About Combustible Gases
A combustible gas is one that will burn when mixed with air (or oxygen) and ignited. Combustible gas-air mixtures can be burned over a wide range of concentrations. The actual minimum concentration varies from about 0.5% to about 15% by volume in air for most common CHCs. This concentration is always referred to as 100% LEL or LFL for that gas.

Some Combustible Gases & Vapors are:
Alcohols: Methanol, Ethanol, Propanol
Ester: Ethyl Acetate
Ethers: Ethyl Ether, Methyl Ether
Hydrocarbons: Methane, Propane, Butane, Hexane,
Heptane, Acetylene, Gasoline, Jet Fuel, Naptha, Turpentine
Cyclic Compounds: Toluene, Exlene, Ethylene Oxide
Ketones: Acetone, Methyl Ethyl Ketone
Inorganic Gases: Carbon Monoxide, Hydrogen Sulfide, Ammonia, Hydrogen