Practical Electrical Equipment and Installations in Hazardous Areas

423 Pages·2005·8.26 MB·English

by  Geoffrey Bottrill

Practical Electrical Equipment and Installations in
Hazardous Areas
ii Contents
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Contents iii
Practical Electrical Equipment and
Installations in Hazardous Areas
Geoffrey Bottrill
Bottrill and Associates, London, United Kingdom
Derek Cheyne
PrEng, BSc (ElecEng), Chief Electrical and Instrument Engineer,
South Africa
G. Vijayaraghavan
Vijayaraghavan and Associates, Mumbai, India
Series editor: Steve Mackay
FIE (Aust), CPEng, BSc (ElecEng), BSc (Hons), MBA,
Gov.Cert.Comp. Technical Director – IDC Technologies
AMSTERDAM (cid:127) BOSTON (cid:127) HEIDELBERG (cid:127) LONDON
NEW YORK (cid:127) OXFORD (cid:127) PARIS (cid:127) SAN DIEGO
SAN FRANCISCO (cid:127) SINGAPORE (cid:127) SYDNEY (cid:127) TOKYO
Newnes is an imprint of Elsevier
iv Contents
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First published 2005
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British Library Cataloguing in Publication Data
Botrill, G.
Practical electrical equipment and installations in hazardous areas
(Practical professional)
1. Electric apparatus and appliances – installation – safety measures
2. I. Title II. Cheyne, D. III. Vijayaraghavan, G.
3. 621. 3'1'042'0289

Library of Congress Cataloguing in Publication Data
A catalogue record for this book is available from the Library of Congress

