Shutting off a single tank diver's air supply in a free-flow?

[dumpsterDiver]

I'm finding this thread to be fascinating -- not so much for the content but for the mindsets and assumptions. The vast majority of posters seem to believe that the "average" diver is not very competent and can't be trusted to do an air sharing ascent without some problems. In addition, an additional prime assumption is that the "injured" diver's "buddy" is pretty damn worthless.

Given those assumptions, I suppose I'd agree that the best thing to do is to immediately go up with the hope that there will be enough gas to breathe from the free flowing reg all the way to the surface -- and that the free flow won't blast the mask off, won't rattle the diver in other ways and that she'll keep her wits about her NOT to cork and/or embolize because she got so nervous she actually forgot to breathe.

Me, MY assumption is that I'm going to have a competent buddy and that my buddy will kindly provide me with a working reg and then kindly turn off my free flowing gas. We will then exit from wherever we are and go to the surface in a calm and reasonable manner -- and if I need the gas that is still on my back, I'll be able to reach the valve and open it OR have my buddy (to whom I'm attached) reach over and open it.

Just a matter of assumptions, is it not?

Yes but important assumptions. I have no doubt that you would be comfortable doing this procedure with a good buddy. But is it to be recommended for the typical recreational diver?

I used to dive with my younger brother and he was less expereinced and would use more air than me. Often about half way through the dive we would remove our scuba units (BC/tank/reg) and switch them in order to extend the dive. We would sometimes do this in 90-100 feet of water on an ocean dive. Many people would think this is not advisable for most recreational divers (to extend a dive), but we felt comfortable doing it.. Guess it is all about perspective on issues like this.

Also you should not make the assumption that the diver MUST breath from the freeflowing reg on ascent if there is no valve shut down. If it bothers them too much, then they might be able to breath from their own octopus instead.

 

[Doc Harry]

...An uncontrolled free flow for the diver following the Rule of Thirds should always have him with enough air to make a direct ascent from sport diving depths...

Hmmm.... I think your assumptions require re-evaluation.

In my free flow incident, I had a free flow near the start of my dive (i.e., nearly full AL80) at 70 feet and I was OOA before I got to the surface.

I spent a minute or two fiddling with the regulator. When I realized the free flow wasn't going to stop, my buddy was already at my side. We started ascending together and shortly thereafter I was already OOA.

 

[TSandM]

Yes, I think most people would spend at least a little time trying to get the freeflow stopped. I know I did. During that time, you're losing gas. My freeflow occurred at 30 fsw, when I still had about 2000 psi in a 95, and the tank was empty before we got to the surface. It doesn't take long (IIRC, about 90 seconds in an Al80).

I think, even in the revised circumstance, I would turn the tank off -- But I would have a DEATH grip on the other diver and I would do everything I could to make sure I had that person's attention, and to convince them that I was in control of what was going to happen. And I would have my teammate/s with me, and they would understand what was happening and be prepared to assist as well.

 

[Peter Guy]

Couple of preliminary comments -- You can always change the assumptions to get the answer you "want" and yes, there are conditions under which I wouldn't share gas with someone (for example, he was waving a knife at me!), I wouldn't turn off the free flowing reg (too much panic), etc.

Now, given YOUR current assumptions, what would I do and why?

a. First of all, I'd donate my reg so that the diver was breathing off a good working reg with lots of gas.

b. Second, I'd "assist" her in holding the free flowing reg FAR AWAY from her body -- as far as possible, which means I'm also holding onto her.

c. I'd assess the situation -- is she OK, is she ready to bolt, what is the situation with her AT THAT TIME with a working reg and NOT having a bubble shield blow her mask off.

d. IF she responded and looked OK, I'd shut her valve off -- all the time holding onto her and giving as much calming influence as I could.

e. I'd wait around a little while (count to 10?) to see how she's doing, then I'd start the appropriate ascent -- which might mean swimming upslope to shore, over to the upline or whatever -- depends on the situation.

Why this procedure? I've not had a free flowing reg but I've been with a buddy who has had such and there are a LOT of bubbles which are very distracting both physically, visually and audibly. Once the buddy is under control, then stopping the distraction is a very good thing to do.

In OW, one of the standard drills is to breathe off a free flowing reg for 60 seconds. I've watched new students do this drill many times and they do it, no problem -- well, not so much NO problem, but they do it. Many learn that unless they do it "just right" they lose their mask and, at least from my limited experience, having a "new diver" lose their mask on top of everything else, would just about blow them out of the water. Thus, I'd never try to keep them breathing off a free flowing reg IF there was a reasonable alternative, that is, my working reg.

Once they are on my working reg, what's the benefit of having all that gas flow into the water? None that I can think of, so why NOT turn off the valve?

Re the comment about gas planning by Nemrod -- I don't know who taught you the "Rule of Thirds" but my understanding is that it only applies when you HAVE to get back to your starting point (i.e. the upline in a non-overhead environment). On a drift dive the "rule" is all available gas -- you dive until you hit your minimum reserve and then you surface because the boat is there to pick you up; on a shore dive the "rule" is halves -- it's nice to get back to where you started but you don't have to. In those two cases, you can have your free flow late in the dive and your tank will probably be empty very quickly!

