Question NITROX (in less than 40 foot of water)

[rjack321]

Are you sure? I don't remember the last time an incident occurred where an air diver got nitrox. Do you?

However, this just lends strength to my argument that all modern OW scuba classes should include Nitrox certification. If you can't dive air without verifying the contents your self, they you can't dive till Nitrox Certified.

I know a few people who've picked up tanks that hadnt gotten an air top off and were basically 100% o2.

The OP doesnt know ANYTHING about the gas in these tanks. Not even who filled it and if they used a paintball compressor with no filtration.

 

[steinbil]

I see a pretty cavalier attitude when doing the oxygen analysis, saying that the gas needed to be analyzed before diving. I don’t see much about calibration of these meters. If, as many here state, your life depends upon a very accurate measurement of the amount of oxygen in the tank, then you need to also take calibration seriously too.

I find these technical divers are rather fanatical about testing; I’d like to see them just as fanatical at calibration of their meters, and recording their findings.

Nothing like a technical discussion to bring out the perfect people. Nobody said a word about calibration until I mentioned it and now they will tell us how they carefully calibrate every day.

I'm not a technical diver, but I analyze every fill. My calibration is probably not "perfect", as I use outdoor air to calibrate before analysis. If this is problematic, I would love to learn more. However, I still think the analysis is very useful, as what I'm looking for is not pinpoint accuracy. I don't care if the gas I'm breathing is 30% instead of 32%, as it doesn't affect my diving in any meaningful way, since I dive with enough safety margin for that not to matter. Even a poorly calibrated analyzer would give me an indication that something is off if I happen to get a fill of 100% O2, 50% O2, or air instead of nitrox - which would probably be the most likely mixups where I get gas, and with varying degree of risk.

 

[John C. Ratliff]

I know a few people who've picked up tanks that hadnt gotten an air top off and were basically 100% o2.

The OP doesnt know ANYTHING about the gas in these tanks. Not even who filled it and if they used a paintball compressor with no filtration. (Emphasis added, jcr)

Actually, he does now, as he got the tanks tested. He posted that a page or so back. And, they were as marked.

SeaRat

 

[L13]

I know a few people who've picked up tanks that hadnt gotten an air top off and were basically 100% o2.

If the tanks hadn't gotten an air top off, the pressure would be much too low.

 

[boulderjohn]

Nothing like a technical discussion to bring out the perfect people. Nobody said a word about calibration until I mentioned it and now they will tell us how they carefully calibrate every day.

I don't think anyone thought calibration was an issue. I have been diving nitrox for more than two decades, and I have been diving trimix for about 14 years. I have never seen a time that nitrox or trimix tanks were analyzed without calibration.

 

[formernuke]

I see a pretty cavalier attitude when doing the oxygen analysis, saying that the gas needed to be analyzed before diving. I don’t see much about calibration of these meters. If, as many here state, your life depends upon a very accurate measurement of the amount of oxygen in the tank, then you need to also take calibration seriously too.

I find these technical divers are rather fanatical about testing; I’d like to see them just as fanatical at calibration of their meters, and recording their findings. If you ever need to go to court about an trimix fill, and you have not calibrated your instrument (preferably before and after taking the sample), you may not have much to stand on in a legal case.

Calibration is part of analyzing, it's the first step. I didn't realize I needed to give step by step on how to do it in a thread that not asking how to analyze. I'm answering the questions asked.

 

[AsherN]

And somehow, all those "Air" divers manage to dive safely with analyzing their tanks themselves. But all the nitrox divers are "unsafe" if they don't.

Because I'm confident that my air tanks are filled with a compressor that only does air. but a nitrox tank can have a little more or less O2 in the mix.

 

[CT-Rich]

My two psi. First, how do you know the tanks are nitrox? The big green nitrox stickers don't really mean there is nitrox in the tank. It means the the guy who put the stickers on the tank INTENDED to use them for nitrox. It may be air. Most nitrox fills will have a piece of tape with "32%" written on it. This means the guy that filled the tank thought it was 32% nitrox. You can show up at your LDS and say, "hey, I just bought these two tanks, can you check to see if they are really EAN 32?" they will probably test them for and you would know.

Second, what should you do with the tanks of unknown sure mixture? If you you were told they were nitrox and labeled as such, they probably are nitrox. Should you dump them because they are and you are not nitrox certified? you could, but you would be throwing away two perfectly good fills. Diving them to 40' just like air is perfectly safe, as long as they are just nitrox. I doubt the seller is accidentally giving you pure O2 or pure nitrogen. both of which are extremely dangerous to dive with. The O2 would make you pass out below 20-30' and nitrogen would make you pass out almost immediately (no oxygen is bad). Both are extremely unlikely, unless the guy that sold them to you was an incredibly careless Tech diver.

I am not a big fan of rapidly draining tanks unless you are doing it for inspection. If you crank the valve open and let it drain, the tank will cool down a lot and water vapor in side the tank will start to condense on the inside walls.

Personally, I would dive them to 40' as if they were air. It is not dangerous as long as they are what you said they were..

 

[Celt]

Hey folks QQ for you. I just moved to a quarry where I plan to dive more often (just for training) and I have a question that I want to ask. I am not nitrox certified, nor have I had the need to dive with nitrox yet (one day I will expand to deeper dives). But I have two tanks I purchased where they filled with nitrox instead of air. If I were to dive in the quarry in 20-40 foot of water, would it be OK? Or should I dump the air, and get them refilled with air instead? I know I need the cert for proper use... I just have two tanks with 32% sitting here and thought it would be nice if I didn't need to go into town for a fill is all. If I do, then I do... not the worst thing in the world. If it doesn't matter, then I can select 32% Nitrox on my dive computer and use what's in the tanks.

If you have any worries about the gas in a tank, dump it and refill. Its just going to spoil your diving thinking about it with the reg in your mouth.

 

[Valyngar]

Now that he knows it’s 32% and hard bottom is 40 feet, I can’t see how it would be dangerous to dive it as nitrox 32% if he has computer that has ability. He can’t have hyperoxia because of so shallow hard bottom. Can’t really do anything wrong vs air even if you don’t know anything about nitrox diving. Other places that are deeper, it’s different thing, but his dive site I can’t see problem.