Why doesn’t the flame from a propane torch travel back to the can and blow it up?

Question

I’ve always been a little embarrassed to ask, but when I have, say, a propane torch, how come the flame doesn’t go back through the line and blow up the can?

In: Engineering

Answer 1

It can with other gasses, like acetylene. Propane is kept at a fairly high pressure before being reduced at the regulator. This pretty much prevents a flashback. Not having the right mix helps as well. Acetylene, on the other hand, is never at very high pressure (it can self combust). Ace also requires much less oxygen to combust. On torches using ace there are safety valves called flashback arrestors, they hopefully close in the event of a flashback.