Valve (not a) drill

[cerich]

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.

I said it was a compromise didn't I?

I would prefer 3 man teams, I will not dive solo (obvious safety advantages aside it's boring as all get out...).

Nothing we do underwater will make it 100% safe and perfect but we can try to do all we can to evaluate risk and attach sound risk/benifit analayses.

Even in a team of 3(or more) if I experince a massive gass loss I still want as much gas as possible of my own left to me to escape an enviornment that will kill me if much more goes wrong. If a team member has a massive gas loss I'm more than happy to share but want him/her to use what gas they have available before we get into the additional stress of an exit on the long hose.

 

[grazie42]

Unless I was sure, I knew what the problem was, I´d go for the isolator and then start "the guessing game"...Like cerich said, if it´s a bad reg you´ll know, if it´s something more mysterious you have a 50/50 chance of guessing wrong...

I´d prefer the team member to conserve as much gas as possible so that if something really bad happens (he gets cut off from the donors gassupply) he´ll still have some chance of survival...

YMMV

 

[TSandM]

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.

Chris, thanks for this information. I don't think I've ever read anything about buoyancy loss in bubbles, but it makes sense.

A question from the completely ignorant -- if you have a failure which causes air loss at the isolator valve, is it very likely to be anything that will stop if you close the isolator?

 

[cerich]

Chris, thanks for this information. I don't think I've ever read anything about buoyancy loss in bubbles, but it makes sense.

A question from the completely ignorant -- if you have a failure which causes air loss at the isolator valve, is it very likely to be anything that will stop if you close the isolator?

I've attached a picture of the center piece of a manifold. This one is an OMS product, they have 3 orings on each side (highlighted in the picture on one side in red), other manifolds of the same basic design have 2 (OMS added one more on each side as a selling feature). The recommended DIR manifold is this type(not this make however...). In the event of a air loss at the isolator these orings are the most likely to fail (in particular in DIR/GUE the center piece is left loose so it can turn, thus making the orings dynamic vs. static which they are designed to be, I've actually gone away from that and fix my center piece where I want it. I feel the risk of "breaking" the center piece from impact (the DIR/GUE argument for it being loose) is less than the risk of having it move to a place I can't easily reach if I need to shut down and to reduce the likelyhood that these orings will fail).

If these orings are the source of the loss then the isolator will protect the non leaking side from gas loss.

Best,

Chris

 

[cerich]

Chris, thanks for this information. I don't think I've ever read anything about buoyancy loss in bubbles, but it makes sense.

QUOTE]

Because it is so rare. In fact the massive gas loss situation is also very rare. I haven't personally experienced this but know one recreational instr. who has when a students LP hose blew (His name is Brad you can call him at 1-800-601-Dive if you want to ask him about it). But knowing this and knowing the GUE protocol it's easy to connect the dots and see a flaw that isn't being addressed. Unfortunatly, while among the very best training in the business GUE instrs.(not all) and divers tend to narrow things down to DIR or Not, if Not then it doesn't exist....

It's actually kind of funny, Dive computers are bad because it bypasses the most important tool, the brain. The stuff taught by GUE is presented in such a "black and white" method that for many the brain gets bypassed in favor of the DIR method.
AG and I had a conversation regarding this a couple of weeks ago and we both have concerns that students are so attracted to the "way" that critical thinking begins to take a back seat. I'm amazed at how many after a fundies course toss the computer and follow ratio deco with serious flaws in their understanding. (If you follow DIR you've noticed this I'm sure by the simple volume of GUE trained and certified divers asking questions constantly about just this)

Best,

Chris

 

[TSandM]

Okay, you guys keep talking about this. I keep thinking it through and coming up with ideas, but I'm too uneducated to mention them.

BTW, I still have and use my computer . . . And ask questions.

 

[cerich]

Okay, you guys keep talking about this. I keep thinking it through and coming up with ideas, but I'm too uneducated to mention them
BTW, I still have and use my computer . . . And ask questions.

PM me with the ideas, I'll be honest.

The computer, sounds like you know enough to know what you don't know and are smart enough to think independently.

 

[Rick Inman]

...and are smart enough to think independently.

Good God, let's hope not.



eyebrow

 

[TSandM]

Well, I keep trying to be a good lemming, but the analytical part of me is hard to turn off

 

[lamont]

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.

Well, if your long hose shreds and you shut off the right post first, you've actually just done the optimal thing to reduce your gas loss. Shutting down the isolator doesn't stop the loss out of the right tank in that situation.

Plus, I think the moral here is going to be adaptable. If there's a huge bang and a massive jacuzzi behind you and your bowels immediately cut loose, going for the isolator may be a better choice. As a rule, though, I don't think i agree with teaching the isolator first, always. Its most likely to be something solvable by shutting down the right or left post, and if you can reach your valves you should be able to feel the bubbles coming out of one side or the other (otherwise it isn't much of a leak) and can shut down the correct one, that minimizes the gas loss. Shutting down the isolator first in the common situation actually wastes gas while you're doing that shutdown.