NFPA 496

Abstract

This standard applies to purging and pressurizing for the following: <br>(1) Electrical equipment located in areas classified as hazardous by Article 500 or Article 505 of <em>NFPA 70</em> <br>(2) Electrical equipment containing sources of flammable vapors or gases and located in either classified or unclassified areas <br>(3) Control rooms or buildings located in areas classified as hazardous by Article 500 or Article 505 of <em>NFPA 70</em> <br>(4) Analyzer rooms containing sources of flammable vapors or gases and located in areas classified as hazardous by Article 500 or Article 505 of <em>NFPA 70</em> <br>This standard does not apply to electrical equipment located in: <br>(1) Areas classified as Class I, Zone 0 <br>(2) Areas classified as Class III <br>(3) Areas where flammable liquids may be splashed or spilled on the electrical equipment <br><strong>Purpose.</strong> <br>This standard provides information on the methods for purging and pressurizing enclosures to prevent ignition of a flammable atmosphere. Such an atmosphere may be introduced into the enclosure by a surrounding external atmosphere or by an internal source. By these means, electrical equipment that is not otherwise acceptable for a flammable atmosphere may be utilized in accordance with Article 500 or Article 505 of <em>NFPA 70</em>.