What can cause an out-of-air situation?

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scottfiji

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Apart from actually breathing all of the air in your tank (not paying attention, poor planning, unexpected deco obligation, broken air pressure guage, etc.), I was wondering what type of equipment failure can cause an out-of-air situation, at what rate the air runs out, and if anyone knows of instances where it happened.

Things that come to my mind are burst o-rings or discs on a tank, regulator free-flows or 1st/2nd stage failures, broken low/high pressure hose, etc.

Which of these do people know have actually happened underwater, why do they happen, and how quickly does the air run out (at what rate?) Do most equipment failures cause you to run out of air immediately, or do you have a little "time" before that happens?

Real stories are encouraged! Luckily I have none of my own to share; and if it happened to me, hopefully my buddy would be in sight and reachable.

thanks alot,
Scott
 
Last night at the South Orange County Dive Club meeting we had a speaker from Spare Air. I wasn't able to make it to the meeting, but went onto his website where I found the following:

There are over 21 ways
you could run out of air!
How many can you list?


Forgetting to watch the time and staying down too long.

Using air quicker than planned due to overshooting depth, getting caught in a current, getting lost, nitrogen narcosis, diving in cold water, getting caught in kelp or fishing line.

Sudden regulator malfunction due to corrosion or too much time between overhaul.

O-ring failure on any of the First stage regulator ports.

Regulator stuck in "free-flow" due to foreign particles or sand.

Regulator "freezing up" in cold water leaving you suddenly without air.

Stuck Pressure Gauge reflecting incorrect pressure in your tank.

Air cut off due to tank valve not turned on all the way.

Rupture of SCUBA tank o-ring due to misalignment or wear.

Second stage regulator diaphragm develops a tear or slips out of place.

O-ring failure on BC air inflator or valve stuck in the open position.

Burst disc failure on SCUBA Tank valve due to corrosion or age.

Clogged filter on first stage regulator due to sediment or rust from tank.

Leak develops at any one of the High or Low pressure hose fittings.

Mouthpiece on second stage suddenly coming off regulator.

O-ring failure on pressure gauge.

Rupture of either High or Low Pressure hoses.

O-ring failure on Octopus regulator.

Rental tank not filled completely.

Damaged First stage regulator due to falling object / impact.

High or Low pressure hose cut or severed on sharp rock / impediment.
 
Hi scott- I am sure you will have a wealth of responses to this one- heres my two examples- well three actually.
1) first was a reg-free flow on one of my earlier dive outings- was at about 1200 psi and reg started to go- I did the 'sip' method- slowly ascended, did a 5 min safty stop and got back to the boat with 900 remaining. In this instance, it really wasn;t a problem, but maybe it wasn;t a full free-flow- I dunno.

2) buddy's bc inflator valva got stuck- causing him to have to continually dump air to prvent rapid ascent- ended dive- did safety stop of 5 mins and still had air left.

3) - not strictly fitting in with your criteria, but my very first dive out in OW after my cert was with a buddy who refused to let me check his air gauge (I was a nervous new diver and tryin gto be a god buddy) - I realised why when he starts thumbing for me to ascend- I noticed he hasn't breathing out- long story short- I completed safety stop- he didn;t. He'd sucked it dry. This was the only time there appeard to be a problem.
 
Last weekend my buddy jumps out of the gate on a boat and his dive computer is hooked up on the boat and the high pressure hose rips off. Lots of noise and bubbles as the air escapes. I jumpped in just in case he might need help. He didn't. We both swam to the back of the boat, climbed up the ladder and turned off his air. So now I know that even with an HP hose completely severed it takes more then a couple minutes to drain a tank. (We left the air on so as to keep water out of the reg.)

One other way to run out of air but I only read about this one. Water in the tank.
Lot of water. Then diver turns head down. Water level in tank must be several inches to cover the dip tube but if it does reg shuts off real quick. It's hard to get that much water in a tank.

If your octo were hangging loose, got caught in rocks and then surge pushed you hard you _might_ maybe be able to rip the octo off the LP hose. I think a full tank would empty in 30 seconds.

