Unable to breathe with nitrox enriched air

[Ben Prusinski]

I tried both and could not get air from either the reg or octo. I am still investigating the root cause of this issue. Before the descent, I checked air in the SPG and dive computer (Cobalt) to see that there was air available. Both registed 2800 psi for the tank so I know air was there. I did not panic. I signalled my dive buddy of the issue and we both surfaced. Weird as this never happened to me before. Anyways, I will do more checks before diving in the future to avoid this issue from occurring. Glad it happened at 22 feet instead of 100 feet.

 

[DevonDiver]

Primary culprit: Valve not turned fully open. A partially opened valve may supply enough air at surface pressure, but struggle to supply demand at depth.

Issue: Where was your buddy? CESA shouldn't be your first recourse in an OOA scenario.

 

[racerx_]

Where was your buddy? CESA shouldn't be your first recourse in an OOA scenario.

Thinking the same thing.. why didn't he share his backup with you? Seems like you increased risk by not doing that

Sent from my HTC Incredible S using Tapatalk

 

[SeaCobra]

This is not a nitrox issue. That you think it may be doesn't say much for your nitrox class. Or training over all.

Nitrox will not affect how you breathe or if you can breathe.

This is not a Nitrox issue but a gear issue. Was the valve all the way open?
Where did the tank come from?
When was the last visual?
Did you report it to the shop?
There may have been something in the tank that needs attention.
Did the reg stop delivering air altogether or just become very hard to breathe?
Is it your reg or a rental?
How did you check the tank and regulator?
If the valve is not all the way open the tank will breathe fine on the surface but not deliver air at depth.

Another item that should have been covered in your training. This should have been in your OW class training.

In order to offer a more concise opinion we need more info. And why was it necessary to do an emergency ascent? Where was your buddy? OOA, tank dry or not delivering air, is not a life threatening event if you are using good buddy procedures.

easy Jim, this may be perceived as bitterness on the part of an instructor

 

[SeaCobra]

also wondering if anyone has experience with the "response time" of a digital spg or ai dive computer? with an analog gauge, if the valve is only partially open, the needle with often drop during an inhalation during your pre-dive brief. Will a digital spg show that? Can't say I have ever tried, but just may now.

 

[D_B]

... You did not say if you breathed off of the reg while looking at your pressure gage ?
Also .. Proper drill is to get breathing air first from your buddy , then you can sort out next move

 

[yodelhawk]

Glad you made it out of the water safe. During a recent pool session, while a student was doing a buddy check on me, I suspect that student closed my valve part way. I was breathing fine, but at 12 feet I noticed the needle dropping down to almost nothing with every breath. I had almost 2000 psi when I noticed this. On the surface it did not do this and once the valve was open, I no longer had that problem. I suspect that a partially open valve was your problem. Since that day I ask whoever is doing my buddy check to please not touch my valve. Again... Glad you are safe

 

[dumpsterDiver]

Some clues from the OP's post certainly suggest that this was a case of "Opening the valve all the way and turning it back 1/4 turn" when the valved had already been opened -- that is, someone closed the valve and then opened it 1/4 turn.



To me the telling point was that "I checked the tank and regulator and both were functional" which argues against something like a clogged dip tube or other malfunction.

OP -- when you did your gear check prior to entering the water, did you watch your SPG while you breathed your regs?

[edit -- Quero -- great minds think alike.]

The obvious answer is probably correct..the valve just cracked..if it were a psychological issue the guy would have felt that it was delivering too little air.. probably not none.

However.. it IS possible that something could block the dip tube underwater and then later when the tank is in a different position, the tube could become unobstructed.. If I was not entirely sure of the valve position, I would be looking inside the tank and at the screen on the first stage.

 

[Ayisha]

also wondering if anyone has experience with the "response time" of a digital spg or ai dive computer? with an analog gauge, if the valve is only partially open, the needle with often drop during an inhalation during your pre-dive brief. Will a digital spg show that? Can't say I have ever tried, but just may now.

Yes, the digital pressure wavers up and down as you breathe unpurged lines off a closed tank, at least it does with my computer. I've never tried to breathe off a partially open valve, will have to try some time and watch the computer and see if it registers... prior to diving, of course.

 

[Ben Prusinski]

Primary culprit: Valve not turned fully open.

This makes sense. Anyways, as my gear is very new, I will do some testing at the pool this week before the next dive to be sure all is functioning correctly. The nitrox tank had inspection recently so based on this, unless there was CO2 in the tank that contaminated it, a tank with its valve not completely open seems like the root cause. More reason for me to buy a tester to ensure no contamination is present in a tank before diving. I know of an experienced diver who recently died from a dive accident in Cozumel due to CO2 contamination in the tank. Thanks for your support. I am also glad to make it back to the surface safe and sound.