Food Truck Explosion in Philly- propane!

Harvard wrote:
Maybe the tank was full and little or no vapour space to allow the liquid to expand, then the pressure relief valve failed to release the resulting pressure. The propane certainly did not ignite inside the tank.

This sounds exactly right- especially given the clearly visible cloud of propane seen in the vid immediately before it caught fire, likely from an ignition source inside the rig. It wasn't afire when it left the tank.

Overfilling leaves no room for expansion of the liquid propane, and it will do so very quickly in hot conditions. Per the tank "exploding": They don't show a pic of the bad tank with a hole in it so it's hard to say if the gas got out through the valve or not...doesn't really matter since that vapor cloud would appear regardless of the point of exit.

Prevention of this sort of thing is exactly why the tanks most of us use are now equipped with overfill prevention devices. The tanks on this truck were of a size not covered by that requirement.