Do you turn the air off or leave it on after setting up on a tank?

[Brett Hatch]

@johndiver999 I understand that you are not making a semantic argument here, and are not arguing for funsies, and have a real point about risk and failure points. Reading your post, I get the sense that we're more or less on the same page here, just maybe expressing it differently.

So the scenario is that a diver has set up their gear, verified everything works, and closed the valve for the bumpy boat ride, perfectly normal. They arrive at the site, and normally they would re-open the valve at that time, but they're distracted or whatever, so neglect to this day, and don their gear. They deflate their BC to become very negative, and roll off the boat for a negative, head-first descent with hands full of expensive equipment, they intentionally hold their breath until 10 or 25 feet, take a breath or two from what's left in the LP hose, and kick down to 35 feet or so. They stop, go to clear their ears, take a breath and no air comes out. Crap!

Now they're sinking like a rock and their ears are about to explode, panic is setting in. They have to choose between dropping or taking the time to clip off their gear to free a hand to reach their valve, or focusing on kicking as hard as they can, or dumping weight, or diverting focus to things that would definitely not help like switching regs, or any number of possible things that will come to their increasingly hysterical mind.

Yeah, I think we can agree that the diver is having a really bad day, and they will be glad to make it out without a serious injury.

I don't think that the stakes are low here, but the stakes are not the only problem. Another problem is the multiple failures of process along the way. Forgetting a step of your setup (turning the valve back on) is one thing, it happens, we're human. But we should strive to put ourselves in a position where one dumb mistake doesn't get us killed. That's why some posters in this thread take a breath or two from each reg while watching the SPG needle (I do this too). That's why some purge the regs after closing the valve. That's why some regularly practice in-water valve manipulation. That's why some people have the colorful knobs that are red when closed. That's why buddy checks are standard operating procedure in many diving circles. That's why many deckhands are in the habit of giving the valve a little twist as you walk by them on the boat (which annoys me, but probably has saved a few people too).

Right? Layers of defense, such that one completely human and completely understandable little thing doesn't increase the stakes from basically none all the way up to life-or-death. I'm not gonna try to convince anybody that these negative descents with no free hands are over-the-top dangerous or anything like that. But if someone is doing this kind of dive and is relying entirely on their memory to keep them out of a nightmare scenario, maybe the should re-think their process, and work some redundant steps into their procedure. That will help to keep the stakes low for any one particular mistake.

 

[Dan]

They deflate their BC to become very negative, and roll off the boat for a negative, head-first descent with hands full of expensive equipment, they intentionally hold their breath until 10 or 25 feet, take a breath or two from what's left in the LP hose, and kick down to 35 feet or so.

I’m not picking on you. I’m just wondering about the statement of having your hands full of expensive stuff scenario while doing fast negative entry is really happening in the real world. I do this kind of entry many times in Galápagos, Cocos, Palau, Sangalaki, Komodo, Raja Ampat and Maldives. You need at least one hand free to pinch your nose and equilize just about every foot of descent, if you don’t want to miss a dive in a 20+ (3-4 dives/day) liveaboard trips. The minute you feel pressure on your ears, it’s too late, the damage is done. I saw those guys, who were not doing that equalization frequently, would skip their 3rd / 4th day of their trip due to ear problem, wasting those expensive trips. I have my camera hanging on my chest D-ring, just in case I need to let go of it.

 

[johndiver999]

@johndiver999 I understand that you are not making a semantic argument here, and are not arguing for funsies, and have a real point about risk and failure points. Reading your post, I get the sense that we're more or less on the same page here, just maybe expressing it differently.

So the scenario is that a diver has set up their gear, verified everything works, and closed the valve for the bumpy boat ride, perfectly normal. They arrive at the site, and normally they would re-open the valve at that time, but they're distracted or whatever, so neglect to this day, and don their gear. They deflate their BC to become very negative, and roll off the boat for a negative, head-first descent with hands full of expensive equipment, they intentionally hold their breath until 10 or 25 feet, take a breath or two from what's left in the LP hose, and kick down to 35 feet or so. They stop, go to clear their ears, take a breath and no air comes out. Crap!

Now they're sinking like a rock and their ears are about to explode, panic is setting in. They have to choose between dropping or taking the time to clip off their gear to free a hand to reach their valve, or focusing on kicking as hard as they can, or dumping weight, or diverting focus to things that would definitely not help like switching regs, or any number of possible things that will come to their increasingly hysterical mind.

