All Equipment inside the enclosure must be Division 2 rated. For Class I applications this system operates by forcing air or an inert gas through the enclosure for a specified time until all of the hazardous gas has been removed (purging). After purging, a constant pressure with the enclosure is maintained and the equipment with the enclosure can be energized. Loss of safe pressure requires immediate attention if power is not discontinued to the enclosure.
For Class II applications no purging is performed but the enclosure must be cleaned of all
combustible material, then pressurized before energizing the equipment with the enclosure. Loss of safe pressure requires immediate attention if power is not discontinued to the enclosure.