Enclosure Pressure Purging

Purge and pressurization systems are used to ensure that once an enclosure is purged and pressurized with a protective gas supply, the electrical equipment inside the enclosure can be powered on. The purge process is used to remove any potentially hazardous gas from inside the enclosure. The purge cycle displaces any explosive gas with an inert, protective gas. The pressurization process creates a higher internal pressure by providing a protective gas supply, which prevents any hazardous gas or dust from entering the enclosure. Any leaks in the enclosure will have protective gas exiting instead of hazardous gas or dust entering. 

Two methods of purge and pressurization are: continuous flow and leakage compensation. Continuous flow provides an uninterrupted, steady flow of air into the pressurized enclosure. This is maintained after the purge process and keeps the internal enclosure pressure higher than the surrounding atmosphere. Continuous flow systems are typically used with smaller enclosures (less than 17 cubic feet) or with enclosures that are infrequently used. Leakage compensation uses a controller to regulate a smaller flow of air into the enclosure to maintain the minimum required pressure and to compensate for any leaks. Leakage compensation uses an initial high flow rate purge to clear any hazardous gases and is suitable for any size enclosure.