Valve (not a) drill

[TSandM]

Rob, as a fledgling reading this discussion, is there not value in making a list of the possible failures that cause air loss at the different sites, and then sitting down and figuring out which ones are "fixable" and how they are fixed, and which ones are "unfixable", so that you don't waste time trying to fix them? Or will it not be apparent enough what kind of problem you have to make that kind of mental checklist worth while?

 

[Diver0001]

Well.....My thinking is this. If there's a big problem you're going to know pretty much immediately *where* the problem is--left or right. That's all you really need to know to make a decision about what to do. Knowing *what* the problem is/was can come after you've secured the air supply, when you have the time. Maybe even after the dive.

If you make a big "decision tree" out of these things then you'll spend too much time wondering what's going on or even getting confused about what to do. The response you need to train is to just shut down the post where all the noise is coming from and *then* think about what to do about the problem.

There is also some debate possible about whether or not to isolate at all or isolate first or last. Personally, I'm in the "last" camp based on the thinking that a blown manifold or tank neck is much less likely than a problem with the reg. If shutting down the post didn't work to stop the air loss then I would isolate it. Other people have differing views about this.

R..

 

[cerich]

In my experience reg issue are easy to i.d. and shut down the post. It when you have honking amouts of air from behind you that things aren't so clear. Isolate the manifold then try to specify the issue and IF a post being shut down will stop the gas loss.
A tank oring, I've seen them hiss (no big deal) and extrude and blow (think huge noise and bubbles), burst disc will show/sound like an extruded and blown tank oring.

 

[Diver0001]

In my experience reg issue are easy to i.d. and shut down the post. It when you have honking amouts of air from behind you that things aren't so clear. Isolate the manifold then try to specify the issue and IF a post being shut down will stop the gas loss.
A tank oring, I've seen them hiss (no big deal) and extrude and blow (think huge noise and bubbles), burst disc will show/sound like an extruded and blown tank oring.

Well.....I'll have to concede to your experience on this. I've never seen something blow-out bad enough that I didn't have a clue where it was coming from.

I can only speculate that if you've blown one side of your manifold or a tank o-ring that a quick feel with your hand will tell you which side needs to be shut down. Even at that, I think we would agree that you should focus on where the sound is coming from and forget about all the if-then-else scenarios.

R..

 

[Kevrumbo]

First a question. Have you had a gas loss due to a manifold issue? (neck oring, burst disc, centerpiece oring issue, din issue) I have experienced one and been in the water when members of my team have. I have also dealt with reg failures which honestly are a separate beast. If you have then I am shocked that you find my arguments convoluted, simply because they are based on reality.

My "suppositions" are based upon real world experience of how these failures manifest themselves and real world experience of how quickly planning goes out the window in an emergency. There is a reason that 1/6's vs. 1/3's is recommended in a Cave 1 diver and that has to do with the fact that gas at 1/3's will not be sufficient in a emergency. At higher levels of diving, 1/3's is a compromise between the mission and a reasonable margin of safety. In reality at or near turn 1/3's is woefully short of the amount of gas required to deal with an emergency, particularly in a two diver team.

I'm not talking fundamental type dives, I'm addressing more significant technical diving.(yes, i am fully aware that DIR is used in significant dives). It is my belief however that even in the fundie level of training the drill must be taught in a fashion that will also apply as the diver advances.

Your reply is exactly what I asked not to get, which boils down to "this is what I was taught and it's DIR so it must be right" You used "heuristically sound approach for problem solving Post & Manifold Failures/Malfunctions" which sounds impressive but doesn't address my points, it side steps it with boilerplate.

Which part in particular do you disagree with? Why?

Show me where I'm wrong, not just a party line.
Best,

Chris

Exactly because that's not how I was trained; your real life anecdotal experiences, methods & rationale are not necessarily wrong, but I'm having trouble relating it to the step-by-step schema of the GUE approach --which IMO makes better inductive and qualitative sense. Therefore I choose to retain and stand by the methods I was taught and are comfortable with, especially in this most critical skill. I'll leave it there for others to address your points. . .
Good Diving,
Kevin

 

[Kevrumbo]

Rob, as a fledgling reading this discussion, is there not value in making a list of the possible failures that cause air loss at the different sites, and then sitting down and figuring out which ones are "fixable" and how they are fixed, and which ones are "unfixable", so that you don't waste time trying to fix them? Or will it not be apparent enough what kind of problem you have to make that kind of mental checklist worth while?

