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 or ignitable mixtures. Class I locations are further subdivided into two Divisions and three Zones. Class I, Division 1: There are three different situations that could exist to classify an area as a Class I, Division 1 location ·          Ignitable concentrations of flammable gases or vapors may exist under normal operating conditions. ·          Ignitable concentrations of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage. ·          Breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapors, and mig...