Strange event, no air

[mrtechbench]

There is a gas exhange. The air in my lungs was 32% at start of event, the exchange would have been reduced but not stopped..

Imla:
Question: What was your rationale for not going straight to the surface when you had two failing regs? If you are not breathing, you are not really offgassing either, so a safety stop is neither effective nor warranted? Wouldn't the safer option be to surface sooner?

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That was my question too Imla, I wonder how much gas exchange happens when you're not breathing.

 

[johndiver999]

I don't think that the amount of offgassing that takes place when you pause on a single breath at 20 feet is significant, but your heart is beating, your blood is circulating, and the lungs are filled with nitrox, so nitrogen should be moving from the blood into the lungs, during the pause.

I think it is analogous to freedivers (who absorb N2 at depth), even though they are not actively moving air in and out of their lungs.

The safe resolution of this failure, is another example (in my mind anyway) of the benefits of freediving and general comfort in the water.

 

[BRT]

Imla:
Question: What was your rationale for not going straight to the surface when you had two failing regs? If you are not breathing, you are not really offgassing either, so a safety stop is neither effective nor warranted? Wouldn't the safer option be to surface sooner?

#####
That was my question too Imla, I wonder how much gas exchange happens when you're not breathing.

Going too far down that road will make you believe that people who use less air have less chance of the bends if they breathe faster as they come up.

 

[pauldw]

Y'all are confusing me. I thought proper ascent rate was as fast as your smallest bubbles. Am I several decades out of date?

 

[Pressurehead]

the critter and began moving their way, not that far. Noted my spg was reading 1200 psi so I wanted to group up before ascent. Then no air, none. Just like that. The last breath, I may have noted a flutter but thought nothing of it. Hmmm, well, hmmm. A moment of disbelief, third dive of the day so I did want to do a bit of a safety stop. Am I imagining this? Inhaled again, absolutely nothing. Okay, let's not delay switching regs like in my other event (not going into here from a few years back, much deeper though) so I went to my BCI, got one little bit of a breath and nothing. Started up. Got to 15 feet, now about a minute since last full breath. Checked my Shearwater, it was in safety stop and was counting down. Tried to inhale again and got another little bit of air. Now about a minute and half since last good breath. I wanted some air really bad by about then so now at 2 minutes approximate since last breath I decided to surface and hit the surface I would say at 2:15 since last breath. Hit inflator button and very little to nothing. Spit reg out and clipped it off, took some sweet breaths, orally inflated and just hung there a moment resting and ventilating and mulling the event over. Boat swung over and picked me up. Tank was at 1000 psi on the boat. Double checked with another regulator with both spg and AI, 1000 psi! No doubt. Oh, yes, we did check the valve to be full on and it was. No roll off, no partial valve. And with the reg removed air flowed from the tank as normal.

It being dark now I did not see anything wrong and after turning the tank valve on and off the regulator began to function again but with a huge spg drop with each cycle. So I get back to the room, toss the reg aside and grab my Mark 17E and G260 set for the next day of diving and went to eat. Next day after dives complete I got back to looking into what went wrong. Guess what I found? Two things actually. One, the LP regulator hose was loose and the O-ring was partially extruded but not leaking. Then I looked at the regulator sintered filter to see if there was some sort of crud or FOD. Yep, there it was, a destroyed tank O-ring was completely shoved into the cone of the sintered filter obscuring the inlet of air.

So, there was an O-ring on the tank and it passed pre dive leak check. Pre dive spg check there was no unusual spg drop or indication nor during the 45 minutes in the water until the sudden no air event. So where did the O-ring come from, well, beats the cxxp out of me because it was NOT in there before the dive. The tank O-ring was in place before, during and after event. My two guess are that the O-ring may have come from the previous tank when the crew blew out the cap and that it was not seen in the dark when the regulator was

My take awayso

Check filter before installing the regulator
Check hoses tight during pre dive checks
Make sure valve is full on
Test for spg drop when cycled

Number 4 on this list saved some drama only yesterday 'Test for SPG drop when cycled" I have been diving in Bali for a week and insist I alone put my gear together and check the gas on/off ,the local boat driver decided to check my gas ,and of course, turned it off, I tried to cycle a couple of breaths only to see the SPG drop to zip. Another reason I will not give up my SPG even though I carry 2 computers (OK, only one is AI) . Thanks for the heads up Nemrod.

