A FB friend posted his brother died today in Ginnie Springs

[ucfdiver]

How many of you have failed to analyze a tank that you thought had air?

Does this question point to an inherent fault in our training process from day one of Open Water training?

I've seen a buddy I was diving with check his 100% o2 bottle and find out it had <40% o2 in it.

I've gotten 37% when requesting banked 32%.

I've gotten a fill around 40% when requesting 50% in a 70ft bottle.

My fiancee is taking her open water class soon, and I made sure to enroll her with an agency that teaches how to analyze gas before they even get in a pool.

 

[Tortuga68]

This is the right forum to engage in what-ifs...

What ifs about the incident, yes. Some earlier posts about deliberately taking the wrong gas were way off the scope of this forum

As other have said, analyse, mark. There's nothing else constructive to be gained

 

[Dr. Lecter]

I've seen a buddy I was diving with check his 100% o2 bottle and find out it had <40% o2 in it.

I've gotten 37% when requesting banked 32%.

I've gotten a fill around 40% when requesting 50% in a 70ft bottle.

Worst I ever got was 56% on a bottle of 80% and 43% on a 50% bottle on the same day. I dove the 43% because it actually worked better -- got on it one stop earlier and shaved a few minutes off the deco -- but if I'd just assumed my 80% was right I'd have been bent for sure given the dive I was using it on. Made them do it over again while I waited; to their credit, they were very good about it... but nobody could explain how a blender could fill a bottle of 80% to 3000psi and not figure out it wasn't even 60%.

 

[PfcAJ]

I got over 40% in a bottle that was supposed to have 18% (planned for 200'). Probably would have been game-over if it wasn't analyzed.

 

[boulderjohn]

To tell you how some mistakes can happen...

When I was still a beginner filling tanks with the partial pressure process, I used a transfill whip that was a bit funky. It kept shutting off while you were filling, especially when you were filling with O2, which is done extremely slowly. When I would hurriedly turn it back on, it would sometimes switch to a different set of units, and I did not notice it at first. If it jumped off of PSI to millibars and you didn't notice, your outcome would be far, far off from what you planned. One day I put way too much O2 in a bunch of tanks before I realized what had happened. I did a quick "Oh Crap!" and fixed it.

Another way it can happen is simply due to the confusion that can come when blending a lot of tanks that way in a hurry. You get into something like an assembly line format. You put a strip of tape down each tank in which you mark off the results of every step of the process. If you are working without a booster, as I was, it can get very complicated. You may have to add O2 to a tank in four different steps from 4 different O2 bottles. It can be very, very easy to mark down a step as completed when it didn't actually happen. It can be very easy to forget to mark off a step.

On another occasion, a friend put both the helium and O2 in my tanks before we got them to the compressor for topping off. The normal order of adding gases is helium first, then O2. The best I can figure from the result is that he put in helium twice and marked the second fill as O2. That mistake can happen easily in a hurried atmosphere. But there is a worse possibility. In the case in which Andrew Georgitsis saved a man in an oxtox incident, the man put O2 in his tanks twice instead of helium. Because he himself had blended the tanks, he did not bother to test them.

 

[elan]

How many of you have failed to analyze a tank that you thought had air?

Does this question point to an inherent fault in our training process from day one of Open Water training?

I would say it is an inherent fault in the training process because it operates on an assumption that what the fill operator assumes about the content of the tank and tells the diver is actually correct. OW at least the PADI one I took never tells that this logic is totally flawed.

 

[boulderjohn]

How many of you have failed to analyze a tank that you thought had air?

Does this question point to an inherent fault in our training process from day one of Open Water training?

I would say it is an inherent fault in the training process because it operates on an assumption that what the fill operator assumes about the content of the tank and tells the diver is actually correct. OW at least the PADI one I took never tells that this logic is totally flawed.

I think the problem is a very old tradition that is in the midst of change. The tradition is that we dive with tanks filled with air, and the only tanks that get filled with nitrox are clearly marked as such. You don't put one in the other. That is simply no longer true. All of the tanks I own are O2 clean; not one of them has a nitrox sticker. That is true of almost everyone I know well.

