Question NITROX (in less than 40 foot of water)

[myrddin]

If you can watch while they are analyzed, then I'd dive it as air.

There's no magic to diving nitrox and no new technique requirements other than knowing your maximum operating depth. This is why the operating a motorcycle on a car license analogy is inapplicable here. A conservative maximum operating depth for 32% is 110ft. Stay away from that and you'll be fine.

Thanks! This is what I figured. But I’ll still work on getting the cert. calling the dive shop tomorrow. But at this point I’ll also see if they will analyze them. Not going to buy an analyzer though. Not unless I’m diving Nitrox more often. Right now I dive in my neighborhood. Again it’s fresh water. And at peek it’s 40+ feet in spots. Right now it’s about 30+ feet. I don’t get the chance to do deep dives often.

Sorry I asked. I was hesitant because as I said. I know the right answer is to be certified. But I wanted opinions on this one. I didn’t mean to get some of you worked up.

 

[MaxBottomtime]

Unless the shop is partial pressure blending, there wouldn't be anything higher than 36% in the tanks. They are aluminum 80s, so if they were to be filled with deco gas the tanks would have to be labeled as such. I would dive them in less than 40 feet.

 

[broncobowsher]

I know the person I asked dives in Cozumel and every shop can get air or nitrox tanks. But the point remains, every day thousands of "air" divers use tanks provided by dive charters or filled by shops that can do both. Should they be analyzing?

Probably, yes.
Where I get my air, I know it is just air. I helped setup the compressor. The Nitrox fills are a seperate area, done at a different time, with a different batch of tanks, partial pressure fills. For all practical purposes two completely separate systems. When you get air, all you are getting is air. I'll state most shops are like that. Air fills are air. Unless the shop does a lot of Nitrox there is little to worry about. Once they are making enough that they have a Nitrox stick and blending it through the compressor, then there is a chance of odd hot mixes.

I bought a used drysuit bottle once, had an Argon sticker on it and it was full. I was surprised to find it had 20% Argon in it when I ran it through the analyzer. The only time I ever did a drysuit bottle. I do check mystery stuff. And anything blended, I've messed up a few blends in the past.

There are the random old fills that are low O2 since it was consumed in the oxidation process inside the cylinder. Analyzing air would show that. About the only way to get low O2 without getting a shot of Helium in there.

 

[Brett Hatch]

Thanks! This is what I figured. But I’ll still work on getting the cert. calling the dive shop tomorrow. But at this point I’ll also see if they will analyze them. Not going to buy an analyzer though. Not unless I’m diving Nitrox more often. Right now I dive in my neighborhood. Again it’s fresh water. And at peek it’s 40+ feet in spots. Right now it’s about 30+ feet. I don’t get the chance to do deep dives often.

Sorry I asked. I was hesitant because as I said. I know the right answer is to be certified. But I wanted opinions on this one. I didn’t mean to get some of you worked up.

Apologize for nothing! I think you scored some good tanks, asked good questions, got usable answers, and you're on the right path. Much better to ask these kinds of questions than to wing it. I bet you can think of somebody who would have just thought "eh, what could go wrong," and gone ahead and dived them -- I know I can think of a few.

That risk factor exists on every tank you didn't personally observe being filled, even allegedly "air" tanks. Nobody tells air divers to analyze their tanks.

Eh, I disagree. The risk of a tank labeled 32% but which actually contains 100% is not zero if the tank was filled by partial pressure blending, which is pretty common on a lot of areas. Not so much for one labelled air-only, or at a shop that only does air fills, or at a shop that uses a different method of blending. But, the OP does not really have access to the information needed reason this all out. Sounds like that problem will be solved soon though, according to post #22.

If your point is that all divers should be taught to analyze their tanks, well, we are in agreement. Making this a separate course from OW is a little silly, but for one reason or another, that is the industry standard. If I were king of the world, nitrox would be included in OW instruction -- but I'm not an instructor, or a course director, or a nitrox salesman, or even king of the world for that matter, so what do I know

 

[stretchthepenn]

Sorry I asked. I was hesitant because as I said. I know the right answer is to be certified. But I wanted opinions on this one. I didn’t mean to get some of you worked up.

Don't sweat it. Every good thread gets at least one person worked up into a raging froth.

 

[jstrom]

I would never dive a tank I don’t know the content of. If you know the content is XX% enriched O2 and YY% N. Then I’d dive it like it was air.

 

[rick00001967]

sorry i did not read all the responses so i may be repeating what others have said.

first....my question is.....how did you end up with tanks filled with anything other than air? that is a significant issue. it either means the shop gave you a mixed gas on purpose, or without knowing. both are unacceptable and could get someone killed.

the reality is, if you know for sure that the tanks contain 32% O2 (and that would mean you would have to analyze the tanks yourself), then there is no physical harm in using them in the shallow depths you mentioned.

but the bigger issues are.....one.....you are not nitrox certified and have zero knowledge on the proper procedures needed to safely obtain it and use it.

and two.....it is a dangerous idea to ever tell anyone it is ok to breath any gas under any circumstances unless they know what is in their tanks. this may sound a bit over the top but it is a core principal that needs to be adhered to, especially if the diver ever goes beyond your average shallow rec diving with one tank of air on your back.

my advise is to go back to the shop. have a friendly discussion about what happened. and make damn sure the shop makes whatever changes are needed so it doesn't happen again.

 

[L13]

sorry i did not read all the responses so i may be repeating what others have said.

first....my question is.....how did you end up with tanks filled with anything other than air? that is a significant issue. it either means the shop gave you a mixed gas on purpose, or without knowing. both are unacceptable and could get someone killed.

Read the OP. He bought the TANKS from an individual seller, and they came already filled.

No shop was involved.

 

[rick00001967]

Read the OP. He bought the TANKS from an individual seller, and they came already filled.

No shop was involved.

thx for pointing that out. the original post did not say where they were purchased.

 

[lostsheep]

Do you analyze Every Single Tank you dive, even when diving "air"? How do you really know it's only 21% and the filler didn't make a mistake?

Yes, analyze everything.

I can’t believe no one has brought up that air is for tires