Okay just for clarification, if it is compressed gas as in natural gas it will explode. If it is gasoline, then it depends if it an empty or full container.

If is an empty container it will blow, because the gasoline has vaporized and mixed with air to explode like in a combustion chamber.

That is what a fuel injector or carburetor does is put in proper portions the air/gasoline ratio so it will explode for maximum combustion (explosion).

If the barrel is full of gasoline, then the top will just burn.

Bottom line: Ya gotta have air mixed with it to explode.