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Hey guys, so I bought this 80cf aluminum scuba tank brand new from Sports Chalet dive department about 10 years ago to shoot my Steyr LP10, I ran a few cylinders in the pistol then lost interest. The tanks been sitting covered in my So.Cal. garage ever since nearly full of air, it looks like new and has never been knocked over or hit. As I mentioned in another thread I have a Morini 162ei that was bought new about 5 years ago but never used that I’d like to start using. So I called a few dive shops and got a few different responses, all said the air is stale, so is stale air going to be corrosive to the pistols air cylinder? I also asked them all about safety regarding a scuba tank that’s been sitting unused full of air for 10 years and got different responses, one guy said it’s probably ok to use it but it’s best to bring it down and have it sent out for a hydro, another guy said Sports Chalets employees were kids who didn’t always practice the best filling procedures .. and their could be gases in the tank that could ignite and blow up killing me and my family! The third shop said the tanks not going to kill me but still bring it down for a hydro and refill before using. So I’m a little spooked now and am not sure weather to use up the air then take it in .. or just take it in now? Any advice from those experienced would be appreciated.

Thanks ..... Chris

Question: When was the last time you heard of a tank exploding because it was old?

Here is the thing. They have to be tested once a year to be filled by the dive shop. A hydro test every 5 years. This is for your safety. If it was me I would put safety first.

I don't know how the air could go stale, or increase in moisture content. I doubt anyone filled it with anything but air. Assuming it was dangerous for the sake if argument, would it be safer to move it full, or bleed it off? You may as well just bleed off pressure by using it in your Morini.

I was in the same situation as you a year ago. I just used the air that was in it and then had it hydro tested the next time I got it filled.

brent375hh wrote: ↑Sun Jan 02, 2022 6:03 pm I don't know how the air could go stale, or increase in moisture content. I doubt anyone filled it with anything but air. Assuming it was dangerous for the sake if argument, would it be safer to move it full, or bleed it off? You may as well just bleed off pressure by using it in your Morini.

I was in the same situation as you a year ago. I just used the air that was in it and then had it hydro tested the next time I got it filled.

Yeah I was asking them if it was dangerous to move an old tank under full pressure and they all said no. Interestingly I called the only dive shop in my County who is an official hydro testing station (the other shops send them out) and it turns out two of the guys there are avid big bore air rifle shooters, the guy I was talking to has a .50Cal FX air rifle and said personally he wouldn’t use air that old in his own FX, and the other shops I called said there was no way they’d breathe air that old on a dive .. so somethings happening to that air over time I guess. So I think I’ll just take it down to the testing station guys next week and just keep dry firing practice going in the mean time. Thx!

If you ever get an answer of what goes bad in "old" air that makes it unsuitable for air pistol use, I would love to know. I used my old air, and the the old air that was stored in the cylinders, my guns still shoot fine and I have put 25K rounds through them after the old air was used up. Your air tank is made of the same materials as your gun. If it isn't compromised, why would it affect your gun? BTW when I called my scuba center last year, the owner wasn't concerned about it's use in my airgun, he knew he would get my $72 for a hydro and fill soon enough.

Hopefully the shop that does your hydro testing will provide you a loaner tank if they can't do it while you wait. Do you still have your LP10?

wow, my hydro's are 48 bucks, and my annuals include an eddy current for 32 bucks

spektr wrote: ↑Mon Jan 03, 2022 12:04 am wow, my hydro's are 48 bucks, and my annuals include an eddy current for 32 bucks

It's well worth it to get all of the old air out them

I'm sure the compressed air is fine to use to refill your air pistol but of course I would not use it for scuba diving.
When the compressed air is used up you will have to have the tank hydro tested if you want to refill it.

lakiraly wrote: ↑Mon Jan 03, 2022 7:45 am I'm sure the compressed air is fine to use to refill your air pistol but of course I would not use it for scuba diving.
When the compressed air is used up you will have to have the tank hydro tested if you want to refill it.

This guy is dead on.

Think about it: air is about 78percent nitrogen, a neutral gas; 21percent oxygen, which will rust steel (iron) if there is water present; the rest is pretty much neutral. There is absolutely no reason NOT to use it in your air pistol.

