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

Well, for one thing it’s pressurized; which means the flow of gasses always wants to leave the line, not travel backwards to the can. Secondly, you need a certain mixture of air and propane fumes to enable combustion, and that does not exist inside the can.