I found a gizmo at the dump that had a small propane cylinder (about 1/2 the volume of a 14 oz cylinder). Propane, I think - it has propane cylinder threads and the gizmo had a flame detector at the end of the pipe. And it had a tap on it that pierces the cylinder, but does not have a built-in valve.
I never seen this size cylinder, nor one that needed to be pierced. Anybody know what they're used for? And why the piercing (the only thing that I've thought of is the elimination of the check valve that normal cylinders have)?
Inquiring minds ... Bob