Hazardous area classification

Hazardous area classification is the process of dividing spaces where flammable gas or vapor may be present into zones by the likelihood and duration of an explosive atmosphere, so that only suitably certified electrical equipment is installed there. IEC 60079-10-1 defines the gas zones: Zone 0 (explosive atmosphere present continuously or for long periods), Zone 1 (likely in normal operation), and Zone 2 (unlikely, and only briefly if it occurs). On tankers and gas carriers the cargo area, pump rooms, and adjacent spaces are classified to drive equipment selection (Ex ratings), ventilation, and ignition-source control. The IEC 60092 series applies the principle to shipboard installations, and class approves the resulting hazardous-area plan.