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Explosion Protection Guide
June 30th, 2021
Classifications Inside North America
Classes
Class I
Flammable gases or vapors are present in the air in quantities sufficient to produce explosive or ignitable mixtures.
Class II
Combustible or conductive dusts are present.
Class III
Ignitable fibers or flyings are present, but not likely to be in suspension in sufficient quantities to produce ignitable mixtures. (Group classifications are not applied to this class.)
Divisions
Division 1
The substance referred to by class is present during normal conditions.
Division 2
The substance referred to by class is present only in abnormal conditions, such as a container failure or system breakdown.
Groups
Group A
Acetylene
Group B
Hydrogen (or gases of equivalent hazard)
Group C
Ethylene (or gases of equivalent hazard)
Group D
Gasoline (or gases of equivalent hazard)
Group E
Metal Dust
Group F
Coal Dust
Group G
Grain Dust
Classification Outside North America
Zones
Zone 0
Area in which an explosive gas-air mixture is continuously present or present for long periods.
Zone 1
Combustible or conductive dusts are present.Area in which an explosive gas-air mixture is likely to occur in normal operation.
Zone 2
Area in which an explosive gas-air mixture is not likely to occur, and if it occurs it will only exist for a short time.
For application in below ground installations (mines) where methane (firedamp) and coal dust may be present.
Group IIA
For application in above ground installation where hazards due to propane may exist. This group most closely matches the North American Group D.
Group IIB
For application in above ground installations where hazards due to ethylene may exist. This group most closely matches the North American Group C.
Group IIC
For application in above ground installations where hazards due to hydrogen or acetylene may exist. This group most closely matches the North American Groups A and B.