Yeah, I think we can agree that the diver is having a really bad day, and they will be glad to make it out without a serious injury.

I don't think that the stakes are low here, but the stakes are not the only problem. Another problem is the multiple failures of process along the way. Forgetting a step of your setup (turning the valve back on) is one thing, it happens, we're human. But we should strive to put ourselves in a position where one dumb mistake doesn't get us killed. That's why some posters in this thread take a breath or two from each reg while watching the SPG needle (I do this too). That's why some purge the regs after closing the valve. That's why some regularly practice in-water valve manipulation. That's why some people have the colorful knobs that are red when closed. That's why buddy checks are standard operating procedure in many diving circles. That's why many deckhands are in the habit of giving the valve a little twist as you walk by them on the boat (which annoys me, but probably has saved a few people too).

Right? Layers of defense, such that one completely human and completely understandable little thing doesn't increase the stakes from basically none all the way up to life-or-death. I'm not gonna try to convince anybody that these negative descents with no free hands are over-the-top dangerous or anything like that. But if someone is doing this kind of dive and is relying entirely on their memory to keep them out of a nightmare scenario, maybe the should re-think their process, and work some redundant steps into their procedure. That will help to keep the stakes low for any one particular mistake.

Well, I think you understood the scenario of cascading problems that I described, but you MIGHT have not caught the nuance of what I do (to help offset my propensity for stupidity and carelessness). After I set up and test: I PURGE the reg.

This step is done so that IF I forget to turn the tank on before I splash, I will get ZERO air. I hopefully will not get too deep without even one fart of air. In addition, IF I remember to check my spg before I splash, I will see ZERO air. IF I pop my inflator for a second before I splash, it will not work, If I tap my purge buttton it will deliver no air. This should signal to even the most distracted diver that they might want to check things. This amounts to exactly what you referred to as "layers of defense".

That is what I do and why I do it. Who knows if it is the best way, but it is what I try to do. I agree that if a diver does the proper pre-dive checks, valve position following set up is probably of little consequence.

 

[Brett Hatch]

I’m not picking on you. I’m just wondering about the statement of having your hands full of expensive stuff scenario while doing fast negative entry is really happening in the real world. I do this kind of entry many times in Galápagos, Cocos, Palau, Sangalaki, Komodo, Raja Ampat and Maldives. You need at least one hand free to pinch your nose and equilize just about every foot of descent, if you don’t want to miss a dive in a 20+ (3-4 dives/day) liveaboard trips. The minute you feel pressure on your ears, it’s too late, the damage is done. I saw those guys, who were not doing that equalization frequently, would skip their 3rd / 4th day of their trip due to ear problem, wasting those expensive trips. I have my camera hanging on my chest D-ring, just in case I need to let go of it.

Dan, the example here was provided by John in post #61. I have not done a dive like this so can't speak to whether it is common to have no hands free. I disagree that it's impossible on ear-clearing grounds, since many divers can clear their ears without pinching their nose. You might want to keep at least one hand free anyway for safety and convenience, I know I would prefer it that way. But I would hope that divers doing these sorts of entries would take enough care gearing up that they would be unlikely to end up in this situation in the first place, with the kinds of double-checks this thread is full of.

Well, I think you understood the scenario of cascading problems that I described, but you MIGHT have not caught the nuance of what I do (to help offset my propensity for stupidity and carelessness). After I set up and test: I PURGE the reg.

You're right, I missed that you are one of the posters who purges the reg after closing the valve.

This step is done so that IF I forget to turn the tank on before I splash, I will get ZERO air. I hopefully will not get too deep without even one fart of air. In addition, IF I remember to check my spg before I splash, I will see ZERO air. IF I pop my inflator for a second before I splash, it will not work, If I tap my purge buttton it will deliver no air. This should signal to even the most distracted diver that they might want to check things. This amounts to exactly what you referred to as "layers of defense".

That is what I do and why I do it. Who knows if it is the best way, but it is what I try to do. I agree that if a diver does the proper pre-dive checks, valve position following set up is probably of little consequence.

Good, then it sounds like we're in agreement. I agree that if you're gonna close your valve, then purging the reg should give you plenty of opportunities to notice when you've forgotten to open it again. You'd have to be really distracted or something to miss all of the signs, so it sounds like a solid plan. Different people will do this differently of course, but as long as they are double-checking themselves somehow or another, they should be OK.

