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098: Hazardous areas classification and level of danger

Hazardous area is an area where fire and explosion may occurred due to presence of an explosive gas or combustible dust atmospheres.

Note1: The acronym for ATmospheres EXplosible is ATEX.

Note2: Danger level are classified in Europe with Zones and in North America with Classes/Divisions.

Hazardous area according to European standards (Zones):

  1. A)  Explosive gas atmospheres (Ignitable concentrations of flammable gases or vapours)
  • Zone 0 (Class I Division 1): Area in which an explosive gas atmosphere is present continuously or for long periods of time (will frequently occur).
  • Zone 1 (Class I Division 1): Area in which an explosive gas atmosphere is likely to occur (occasionally in normal operation)
  • Zone 2 (Class I Division 2): Area in which an explosive gas atmosphere is not likely to occur in normal operation and only occur infrequently for a short period.
  1. B) Combustible dust atmospheres (combustible dusts or ignitable fibers and flyings)
  • Zone 20 (Class II Division 1): Area in which a combustible dust atmosphere is present continuously or for long periods of time (will frequently occur).
  • Zone 21 (Class II Division 1): Area in which an combustible dust atmosphere is likely to occur (occasionally in normal operation)
  • Zone 22 (Class II Division 2): Area in which a combustible dust atmosphere is not likely to occur in normal operation and only occur infrequently for a short period.

Note3: The material type for hazardous atmosphere and location are defined by the Groups.

Note4: In European standards we have 3 groups (I,II and III) but in North America there are 7 groups (A,B,C,D,E,F,G) for classification.

1- Group I: Mines

2- Group II: Explosive gas (except mines)

  • A: Propane, acetone, benzene, butane, methane, petrol, hexane, paint solvents or gases and vapours of equivalent hazard.
  • B: Ethylene, propylene oxide, ethylene oxide, butadiene, cyclopropane, ethyl ether, or gases and vapours of equivalent hazard.
  • C: Acetylene, hydrogen, carbon disulphide or gases and vapours of equivalent hazard

3- Group III: Explosive dust

  • A: Combustible flyings
  • B: Non-conductive dust
  • C: Conductive dust

Related standards:

  • EN/IEC 60079
  • NFPA 70

 

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