ISBN 0 7506 6398 7

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Contents v
Contents
Preface .................................................................................................................................x
1 Introduction ................................................................................................................1
1.1 Introduction .................................................................................................1
1.2 Approach .....................................................................................................4
1.3 Historical development ................................................................................5
1.4 Bird’s eye view of legislation and research in other countries ......................6
1.5 The certification ...........................................................................................8
1.6 Conclusion ..................................................................................................9
2 Electrical energy, ignition and flammability ..............................................................10
2.1 Electrical energy and ignition .....................................................................10
2.2 The basics of electricity .............................................................................10
2.3 Electrical heat energy ................................................................................19
2.4 Sources of ignition .....................................................................................20
2.5 Flammability ..............................................................................................22
2.6 Flammability principles ..............................................................................25
3 Area classification ....................................................................................................27
3.1 General .....................................................................................................27
3.2 Principles of safety ....................................................................................28
3.3 Hazards and hazardous areas ...................................................................28
3.4 Basic properties of combustible and ignitable material ..............................30
3.5 Basis of area classification ........................................................................32
3.6 Zonal classification ....................................................................................34
3.7 Plant operations – normal and abnormal ...................................................35
3.8 Area classification – gas and vapors .........................................................36
3.9 Area classification – dust ...........................................................................53
3.10 Classification procedure ............................................................................55
3.11 Responsibility and personnel involved .......................................................56
3.12 Documentation ..........................................................................................57
3.13 Policy and guidelines for implementation ...................................................58
3.14 Area classification examples .....................................................................62
3.15 Summary of area classification ..................................................................78
3.16 A case study ..............................................................................................79
vi Contents
4 Design philosophy and selection of equipment/apparatus ........................................81
4.1 General ......................................................................................................81
4.2 Risks … history ..........................................................................................82
4.3 Classification concepts ..............................................................................84
4.4 Equipment … a definition ...........................................................................85
4.5 Apparatus grouping ...................................................................................86
4.6 Surface temperature classification .............................................................88
4.7 Concepts and techniques of explosion protection ......................................92
4.8 Methods of explosion protection ................................................................93
4.9 Typical applications of methods of protection .............................................97
4.10 Mixed techniques .......................................................................................98
4.11 Dust explosion-protection methods ..........................................................100
4.12 Selection of explosion-protection technique for safeguarding ..................102
4.13 Conclusion ...............................................................................................105
5 Protection concept ‘d’ .............................................................................................106
5.1 General ....................................................................................................106
5.2 Definitions ................................................................................................107
5.3 Certification in brief ..................................................................................109
5.4 Construction requirements .......................................................................109
5.5 Flameproof theory ....................................................................................112
5.6 Other general requirements for explosive atmospheres ...........................113
5.7 Testing .....................................................................................................114
5.8 Grouping and effect of temperature classification ....................................114
5.9 Conditions of use .....................................................................................116
5.10 Illustrations of mechanical construction types...........................................118
5.11 Summary .................................................................................................123
6 Protection concept ‘e’ .............................................................................................124
6.1 General ....................................................................................................124
6.2 Definitions ................................................................................................124
6.3 Principles of design for increased safety ..................................................125
6.4 Certification (components) .......................................................................126
6.5 Construction requirements .......................................................................126
6.6 Principles of testing ..................................................................................130
6.7 Periodic testing and repair of electrical apparatus ....................................132
6.8 Conditions of use .....................................................................................135
6.9 Standards for Ex ‘e’ .................................................................................137
7 Protection concept ‘n’ .............................................................................................138
7.1 General ....................................................................................................138
7.2 Definitions ................................................................................................138
7.3 Principles of design ..................................................................................139
7.4 Certification ..............................................................................................139
7.5 Construction requirements .......................................................................139
7.6 Conditions of use .....................................................................................142
7.7 Illustrations ..............................................................................................142
7.8 Standards for Ex ‘n’ .................................................................................143
Contents vii
8 Protection concept ‘i’ principles ...............................................................................144
8.1 Origins of intrinsic safety ..........................................................................144
8.2 Principles of IS .........................................................................................145
8.3 Electrical theory to explain IS ...................................................................146
8.4 Implementation of IS .................................................................................153
8.5 The shunt diode safety barrier ..................................................................157
8.6 Associated apparatus ...............................................................................167
8.7 Electrical apparatus in the hazardous area ...............................................169
8.8 Enclosures ...............................................................................................176
8.9 Temperature .............................................................................................177
8.10 The IS systems concept ...........................................................................179
8.11 An IS ‘system’ ...........................................................................................179
8.12 System documentation .............................................................................179
8.13 Assessment of safety ...............................................................................180
8.14 Simple apparatus .....................................................................................181
8.15 Safety parameters ....................................................................................182
8.16 Temperature classification of systems ......................................................182
8.17 Systems concepts in other standards .......................................................182
8.18 Standards for Ex ‘i’ ...................................................................................183
9 Protection concept ‘p’ .............................................................................................184
