ISA RP12.24.01 : 1998

Foreword
1 General
      1.1 Scope
      1.2 References
      1.3 Purpose
2 Definitions and terms
      2.10 Explosive limits
3 Safety and area classification
      3.1 Safety principles
      3.2 Area classification objectives
4 Area classification procedure
      4.1 General
      4.2 Sources of release
      4.3 Type of Zone
      4.4 Extent of Zone
      4.5 Extent of Zone - General comments
5 Ventilation
      5.1 General
      5.2 Main types of ventilation
      5.3 Degree of ventilation
      5.4 Availability of ventilation
6 Documentation
      6.1 General
      6.2 Drawings, data sheets and tables
Annex A (informative) - Examples of source of release
      A.1 - Process plants and facilities
      A.2 - Openings
Annex B (informative) - Ventilation
      B.1 - Natural ventilation
      B.2 - Artificial ventilation
      B.3 - Degree of ventilation
      B.4 - Assessment of degree of ventilation and its
            influence on the hazardous area
      B.5 - Availability of ventilation
      B.6 - Practical guide
      B.7 - Calculations to ascertain the degree of
            ventilation
Annex C (informative) - Examples of hazardous area
                        classification
Annex D (informative) - Use of combustible gas detection
                        equipment
Annex E (informative) - United States major deviations

Deals with classification of hazardous areas where flammable gas or vapor risks may occur, so as to allow proper selection and installation of apparatus used in these hazardous areas. Applies where there may be risk of ignition due to presence of flammable gas or vapor, mixed with air under normal conditions, but does not cover mines susceptible to firedamp, process and manufacture of explosives, areas where risk may arise due to presence of ignitable fibers and dusts, catastrophic failures beyond the concept of abnormality dealt with, rooms for medical purposes and areas where presence of flammable mist could give rise to unpredicatble risk and which need special consideration.