Page 64 - Electrical Installation in Hazardous Area

40 Electrical installations in hazardous areas

Does the process contain more than a NO Area classification may not be necessary’
specified minimum of flammable - but special precautions may be needed
material?

NO 4 Non-ha; irdous area I
YES

a lower arade of release?

b

2.6
see
Fig.
Fig. 2.5 Area classification procedure for explosive atmospheres

Determination of
hazardous areas
(see Fig. 2.5)
- material during normal -

Determine the distance
Determine the rate of release of
upon release rate and
YES flammable NO to below the LEL based Extent of Zone
operation. Can it be reduced?
other characteristics
Determine the distance
Determine the rate of release of NO to below the LEL based
YES flammable material during abnormal upon release rate and Extent of Zone
operation. Can it be reduced? other characteristics

Note:- If the release rate during
abnormal operation is equal to
or less than that in normal
operation. No Zone 2 is required
Fig. 2.6 Extent of hazardous areas