3111F.4 Purged or Pressurized Enclosures for Equipment in Hazardous Locations (N/E)
Purged or pressurized enclosures shall be capable of preventing the entry of combustible gases into such spaces, in accordance with NFPA 496 [11.4]. Special emphasis shall be placed on reliability and ease of operation. The pressurizing equipment shall be electrically monitored and alarms shall be provided to indicate failure of the pressurizing or purging systems.
Pressurized control rooms shall conform to Chapter 7 of NFPA 496 [11.4].