Page 108 - Electrical Installation in Hazardous Area

84 Electrical installations in hazardous areas

a = Distance of wall from source of hazard
b = Extent of hazardous area ignoring wall
c = b-a

Fig. 3.18 Hazardous areas due to short walls

Fig. 3.19 Release at vent. a = 1 m, b = Calculated from Chapter 4 based on jelre-
lease extent equation and volume of gashapour released. Note: Where
release is from a bursting disc Zone 0 inside vent and Zone 1 immediately
surrounding the vent, both become Zone 2