Page 11 - Electrical Installation in Hazardous Area

viii Contents

6.3 Practical situations 161
6.3.1 Cyclones and bag filters 161
6.3.2 Loading hoppers within buildings 162
6.3.3 Loading hoppers outside buildings 163

7 Design philosophy for electrical apparatus for explosive
atmospheres 164
General approach and applicable standards 164
7.1 History 164
7.1.1 Gas, vapour and mist risks 164
7.1.2 Dust risks 165
7.2 Protection of electrical apparatus for gas, vapour and
mist risks 166
7.2.1 Exclusion of the explosive atmosphere
(criterion a) 166
7.2.2 Prevention of sparking (criterion b) 167
7.2.3 Containment of explosions (criterion c) 168
7.2.4 Energy limitation (criterion d) 168
7.2.5 Special situations 169
7.3 Situation in respect of Zone 2 apparatus 169
7.4 Protection of electrical apparatus for dust risks 170
7.5 Apparatus construction Standards 170
7.5.1 Zone 0 and/or Zone 1 compatible
apparatus for gases, vapours and mists 171
7.5.2 The marketing situation in respect of
European Standards 174
7.5.3 Zone 2 compatible apparatus for gases,
vapours and mists 1 75
7.5.4 Electrical apparatus for dust risks 176
8 General requirements for explosion protected apparatus
(gas, vapour and mist risks) 178
Apparatus to European Standards 178
8.1 BS/EN 50014 (1993) (including amendment 1 (1994)) 1 79
8.1.1 Definitions 180
8.1.2 Division of apparatus into
sub-groups and surface temperature classes 181
8.1.3 Requirements for enclosures 188
8.1.4 Fasteners, interlocking devices, bushings and
cements 195
8.1.5 Connection facilities and cable entries 199
8.1.6 Additional requirements for particular types of
apparatus 201
8.1.7 Ex components 204
8.1.8 Marking requirements 204