What Does Flammability Limit Mean?
Flammability limit can be defined as the limit or range of the composition of gases in fixed temperature and pressure conditions within which gaseous vapors can catch fire or an explosive condition is reached when an external source of ignition is introduced. Flammability limit is generally associated with petroleum vapors. The concentration of vapor depends on the percentage ratio of fuel to the total volume.
Corrosionpedia Explains Flammability Limit
Flammability limits are not absolute, i.e. they do not depend on absolute atmospheric conditions; however, they do depend on the strength and type of the source of ignition. Studies have shown that the flammability limits for petroleum vapors depend on the strength of ignition stimulus as well as the percentage of oxygen in the air, atmospheric pressure and temperature conditions. Flammability limits can be categorized in two ways:
- Upper flammability limits (UFL) – In this condition, the mixture of petroleum vapors and air is “too rich” to burn. Also called upper explosive limit (UEL).
- Lower flammability limits (LFL) – In this condition, the mixture of petroleum vapors and air is “too lean” to burn. Also called lower explosive limit (LEL).