old air?

[bjpell]

I have a few lp120's with 40% air in them. The air is about 2-2.5 years old. I don't remember for sure but isn't it for some reason bad to breath old air? I don't remember why though? I cant think of a reason why the air would be bad unless something was growing in the tank like bacteria etc. Anyone know what I'm talking about or remember something about this form the fundamentals class.

 

[h90]

one book told me that corrosion may eat part of the oxygen in steel tanks.
another book told me that it starts to taste bad.

I would take it out and fill in a new one...

 

[Tassie_Rohan]

If a steel tank has some moisture in it then the rusting process can, over enough time, use up some or all of the oxygen. In rare cases people have died as there was not enough oxygen left in the gas.

By 40% air to you mean 40% of a normal air fill, or 40% Nitrox?

After 2-2.5 years your tanks are overdue for an inspection anyway.

Fills are cheap. Your health isn't. Get a new fill but, if you are curious, get the shop to check the % oxygen before draining them.

Cheers,
Rohan.

 

[DA Aquamaster]

If you ended up with water in the tank, you might get enough rust to impact the O2 percentage but otherwise it is a non issue. I'd analyze it and if if it still reads 40% and does not smell or taste, bad I'd use it. 2.5 years is not long in terms of storage for a gas as long as it and the tank were both clean and diveable when it was filled.

 

[dannobee]

I would analyze it (including a sniff test), then dive it. As a matter of fact, I had some tanks laying around that I did just that to.

 

[skippy31]

I would analyze it (including a sniff test), then dive it. As a matter of fact, I had some tanks laying around that I did just that to.

Agreed. If the gas and tank do not have excess moisture there is no reason for there to be any issue. If it analyzes right and smells right, then your good to go.

Mat.

 

[bjpell]

They are EAN 40 and were perfectly usable when I put them away. The reason I don't want to empty them is that the air was not cheap and I would rather use the tanks on a warm up shore dive bugging first. Then I was going to get my al80 hydro/visualized and the two 120's need the visuals too.

The air in the tanks is very high quality, its from fill express so the moisture content that they advertise if my memory is right is: < 0.1%. Isn't that 10X less then most places at 1%? Anyway, the air smells fine. I rebuilt my halcyon inflater hose and my reg yesterday and attached them to the tanks. I sensed no "odor or taste" that I can pick up on.

Thanks for your suggestions.

-=ben