NFPA 497: Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas (2008)

NFPA 497: Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas has a close relationship to the electrical installation requirements for hazardous (classified) locations contained in NFPA 70®: National Electrical Code®. To ensure correlation with revisions made to the 2008 NEC®, the 2008 NFPA 497 now includes: Changes to the scope to specify that explosives, pyrotechnics, and blasting agents have unique hazards that are not addressed by the recommendations of the document Recognition of areas as being unclassified where the gas or vapor concentration is insufficient to reach 25% of the lower flammable limit (LFL) Additions and revisions to Table 4.4.2 on physical properties of selected chemicals in order to provide information on commonly used materials not previously covered and to resolve differences that existed between this table and similar information contained in other documents Revision to the Annex B example on determining the maximum experimental safe gap and NEC group classification for mixtures