a comment if you are dealing with kids and gas cylinders...we used to use the GAZ cylinders for our "Bunsen burners" in chem lab, with the type shown in CANOEDOGS's photo, once punctured, no way to shut off the gas except with the burner valve... a fellow teacher walked into my class one day with a punctured cylinder spewing gas (one of his angels had popped the top off)... I grabbed it and headed for the window, but a PE class was passing underneath, threw it in the vent hood, had the students look away, and hoped the vent switch and motor were explosion proof as noted and flipped the switch... we affectionately referred to them thereafter as hand grenades...switched to a source (Lentz?) with a self contained Schrader valve (tire type valve) to shut off fuel if the burner is removed...