lower flammable limit(The lower flammable limit (LFL) describes the leanest mixture that still sustains a flame, i.e. the mixture with the smallest fraction of combustible gas, while the upper flammable limit (UFL) gives the richest flammable mixture. wiki Alexander Demidov)
lower flammability limit(the lower end of the concentration range of a flammable solvent at a given temperature and pressure for which air/vapor mixtures can ignite. wiki – LFL Alexander Demidov)