"old" air?

tep · Jun 19, 2011

I searched but couldn't find a thread about this, although I'm sure I remember seeing one last year?

I have two Al80 tanks that were a gift. They were filled when they were VIP'ed July 2010. Is there any reason to NOT go ahead and dive these before I take them in for a VIP in about 2-3 weeks?

Is there really such a thing as "old air" in a properly maintained tank? I can see that if there was corrosion, that the O2 content might be down (in addition to the oxidation byproducts), but is the a real concern?

Reefshark11 · Jun 19, 2011

I was told one time that air doesn't go bad. I had a tank with some year old air before and I used it with no problems. If you can taste anything funny I would not use it. Call your local dive shop to be on the safe side if you have any concerns.

DandyDon · Jun 19, 2011

I'd test the O2 content and dive them.

elmer fudd · Jun 19, 2011

I just picked up two full tanks yesterday with the most recent hydro stamp from 1970.

Not gonna even try breathing that air.

Now if, like you, I had fills from 2010 I'd go ahead and dive 'em.

DevonDiver · Jun 20, 2011

How 'old' do you think the air that you are breathing right now is?

The only real concern is the oxygen content. If there was any oxidation inside the tank, then some oxygen may have been consumed. That oxidation would have to be very severe to reduce O2 levels below a safe amount. If in doubt, do a quick O2 check of the air. Anything below 20% should cause concern.... especially as it would indicate a significant problem with the cylinders themselves.

DandyDon · Jun 20, 2011

DevonDiver:
How 'old' do you think the air that you are breathing right now is?

The only real concern is the oxygen content. If there was any oxidation inside the tank, then some oxygen may have been consumed. That oxidation would have to be very severe to reduce O2 levels below a safe amount. If in doubt, do a quick O2 check of the air. Anything below 20% should cause concern.... especially as it would indicate a significant problem with the cylinders themselves.

Ok I failed to explain why I'd test the O2. That's why - thanks.

Wet Ham · Jun 20, 2011

I'd dive 'em for sure. Being an aluminium tank oxidation wouldn't be a problem anyway. If you don't have easy access to an O2 analyser, I would just go ahead and use them. Of course if the air didn't taste right, I wouldn't touch them with a 10ft barge pole (whatever that is?)!

PatW · Jun 20, 2011

There is another issue here, how much does it take to just refill them? It probably would not be necessary. But there is a peace of mind issue here. I don't think it is a particularly good idea to dive with tanks that one has reservations about. Wondering about the quality of the air at 80' is not a particularly good thing. Locally here, I think a tank fill is $4. To me it is just run down and get them refilled and then there are no worries.

Garrobo · Jun 20, 2011

Use 'em.

DrunkenParrot · Jun 20, 2011

Garrobo:
Use 'em.

This..

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"old" air?

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