Page 12 - Electrical Installation in Hazardous Area

Contents ix

9 Apparatus using protection concepts encapsulation 'm', oil
immersion '0' and powder filling 'q' 209

9.1 Encapsulation - 'm' 209
9.1.1 Exclusions from BS 5501, Part 1 (1977) 209
9.1.2 Specification of the encapsulation 210
9.1.3 Types of apparatus for encapsulation 21 1
9.1.4 Encapsulated circuits and components 212
9.1.5 The encapsulation process 213
9.1.6 Particular component problems 213
9.1.7 Type testing 215
9.2 Oil immersion - '0' 215
9.2.1 Construction of the apparatus 215
9.2.2 Containment of the oil 216
9.2.3 Requirements for the protective fluid (oil) 218
9.2.4 External connections 218
9.2.5 Type testing 218
9.3 Powder filling - 'q' 219
9.3.1 The filling material 219
9.3.2 The enclosure 219
9.3.3 Electrical components and circuits 220
9.3.4 External connections 223
9.3.5 Type testing 223

10 Apparatus using protection concept flameproof enclosure 'd'
226

10.1 Standards for flameproof apparatus 228
10.2 Construction and testing requirements for flamepaths 230
10.2.1 Joints between the interior of flameproof
enclosures and the external atmosphere 230
10.2.2 Joints for rotary or longitudinal shafts and
operating rods 250
10.2.3 Joints for shafts and rotating machines 252
10.2.4 Bearing greasing arrangements 253
10.2.5 Tests for flameproof joints 254
10.3 Construction of flameproof enclosures, entry
facilities and component parts 256
10.3.1 Enclosure construction 256
10.3.2 Bushings 261
10.3.3 Arrangements for entry facilities 261
10.3.4 Fasteners 262
10.3.5 Component parts 263
10.3.6 Freestanding flameproof components 269