1、Hazardous Locations John A. Bossert Guide for the Design, Testing, Construction, and Installation of Equipment in Explosive Atmospheres (Third Edition) CSA INTERNATIONAL CSA INTERNATIONAL Hazardous Locations Guide for the Design, Testing, Construction, and Installation of Equipment in Explosive Atmo
2、spheres (Third Edition) John A. Bosser? CSA International 178 Rexdale Boulevard, Toronto, Ontario M9W 1R3 Registered trade-mark of Canadian Standards Association STD-CSA PLUS 2203 HAZLOC-OJ-ENGL 2001 LB75068 Ob49381 043 W Technical Editor: Rick Cilmour Managing Editor: Cary Butford Cover Design: Pau
3、l Dorsett Administrative Assistant: Elizabeth Hope Document Analyst: lndira Kumaralagan Document Processor: Hematie Hassan Editors: Maria Adragna/Samantha Coyle/Sandra Hawryn/Ann Martin/ohn McConnell Cruplria Coordinator: Cindy Kerkmann Ihblishing System Coordinators: Ursula Dos/Croce Da Silva/Seeth
4、a Rajagopalan SCML Project Manager: Alison Macintosh -c This handbook is intended as a guideline only and should not be considered as a substitute for detailed review of the Canadian lectrical Code or the National Uectrical Code. Its aim is to enhance understanding and facilitate implementation of t
5、he requirements in Secons 18 and 20 of the Canadian Electrical Code, Part I, and Article 500 of the National Electrical Code. The opinions expressed herein should not be construed to reflect the official policy of the Canadian Standards Association. ISBN 1-55324-356-0 O CSA International - 200 1 All
6、 rights reserved. No part of this publication may be reproduced in any form whatsoever without the prior permission of the publisher. ii STDmCSA PLUS 2203 HAZLOC-01-ENGL 2001 M 1875068 0649382 TBT m Acknowledgements I wish to acknowledge the assistance of Frank McGowan, Chair of ISA SP12, formerly o
7、f Factory Mutual, who proofread Chapter 7 on intrinsic safety and Richard Masek of Bailey Controls, Project Leader of the IEC Working Group on pressurization, who proofread Chapter 9 on pressurized enclosures. For their input on field-bus, I wish to thank Mans Graube of Relcom Inc. and Tony Cape1 of
8、 Comgate Engineering Ltd., Chair of IEC SC 65C. For their input on fuel cells, I wish to thank Brennon Knaggs of Ballard Generation Systems and Jeff Grant of Ballard Power Systems. For his advice on the testing methods for flame arresters, I wish to thank George Lobay of the Canadian Explosive Resea
9、rch Laboratory, CANMET Division of Natural Resources Canada and Chair of IEC SC 31A. Finally, I wish to thank Rick Gilmour of CSA International who did the final technical review of this manuscript and Jose Gauthier, also of CSA International, who made this new edition happen. John A. Bossert March
10、2001 iii STD-CSA PLUS 2203 HAZLOC-OL-ENGL ZOOL m 1875068 Ob47383 9Lb = Contents Chapter 1 Principles of Area Classification 1 Historical Background - Definition - Classes, Divisions, and Zones in North America - Principles of Area Classification for Gases and Vapours - Principles of Area Classificat
11、ion for Dusts, Fibres, and Flyings - Groups of Gases, Vapours, and Dusts Chapter 2 Area Classification Applications 13 Legal Responsibility - Code References - American Petroleum Institute (API) - American Gas Association (AGA) - National Fire Protection Association (NFPA) - International Electrotec
12、hnical Commission (IEC) - Coast Guard Regulations - International Marine Organization (IMO) - Underground Coal Mines Chapter 3 Flameproof Enclosures 23 History and Principle of Operation - Flat or Straight Flameproof Joints - Other Types of Joints - Protection Joints - Windows and Transparent Parts
13、of Enclosures - Enclosure Design - Special Fasteners - Breathers and Drains - Explosive Fluid Seals - Entries - Testing Flameproof Enclosures Chapter 4 Flameproof Installations 39 Conduit-Connected Systems - Sealing of Conduits - Pouring Seals - Cable-Connected Systems - Flexible Connections - Flexi
14、ble Cords and Cables - Factory-Sealed Devices - Installation of Flameproof Devices - Maintenance Chapter 5 Dust-Ignition-Proof Enclosures History and Principle of Operation - Dual-Rated Enclosures - Enclosure Requirements - International Standards - Divisions, Zones, and Groups - Temperature Require
15、ments - Marking Requirements Chapter 6 Dust-Ignition-Proof Installations Conduit-Connected Systems - Sealing of Conduits - Cable-Connected Systems - Installation of Dust-Tight Equipment - Maintenance of Dust-Tight Installations Chapter 7 49 55 Intrinsic Safety 59 History and Principie of Operation -
16、 Testing Devices for Intrinsic Safety - Published Ignition Curves - Fault Analysis of Intrinsically Safe Circuits - Zener Barriers - The Entity Concept - Control Drawings - Standards for Intrinsic Safety - Field-Bus V STD-CSA PLUS 2203 HAZLOC-01-ENGL 2001 1875068 0649384 52 Chapter 8 Intrinsic Safet
17、y Installations 79 Wiring Methods - Grounding of Barriers - Entity Concept - Cable Requirements - Portable Equipment - Maintenance - Repair Chapter 9 Purged and Pressurized Enclosures 83 Principle of Operation - Pressurizing by Blower - Compressed Air Systems - Protective Measures - Pressurized Room
