GAS AREA 

Zone 0 

Areas where a dangerous explosive gas atmosphere is present continuously or for a long period of time or frequently. Usually these conditions will occur inside containers, pipes, and vessels. 

Zone 1 

Areas where a dangerous explosive gas atmosphere may form during normal working operations. 

Zone 2 

Areas where a dangerous explosive gas atmosphere should not form during normal working operations, and when this occurs, it is only for a short period of time.