switch regs in sidemount if you have a spare reg to play with (stage,deco tank) Switching regs with only 2 regs (so you have nothing to breathe for a while) would be a real last ditch effort. Imagine unscrewing a reg on a breath hold and watching the DIN O ring fall into the abyss!

I agree about the gas planning, this is a hypothetical situation. Basically with the exception of a hose failure I am having difficulty understanding how you could loose half of your gas due to reg failure. I am not looking for a contingency or a "you should have done this or planned for that." Does anyone have an idea?

[dumpsterDiver]

..... Neck Oring, burst disc, blown reg face O-ring, smashed cracked second stage...

[Teller]

This isn't going anywhere. Never mind.

BTW, neck o-rings and burst disk are not reg failures they are valve failures. I don't know why people keep mentioning them. Obviously if the valve on the cylinder cant hold pressure than that's a problem with the valve.

[halocline]

Manifolded doubles do have additional redundancy vs independent doubles IMO. The reason is that in the VAST majority of cases, a free flow would be caused a reg failure or possibly something in the valve. Burst disc and manifold failures are VERY rare. In the case of a reg failure, you still have access to the gas in both tanks. This means that with a manifold, you are far less likely to lose half your gas than with independent doubles. I think it's perfectly reasonable to consider that additional redundancy.

In the case of both a bust disc/tank neck o-ring failure AND a manifold failure, yes you would lose all your gas. To my knowledge, that scenario has not happened in the real world, although it happens on every single thread discussing this very topic.;)

I'm sure there are other reasons that sidemount is as popular as it is; trim considerations, easy travel, super easy valve access, but I would not dive sidemount for any perceived increase in safety due to independent tanks. Just my opinion....

[Teller]

Manifolded doubles do have additional redundancy vs independent doubles IMO. The reason is that in the VAST majority of cases, a free flow would be caused a reg failure or possibly something in the valve. Burst disc and manifold failures are VERY rare. In the case of a reg failure, you still have access to the gas in both tanks. This means that with a manifold, you are far less likely to lose half your gas than with independent doubles. I think it's perfectly reasonable to consider that additional redundancy.

This is exactly why I am asking this question. You say BM has more redundancy then SM due to the fact that in SM I can loose half my gas if I have a reg failure. I am not sure if I am asking the question clear enough but I will try again. With SM a free flow can be dealt with by feathering the valve and breathing off of the free flowing reg. Knowing that I would like to know what can happen to make a reg not work completely (you can not breath from the reg at all, no free flow). I understand the debris blocking the dip tube and the tank neck o-ring and burst disk but those issues apply to BM as well so lets forget those for right now. One person mention a cracked/smashed second stage. I would imagine that smashed second stage would result in a free flow. Is that not correct?

[ianr33]

I would imagine that smashed second stage would result in a free flow. Is that not correct?

No, I don't think it is.

If you crack the body of a second stage there's no reason for it to freeflow. What will happen though is you may be sucking more air than water when you do inhale. If the diaphragm is nor correctly seated you get the same thing. (Been there done that! )

I think the answer to your original question is that although it may be possible for a reg to suddenly stop delivering gas, the chances of that actually happening are vanishingly remote. So I agree with you the "you can lose half your gas in sidemount" argument is a little overdone

Personally I know I feel safer in sidemount. With appropriate gas planning any single failure can not be life threatening,you don't even have to do anything to fix the problem or close any valves. Just turn the dive and head home. That gives me a warm fuzzy feeling.

I know lots of divers that will do solo cave dives sidemount. Suspect very few would do those dives backmount. (at least without a stage/buddy bottle)

[dumpsterDiver]

This is exactly why I am asking this question. You say BM has more redundancy then SM due to the fact that in SM I can loose half my gas if I have a reg failure. I am not sure if I am asking the question clear enough but I will try again. With SM a free flow can be dealt with by feathering the valve and breathing off of the free flowing reg. Knowing that I would like to know what can happen to make a reg not work completely (you can not breath from the reg at all, no free flow). I understand the debris blocking the dip tube and the tank neck o-ring and burst disk but those issues apply to BM as well so lets forget those for right now. One person mention a cracked/smashed second stage. I would imagine that smashed second stage would result in a free flow. Is that not correct?

