The release of flammable, combustible substances into an atmosphere with electrical systems or equipment can result in a potentially deadly and destructive incident. 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, delivers broad-based requirements for better safeguarding locations that handle these substances.

This vital safety document offers recommended practices that provide a basic understanding of parameters used to classify the extent of a hazardous location. You get criteria for assessing ignitability hazards in chemical process areas, as well as provisions for selecting the appropriate electrical systems and equipment for optimal safety.

NFPA 497 is a must-have guideline for:

• Installers and maintainers of electrical equipment located in or near areas where flammable or combustible liquids or flammable gases or vapors are present
• Equipment manufacturers providing equipment suitable for use in applicable electrically classified areas
• Design engineers, consultants, loss prevention or safety engineers, insurance professionals, enforcing officials, and owners/operators of industrial facilities

Changes for 2024 include:

• Definition for hazardous (classified) location was added from the NEC to provide clarity
• Two new figures added to establish classification areas around pressure relief valve vents.
• Figures in Section 5.11 have been removed to eliminate confusion