What is Zone 2 and why is it painful?
In ATEX classifications, hazardous areas are divided into zones based on the presence of explosive atmospheres. There are three ATEX zones for gas and three for dust:
• Gas Zone 0 – High risk, where an explosive atmosphere is continuously present, or present for long periods (more than 1,000 hours per year).
• Gas Zone 1 – Moderate risk, where an explosive atmosphere is likely to occur during normal operation (10 to 1,000 hours per year).
• Gas Zone 2 – Low risk, where an explosive atmosphere would only occur under abnormal conditions (less than 10 hours per year).
Dust zones are 20, 21, and 22 and have similar definitions to gas, but for an explosive dust cloud.
So, if it poses such a low risk, why is Zone 2 considered to be so
painful? “For at least 99.9 percent of the time, or 8,750 hours per year, the area is perceived as just like any other non-hazardous area in the factory,” explained Tony Coghlan of Turck Banner.
“However, special precautions must be taken whenever that equipment is used, maintained or introduced
to the area. This equipment costs more to purchase and maintain, and typically takes longer to do.
“While no one thinks that special precautions in the higher zones are not required, to use an analogy of a domestic kitchen, would you search for a gas leak with a match?”
Read the full article in DPA's June 2025 issue