Gas explosion

[1] In household accidents, the principal explosive gases are those used for heating or cooking purposes such as natural gas, methane, propane, butane.

In industrial explosions, many other gases, like hydrogen, as well as evaporated (gaseous) gasoline or ethanol play an important role.

Whether a mixture of air and gas is combustible depends on the air-to-fuel ratio.

For each fuel, ignition occurs only within a certain range of concentration, known as the upper and lower flammability limits.

An explosion can only occur when fuel concentration is within these limits[citation needed]