expired VIP... air still good?

[Walter]

A friend of mine once gave me a set of tanks that had last been hydroed in 1991. They had air in them, so I used them before doing anything to them (I did check the air - 21%). Assuming they were filled in '96, and knowing I used them in '06, the air had been sitting at least 10 years. No issues.

 

[ClayJar]

I remember at least one clever chemist type posting about a year ago[...]

That was likely my post(s) in the Stale air thread last June.

 

[CompuDude]

Yeah. I'd say the rule of thumb is anything around year old is probably fine, more than that, isn't worth $5 to be sure you're breathing safe air?

 

[Nemrod]

I found a tank I had forgotten about in my hanger. The air was twenty years old and sweet as a Spring Breeze. I dove it. No worries. N

 

[ClayJar]

The air was twenty years old and sweet as a Spring Breeze.

Hehe, it likely had a somewhat lower concentration of carbon dioxide, too.

 

[Luis H]

Last year I bought a steel tank from an old retired diver. He told me the last time he used the tank was around 1968. I tested the air for O2 content. It was 21%, not bad for air that has being in the cylinder for close to 40 years.

The cylinder also passed hydro test with the + stamp. No problems at all.