Flameproof

FM Approved flameproof equipment is enclosed in a case that will withstand an internal explosion of a flammable mixture that has penetrated into the interior without suffering damage and without causing ignition through any joints or structural openings in the enclosure of an external explosive gas atmosphere consisting of one or more of the gases or vapors for which it is designed.

Equipment certified using this protection method is suitable for use in Class I, Zone 1.