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

Classification of flammable liquids, gases, or vapors and of hazardous (classified) locations for electrical installations in chemical process areas.

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 2012 Edition

Chapter 1 Administration

1.1 Scope 
1.2 Purpose 
1.3 Relationship to NFPA Codes and Standards

Chapter 2 Referenced Publications

2.1 General 
2.2 NFPA Publications 
2.3 Other Publications 
2.4 References for Extracts in Recommendations Sections

Chapter 3 Definitions

3.1 General 
3.2 NFPA Official Definitions 
3.3 General Definitions

Chapter 4 Classification of Combustible Materials

4.1 National Electrical Code Criteria 
4.2 Behavior of Class I (Combustible Material) Gases, Vapors, and Liquids 
4.3 Conditions Necessary for Ignition 
4.4 Classification of Class I Combustible Materials

Chapter 5 Classification of Class I (Combustible Material) Areas

5.1 General 
5.2 Class, Division, Classified Locations 
5.3 Class I, Zone Classified Locations 
5.4 Unclassified Locations 
5.5 Extent of Classified Locations 
5.6 Discussion of Diagrams and Recommendations 
5.7 Basis for Recommendations 
5.8 Procedure for Classifying Locations 
5.9 Classification Diagrams for Class I, Divisions 
5.10 Classification Diagrams for Class I, Zones

Annex A Explanatory Material 
Annex B Example of a Method for Determining NEC Group Classification for Mixtures 
Annex C Informational References 
Index