NFPA has updated its 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, with a few minor revisions. Probably the most significant revision is NFPA’s position on “intentional releases and maintenance venting.” The most beneficial revision was NFPA officially defining “Unpierced.” Let’s discuss the 2027 revisions…