 

[Nemrod]

 

[USdiver1]

Nem, Glad to see that the only post-mortem analysis concerns how your regulator acquired an o-ring. You are an experienced diver, not a noob and didn't panic when faced with an OOA situation. You passed the test.

You were diving +/- 30 feet of DSW and on NITROX-32, and had for all practical purposes an infinite NDL profile. Therefore, off-gassing nitrogen is not an issue, and the only concern I would have in skipping a safety stop and ascending faster than 60 FPM would be regarding air embolism from a rapid ascent.

You kept your regulator in your mouth, attempted with limited success to suck a bit more gas out through your regulator, not a blow and go, but if you were trying to get more into your lungs, they must have been underinflated, again you passed the test.

How did that o-ring get there? Did you or a member of the dive boat crew put your reg on the tank? If it was a crew member, could the o-ring have come loose, entered your first stage, and then the regulator was taken off, a new o-ring placed on the valve and everything hooked back up? Is it possible that there were two o-rings on the valve and one extruded and was thereafter blown into your 1st stage?

Should you have been closer to your dive buddy? Maybe, but given the circumstances of a shallow dive at night, it is almost easier to self-help than wait for another to come to assist.

 

[Nemrod]

How did that o-ring get there? Did you or a member of the dive boat crew put your reg on the tank? If it was a crew member, could the o-ring have come loose, entered your first stage, and then the regulator was taken off, a new o-ring placed on the valve and everything hooked back up? Is it possible that there were two o-rings on the valve and one extruded and was thereafter blown into your 1st stage?

The DM installed the regulator. I did watch them put it on and I did tidy it all up and recheck. They wanted all gear and everybody ready to go before the boat left the dock. It was a small panga so it is easier for the crew to do the set up than having a bunch of divers and crew slinging gear and bags and stepping on one another. I handed him the regulator and I looked it over including the filter as did he but it was getting dark. The Scubapro cap is hollow inside, I think I put the cap back on before handing him the regulator. I did not look inside that cap. But how would it get from the cap to the valve, I do not know.

There were no issues installing the reg, it went right on and sealed up and held pressure and cycled normally with no spg swing or drop. As to where the O-ring came from, I have no ideas other than what I said in the first post. I guess it is possible that there were two O-rings on the tank and the outer one was squeezed inward when the reg was installed and subsequently into the sintered filter and then 45 minutes later into the dive blocked the flow. I do not know. I have come to believe but cannot prove or disprove that the O-ring was down in the dip tube.

 

[Scott G. Bonser]

I am going to post this in Basic, if it needs to be moved, please do. So then, I was diving a just serviced (by me) G250, brand spanking new Mark 11 (around 50 dives since new) and new DGX BCI on a night dive in Cozumel, Paradise Reef. Shallow, maybe 30 feet, 40 maximum maybe. Dive was going well seeing the usual critters and on the look for the elusive octopus. Nothing unusual. Nitrox 32% mix, regulator performing wonderfully for previous four days. I found a little critter and began to photo and of course, my group moved a little off due to the current. I decided they (and buddy) were getting too far so I left the critter and began moving their way, not that far. Noted my spg was reading 1200 psi so I wanted to group up before ascent. Then no air, none. Just like that. The last breath, I may have noted a flutter but thought nothing of it. Hmmm, well, hmmm. A moment of disbelief, third dive of the day so I did want to do a bit of a safety stop. Am I imagining this? Inhaled again, absolutely nothing. Okay, let's not delay switching regs like in my other event (not going into here from a few years back, much deeper though) so I went to my BCI, got one little bit of a breath and nothing. Started up. Got to 15 feet, now about a minute since last full breath. Checked my Shearwater, it was in safety stop and was counting down. Tried to inhale again and got another little bit of air. Now about a minute and half since last good breath. I wanted some air really bad by about then so now at 2 minutes approximate since last breath I decided to surface and hit the surface I would say at 2:15 since last breath. Hit inflator button and very little to nothing. Spit reg out and clipped it off, took some sweet breaths, orally inflated and just hung there a moment resting and ventilating and mulling the event over. Boat swung over and picked me up. Tank was at 1000 psi on the boat. Double checked with another regulator with both spg and AI, 1000 psi! No doubt. Oh, yes, we did check the valve to be full on and it was. No roll off, no partial valve. And with the reg removed air flowed from the tank as normal.

