Dan
Contributor
Isn't the Aqualung 1st stage diaphragm reg?
1st stage of regulator failed in close position - new diver freaking out a bit :)
- Thread starter david gutkin
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Not at all and for the op I agree. The right tool for the task and a pony bottle is not a panacea for all things scuba.
2airishuman
Contributor
Hello David
Thanks for posting. I believe this is the fourth such occurrence that has been posted here over the time I've been participating in Scubaboard (about a year). Thank you for sharing it.
You followed your training and handled the situation perfectly.
These situations, while uncommon, make it clear that OOA emergencies are not always the result of exhaustion of the gas supply due to poor gas planning. An abrupt failure like this is more difficult to recover from, unlike exhaustion of the cylinder contents where there is typically some warning in the form of progressively more difficult breathing.
There are two approaches to staying safe on dives like this. Either you can work on your skills as a buddy team, or you can bring redundant air of your own, in the form of a pony cylinder or twinset. I bring redundant air on deeper dives -- typically anything over 35' -- when it is feasible to do so. In some travel situations it is simply not practical. If you go this route, get something large enough and familiarize yourself with the tradeoffs and techniques. The best size and means of carrying a pony cylinder are debated endlessly as there is no industry standard.
This is good advice. There isn't any evidence to suggest that cheap regulators are more likely to fail shut during a dive. In fact some of the cheapest downstream piston designs are thought to be most reliable in this regard. But it's not at all clear that the regulator is at fault -- I agree with others that the cylinder valve is the likely culprit.
We'll probably never know for sure but I believe that dD's assessment is sound. Maybe the valve wasn't open all the way, or maybe there was debris clogging the valve passages. Or who knows, maybe it was something with the ACD on the regulator, even though they're supposed to be fail safe.
There's typically about a 4 minute window between loss of air supply and unconsciousness. Varies depending on individual and circumstances, but you can last a lot longer than you think you can. People typically do not lose consciousness in a controlled ascent from 75 feet, but they often panic, and either inhale water or suffer an AGE, either of which can be a life-changing or fatal injury.
Like many, I maintain my own gear, including maintaining my own cylinder valves. I have become very picky about where I get my air fills since contaminated fills can be a major cause of valve and 1st stage failures.
Some people fly with them with the valve removed, some people rent them from the dive op they're using, some people find that a second AL80 makes a great "pony" cylinder.
Based on the information you have provided, I would guess that the cylinder valve was clogged with debris. It is also possible that it wasn't turned on all the way. It is also possible that the problem was a combination of these two factors.
The mechanics of it are that the valve seat and the valve assembly inherently have some elasticity in them. The force on the seat from a full cylinder is somewhere in the neighborhood of 50-100 pounds. If the valve is barely open, the reduced force on the seat can cause it to move a tiny fraction of an inch, which can be just enough that it will no longer flow gas. Temperature changes can also play a role.
During ascent, you weren't breathing from the reg. Chances are that the valve didn't really open, but rather was flowing a tiny amount of gas which accumulated to the point where the SPG would read as it did.
I concur. That is the more likely scenario, based on the information provided.
There is no filter in the valve, although they do have dip tubes to reduce the likelihood of a particle of debris entering. I have no idea what happened in your situation, but in other reports, valve teardowns have shown pieces of rust that abruptly blocked the valve passages, or have shown an accumulation of sooty deposits in the dip tube from poor compressor maintenance.
Well, not when traveling. I have my own cylinders that I use locally, and I do tear the valves down and check them from time to time. When traveling, the best you can do is select the most reliable dive op.
Could it? Depends on the person and whether it's their lucky day. Many scuba divers freedive, even if only to fairly modest depths, and a small amount of experience makes a big difference. There are experienced divers who have been badly injured performing emergency ascents from 25 meters. There are experienced divers who have completed them without incident.
Thanks for posting. I believe this is the fourth such occurrence that has been posted here over the time I've been participating in Scubaboard (about a year). Thank you for sharing it.
You followed your training and handled the situation perfectly.
These situations, while uncommon, make it clear that OOA emergencies are not always the result of exhaustion of the gas supply due to poor gas planning. An abrupt failure like this is more difficult to recover from, unlike exhaustion of the cylinder contents where there is typically some warning in the form of progressively more difficult breathing.
There are two approaches to staying safe on dives like this. Either you can work on your skills as a buddy team, or you can bring redundant air of your own, in the form of a pony cylinder or twinset. I bring redundant air on deeper dives -- typically anything over 35' -- when it is feasible to do so. In some travel situations it is simply not practical. If you go this route, get something large enough and familiarize yourself with the tradeoffs and techniques. The best size and means of carrying a pony cylinder are debated endlessly as there is no industry standard.
This is good advice. There isn't any evidence to suggest that cheap regulators are more likely to fail shut during a dive. In fact some of the cheapest downstream piston designs are thought to be most reliable in this regard. But it's not at all clear that the regulator is at fault -- I agree with others that the cylinder valve is the likely culprit.
We'll probably never know for sure but I believe that dD's assessment is sound. Maybe the valve wasn't open all the way, or maybe there was debris clogging the valve passages. Or who knows, maybe it was something with the ACD on the regulator, even though they're supposed to be fail safe.
