Pressurization 3 : The process of supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitible fiber
NFPA 496 Standard for Purged and Pressurized Enclosures for Electrical Equipment, 2008 ed. (Std: Purged and Pressurized Enclosures for Elctr Equip - Amer) {322 NFC}