All those in the industry know the importance of purging systems. This technique of purging enclosures and pressurising of the electrical apparatus is done to prevent the probability of any flammable atmosphere. It is a globally accepted protection concept that is used for explosion protection.
If there is an electrical control equipment then an air purge system is used to flush it with some clean air before turning it on. This is done to ensure that the contaminants present in the surrounding environment do not affect or damage the functionality of the equipment. These air purge systems are used for that analytic and control technology, which is exposed to flue gas that results due to an industrial process. The purge control panel is centrally placed to maintain a clear periphery path.
To determine which purge system will be appropriate for a specific application, the following primary factors are considered.
- Area Classification: Depending on the area, a particular purge system is employed. The Ex px /Type X system is used for Zone 1/Division 1 areas. This equipment is meant for general-purpose. But, if the area comes under Division 2/Zone 2, then Ex py /Type Y system is used.
- Ratings of the Equipment: The rating of the equipment that is used inside the enclosure is important based on which the purge system is decided. It is also to be seen if the enclosure has some hazardous gas in it.
- Size of Enclosure: It is the free volume inside the enclosure that determines the size of the enclosure. Other than that, the position of doors and windows is taken into consideration to choose the appropriate purge system.
The main advantage of using the purging systems over the explosion-proof enclosures is that it is safe in hazardous areas. In the case of explosion-proof enclosures if the explosion occurs it is contained within the enclosure. These enclosures are specifically made taking size and weight into consideration. If all bolts provided in these enclosures are torqued down as per the specifications then the explosion, if it happens, is contained within the enclosure.
Purged panels, on the other hand, use purge/pressurisation in any standard enclosures and do not allow the explosion to take place only. Thus, they are safe to be installed in the hazardous areas. The only downside of using the purge enclosures is that it requires an inert source or constant air during its operation. If very small enclosures are used then explosion-proof might have an edge on the cost factor but anything above 1 cubic foot, the purge is the best to use.