Keywords:  ignition, ufl, uel, flammable, combust
The point at which the concentration of a gas in air becomes too great to allow an explosion upon ignition due to insufficient oxygen present. Found in: Water Treatment Plant Operation, Vol I & II Water Distribution System O&M Small Water System O&M Operation of Wastewater Treatment Plants, Vol II Pretreatment Facility Inspection
the maximum concentration of vapors or gas in the air above which it is not possible to cause ignition of the vapors with a proper ignition source.
Maximum concentration of a gas in percent that will combust in the atmosphere.