Some dive shops will not bother with the "formalities" if they know you're not a diver. They might give you a deal if you trade in your tank on a used tank, preferably 100 cf. Paint ball shops are even less fussy.

brent375hh wrote: ↑Sun Jan 02, 2022 7:03 pm If you ever get an answer of what goes bad in "old" air that makes it unsuitable for air pistol use, I would love to know. I used my old air, and the the old air that was stored in the cylinders, my guns still shoot fine and I have put 25K rounds through them after the old air was used up. Your air tank is made of the same materials as your gun. If it isn't compromised, why would it affect your gun? BTW when I called my scuba center last year, the owner wasn't concerned about it's use in my airgun, he knew he would get my $72 for a hydro and fill soon enough.

Hopefully the shop that does your hydro testing will provide you a loaner tank if they can't do it while you wait. Do you still have your LP10?

Well it was the hydro test center itself that was talking the most about bad air, roughly paraphrasing .. what I heard him say was it can depend on the air in the room where it was filled and the condition of the fill equipment, filters, etc. as to the quality of air in a tank. He was saying in worse case scenarios a badly filled tank over time can produce flammable gases (he was rattling off gas names but I don’t remember) that under the heat of filling the gun could ignite, and that it could also be corrosive to the pistols air cylinder. I live in coastal Southern California and we have a LOT of dive shops all over the place, so I was able to call quite a few of them yesterday, it’s really only the shop above that also a certified hydro station that really got me spooked. I figured out how to read the tanks manufacturing date and it was made 15 years ago, so I think just to play it safe I’m going to take it down to the hydro station this week, they say they can do it pretty fast, all the other dive shops were quoting me 2-3 weeks.

On the the LP10 .. it was a silver one I bought new from Pilk years ago the same time as the tank, shot it for a couple months, then sold it here in the classifieds. It was a marvelous shooting pistol but I just didn’t like the aesthetics of it, so I sold it in still like new condition with the intention of getting a Morini of who’s aesthetics are more pleasing personally to my eye, but ended up using the money instead on a .45 1911 for NRA Bullseye, and it would be some years later that I finally got the Morini 162ei.

Most good/honest scuba centers will not fill an out of date scuba tank unless it has been hydro tested and recertified. It's an easy process that they can do and then refill with clean, dry air. I had my eight year old tank that I bought used around 2012 recertified last Spring. Recertification along with a refill cost me $45.

The 10-year service life of aluminium alloy diving bottles cannot be confused with the service life of air cylinders or rifles. Both are designed for different ambient conditions and are made from other alloys and materials and by a different method of production. From the technical point of view and the risks of possible damage, the cylinders of small sport weapons are not pressure vessels with the risk of great damage. The only technical criterion is the product of internal pressure and internal volume. From this point of view, the real stress and operating load of diving bottles (scuba tanks) are several times greater. On the contrary, with air weapons for sport shooting, it is only on the part of the manufacturers of these weapons, who thus cover their backs to solve their problems. In this case, I have expressed my doubts many times about the correctness of such a request. On the contrary, for diving bottles made of Al alloys, the requirement for a pressure test after 5 years or after 10 years for steel cylinders is completely justified.

B Lafferty wrote: ↑Mon Jan 03, 2022 11:30 am Most good/honest scuba centers will not fill an out of date scuba tank unless it has been hydro tested and recertified. It's an easy process that they can do and then refill with clean, dry air. I had my eight year old tank that I bought used around 2012 recertified last Spring. Recertification along with a refill cost me $45.

The 5-year hydro test is a US Department of Transportation legal requirement. Any dive shop that skips that is asking for trouble. The annual visual inspection is considered "best practice" by any good dive shop for breathing air. It's mostly to check for corrosion, which shouldn't be an issue if it never goes near the ocean. User friendly dive shops will skip the annual inspection if you promise not to use the tank for diving. You used to be able to get stickers that you could put on tanks that labeled them for air guns & not for breathing, and shops would take that into account.

The only local dive shop left around here insists on doing the annual inspection no matter what.

I have never heard of compressed air turning into a flammable gas over time. I guess I will leave it to the professional shops to advise you.

Perhaps a new energy source can come from it.

Perhaps the shop had encountered a "flaming asshole."

Nothing is going to turn the breathable air into flammable gas. I would go anywhere except whoever told you that.

The only thing I have ever heard as an explanation for "bad old air" (but was never sure if it was real or just theoretical) was someone who claimed that if the tank is filled badly and contains some amount of moisture, over time the formation of rust/oxides inside the tank will consume the oxygen, leaving you with something <20% O2. That can be dangerous on a dive, where it will essentially asphyxiate you, but it won't harm your gun.

I've never done the math to determine if it's even possible for oxides to consume enough of the oxygen to be meaningful.

So all that considered, do what makes you feel comfortable, but I'd use up the air that in there, then fill/inspect when needed.

marky-d