SCUBA Tank for Shop Air

[Dougryan]

Hi,
Scuba tanks are designed to hold ~3,000psi. And they have a life span that is checked by periodic visual and pressure testing. Eventually, they fail a test and get decommissioned. No longer certified to serve their intended purpose... BUT I am wondering if they might still be useful for ~120psi shop air?

The capacity is not great... For example an "80 cubic foot aluminum tank" (80 CuFt @ 3,000psi) has an actual volume of 0.4 CuFt. The benefit here is that these decommissioned tanks are cheap. People sometimes give then away or scrap them.

So, one could plumb several of them together to provide some extra capacity. Also the tanks could be remote from the compressor, so placement could be flexible. They would probably have to be mounted vertically with the opening down so that any condensation could drain.

Any thoughts on this?

Thanks,
Doug

 

[RedNeckRacin]

Why not get a "bad" compressor and salvage the tank off of it? It should already have a drain and a means of support installed. That would eliminate the mounting hassle of a round tank and the possible plumbing fiasco with having multiple small tanks plumbed together. Now if you want to use it as a portable tank, sure why not?

 

[Firemanbuck82]

The tanks are scrapped because they are out of date or fail a hydro test. Using discarded tanks to fill at 3,000 psi is playing Russian roulette betting on that they won't explode in your shop.

Your call.

 

[Ortimber]

The tanks are scrapped because they are out of date or fail a hydro test. Using discarded tanks to fill at 3,000 psi is playing Russian roulette betting on that they won't explode in your shop.

Your call.

But he is asking if they will be good for 120psi.

I would not hesitate to use one, but seems more logical to just find a good used air compressor.

 

[Firemanbuck82]

O.4 ft^3 capacity of the tank at 120 psi seems like a pitiful small amount of air to be able to run anything in a shop. You might be able to inflate a tire or something... Most air driven tools run between 4 and 10 cfm at 90psi so you'd get a quick "brrrrp" on the impact wrench, then have to refill the system. Now, at 3k psi it's a different story...but then back to my other post.

 

[flyerdan]

It would take 150 of them to equal a 60 gallon tank, and unless one was quite fastidious with the pluming, the leakage would result in the compressor running a lot more. I could see a few mounted up on a wall at the end of a long run that was far away from the main tank to act as surge tanks to counter the initial pressure drop.

 

[Diwali]

I'm not sure I would want to use an uncertified pressure vessel in my shop even for 120psi.
I have used (certified) SCUBA tanks in the desert to reinflate tyres and it sure beats a foot pump or a slow electric pump.

 

[Dougryan]

Yes, it would be for 120psi... And I agree that the volume would be crazy low.

I was thinking about using them as a "surge tank" on the opposite side of the garage from my compressor. But based on the comments, it sounds like I'd be better off using a tank from a bad compressor instead of a bank of scuba tanks. Even if the scuba tanks were free, the cost of mounting them, fittings, etc would make this project pretty inefficient.

Great feedback. I appreciate it.
Thanks,
Doug

 

[LD1]

Unless you got a large factory for a garage, you really won't see any benefit to a surge tank.

And I agree with others, get an actual 30 gal + tank or whatever size you want.

Sure, you may get the tanks for free. But plumbing them??? All the fittings and stuff you need...will cost alot of money.

Novel idea about trying to repurpose, but save yourself the headache.