The best alternative is NOT to try to suck gas from a fire hose while trying to keep your mask on but to sip it from someone else's working reg.

 

[String]

On the other issue, I would think that shutting down someone else's valve on a single tank diver qualifies as homicide in most jurisdictions.

Only those run by mentally deficient lunatics that lack the mental capacity to walk and talk at the same time. What next? Attempted suicide if you feather your own valve?

The best thing is to get both of you to the surface, without delay, since one of you, if not both, is going to have an empty tank very soon.

Not necessarily if its at the start of a dive and its turned off quickly.

Imagine not being able to inflate your B/C-vest-BPW, judging from how overweighted many divers are these days?

Oral inflate. Its taught from day 1 in all courses.

Breathe (that would be the problem, on a long term basis).

You have enough time.

Think (better abort this dive and get to the surface).

So think about getting on an AAS while getting the valve turned off to defrost.

Drop weight belt at the surface (just to be extra safe - I know I know most people won't do this).

Why bother? Orally inflate jacket. Float happily.

Avoid further diving today, due to omitted safety stop.

Firstly why not just share air and do the stop? Secondly, a safety stop is optional. It doesnt preclude further diving. Its not a mandatory stop.


Someone else mentioned thirds here - that isnt guaranteed to help. If the guy with the freeflow has a higher gas consumption than the other guy its not impossible that 1/3 gas will not be enough for 2 divers.

 

[sabbath999]

My freeflow occurred at 30 fsw, when I still had about 2000 psi in a 95, and the tank was empty before we got to the surface. It doesn't take long (IIRC, about 90 seconds in an Al80).

During training OW training (I assume this is done with every training class and that it is a required skill, don't know) the last thing we did was learn to breath from a freeflowing regulator (holding in purge valve and sipping off of the air)... they save it for last because it blows through the air so quickly.

I ran out of air (down to 500 PSI not REALLY OOA) before this drill, so they set me up with a new tank with 3000 in it (AL80). I did it with the rest of the class and went through 400 PSI in just a few seconds. The instructor told the rest of the class who had about emptied their tanks to gather around me. He grabbed my console, and had me duck under and continue the exercise so that he could count off to the class how quickly the air was being blown out... it was shocking how fast that tank emptied, while at the same time it was kind of cool (since it was training and I was standing in water that came up to my chest so there was zero danger). It took about 35 seconds until he tapped me... the tank was down to 300 PSI.

Totally beside the point, I found it fascinating how a person can "drink air" that way, breathing like you are sipping on a water fountain. It is one of those things that you can't adequately describe to non-divers (at least I can't). Generally, when we get done with our dives, I go through more air than my wife does... she generally has 1000 pounds left in her tank when I am OUT (again, for use OUT=500 PSI), so what we do (on our training dives) is do the OOA drills on her regulator. We haven't practiced turning the air off, but frankly when I think about how fast the tank empties on a free flowing regulator I am not really sure how helpful turning it off would be (except to aid buoyancy... an empty AL80 would add a lot of lift I wouldn't necessarily want.)

DISCLAIMER, as I always try to say, I am a NOOB and therefore don't know what I am talking about, so please don't take anything I say as coming from somebody who is experienced enough to know his ass from a hole in the ground.

 

[Dtaine]

Couple of preliminary comments -- You can always change the assumptions to get the answer you "want" and yes, there are conditions under which I wouldn't share gas with someone (for example, he was waving a knife at me!), I wouldn't turn off the free flowing reg (too much panic), etc.

I think I know what you're referencing about the knife.

I don't want any specific answer - I just wanted to see if people would do the procedure differently with a known buddy or a new OW diver, thanks for playing along.

 

[Web Monkey]

With the new situation, I'd share air, drop the offending reg behind the OOA diver, grab his BC, and do a nice normal air-sharing ascent. On the surface I'd inflate me, and if he doesn't inflate himself immediately, I'd do it, manually if necessary.

I wouldn't bother turning off his tank, since it's only an annoyance at that point, takes time and removes my attention from the diver. At that point i don't care about the tank. Whoever owns the tank can deal with the VIP. I'm only worried about the diver.

This is different from the first scenario because I maintain sufficient reserve air pressure to always be able to do an air-sharing ascent and dive with a cold-water reg that won't freeflow.

Terry

 

[Web Monkey]

You can always change the assumptions to get the answer you "want" and yes, there are conditions under which I wouldn't share gas with someone (for example, he was waving a knife at me!),

I can't say why, but I've recently started wearing a knife-proof drysuit.

Terry

 

[Nemrod]

Hmmm.... I think your assumptions require re-evaluation.

In my free flow incident, I had a free flow near the start of my dive (i.e., nearly full AL80) at 70 feet and I was OOA before I got to the surface.

I spent a minute or two fiddling with the regulator. When I realized the free flow wasn't going to stop, my buddy was already at my side. We started ascending together and shortly thereafter I was already OOA.

Per yourself you spent a "minute or two fiddling" with the regulator. Did you read what I said. I said to signal to your buddy and begin an IMMEDIATE ascent. From 70 feet, let's do the math, at 60 FPM thta is a 70 seconds. You said you fiddled for a minute or two, there was your error.

N