098: Hazardous areas classification and level of danger

3903

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):

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.

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