For applications in Zone 22/Class II (dust)

Purging and pressurizing systems is one of the most versatile explosion protection methods Purging and pressurizing systems is one of the most versatile explosion protection methods. These systems are based on the principle that in Zone 1 or 2, Division 1 or 2, the gas mixture in the ambient atmosphere, which may ignite under certain circumstances, is removed from the housing by an initial purge process. After the purge phase, sufficient compressed air or inert gas is supplied to compensate for leaks in the enclosure. This permanent overpressure, achieved using compressed air or inert gas, prevents any potentially explosive atmosphere in the ambient air from entering the enclosure.

During the rapid exchange purge phase, an internal pressure of approximately 3.5 - 12 mbar (1.3” to 5.0” Water Column) is achieved. During operation, this internal pressure reaches 0.6 - 3 mbar (0.3 to 1.2” Water Column).

For applications in Zone 22/Class II (dust), the purge process is omitted because purging would raise explosive dust. Instead of pre-purging, the interior of the housing is inspected for dust technology and cleaned manually if dust is present.