Upper Flammable Limit 1 : (UFL) The highest concentration of flammable vapor in air that will burn with a flame. See: Upper Explosive Limit; See also: Flammable Limit
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}