Originally Posted by Trigger Finger
...also they do go out of hydro. there is not a tank in production that has unlimited life...
That's not accurate. CFR 49 180.209
specifies "Any cylinder not exceeding 2 inches outside diameter and less than 2 feet in length is excepted from volumetric expansion test."
The exception is not based on cylinder contents (e.g. CO2, N2, O2, etc.). The majority of small 13 ci paintball cylinders will fall under this exception and will never need hydro testing.