Lynne, to use a drastic analogy, this is like a Patient presenting with Full Cardio-Respiratory Arrest: Priority Basic Life Support Procedures and Vitals Stabilization is paramount; leave the Case Study Etiologies for later. . .

 

[TSandM]

Yeah, but if the cause of arrest is a tension pneumo, you aren't going to get the patient back until you fix it

It seems like priority one is stop the gas loss, if it can be stopped. That's the valve drill sequence, and it seems as though there are legitimate arguments for putting the isolator at two different points in the sequence. Once the gas loss is stopped, the second priority is determining whether the cause is something which can be corrected underwater, or whether your ascent/exit will have to be managed with something turned off . . . and if so, what modifications have to be made on that basis.

Still seems as though thinking through the causes and having a ready remedy for the fixable ones would be a worthy mental exercise -- even if done above water.

 

[lamont]

My "suppositions" are based upon real world experience of how these failures manifest themselves and real world experience of how quickly planning goes out the window in an emergency. There is a reason that 1/6's vs. 1/3's is recommended in a Cave 1 diver and that has to do with the fact that gas at 1/3's will not be sufficient in a emergency. At higher levels of diving, 1/3's is a compromise between the mission and a reasonable margin of safety. In reality at or near turn 1/3's is woefully short of the amount of gas required to deal with an emergency, particularly in a two diver team.

IMO, i think that argues for not diving 1/3rds, particularly with 2 diver teams, rather than fiddling to try to optimize your gas shutdown routine.

 

[Kevrumbo]

Yeah, but if the cause of arrest is a tension pneumo, you aren't going to get the patient back until you fix it

Good point . . .as a First Responder though, all I can do is to just continue compressions and ventilations 'til I get Paramedic Support & Transport

It seems like priority one is stop the gas loss, if it can be stopped. That's the valve drill sequence, and it seems as though there are legitimate arguments for putting the isolator at two different points in the sequence. Once the gas loss is stopped, the second priority is determining whether the cause is something which can be corrected underwater, or whether your ascent/exit will have to be managed with something turned off . . . and if so, what modifications have to be made on that basis.

Still seems as though thinking through the causes and having a ready remedy for the fixable ones would be a worthy mental exercise -- even if done above water.

It is a worthy exercise and very much covered in Lecture during the Tech 1 Class. . .

 

[cerich]

Exactly because that's not how I was trained; your real life anecdotal experiences, methods & rationale are not necessarily wrong, but I'm having trouble relating it to the step-by-step schema of the GUE approach --which IMO makes better inductive and qualitative sense. Therefore I choose to retain and stand by the methods I was taught and are comfortable with, especially in this most critical skill. I'll leave it there for others to address your points. . .
Good Diving,
Kevin

Fair enough. My method is still a step by step approach just different in what I approach first. My first concern is to reduce gas loss, then determine exactly where I'm losing it from and if I can fix it. What is broken is less important that the result of something being broken. The set approach you have been taught works, but it's slower to address the need to conserve gas. It's also does not take into account that "minor" (think not "big noisy fast" loss) and "major" will not present the same at all. Short of unscrewing a burst disc on your back untill you see a major gas loss in the water it's hard to visualize how scary, loud and crazy things get.

My other concern, and I just would like you to think about this. The method you have been taught calls for a team member to swim up and examine your manifold to assist in the I.D. of the problem. You are horizontal (I hope ). That means your buddy might decide to be above you(were you taught how to approach this?). If you do have a massive gas loss issue your buddy NEEDS to stay out of the bubbles. If they enter the very large bubbles (which there will be) they will have an instant and massive loss of bouyancy causing you to have a buddy on your back. It will add more trouble to an already bad situation. Fixable but adding to the "snowball rolling downhill" your team needs to deal with.

In the event you do penetration diving (wreck/cave) also be aware that another aspect of one team member having a massive gas loss is that visibility will very quickly reduce to zero (not all the time but more often than not) While everything else is going on, you and your teams members MUST get in physical contact with your guideline and be prepared to make a "Braile" exit. In some enviornments this area of low vis. will follow you out.

Best,

Chris