ISA RP12.4-1996

Provides performance and test recommendations for pressurized enclosures and guidance to those who design and install pressurized systems for hazardous (classified) locations. The document should be used in conjunction with ANSI/NFPA 496. This Recommended Practice applies to equipment suitable for use in hazardous (classified) locations by using a pressurizing system and to equipment with and without an internal release of flammable gas or vapor. It does not apply to occupied portions of buildings such as ventilated or pressurized control rooms.