Weidmueller Enclosures & Cable Glands

Directive 1999/92/EC
Technical appendix
Classification of explosive groups
Electrical devices for groups II and III are classified further as
a function of the properties of the explosive atmosphere for
which they are intended.
The danger of the atmosphere increases from IIA(IIIA) to
IIC(IIIC) so that all equipment certified for use in IIC(IIIC)
areas may also be used in IIA(IIIA) and IIB(IIIB) areas.
Classification of explosive groups
Group Material, e.g. Ignition energy Group Material
IIA Propane 266 µJ IIA Flammable fluff
IIB Ethylene 85 µJ IIB Non-conductive dust
IIC Hydrogen 19 µJ IIC Conductive dust
Classification of zones and equipment categories
Combustible
ingredients
Explosive
atmospheres
Zone
division
EPL safety level
Equipment group
Identification
Device category
Gas, mist,
vapours/fumes (G / Gas)
permanent, long-term Zone 0 Ga II 1G
occasionally Zone 1 Gb II 2G
unlikely,
short-term
Zone 2 Gc II 3G
Dusts (D / Dust) permanent, long-term Zone 20 Da II 1D
W
occasionally Zone 21 Db II 2D
unlikely,
short-term
Zone 22 Dc II 3D
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