Gases that ignite pose a serious safety hazard, especially since most gases are stored in cylinders or other containers. Many of these gases have no odor and their presence cannot be detected without the use of a specific detector. Should a leak occur, the gas often accumulates, forming a pocket of gas. These pockets can accumulate at ground level or towards the room’s ceiling, depending on the gas’ density. Pockets of certain gases can, in turn, lead to fires or explosions. The gas’ container may provide another hazard because, should it explode, the container may become a missile/projectile or send parts of the container in all directions.


Flammable gas means a gas having a flammable range with air at 20 °C (68 °F) and a standard pressure of 101.3 kPa (14.7 psi).

Flammable range (often referred to as the explosive range) is the range between the lower and upper flammable limit, expressed in terms of percentage of vapor or gas in air by volume. The flammable range includes all concentrations of flammable vapor or gas in air, in which a flash will occur or a flame will travel if the mixture is ignited and includes rapid combustion or an explosion.