Classes (locations)

Class I locations

Class I locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive gas atmospheres

Class II locations

Class II locations are those which are hazardous because of the presence of combustible or electrically conductive combustible dusts

Class III locations

Class III locations are those which are hazardous because of the presence of easily ignitable fibers or flyings, but in which such fibers or flyings or fluff are not likely to be in suspension in air in quantities sufficient to produce ignitable mixtures