18、s - Static Pressurization - Pressurization with Dilution - Continuous Dilution - Analyzer Houses - Coal Storage Silos - Self-Unloading Coal-Carrying Ships - Gas Turbines - Maintenance and Repair Chapter 10 Background - Principle of Operation - Special Provisions - Advantages of Increased Safety - Hy
19、brid Devices - Maintenance - Repair Increased Safety Chapter 11 Exclusion of Explosive Mixtures Principle of Operation - Powder Filling - Oil-Immersion -Encapsulation - Applications - Maintenance and Repair Chapter 12 Combustible Gas Detection Equipment History - Principle of Operation -Testing Proc
20、edures - Electromagnetic Stability - Applications - Installation - Calibration and Maintenance Chapter 13 Class I, Division 2 (Zone 2) Equipment History - Non-Incendive Circuits - Endosed Break Device - Non-Incendive Component - Hermetically Sealed Device - Sealed Device - Fuses and Fuseholders - Pl
21、ugs and Sockets - Lighting Fixtures (Luminaires) - Restricted Breathing Enclosures - Pressurization - Rotating Machines - Wiring Methods 91 97 101 107 Chapter 14 Flame Arresters 113 Principle of Operation - Flat Plate Arrester - Loose-Fitting Threads - Crimped Ribbon Flame Arresters - Sintered Metal
22、 Flame Arresters - Metal Foam Elements - Pressed Metai Wire Elements - Baffe Plate Flame Arresters - Wire Mesh Flame Anesters - Expanded Metal Flame Arresters - Testing of Fiame Arresters - Rpeline Flame Arresters Chapter 15 History - North American Requirements - European Requirements - Requirement
23、s for Mining Vehicles - Maintenance - Fuel Cells Electric Vehicles and Fuel Cells 119 vi STD.CSA PLUS 2203 HAZLOC-OL-ENGL 2OOL = 1875068 Ob49385 i99 Chapter 16 Flameproof Diesel Vehicles History and Principles of Operation - Flameproof Requirements - Exhaust Emissions - Maintenance Chapter 17 Standa
24、rds-Writing Bodies National Standards Bodies - European Community Standards - International Standards-Writing Bodies - Marine Standards-Writing Bodies Chapter 18 Certification Requirements - Australia - Canada - Europe - United States - Bilateral Agreements - International Certification Chapter 19 F
25、ibre Optics Ignition Possibility - Recent Research Findings - Electrical Codes 123 127 131 137 Chapter 20 Certified Repair Facilities 139 Introduction - Canadian Explosives Research Laboratory - CSA International (Certification Division) - Factory Mutual Research Corporation - Underwriters Laborator
26、ies Incorporated Appendix A Hazardous Locations Standards Appendix B Canadian Inspection Authorities Appendix C Glossary 145 151 153 157 Index vii STD-CSA PLUS 2203 HAZLOC-01-ENGL ZOOIJ H 1875068 Ob4738b 625 Chapter 1 Principles of Area Classification Historical Background Probably the first hazardo
27、us location to be discovered was in early coal mines, where there was a double hazard: methane gas and coal dust. Figure 1-1 is a very old etching depicting what happens when methane gas is ignited in a coal mine. This is usually followed by a much more violent explosion of coal dust, which is raise
28、d into a dust cloud by the methane explosion and ignited to form a secondary explosion that can travel right through the mine. One of the first methods used to prevent such explosions is depicted in Figure 1-2. The methane gas is adsorbed in the Dores of the coal. When the coal is mined, the gas is
29、“desorbed”, a process that takes a rather long period of time. To be completely free of methane, coal has to be stored for a period of up to 1000 hours in a well-ventilated location. If the miners worked an eight-hour shift, leaving the mined coal in the shaft until the next day, the gas that was de
30、sorbed while they were absent would collect at the roof of the mine (because methane is lighter than air) and would form an explosive “layer” at the roof. It was found that a man carrying a lighted torch could crawl along the floor of the mine and “safely” ignite the methane layer, burning it off be
31、fore the other miners started work. Courtesy of Health nnd Safety IXecutive, Sheffield, England. Figure 1-1 Explosion in a CoaZ Mine 1 _ STD.CSA PLUS 2203 HAZLOC-01-ENGL 2OOL I 18750b6 Ob49367 561 Hazardous Locations Courtesy of Health and Safety Executive, Sheffield, ng/and. Figure 1-2 The Penitent
32、, or Fire-Man, miling Fire-Damp (Methane) fn a Coal Mne The person performing this task, called the “fire-man”, tried to protect himself by wrapping up in a wet blanket, so that he looked like a monk with his hood up. It was soon found that there were very few volunteers for this hazardous occupatio
33、n. For this reason, convicts were offered a shorter prison term if they volunteered for the job. This is why the etching refers to the “penitent”. (This was perhaps the earliest form of “community service” for convicts.) volunteers - even from the prisons - some mines used their mine ponies to perfo