There's typically about a 4 minute window between loss of air supply and unconsciousness. Varies depending on individual and circumstances, but you can last a lot longer than you think you can. People typically do not lose consciousness in a controlled ascent from 75 feet, but they often panic, and either inhale water or suffer an AGE, either of which can be a life-changing or fatal injury.
Regarding the "most expensive regulator" --really, I am talking from a pure placebo effectBut key being to have my stuff maintained properly --i keep thinking it was a maintenance issue.
Like many, I maintain my own gear, including maintaining my own cylinder valves. I have become very picky about where I get my air fills since contaminated fills can be a major cause of valve and 1st stage failures.
Some people fly with them with the valve removed, some people rent them from the dive op they're using, some people find that a second AL80 makes a great "pony" cylinder.
Based on the information you have provided, I would guess that the cylinder valve was clogged with debris. It is also possible that it wasn't turned on all the way. It is also possible that the problem was a combination of these two factors.
The mechanics of it are that the valve seat and the valve assembly inherently have some elasticity in them. The force on the seat from a full cylinder is somewhere in the neighborhood of 50-100 pounds. If the valve is barely open, the reduced force on the seat can cause it to move a tiny fraction of an inch, which can be just enough that it will no longer flow gas. Temperature changes can also play a role.
During ascent, you weren't breathing from the reg. Chances are that the valve didn't really open, but rather was flowing a tiny amount of gas which accumulated to the point where the SPG would read as it did.
I concur. That is the more likely scenario, based on the information provided.
There is no filter in the valve, although they do have dip tubes to reduce the likelihood of a particle of debris entering. I have no idea what happened in your situation, but in other reports, valve teardowns have shown pieces of rust that abruptly blocked the valve passages, or have shown an accumulation of sooty deposits in the dip tube from poor compressor maintenance.
Well, not when traveling. I have my own cylinders that I use locally, and I do tear the valves down and check them from time to time. When traveling, the best you can do is select the most reliable dive op.
Could it? Depends on the person and whether it's their lucky day. Many scuba divers freedive, even if only to fairly modest depths, and a small amount of experience makes a big difference. There are experienced divers who have been badly injured performing emergency ascents from 25 meters. There are experienced divers who have completed them without incident.
R
redacted
Guest
As to why the partly open valve is a problem:
A partly open valve will allow some gas to flow but at a reduced flow rate. Your reg acts as a small reservore for your next breath. With a fully open valve, it fills very quickly and you will not see any lose of supply pressure on the SPG and a next breath is immediately available. Even IP normally only drops 10 to 20 %. But if the valve is only open a bit, eventually the reservoer (I can not spell) will not recover fast enough for a full breath. Your response will naturally be to quickly try again. Since the gas is just trickling into the reservore, you will get little to nothing. It will feel like nothing. When you stop trying to draw a breath, the reservore will slowly refill, your SPG will climb and you can probably get another breath and empty the reservior again.
A partly open valve will allow some gas to flow but at a reduced flow rate. Your reg acts as a small reservore for your next breath. With a fully open valve, it fills very quickly and you will not see any lose of supply pressure on the SPG and a next breath is immediately available. Even IP normally only drops 10 to 20 %. But if the valve is only open a bit, eventually the reservoer (I can not spell) will not recover fast enough for a full breath. Your response will naturally be to quickly try again. Since the gas is just trickling into the reservore, you will get little to nothing. It will feel like nothing. When you stop trying to draw a breath, the reservore will slowly refill, your SPG will climb and you can probably get another breath and empty the reservior again.
2airishuman
Contributor
A pony is useful in the specific situation that was described in the opening post. So, for that matter, is a twinset, as @tbone1004 would be quick to point out. Either a pony or a twinset is also the most useful thing to have in the event of a freeflow due to a frozen reg.
The OP encountered problems at 25m (80 feet) while on a liveaboard. I believe it is appropriate for any diver who is skilled enough to dive safely to 80 feet, to dive with a pony -- after learning how to set one up, how to use it, and the various risks.
Captain Swoop
Contributor
I'll state it again, as I've already done elsewhere and got flamed for...
A slightly open (less than a quarter turn) valve WILL NOT be detected by the "breathe your reg and look at your spg" thing. The only way to get that test to work is to ditch the quarter turn non-sense.
Seeing what you present, I'd say it's the most likely even here, a quarter turned open valve...
A slightly open (less than a quarter turn) valve WILL NOT be detected by the "breathe your reg and look at your spg" thing. The only way to get that test to work is to ditch the quarter turn non-sense.
Seeing what you present, I'd say it's the most likely even here, a quarter turned open valve...
LOL! Consider yourself flamed again! Doesn't it depend on the valve? Seems like you are making a mountain out of a quarter-turn molehill, when your concern ought to be running a test that indicates the gas is fully getting to the reg. What if you have a really crappy, dirty valve; are you comfortable just turning it on all the way, or do you want to give it (say) three good breaths while watching the SPG? If you prefer to run the test, then what is the big deal about whether you have turned it all the way open or not? Haven't you run the test and it is OK?
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