250 psi would be alot for a square tube, but reasonable for a round tube. With the square tube, the internal pressure is trying to make the tube round.

If it has been proof tested to 250 psi and it did not split or crack the welds, you should have no problems holding 150 psi unless you bust the tube on a rock.

 

Did you mean 120 psi? I'm talking about the output of the air compressor. CFM(cubic feet per minute)

 

Agreed, Making squares into air tanks = bad. There is a reason air tanks bought at stores are round or oval. Thats because the hoop and radial stresses are equal throughout the tank. The corners of a square tube concentrate stresses....add any impact and you risk blowing one apart....even at 150psi that is enough to seriously be injured. Also when tanks are filled and emptied they go through stress cycles that fatigue the metal making it weaker and more likely to rupture, hence why air tanks have to be tested every few years.

Best bet is go to local welding shop and buy a small bottle of co2 that can be traded in when empty for nominal amount. The go to fire fighting supplier and buy a screw in regulator..all in all should run about $60-80 bucks but will pay for itself in safety and time.

 

I made this one for my YJ.

I also have a york OBA, & all welding was done with my on board 220 amp alternator welder.

One thing I would like to suggest, is to always let the air out of these things before you drive on the road. If you get rear ended with 150psi in there & BOOM!

Also anyone attempting this should have some kind of experience, welding pressure vessels.

 

Heck I don't know now... I thought it said 120cfm but maybe it was Psi... lol... probly was... got me all confused now... gotta go reread it... lol