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
It can! It’s called flashback.
To prevent it from happening you put a device called a flashback arrestor in between the tank and the torch. It’s a legal requirement on the job in most places.
…But only for an oxy-propane torch. Because the oxygen is also under pressure and can push its way through the propane line and into the tank. If you’re just using a standard propane torch with no compressed air or oxygen hooked up then there is not really a need because no air would be able to overcome the pressure of the propane and create the required flammable air-fuel mixture inside the hose and tank.
Propane only burns if the volume of propane gas in the air is between 2.1% and 9.5%. In the tank it’s higher than that. Unless you introduce oxygen.
Although it could theoretically happen if you ran the tank empty and it was really really windy
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