"Francois" wrote: (clip) Last time I used it, I was reading 50 on the
first meter of the acetylen bottle and that pressure drop to 0 pretty fast
(maybe 30 sec.) After a couple minuts, the pressure came back to 50.(clip)
^^^^^^^^^^^^
The acetylene gas is dissolved in something like acetone, which, in turn, is
soaked into a solid porous material like charcoal (?), to lessen the risk of
explosion. At your low temperatures, the gas cannot come out of solution
fast enough to supply the torch, so the pressure falls off. You need to
warm the cylinder up.

SOMEWHERE, I READ THAT YOU MUST NOT DO THIS BY TURNING THE TORCH ON THE
CYLINDER.