9.1 General ....................................................................................................184
9.2 Definitions ................................................................................................185
9.3 Development of standards for Ex ‘p’ .........................................................186
9.4 Construction requirements .......................................................................186
9.5 Principles of application ............................................................................189
9.6 Other design requirements .......................................................................192
9.7 Operation of .............................................................................................194
9.8 Testing .....................................................................................................195
9.9 Summary ..................................................................................................196
9.10 Standards of Ex ‘p’ ...................................................................................197
10 Other concepts .......................................................................................................198
10.1 General ....................................................................................................198
10.2 Ex ‘o’: oil filling ..........................................................................................198
10.3 Ex ‘q’: quartz/sand filling ...........................................................................199
10.4 Ex ‘m’: encapsulation ................................................................................200
10.5 Component certification ............................................................................201
10.6 Special type of protection ‘s’ (IEC Concept Code Symbol Ex ‘s’) ..............201
10.7 Multiple certification ..................................................................................203
10.8 Selection of certification method ...............................................................204
10.9 Apparatus for use in dust risks .................................................................204
11 Earthing and bonding .............................................................................................207
11.1 Earthing ....................................................................................................207
11.2 Personnel safety .......................................................................................207
11.3 Hazardous area considerations ................................................................209
viii Contents
11.4 Earthing and bonding ...............................................................................210
11.5 Static electricity ........................................................................................212
11.6 Clean and dirty earthing ...........................................................................215
11.7 Electrical interference ..............................................................................216
11.8 Earthing terminology ................................................................................218
11.9 Connection of earthing systems ...............................................................221
11.10 Power supply systems .............................................................................223
11.11 Portable equipment using batteries ..........................................................226
11.12 Earthing arrangement standard solutions ................................................226
11.13 Earth loops ..............................................................................................228
11.14 Computer earthing ...................................................................................229
11.15 Surge protection systems ........................................................................232
11.16 Standards and codes of practice ..............................................................233
12 Installations ............................................................................................................234
12.1 Introduction to installation requirements ...................................................234
12.2 Installation requirements ..........................................................................234
12.3 IEC 60079-14: standard contents ............................................................235
12.4 Other relevant installation standards and codes ......................................236
12.5 Safety documentation ..............................................................................236
12.6 General requirements of the standard ......................................................236
12.7 Practical aspects of IS installations ..........................................................256
12.8 Other considerations affecting installation ................................................268
12.9 Other installation issues ...........................................................................268
13 Inspection and maintenance ..................................................................................270
13.1 Inspection and maintenance ....................................................................270
13.2 Integrity ‘preserved’ .................................................................................271
13.3 Scope of IEC 60079-17 ...........................................................................271
13.4 General requirements ..............................................................................272
13.5 Inspections ..............................................................................................273
13.6 The insulation test ....................................................................................274
13.7 Maintenance ............................................................................................275
13.8 Testing .....................................................................................................278
13.9 Unauthorized modification .......................................................................279
13.10 Earthing integrity verification ....................................................................279
13.11 BS 5345 inspection requirements ............................................................280
14 Safe working practices ...........................................................................................282
14.1 General ....................................................................................................282
14.2 Safety observations .................................................................................282
14.3 Danger signals of electrical malfunctioning ..............................................283
14.4 Need for inspection and maintenance ......................................................284
14.5 Maintenance and safe practices ..............................................................294
14.6 Fault-finding – safety ensured ..................................................................297
14.7 Insulation testing in hazardous area ........................................................297
14.8 Earthing in hazardous area ......................................................................298
14.9 Handling ‘fall out of fire and electrical shock’ ............................................300
Contents ix
15 Fault-finding and testing .........................................................................................302
15.1 Fault-finding .............................................................................................302
15.2 Fault-finding routine ..................................................................................302
15.3 Safety assessment of testing ....................................................................304
15.4 Test equipment .........................................................................................304
15.5 Use of uncertified test apparatus ..............................................................308
15.6 Interface testing ........................................................................................311
15.7 Certified apparatus ...................................................................................314
15.8 IS apparatus repair procedure ..................................................................315
16 ATEX Directive .......................................................................................................318
16.1 General ....................................................................................................318
16.2 Definitions ................................................................................................324
16.3 Scope of the ATEX Directive ....................................................................325
16.4 Bird’s eye view of ATEX Directive .............................................................344
16.5 Summary ..................................................................................................351
Appendix A: IEC series standard titles for explosive atmospheres .....................................352
Appendix B: Listing of IS standards and codes of practice by country ...............................355
Appendix C: IEC 79-17 Ex ‘I’ inspection schedule ............................................................357
Appendix D: CENELEC members .....................................................................................359
Appendix E: IP code ..........................................................................................................360
Appendix F: Standards reference ......................................................................................361
Appendix G: Familiarization with electricity ........................................................................362
Appendix H: ATEX Directive ..............................................................................................372
Appendix I: Properties of combustible compounds ............................................................374
Appendix J: Important changes to AS/NZS 2381.1 ...........................................................377
Appendix K: Practical exercises for hazardous area course ..............................................381
Index .................................................................................................................................405