I did have a real OOA reacently. Guy I was buddied with ran low at 70ft we start to go along anchor chain. Buddy decided it was better to bolt to surface then follow me and ran out of air on the way up. He recoverd after DM pulled him out.



scottfiji:
Apart from actually breathing all of the air in your tank (not paying attention, unexpected deco obligation, broken air pressure guage, etc.), I was wondering what type of equipment failure can cause an out-of-air situation, at what rate the air runs out, and if anyone knows of instances where it happened.

Things that come to my mind are burst o-rings or discs on a tank, regulator free-flows or 1st/2nd stage failures, broken low/high pressure hose, etc.

Which of these do people know have actually happened underwater, why do they happen, and how quickly does the air run out (at what rate?) Do most equipment failures cause you to run out of air immediately, or do you have a little "time" before that happens?

Real stories are encouraged! Luckily I have none of my own to share; and if it happened to me, hopefully my buddy would be in sight and reachable.

thanks alot,
Scott
 
Ann Marie:
Last night at the South Orange County Dive Club meeting we had a speaker from Spare Air. I wasn't able to make it to the meeting, but went onto his website where I found the following:

There are over 21 ways
you could run out of air!
How many can you list?

Thanks, that's a great list.

(Please don't turn this thread into a spare air / pony bottle discussion, there are tons of threads on that already).

I guess I asked my question because I've heard most of those items before, but it seems like if they actually happened, you would probably have a few minutes before all of your air ran out, and you could do a controlled ascent if you weren't able to get to your buddy, specifically with respect to the regulator, hose, and tank failures.

Don't get me wrong, I'm not saying you don't need a buddy or backup-air, I'm just wondering for these equipment failures, how much time you actually have in practice before you are out of air.

All of the stories of CESA's that i've heard have been from people running the air out of their tanks, not from equipment failures. However, I could be completely wrong, and these failures could happen more than I think, and they might expel all of the air in a matter of seconds...any first or second hand experiences?
 
munkispank:
Hi scott- I am sure you will have a wealth of responses to this one- heres my two examples- well three actually.
1) first was a reg-free flow on one of my earlier dive outings- was at about 1200 psi and reg started to go- I did the 'sip' method- slowly ascended, did a 5 min safty stop and got back to the boat with 900 remaining. In this instance, it really wasn;t a problem, but maybe it wasn;t a full free-flow- I dunno.

Excellent example! I was actually thinking of practicing my "sipping" recently.. btw, I assumed you didn't have an octopus? Otherwise, you could have breathed out of that, right?

munkispank:
2) buddy's bc inflator valva got stuck- causing him to have to continually dump air to prvent rapid ascent- ended dive- did safety stop of 5 mins and still had air left.

Another great example.. that's scary stuff.. good thing he got out of it.. there's been a couple long threads about this problem, and what to do about it. It seems to have happened to a few other people.


BTW, I do have one story. I was in the dive shop, and I just had my AL-80 tank filled. A few minutes later, it had a burst disc, and air started coming out like crazy. They said it would take 20-30 minutes for all the air to come out. So they opened the valve all the way to speed things up. Then it took 2-5 minutes, I don't remember exactly.
 
Somewhere in the search feature ( I couldn't find it!) was a member who actually did a test at depth. If my memory is correct, a full AL80 at 100 ft will empty in 30 sec with a blown HP hose/oring.
 
detroit diver:
Somewhere in the search feature ( I couldn't find it!) was a member who actually did a test at depth. If my memory is correct, a full AL80 at 100 ft will empty in 30 sec with a blown HP hose/oring.
Actually..IIRC...I think it was a LP hose rupture he was talking about.
 
JeffG:
Actually..IIRC...I think it was a LP hose rupture he was talking about.

You might be right. Memory is the first thing to go....!!!
 
JeffG:
Actually..IIRC...I think it was a LP hose rupture he was talking about.

The HP hose nipple has a very small orifice which restricts the air flow to a safe level.


Just to add one extra possibility the the extensive list:

- getting carried away in the excitement to fill a big lift bag to get that big brass porthole you just "found" to the surface. It just needed a little more air to get it to move...
 
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