how long is air good?

[maremd50]

I've got 4 tanks full of air, filled two years ago. I thought I'd do some local diving but ended up doing a bunch of traveling instead. So there they sit. Can anyone tell me if the air in those tanks will still be "good"? I want to take a quick couple local dives this weekend. Thanks!

 

[tbone1004]

they could be, they could also not be. You need to get them on an O2 analyzer, and preferably a CO analyzer. Also make sure there was no water ingress that caused any sort of issues inside of the tank. Air is technically good forever, but it's what the air interacts with *if anything* that will determine if it is no longer breathable

 

[Akimbo]

Can anyone tell me if the air in those tanks will still be "good"?

The air is safe to store longer than the hydro is good for.

 

[kelemvor]

I have had a tank of nitrox that sat for about 9 months lose some of the oxygen. I think it went from 32% to 27%, but my memory might be off. I decided not to dive the tank. If you have analyzers, analyze the tank and if you still have 20.9% and no CO then dive them. If you don't have analyzers or get unexpected results then dump the tanks.

You can always just ignore us and dive them anyway. I'm sure a lot of people would, and you might be okay if you do. But you also might not, and that could be a very bad day.

 

[northernone]

As stated, it's your personal risk tolerance without inspection or analyzing the gas. The old sniff test is fairly risky. My oldest air fill was 38 years old. No issues.

Regards,
Cameron

 

[halocline]

Unless these are steel tanks and you have some reason to suspect that they were filled wet, there's almost certainly nothing to worry about. I would forget about the O2 and CO analyzer, unless, again, you have some suspicion about the original source of the fill. Air doesn't 'go bad'.

 

[TrimixToo]

To intermediate depths, I'd dive them if they were my tanks and filled at home, because if there were a problem with either I'd know it much sooner than 2 years after the fill. If in doubt, I'd analyze them and if the O2 was where it was when the tank was filled, I'd dive them.

All that said, air fills are cheap. If you are in any doubt, at all, for any reason including the heebie-jeebies, dump the fills, and have the tanks inspected and refilled. Always remember who it is that's breathing the air. The opinions you see here, mine included, are worth exactly what you paid for them.

 

[2airishuman]

There have been, very rarely, fatalities where someone used a cylinder of air that had been stored a very long time where the oxygen had reacted with the cylinder wall, leading to a hypoxic mix in the cylinder.

There has also been one notable fatality, and perhaps other similar unrecognized or unpublicized ones, where a cylinder was deliberately filled with a non-breathable gas and labeled ambiguously enough that, with the passage of time, the same individual thought it to be safe to breathe.

Air is cheap.

 

[halocline]

There have been, very rarely, fatalities where someone used a cylinder of air that had been stored a very long time where the oxygen had reacted with the cylinder wall, leading to a hypoxic mix in the cylinder.

There has also been one notable fatality, and perhaps other similar unrecognized or unpublicized ones, where a cylinder was deliberately filled with a non-breathable gas and labeled ambiguously enough that, with the passage of time, the same individual thought it to be safe to breathe.

Air is cheap.

I don't doubt that, but considering the millions of air fills that take place annually around the world, a single death due to reactive air is truly an infinitesimal event; sort of like being struck by lightning while buying a winning lottery ticket.

The risk involved with breathing two year old air is for all intents the same as a breathing freshly filled tank. If one is confident of the source of the air fill, in two years that air will still be fine. Mixed gas fills need to be clearly labeled and analyzed before use regardless of their age. One caveat; a very wet fill in a steel tank could be safe (but destructive to the tank and regulator) initially and hypoxic over time. But that kind of wet fill is VERY unusual in any kind of professional setting.

But I do agree that if any diver has doubts about the contents of a tank for any reason, it makes sense to forgo the worry and refill.

 

[arew+4]

By

My oldest air fill was 38 years old. No issues.

Regards,
Cameron

Hmm, wonder how much hipsters would pay for vintage air.