Lower flammable limit

Lower flammability limit (LFL) is the lower end of the flammability range of a flammable solvent, which represents the range of air/vapor mixtures that can ignite. The flammability range is delineated by the upper and lower flammability limit. Outside this range of air/vapor mixtures, the mixture will not ignite.

LFL can also be related to the flash point, however flash point is with regards to the temperature but flammability limits is with regards to the concentration but with higher temperatures come higher concentrations so its really referring to the same situation from a different standpoint.