It being dark now I did not see anything wrong and after turning the tank valve on and off the regulator began to function again but with a huge spg drop with each cycle. So I get back to the room, toss the reg aside and grab my Mark 17E and G260 set for the next day of diving and went to eat. Next day after dives complete I got back to looking into what went wrong. Guess what I found? Two things actually. One, the LP regulator hose was loose and the O-ring was partially extruded but not leaking. Then I looked at the regulator sintered filter to see if there was some sort of crud or FOD. Yep, there it was, a destroyed tank O-ring was completely shoved into the cone of the sintered filter obscuring the inlet of air.

So, there was an O-ring on the tank and it passed pre dive leak check. Pre dive spg check there was no unusual spg drop or indication nor during the 45 minutes in the water until the sudden no air event. So where did the O-ring come from, well, beats the cxxp out of me because it was NOT in there before the dive. The tank O-ring was in place before, during and after event. My two guess are that the O-ring may have come from the previous tank when the crew blew out the cap and that it was not seen in the dark when the regulator was installed and then somehow getting into the filter cone? Or, at the fill station an O-ring was accidentally shoved into the valve during fill and was in the valve dip tube and that the "flutter" I noted on the last good breath was that O-ring being shoved into my regulator filter. Or, I am at a loss.

After several tests and checking the Mark 11/G250/BCI on a near empty tank the regulator was performing normally and I resumed using it. Of course having removed the destroyed O-ring. The cleaning custodian unfortunately wiped the counter and I do not have the O-ring. I guess if one dives long enough weird things can happen. It was not such a big event due to being on a shallow reef with no deco obligation. Had I been on the wall, in a deep swim through, who knows. I do look at and check my regulator prior to diving. In the dark I guess I did not see the O-ring there but that is unlikely therefore I favor the hypothesis that the O-ring was not there but was inside the tank. Because I did look, but, you know, I did not have my glasses on, it was getting dark, everyone was ribbing each other, the usual distracting fun banter we all love. So -----.

My take aways:

Check filter before installing the regulator
Check hoses tight during pre dive checks
Make sure valve is full on
Test for spg drop when cycled
XHopeX there is no FOD in the provided tank

Well, we could dive doubles always or have Y valves with two complete regulators or have an auxiliary pony bottle type system. I am not advocating for any of that. Or keep your buddy at arms length. That right there is on me because the critter was much more cute than my sorta-buddy and I wanted a good picture, which turns out the photo sucked as usual. There you go.

Hey there my friend. I am glad you are OK. I reckon when you are a frequent diver, things like this can happen. My OOA was in ‘78 and no gauge or spare air on a working dive. Just a ‘J’ valve that got flippped on an u/w survey stake and partner that was 220’ upstream. So glad I was in 45’ of murky, cold water with strong current and in much better shape than today. It really makes you think and develop a sense of inspection vigilance. It did for me.

 

[CT-Rich]

I don't think that the amount of offgassing that takes place when you pause on a single breath at 20 feet is significant, but your heart is beating, your blood is circulating, and the lungs are filled with nitrox, so nitrogen should be moving from the blood into the lungs, during the pause.

I think it is analogous to freedivers (who absorb N2 at depth), even though they are not actively moving air in and out of their lungs.

The safe resolution of this failure, is another example (in my mind anyway) of the benefits of freediving and general comfort in the water.

As I understand it, the urge to breath has little to do with the level of O2 and everything to do with the amount of CO2 in your blood. I was wondering why you would try to hold a non-required stop when out of air. Safety stops are a nice thing to do, but you are unlikely to suffer any consequences if you skip it, especially if drowning or blacking out are even remote possibilities.