Can a makeshift flamethrower accidentaly blow up?

Question

I've often heard about how you can make a crude flamethrower by holding a lighter in front of an aerosol can and spraying it. I have also heard that the flame can "travel up the stream and into the can", blowing up the can and severely injuring you. I realize that playing with any fire can be dangerous, but I am wondering weather there is any validity to the statements that the flame can travel backwards into the can. Please no anecdotal evidence, I would much prefer some sort of scientific explanation, and possibly a link to some more information.

Answer 1

This is a bad Idea and do not do this. Most of the propellant in the can is propane or butane blend and the liquid is the container is also likely to be flammable. Besides explosions, there are fire hazards that can lead to very painful injuries/ and or death.

Now the theory. The flames will only last as long as there is oxygen present. In the filling process of the can, much of the air is removed from the aerosol can immediately before the valve is crimped onto the container. The propellant is then inserted into the container through the valve. There is typically no air present inside the container. The combustion will occur only outside of the container at a point where the propellant mixes with air. This assumes that the container was filled correctly and their is no oxidizer present in the container. Again, do not do this. I saw this done as a child but I was smart enoguh not to do this myself.

Answer 2

The flame cannot travel back into the can, since oxygen is required for combustion and is not present within the container.