Lower flammable limit (LFL) Created OnJanuary 10, 2018byCult of Sea Print You are here: Glossary L Lower flammable limit (LFL) < Back to Glossary IndexThe concentration of a hydrocarbon gas in air, below which there is insufficient hydrocarbon to support and propagate combustion. Sometimes referred to as lower explosive limit (LEL). Related:Upper flammable limit (UFL)Flammable rangeHydrocarbon GasExplosive rangeDreadage or Dreading ClauseCombustible gas indicator