Nitrox fills on vacation

[Kali]

I`m currently studying for my nitrox cert. I`m going to Key Largo to dive and was wondering: when renting tanks (with nitrox), do most dive ops fill the tanks on site? I`m very concerned with checking the O2 levels myself (should I be?). Do most people carry their own O2 analyzers?

[vanfant]

No a bad idea to get yer own.

[Ms. Hikaru]

Charles Haber wrote before you go. Not everybody does. I suggest you advise them in advance if you`re going to use their tanks. The shops can get busy just before the boats leave and partial pressure blending takes more time than a simply air fill. If you`re using your own tanks, bring them full and give the ship as much time as possible between trips to refill them. You can dive 32% pretty much anywhere a day charter will be going. I don`t know of any Keys shops in that bank premixed gas or have continuous blending or membrane systems (all of which speed the fill process). Jim Wyatt has a continuous blending system on Cudjoe, but he`s a bit of a drive from Key Largo.
All nitrox courses I know of teach checking your own gas. It is my personal opinion that you should either test it yourself (preferable) or at least observe somebody test it in your presence. In general, it`s important to know what you`re breathing. The more dives you do in a day, the deeper they are and the closer you get to N2 and O2 limits, the more important knowing what you are breathing becomes. Since I breathe nitrox for the added no deco time, I consider knowing what I have very important. I own my own analyzer because I`ve been places that don`t have one to loan me, because I`ve been places that transport tanks from the fill station to the boat, making it impossible for me to see somebody else test my gas, because I`m more comfortable using the same analyzer each time than using whatever is available and, perhaps primarily, because I`m a gadget freak.
I don`t think most people have their own O2 analyzers. Way too many trust the shop to give fill and test their gas accurately, a mistake in my mind. One of the best known tech shops in S. Florida missed the target PPO2 on one of my fills by enough to have given me problems if I had not tested it myself. They only did it once, but once is once to many times. I got a tank of air on a liveaboard using a membrane system. The system was set for 32 and produced it reliably, or would have if they had not hooked my nitrox tank to an air whip. That one got by me and I got bent as a result. I was close enough to my N2 limit at that point for it to matter. Most of those who religiously test their gas, use the shop`s analyzer. Generally, I don`t have a problem with that. Most shop analyzers are as good as mine, but it`s still nice to get an independent test.

[Ms. Hikaru]

Ed wrote away from shops that cater to divers with more unique preferences. It`s pretty much an industry standard to avoid putting gas that does not meet nitrox standards into a tank prepared for O2 service. Air may not be just 21% nitrox. It may be 21% nitrox plus exactly the kind of comtaminants the tank was cleaned to avoid. You want nitrox, go to a shop that makes it available. You want regular air in an O2 service tank, peel the O2 service sticker off and go for it, or learn to fill your own nitrox. I can`t blame anybody for protecting themselves, even if the chance of a problem is very slim. If a tank goes off, it`s the fill tech who is standing closest to it. and they don`t last forever. Most shops I frequent fill only clean air, but their fill prices tend to be a bit higher than average as well. If Ocean Divers didn`t charge you extra for the clean air, thank them. A lot of shops would have. If you don`t need nitrox for lobstering in 25 feet of water, why are you using an O2 service tank?
It`s good to know somebody in the Keys has premix. More often than not, a standard blend is fine for me and fills from a premix source are quicker than from a partial pressure blending source. Better yet, some shops with premix will fill non nitrox tanks, a good thing if that`s what I happen to have empty.

[PhishnHead]

-JimG

[Andrea.B.Previtera]

says...