No that is incorrect. Why would a smashed second stage necessarily free flow? A 60 second examination of a second stage would reveal this fact?

[Teller]

No that is incorrect. Why would a smashed second stage necessarily free flow? A 60 second examination of a second stage would reveal this fact?

Ok so then I guess a smash second stage would result in a catastrophic failure. Is there anything else?

[Fishpie]

Broken or dislodged demand lever.
Broken spring in 1st stage.

........will result in no or very little gas.

I have had both happen.

[halocline]

Torn/folded diaphragm or exhaust valve would be another. Anything that causes the 2nd stage to flood. I also would not assume that the debris in the tank is the same for manifolds and independents. The dip tube is a big opening; small debris could easily (and does)pass through it and get into the filter in the reg, which clogs much more easily. In that case, the manifold still gives you the gas in that tank.

You're making a lot of assumptions IMO. I would not assume that you can feather the tank valve successfully in all cases of reg failure; maybe in some, but I wouldn't count on it. I'd also just pick sidemount vs backmount based on what configuration you like diving more, not on any perceived safety margin based on 'what ifs.' Both systems have proven to be very safe, with good training and dive behavior. Sidemount is very hip these days; but lots and lots of great divers use manifolds in all sorts of extreme environments.

BTW, you're worried about "losing" your gas, not "loosing" it. It's already "loose" in the tank....;)

[awap]

BTW, you're worried about "losing" your gas, not "loosing" it. It's already "loose" in the tank....;)

At my age, I think I worry about loosing it more than losing it.

[couv]

......I would like to know what can happen to make a reg not work completely (you can not breath from the reg at all, no free flow).....

My DIY friends will have a good laugh at my expense on this one. My very first regulator service attempt caused a complete failure to deliver air. I did not torque down a jam nut on an old Dacor reg and it resulted in the orifice putting so much pressure on the second stage seat no air could flow.

Here are few threads that mention failure modes that fit your criteria:
Warning! Scubapro MK 10 fault [Archive] - ScubaBoard (http://www.scubaboard.com/forums/archive/index.php/t-20310.html)
Scubapro MK20 Cracking Problem Deepens: Undercurrent 08/2005 (http://www.undercurrent.org/UCnow/dive_magazine/2005/Scubapro200508.html)

And one that got the attention of a few of us the: MK 5 turret retainer failure.
http://www.scubaboard.com/forums/regulators/173774-complete-1st-stage-failure-scubapro-mk5.html

[CPH]

Ok so then I guess a smash second stage would result in a catastrophic failure. Is there anything else?

Surely though, if you have a burst hose with a manifold, you just shut the valve and still have easy access to all the gass.

Is there any agency that actually teaches 1st stage swapping underwater?

[Teller]

I didn't say anything about choosing one configuration over another based on this thread. I was just curious. When I said swap regs I meant swap which reg I was breathing from not literally swap a first stage to a different valve. Sorry I figured that went without saying since we were discussing SM.

Based on what everyone has said I am led to believe that it is true that manifold doubled do offer more redundancy due to the unlikely but possible event that a reg encounters a catastrophic failure. Although with proper gas management among your team I wouldn't say SM is any less safe even if you did lose half of your gas at the deepest point in the dive. So I guess it just depends on if you see the glass as half empty or half full.

[CPH]

If this is a discussion about side mount loosing half your gas.... couldn't you just hold your breath long enough to switch the regulator from one tank to another? (Maybe 30 seconds?) That doesn't sound too hard... easier than making a free ascent from 100 feet..



I am not saying that I wouldn't switch regs but lets just say I need both cylinders to surface safely.

Ah I see. From what you said earlier it looked like you were willing to do what Dumpster suggested and swap first stages underwater.