API 500 : 2012

1 Scope
2 Normative References
3 Terms, Definitions, and Acronyms
4 Basic Conditions for a Fire or Explosion
5 Flammable and Combustible Liquids, Gases
   and Vapors
6 Classification Criteria
7 Extent of a Classified Location
8 Recommendations for Determining Degree and
   Extent of Classified Locations - Common
   Applications
9 Recommendations for Determining Degree and
   Extent of Classified Locations in Petroleum
   Refineries
10 Recommendations for Determining Degree and
   Extent of Classified Locations at Drilling Rigs
   and Production Facilities on Land and on Marine Fixed
   Platforms
11 Recommendations for Determining Degree and Extent
   of Classified Locations on Mobile Offshore Drilling
   Units (MODUs)
12 Recommendations for Determining Degree and Extent
   of Classified Locations at Drilling Rigs
   and Production Facilities on Floating Production Units
13 Reserved for Future Use
14 Recommendations for Determining Degree and Extent
   of Classified Locations at Petroleum Pipeline
   Transportation Facilities
Annex A (informative) - Sample Calculation to Achieve
        Adequate Ventilation of an Enclosed Area by
        Natural Means Using Equation 1 and Equation 2
Annex B (informative) - Calculation of Minimum Air
        Introduction Rate to Achieve Adequate Ventilation
        Using Fugitive Emissions
Annex C (informative) - Development of Ventilation Criteria
Annex D (informative) - An Alternate Method for Area
        Classification
Annex E (informative) - Procedure for Classifying Locations
Annex F (informative) - Preferred Symbols for Denoting Class I,
        Division 1 and Division 2 Hazardous (Classified) Locations

Gives guidelines for classifying locations Class I, Division 1 and Class I, Division 2 at petroleum facilities for the selection and installation of electrical equipment.