 

[johndiver999]

Good, then it sounds like we're in agreement. I agree that if you're gonna close your valve, then purging the reg should give you plenty of opportunities to notice when you've forgotten to open it again. You'd have to be really distracted or something to miss all of the signs, so it sounds like a solid plan. Different people will do this differently of course, but as long as they are double-checking themselves somehow or another, they should be OK.

Yes and I appreciate your ability to accept a divergent idea without taking it personally or going after the person who doesn't agree with you completely.

I thought of another detail related to this issue. Going back to your "layers of defense" concept, what if the diver does complete ALL the necessary checks of the reg, the BC inflator, the tank pressure, the computer, the BC OP relief valve etc... and then turns the valve off - say because the dive boat has unexpectedly decided to select an alternate dive site 8 minutes away?

If the diver fails to purge the reg after turning valve off, he may wrongly assume that all the detailed checks he did just a few minutes before are sufficient and valid and when he does put the gear on he just makes a cursory check of the spg (showing a full tank)- and erroneously concludes all is good.

I make it a habit of checking the valve position of other divers before they splash. I know this practice would be unwelcome by a majority of the divers on this forum, but I have caught way too many people who have screwed up. Having the reg pressurized and the valve off is, unfortunately not a super rare occurrence in my experience.

So I have to refine my thoughts on the issue somewhat. If you want to leave your regulator pressurized and the valve on - fine. But if you decide to turn it off, just remember to immediately purge the reg - an exceedingly simple thing to do, but something that (if not done) could have significant and non-obvious consequences.

 

[Brett Hatch]

Yes and I appreciate your ability to accept a divergent idea without taking it personally or going after the person who doesn't agree with you completely.

I thought of another detail related to this issue. Going back to your "layers of defense" concept, what if the diver does complete ALL the necessary checks of the reg, the BC inflator, the tank pressure, the computer, the BC OP relief valve etc... and then turns the valve off - say because the dive boat has unexpectedly decided to select an alternate dive site 8 minutes away?

If the diver fails to purge the reg after turning valve off, he may wrongly assume that all the detailed checks he did just a few minutes before are sufficient and valid and when he does put the gear on he just makes a cursory check of the spg (showing a full tank)- and erroneously concludes all is good.

I make it a habit of checking the valve position of other divers before they splash. I know this practice would be unwelcome by a majority of the divers on this forum, but I have caught way too many people who have screwed up. Having the reg pressurized and the valve off is, unfortunately not a super rare occurrence in my experience.

So I have to refine my thoughts on the issue somewhat. If you want to leave your regulator pressurized and the valve on - fine. But if you decide to turn it off, just remember to immediately purge the reg - an exceedingly simple thing to do, but something that (if not done) could have significant and non-obvious consequences.

There's probably other good solutions to that problem, but you might consider this one.

I'm in the habit of taking 2 or 3 breaths from each reg while looking at my SPG, as soon I don the rig. Not so much to specifically address the potential issue of turning off the valve, forgetting to purge, and then forgetting to turn the valve back on. More just as a catch-all, last-second double check. Because before I switch off the big gas tank in the sky, I want to know that there's a bunch of gas on my back, and that I have 2 working ways to access it. When I dive with a pony bottle, I do the same thing before clipping it off.

 

[johndiver999]

Of course that is what everyone should do every time.

 

[Brett Hatch]

I don't understand. If you're already doing that every time, then what's the issue?

 

[johndiver999]

LOL... Not everyone does everything they should - all the time. The issue is to have a simple routine that helps stack things in your favor. Don't leave the tank laying around with the valve off and the reg pressurized.

 

[broncobowsher]

Valve on or off is not the problem. Do whatever you want.
The only problem (that is part of this discussion) is leaving a regulator pressurized with the valve off.
In a perfect world, everything done correctly every time, not a problem. But reality is things are not always perfect. Distractions do happen. Routines get interrupted. Checks get missed. It happens. Deny that it happens and you are setting yourself up for failure.
While depressurizing the reg when the valve is closed will not prevent everything, it will make a damn good indicator most of the time before something bad happens.

I cannot think of a single good reason why keeping a regulator pressurized while the tank valve is off is a good idea on a dive boat. Risk with zero benefit.