Zone classification

Zone classification is the part of hazardous area classification that labels each space by how often a flammable gas atmosphere is present, so equipment and ignition controls match the risk. Under IEC 60079-10-1, Zone 0 has an explosive atmosphere continuously or for long periods (the inside of a cargo tank), Zone 1 has one likely in normal operation (a cargo pump room or areas near tank openings), and Zone 2 has one only rarely and briefly (spaces around vents under fault conditions). On oil, chemical, and gas tankers these zones drive the Ex rating of every electrical fitting, the ventilation regime, and the certified-safe equipment lists. The IEC 60092 series applies the zones to shipboard wiring.