Unable to breathe with nitrox enriched air

[bleeb]

I've seen it suggested that the combination of inexperienced/infrequent vacation diver, boat or dive staff member who mistakenly turns tank off and then 1/4 turn back on, and, system breathes well enough on the surface for any pre-dive check to not catch the error, to cause at least one or two deaths a year in the Caribbean. It seems reasonable that an infrequent low-experience diver would have a much larger chance of failing to handle an unexpected OOA situation adequately, but does anyone have any direct experience or can anyone point to real statistics or accident reports where a fatality was cause by someone on the surface turning the air off?

 

[DiveNav]

A couple of years ago I found at DEMA this nice device

​

I bought a couple of them and now have it on my tanks

But I still take a couple of breaths before entering the water.

Alberto (aka eDiver)

 

[The Chairman]

I bought a couple of them and now have it on my tanks

I think they are great and I have them on my Side Mount tanks. That hasn't stopped an errant DM from turning the left side post off twice now.

BTW, a loose tank valve is an open tank valve for me. It's its not loose then I assume it must be off. I saw a shop monkey strip the handle off trying to open an already open (yet empty) tank. Some valves don't do well unless they are all the way off or on. A scuba tank valve is not one of those types of valves that has a back seat.

 

[electrix]

I don't remember where I read this but it stated that there is no mechanical reason for a scuba valve to be backed off 1/4 turn that it was so that someone checking the valve to see if it was open could do so easily and quickly. Since that is usually the last thing I do before a student gets in the water I can see that point of view. Some people do not know what a 1/4 turn means though. If I am checking a valve and it is tight is it tightly open or closed?

 

[Hickdive]

Aqualung made an indicating handwheel nearly three decades ago. In fact a couple of years ago I sold one to a guy here on SB who was developing his own and wanted to see how the Aqualung version worked. I still have another in my cupboard.​

1/4 turn back means you can put your hand on the valve, partially turn it and know instantly that the valve is either open or closed. It removes all doubt as to whether the valve is simply against the stop. I've seen people trying to force 'open' cylinders that are already open and trying to force 'closed' cylinders that already closed because they were against the stop. 1/4 turn back stops that happening. Unfortunately lots of people seem to have a problem with 'The Two Cs: Clockwise Closes' and end up closing cylinders that were opened and backed off a quarter. Since I don't have that problem I back mine off a quarter so I can tell the valve's status with a touch just before I put the set on but I also double check that I can breathe, inflate etc. immediately before jumping in the water just in case someone who does have that difficulty has helpfully 'checked' for me.

Fortunately, in the UK we don't really have DMs nurse-maiding people on boats, so the chances of someone messing with your kit for tips is minimal.

As for the OP, whether the standard of training he received was good or bad depends on whether you sell CO (or is it C02? ;-)) monitors as a cure for not turning on your cylinder properly.

 

[Ben Prusinski]

Well if its any consolation I see experienced divers make bad mistakes all the time. After my dive episode, I heard the DM upset that the other divers failed to follow the descent line down to the bottom and instead veered off course. Several divers almost got lost and surfaced quite a ways from the boat. One guy surfaced way earlier without notifying his dive buddy and the DM was upset that he bailed on his dive buddy. And these were old guys with 20+ years experience diving in expensive dry suits. So, I don't feel so bad or stupid when I see veteran divers making dumb mistakes a lot. One guy last year did not even know how to dive from a boat. He belly flopped in. The key is to live and learn from these things.

 

[ktkt]

Um, the fact that others make mistakes will not be much consolation if you seriously injure or kill yourself. In scuba diving, what you don't know *can* kill you, so it's your responsibility to learn as much as you can. Something that many of us have found really helpful is the "What if?" series over in the New divers forum -- if you have spent time thinking about potential issues and how to deal with them, you'll likely do much better if you encounter the real thing.

link: http://www.scubaboard.com/forums/ne...514-what-if-what-do-when-things-go-wrong.html

 

[Cave Diver]

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A ScubaBoard Staff Message...

The sidetrack started over posting attitudes has been moved to a separate discussion: http://www.scubaboard.com/forums/near-misses-lessons-learned/413830-thread-split-unable-breathe.html. Please keep this discussion on topic and relevant to the original post

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[Bob DBF]

Well if its any consolation I see experienced divers make bad mistakes all the time. After my dive episode, I heard the DM upset that the other divers failed to follow the descent line down to the bottom and instead veered off course. Several divers almost got lost and surfaced quite a ways from the boat. One guy surfaced way earlier without notifying his dive buddy and the DM was upset that he bailed on his dive buddy. And these were old guys with 20+ years experience diving in expensive dry suits. So, I don't feel so bad or stupid when I see veteran divers making dumb mistakes a lot. One guy last year did not even know how to dive from a boat. He belly flopped in. The key is to live and learn from these things.

20+ year old c-card does not mean the owner has been diving for the last 19 years. There is a difference between 10 dives on vacation each year and someone that dives every month for 50+ dives a year. And of course there are morons in every human endevor. Don't figure someone is a vetran diver 'cause they have an old card, watch them dive and you will know.


Bob
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I may be old, but I’m not dead yet.

 

[boulderjohn]

Well if its any consolation I see experienced divers make bad mistakes all the time. After my dive episode, I heard the DM upset that the other divers failed to follow the descent line down to the bottom and instead veered off course. Several divers almost got lost and surfaced quite a ways from the boat. One guy surfaced way earlier without notifying his dive buddy and the DM was upset that he bailed on his dive buddy. And these were old guys with 20+ years experience diving in expensive dry suits. So, I don't feel so bad or stupid when I see veteran divers making dumb mistakes a lot. One guy last year did not even know how to dive from a boat. He belly flopped in. The key is to live and learn from these things.

Unfortunately, those people might not have been making "mistakes" in the strictest sense of the term.

If you read enough SB threads, you will find a recurring theme related to DMs. Although they are required in very many diver operations around the world, there are people who don't like the fact that they are required. They see themselves as being too good for such restrictions. The rules for mortals are not for them. Read enough of these threads and you will find some who brag about how they nod quietly to the briefing on the boat and then go their own way in the water.

I was buddied up with such a diver in Cozumel. He supposedly had 600+ dives, and I don't question it. After a while I gave up trying to be a good buddy, because he was always darting off on his own, and it was a full time effort to keep track of him. On one dive in particular we had planned to go to a certain spot that most of us were very interested in. As the DM was about to get us there, my "buddy" went off on a side excursion. I tried to stay reasonably close to him while still keeping group contact, and when the DM caught my eyes, I pointed to both the group and my buddy and shrugged to indicate I did not know which way to go. The DM saw that where my buddy had gone made it impossible for him to rejoin the group because of the current, so he took the group to him. We all therefore missed the place we had wanted to see, our entire reason for doing that dive. There was some pointed discussion about this on the b oat, but he was obviously unrepentant. Some people are like that.