Definition(s)
Ignitable (Flammable) Mixture
A gas-air mixture that is capable of being ignited by an open flame, electric arc or spark, or device operating at or above the ignition temperature of the gas air mixture. See flammable (explosive) limits.
API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards