What are Lower and Upper Explosive Limits for Flammable Gases and Vapors?
Lower Explosive Limit abbreviated (LEL) and Upper Explosive Limit abbreviated (UEL). Before a fire or explosion can occur, three conditions must be met simultaneously. A fuel (ie. combustible gas) and oxygen (air) must exist in certain proportions, along with an ignition Reference(s), such as a spark or flame. The ratio of fuel and oxygen that is required varies with each combustible gas or vapor.