Industries like oil & gas, chemicals, and refineries use hazardous area classification to identify locations where explosive gas atmospheres may occur and to ensure safe electrical equipment is used.
These areas are divided into three zones—Zone 0, Zone 1, and Zone 2—based on how often and how long explosive gas is present.
Zone 0 — Continuous Presence (Highest Risk)
. Zone 0 is an area where an explosive gas atmosphere is present continuously or for long periods of time during normal operation.
. This means gas is almost always present in this area.
. It is the most dangerous zone in hazardous area classification.
Zone 0 represents locations where flammable gases are constantly inside the system or equipment. Since the gas is always present, even a small ignition source can cause an explosion at any time.
Zone 1 — Occasional Presence (High Risk)
. Zone 1 is an area where an explosive gas atmosphere is likely to occur during normal operation occasionally.
. Gas is not always present but can appear during operation.
. It is a high-risk zone, but less severe than Zone 0.
Zone 1 covers areas where leaks or gas release can happen during normal working conditions. Equipment operation, opening of valves, or minor seal leakage may release flammable gas into the environment.
Zone 2 — Rare Presence (Lower Risk)
. Zone 2 is an area where an explosive gas atmosphere is not likely to occur during normal operation.
. If it does occur, it will be only for a short period of time and usually due to abnormal conditions or faults.
. It is the least hazardous of the gas zones.
Zone 2 is an area where an explosive gas atmosphere is not likely to occur during normal operation. If it does occur, it is only for a short duration due to abnormal conditions such as leaks or equipment faults. It is the least hazardous gas zone, but equipment must still be designed to prevent ignition, and adequate ventilation helps reduce the risk.