Re-using air from BCD in dire emergency?
- Thread starter DareDevil
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The Kraken
He Who Glows in the Dark Waters (ADVISOR)
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Only if I included the boat.
Interesting answers.
I can see the thread has quickly diverted from the original topic toward the mantra seen in other threads "As-you-should-never-find-yourself-in-that-situation-so-there-is-no-need-to-discuss-what-could-happen" which is of course right, nice and fine, but it is also a kind of moot point given the context.
By following the same principle, then a diver does not need to know, much less practice, CESA just to make another classic example.
As the diver is equipped with a computer that monitors depth, dive time, air usage, heartbeat and tank level, has double regulators (maybe triple since there is also a pony), analog backup instruments (depth and pressure gauges), a watch, tables, electrical and chemical lights, a noise source, a deployable buoy and a reel, and of course knows how to compute rock bottom time and, last but not least, has a trusty buddy so NEVER EVER will run out of air. What's the point of knowing how to make a CESA then?
I fully accept the concept behind this way of thinking, since I always dive with most (probably all) the paraphernalia described above because I think those tools and knowledge are going to help either myself or someone else one day, but at the same time, I do not believe I rule the universe and I can avoid always every possible conceivable problem.
The question about using air from the BCD was exactly a "what if" question. IF (not WHEN) I will ever need to resurface from 100 feet without air, I bet I will have to decide pretty quickly whether a) I can hold the breath for 3 minutes and ascend at 30 feet per minute or b) I can work out something using the air from the BCD or just c) dump the weights and skyrocket up the hell with DCS
It seems anyway the air can be used (possibly reused) and of course, as someone soundly pointed out, that air is better compared to water
DareDevil
I can see the thread has quickly diverted from the original topic toward the mantra seen in other threads "As-you-should-never-find-yourself-in-that-situation-so-there-is-no-need-to-discuss-what-could-happen" which is of course right, nice and fine, but it is also a kind of moot point given the context.
By following the same principle, then a diver does not need to know, much less practice, CESA just to make another classic example.
As the diver is equipped with a computer that monitors depth, dive time, air usage, heartbeat and tank level, has double regulators (maybe triple since there is also a pony), analog backup instruments (depth and pressure gauges), a watch, tables, electrical and chemical lights, a noise source, a deployable buoy and a reel, and of course knows how to compute rock bottom time and, last but not least, has a trusty buddy so NEVER EVER will run out of air. What's the point of knowing how to make a CESA then?
I fully accept the concept behind this way of thinking, since I always dive with most (probably all) the paraphernalia described above because I think those tools and knowledge are going to help either myself or someone else one day, but at the same time, I do not believe I rule the universe and I can avoid always every possible conceivable problem.
The question about using air from the BCD was exactly a "what if" question. IF (not WHEN) I will ever need to resurface from 100 feet without air, I bet I will have to decide pretty quickly whether a) I can hold the breath for 3 minutes and ascend at 30 feet per minute or b) I can work out something using the air from the BCD or just c) dump the weights and skyrocket up the hell with DCS
It seems anyway the air can be used (possibly reused) and of course, as someone soundly pointed out, that air is better compared to water
DareDevil
pittyyofool
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god for bid if you ever pick up a cool looking rock or grab a few lobsters or scallops if you get hungry. That will throw your "buoyancy rated pressure gauge" way off, and you might just find your self in an OOA situation while 10 lbs. negative.
the air doesn't really expand because it is stored in a rigid container. But the apparent pressure in your tank will increase by 14.7 psi per ATM (30ft) as you ascend. this will provide you with about 1/2 of a small breath every ATM.
Trust me, been there and done that, tested it. I was EXPECTING to empty my tank, so don't bust my chops for a OOA
and to the OP's ?
do you wand to know how long the air in your bc will last you.
TEST IT!
Sit in your living room, put an average amount of air in your bc. breath out of it, and have a friend time you until you pass out. Then you know. If you really want some kicks; video tape it and have your buddy call in your unsuspecting wife right before you drop to the floor. Ps. put it on youtube and post it here so we and laugh to.
