How long is a tank of air good?

[Jarrett]

This has to be a routine question, but for some reason I couldn't find any hits on it in the search engine. Sorry ahead of time if it's one of those majorly redundant ones.

So long how is a tank of air "good?" A week, a month, a year? I have some tanks I filled in September and was wanting to dive this weekend and wanted to make sure I was not doing something wrong by using them. Thanks in advance.

 

[BabyDuck]

the best answer i've seen is 'a year. then you need to get your viz done.'

 

[KOMPRESSOR]

I never use air older than 2 months. But then I have my own compressors of course

(Not that it ever goes two months between dives, but I do have 4 tanks....)

 

[Humuhumunukunukuapua'a]

Your tanks from September are fine. I think as long as the vis is still up to date on the tanks (and probably beyond that) you're fine. I can't imagine what would happen to the air itself. It's more the safety of the tank that would be a concern...but not after a month and a half

 

[Wayward Son]

I have a tank that has needed a viz since july, I just haven't dove it yet. The air is fine, it will be whenever I get around to diving it, then I'll take it in for a viz & fill.

 

[Jarrett]

The tanks I bought new in August. Filled and used about 4-5 times each I'd guess. The last fill was late August/early September. I guess the viz is that sticker they put on the side?

 

[Humuhumunukunukuapua'a]

Yes, the sticker on the side.

 

[cyklon_300]

containing air that had been stored in a closet for 9 years...no ill effects.

 

[DandyDon]

Clay Coleman's "The Certified Divers Handbook" - an excellent suggestion for newer divers, he suggests that tanks be stored standing up. There should not be any moisture in the tank, but just in case there is - this will keep the water away from the valve and any possible corrosion will happen at the bottom where the tank walls are thickest.

He further suggests that corrosion is a risk that can also decrease Oxygen content and thereby increase Nitrogen percentage. Aluminum may not corrode as quickly as steel, but it still can happen. Clay suggests storing the tanks at half full, to maintain pressure on the tank so as to prevent further problem, and to prevent a diver from using a tank that had been filled at a long-ago, perhaps unknown date.

I hate to waste a $5 fill, but since we strive for safety is a somewhat safety-challenged sport, this is probably a good suggestion. Right before diving again, drain it to 500#, then refill it with fresh air.

 

[drew52]

Ever smelt the air from an old cylinder? Nasty I wouldn't dive the 9 year old cylinder but a couple of months is all good. If you do decide to drain it, remember slowly don't get any condensation on the outside, remember condensation on the outside probably means condensation on the inside. A no no for dive cylinders unless you don't mind buying a new one fairly soon.