34、rm this task. They had a special saddle for the ponies, which held a lighted candle. The pony was wetted with a hose, fitted with a lighted candle, and sent at a gailop into the mine shaft. After the explosion, the pony came out at a gallop, wide-eyed and somewhat singed, but usually none the worse
35、for the experience. Today, the miners would be charged with cruelty to animals, but those were different times. With the advent of mechanical ventilation, mine operators were able to get rid of the gas by diluting it with fresh air so that it was below the explosive limit. This is still the first li
36、ne of defence against methane in coal mines. When electrical equipment was first introduced into coal mines, some explosions occurred due to electrical sparking. However, mine operators soon found that totaliy enclosed motors were able to contain the explosions so that they did not ignite the mine a
37、tmosphere. This was the origin of the When they eventually ran out of flameproof enclosure. Mine operators then realized that other electrical equipment could also be protected by building substantial cast iron enclosures with tight-fitting joints. Later, low-voltage signalling beiis were introduced
38、 to control the operation of the hoists. Since these bells operated on a very low voltage (12 volts or less), it was believed that they would be safe. However, in 1912 and 1913, two disastrous mine explosions in England were eventually traced to the mine signalling bells. Further research into this
39、problem showed that these low-voltage circuits were capable of igniting the mine gases, but that, with care in the design, they could be made safe. This technique, labelled “intrinsic safety”, was the beginning of a new safety method for explosive atmospheres. Defniton A hazardous location is nonnai
40、ly defined as a location where fire or explosion hazards exist due to the presence of flammable gases or vapours, fiammable liquids, combustible dusts, or ignitable fibres or flyings. Such locations are further defined in the Canadian Electrical Code, Part I (Section O), as places where (a) highly f
41、iammable gases, flammable volatue liquid mixtures, or other highly flammable substances are manufactured or used, or are stored in other than original containers; STDaCSA PLUS 2203 HAZLOC-01-ENGL 2001 187LiOb8 Ob49388 4T8 Principles of Area Classification (b) combustible dust or flyings are likely t
42、o be present in quantities sufficient to produce an explosive or combustible mixture, or it is impracticable to prevent such dust or flyings from collecting in or upon motors or other electrical equipment in such quantities as to produce overheating through normal radiation being prevented, or from
43、being deposited upon incandescent lamps; (c) easily ignitible fibres or materials producing combustible flyings are manufactured, handled, or used in a free open state; or (d) easily ignitible fibres or materials producing combustible flyings are stored in bales or containers but are not manufacture
44、d or handled in a free open state. Taken literally, these definitions could make every kitchen, garage, and workshop a hazardous location. For this reason, a certain amount of discretion, or common sense, must be exercised when classifymg a location as “hazardous“. For example, most kitchens have an
45、 ample supply of flour, powdered sugar, corn starch, etc, all of which are highly flammable dusts. However, the likelihood in a domestic kitchen of a dust cloud of sufficient density to cause an explosion is very remote. Similarly, one would not expect a garage in which a can of gasoline for the fam
46、ily lawnmower is stored to be classified as a hazardous location (although gasoline must be handled with care), and a few cans of paint containing flammable solvents do not mean that every workshop is hazardous. Our concern is with industrial locations where the quantities are large and the handling
47、 is such that there is a real danger of explosion. Classes, Divisions, and Zones in North America In Canada and the United States, there are three Classes of hazardous locations, two Divisions for each Class, and three Zones for Class i. The Classes are distinguished as follows: Class I - A location
48、 where there is a danger of explosion due to the presence of a flammable gas or vapour. Class II - A location where there is a danger of explosion due to the presence of a flammable dust. Class III - A location where there is a danger of explosion or flash fire due to the presence of flammable fibre
49、s or flyings. Each Class contains two Divisions, which may be roughly described as follows: Division 1 - A location where an explosive mixture of gas, vapour, dust, fibres or flyings, and air may exist under normal operating conditions. Division 2 - A location where an explosive mixture of gas, vapour, dust, fibres or flyings, and air may exist under abnormal conditions such as accidental rupture of a vessel or container or failure of a ventilating system. In the case of Classes II and III, Division 2 also includes the possibility that el