It is a good suggestion after all. However I am not sure CO2 build-up rate would be comparable to the real situation!
Maybe it shouldn't be tried in the living room, but instead fully geared in a Jacuzzi (bubbles would simulate precious air being vented and the frantic rush to the surface), or at the very least, in the shower...
Anubis
it_mike
Contributor
In theory, as has already been posted, the air in your bc will expand as you ascend. You will have air in your bc to offset compression due to depth (neutral is at the surface, not 30'/60'/90'). You could, in theory, get some amount of air from your bc as you ascend, the air you would normally vent, and not rebreath it back into the bc. This would be in tandem with your CESA.
This is all in theory and should not be taken as professional advice. Don't try this at home.
This is all in theory and should not be taken as professional advice. Don't try this at home.
Interesting answers.
I can see the thread has quickly diverted from the original topic toward the mantra seen in other threads "As-you-should-never-find-yourself-in-that-situation-so-there-is-no-need-to-discuss-what-could-happen" which is of course right, nice and fine, but it is also a kind of moot point given the context.
By following the same principle, then a diver does not need to know, much less practice, CESA just to make another classic example.
As the diver is equipped with a computer that monitors depth, dive time, air usage, heartbeat and tank level, has double regulators (maybe triple since there is also a pony), analog backup instruments (depth and pressure gauges), a watch, tables, electrical and chemical lights, a noise source, a deployable buoy and a reel, and of course knows how to compute rock bottom time and, last but not least, has a trusty buddy so NEVER EVER will run out of air. What's the point of knowing how to make a CESA then?
I fully accept the concept behind this way of thinking, since I always dive with most (probably all) the paraphernalia described above because I think those tools and knowledge are going to help either myself or someone else one day, but at the same time, I do not believe I rule the universe and I can avoid always every possible conceivable problem.
The question about using air from the BCD was exactly a "what if" question. IF (not WHEN) I will ever need to resurface from 100 feet without air, I bet I will have to decide pretty quickly whether a) I can hold the breath for 3 minutes and ascend at 30 feet per minute or b) I can work out something using the air from the BCD or just c) dump the weights and skyrocket up the hell with DCS
It seems anyway the air can be used (possibly reused) and of course, as someone soundly pointed out, that air is better compared to water
DareDevil
Well said DareDevil. I totally agree. Obviously no one is saying that the BC is the primary source of emergency breathing air, but it may be better than nothing.
In the past, the rebreathing of air has been employed with safe ascents from depths of over 600 feet (successfully employed for submarine escape in the early 60's from 270 ft). Although I would not discount the value of this air source, a concerned would be the possibility of aspiration from using the inflation mouthpiece.
From reading The Terrible Hours, IIRC, the rebreathing that was done by the Navy actually involved a sort of scrubber.
There are a lot of reasons not to breathe the air in your BC. There isn't (or shouldn't be) very much of it, it will build up CO2, and may contain organisms that could put you at risk for pulmonary infection. (Although I chuckle every time I read this, because anybody who has been in a dust storm has probably breathed as many fungal organisms as they'd get out of a couple of BC breaths -- normal lungs are pretty resistant to infection.) But the bottom line is that breathing ANYTHING that has oxygen in it is better than suffocating and drowning. And the gas in your BC has oxygen in it, and no CO2, and is therefore breathable.
I hope I never have to remember that.
There are a lot of reasons not to breathe the air in your BC. There isn't (or shouldn't be) very much of it, it will build up CO2, and may contain organisms that could put you at risk for pulmonary infection. (Although I chuckle every time I read this, because anybody who has been in a dust storm has probably breathed as many fungal organisms as they'd get out of a couple of BC breaths -- normal lungs are pretty resistant to infection.) But the bottom line is that breathing ANYTHING that has oxygen in it is better than suffocating and drowning. And the gas in your BC has oxygen in it, and no CO2, and is therefore breathable.
I hope I never have to remember that.
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