I don't know how many milliions of basic OW dives are done throughout the world annually on air, without anyone giving a thought to analyzing their tanks. How many basic OW divers getting onto a dive boat for a 2-tank dive on air have analyzed those tanks to make sure that it is indeed air in those tanks? I would say the number has to be far less than 0.0001%. How many basic OW divers on basic OW dives have had an incident as a result of accidentally breathing a nitrox mixture instead? I would guess the number would be far less than that, and I would almost be willing to bet it is a flat zero. Why? It is not just that I thnik the operators have that system pretty well figured out. It is also because I think the margin for error in the MOD standards is so large that I wonder if it is even possible for a diver breathing a standard nitrox mix in an AL 80 in a dive to recreational limits to have an oxtox event. IT doesn't happen when you drop below the MOD by 5 feet for 15 seconds.

There is another reason. I was diving with a student a few days ago, and we took a lot of tanks from our dive shop with us. They were all air. The student asked if we should be analyzing the tanks to be sure, and I said that IN THIS CASE, I was not concerned with it. Why? Because I knew darned well the shop does not have the ability to blend nitrox. They don't have an O2 bottle on the premises, they don't have a transfill whip on the premises, and the only one who works for them who knows how to blend it is me. You might be surprised how many operators do not have enough demand for nitrox to make their own. The only thing they can possibly put in a tank is air.

The real problem comes with situations like the one in this thread. It comes when people have the capacity to put any mix in any tank, no matter what it looks like. I did not bother to check the air tanks in the situation above; if the situation were different, I certainly would check.

 

[68raggtop]

Worst I got was 2 80's that were supposed to be air had 18/13 in them :shocked2::shocked2:

 

[Dr. Lecter]

Worst I got was 2 80's that were supposed to be air had 18/13 in them :shocked2::shocked2:

You got a heck of a deal there!

 

[Abdullah]

I think the problem is a very old tradition that is in the midst of change. The tradition is that we dive with tanks filled with air, and the only tanks that get filled with nitrox are clearly marked as such. You don't put one in the other. That is simply no longer true. All of the tanks I own are O2 clean; not one of them has a nitrox sticker. That is true of almost everyone I know well.

I don't know how many milliions of basic OW dives are done throughout the world annually on air, without anyone giving a thought to analyzing their tanks. How many basic OW divers getting onto a dive boat for a 2-tank dive on air have analyzed those tanks to make sure that it is indeed air in those tanks? I would say the number has to be far less than 0.0001%. How many basic OW divers on basic OW dives have had an incident as a result of accidentally breathing a nitrox mixture instead? I would guess the number would be far less than that, and I would almost be willing to bet it is a flat zero. Why? It is not just that I thnik the operators have that system pretty well figured out. It is also because I think the margin for error in the MOD standards is so large that I wonder if it is even possible for a diver breathing a standard nitrox mix in an AL 80 in a dive to recreational limits to have an oxtox event. IT doesn't happen when you drop below the MOD by 5 feet for 15 seconds.

There is another reason. I was diving with a student a few days ago, and we took a lot of tanks from our dive shop with us. They were all air. The student asked if we should be analyzing the tanks to be sure, and I said that IN THIS CASE, I was not concerned with it. Why? Because I knew darned well the shop does not have the ability to blend nitrox. They don't have an O2 bottle on the premises, they don't have a transfill whip on the premises, and the only one who works for them who knows how to blend it is me. You might be surprised how many operators do not have enough demand for nitrox to make their own. The only thing they can possibly put in a tank is air.

The real problem comes with situations like the one in this thread. It comes when people have the capacity to put any mix in any tank, no matter what it looks like. I did not bother to check the air tanks in the situation above; if the situation were different, I certainly would check.

That's probably a good guess on the air tank analysis rate. What do you guess the incident rate is on air tanks that contain some type of mixed gas by mistake? My guess is that it's less than your analysis rate, but I have never seen any mishap statistics to support any conclusion about the actual risk of getting a blend in an air tank. Most of the anecdotal data is related to blending errors (wanted 32%, got 29%), not diving an air tank but got O2 by mistake.

The question for the typical OW recreational diver (who probably doesn't own his own analyzer) is what the risk of an inadvertent EANx mix really means to his safety. A recreational dive in the air NDL range is not likely to be endangered by an accidental one-off use of a 32% or 36% blend marked as air. The chances of a rich deco mix or 100% O2 ending up in an OW rental air tank are pretty remote. Can you honestly say that the risk is significant enough to the predominant population of OW recreational divers to warrant having everyone go out and drop $300 on an O2 analyzer? Seems like an over reaction to me.