NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA. Code for Design of electrical installation For explosive and fire hazardous Atmospheres

Transcription

1 UDC NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA 9=t ~A ~~lrl *tti\il Code for Design of electrical installation For explosive and fire hazardous Atmospheres ~~~*~~~~~~n~~~*~~ GB Beijing 1994

2 NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA CODE FOR DESIGN OF ELECTRICAL INSTALLATION FOR EXPLOSIVE AND FIRE HAZARDOUS ATMOSPHERES GB Edited by: Ministry of Chemical Industry of the People's Republic of China. Approved by: Ministry of Construction of the People's Republic of China. Date of Enforcement: Dec. 1, l992~ NEW WORLD PRESS.! Beijing 1994

3 . ISBN ~263-X/T 002 Code for design of electrical installation for explosive and fire hazardous atmospheres Published by. New World Press 24 Baiwanzhuang Road, Beijing , China Printed in the People's Republic of China

4 Preface This book is the English translation of Code for D~sign of Electrical Installation for Explosive and Fire Hazardous Atmospheres. It is the official translation of the original in Chinese for general use as examined and approved by the Department of Standards and Norms, Ministry of Construction of the People'~ Republic of China. In the event of any inconsistency between t_he Chinese-language text of the Code and the present English-language text of the Cod"e, the Chinese-language text shall be taken as ruling. Department of Standards and Norms, Ministry _of Construction of th~ People' s Republic o:p China COPYRIGHT Department of Standards and Norms, Ministry of Construction, the People's Republic of China, 1994 All rights reserved. No part of this publication may be reproduced, stored ~ a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the Ministry of Construction, the People's Republic of China. I

5 MINISTRY OF CONSTRUCTION, P.R.C June 9, 19?2 NO. JB (1992].354 Notice on promulgation of the national standard, "code for design of electrial installation for explosive. and fire haz.ardo~s atmosh~es" i'cod.e for Design of Electrical Installation for E4plosive and Fire Hazardous. Atmo spheres " which was revised jointly by Ministry of Chemical Industry in junction with rel evant sectors in accordance with the requirement of the document No. JZ[1986] 250 of State Planning Com,mission has been jointly examined by relevant sectors. Now, ". Code fqr Design of Electrical Installation for Explosive and Fire Hazardous Atmospheres " GB i~ approved and as a compulsory nati~nal standard, and will be implemented from December 1, At the same time, the original " Design Code for Electrical Apparatus in Explosive and Fire Hazardous Locations " GBJ will be abolished. This code is placed under the management of Ministry of Chemical Industry, and China Huanqiu Chemical Engineering Corporation is r,esponsible for the.concrete explanatioti thereof. The Standard and Quota Institute of Ministry of. Construction is responsible for the organization of publishing and issuing thereof. II

6 MINISTRY OF CHEMICAL INDUSTRV,P.R.C. Septem"ber, 1991 Explanation of the revisiof! This code had the Ministry of Chemical Industry to act as the compiler in charge, and for concrete co:r;npiling work, " Design Code for Electrical Installations in Explosive and Fire Hazardous Locations " GBJ was jointly revised by China Huanqiu Chem.i-. \ cal Engineering Corporation in junction with relevant units in accordance with the requirement of the document No. JZ [1986] 250 of State Planning Commission. In the course of revision, the code team carried out extensive investigation and study, seriously summed up the experiences since the implementation of the code, assimitated part of scientifi:c re-, search results, widely solicited for opinions of related units over the whole country; and finally, the Ministry in junction with relevant sectors examined and finalized the revised code. The main contents of this revision include: explosive gas (ltmosphere, explosive dust atmosphere, fire hazardous atmosphere, scope of hazardous area, and selection of electrical equipment. In the course of implementation of this code, if there appears any need of amendment or.replenishment, please send your opinion andrelated data to Chiri.C~. Huanqiu Chemical Engineering Corporation (address: post code , north 'mouth of Heping Street, Bei., jing Ci:ty) along with a duplicate to the Ministry of Chemical. Industry, for the sake of i:eference during revision iil future. m

7 CONTENTS 1. General ~ Explosive gas atmosphere General provision Classification of hazardous areas for explosive gas atmosphere Scope of hazardous areas for explosive gas atmosphere Division of classes and groups for explosive gas mixture Electrical installation for explosive gas atmosphere Explosive dust atmosphere Ge neral provision Classification of hazardous areas for explosive dust atmosphere Scope of hazardous areas for explosive dust atmosphere Electrical installation for explosive dust atmosphere ,.4. Fire bazar~ous atmosphere : General provision Cl~sifica tion of fire hazardous areas..... : Ele ctrical installation for fire hazardous atmosphere Appendix 1 Terminology _,.. : , Appendix 2 Appendix 3 Illustrative diagrams and table of requisites for classification of explosive hazardous areas ;.. 52 Examples for divisiqn of classes and groups for explosive mixture I of gases or vapours.... ;.. ' Appendi:x 4 Charateristics of explosive dtist ".. "; 63 Appendix 5 Explanation of wording in this code... ~ Additional Explanation N

8 1. General This code is drawn up for the sake of implementing the policy for electrical installation design of explosive and fire hazardous atmospheres with stress on prevention so a,s to guarantee the safety of people and property, to take preventive measures to suit local conditions, and to make the design with advanced technique, economy and rationality, and safety and suitability This code is suitable for the electrical design of new, extension and renovation engineering projects which emerge or likely emerge explosive and. fire hazardous atmospheres in the procedure of production, processing, treatment, transferring or storing. This code is not suitable for the following atmospheres: 1. Under mine shaft;.2. In the atmosphere where gunpowder, explosives and primer are manufactured, applied and stored;.3. In electrical installation area of electrolysis, electroplating, etc. where eh:~ctric energy is used for production and is direqtly related to the production technological process; 4. In storage battery room; 5. In the atmosphere where strong oxidant as well as material self - ignitable without ignition from external. fire source;.6. In communication and transport vehicles on land, water and in aii, and off - shore platform. for oil well The electrical design for explosive and fire hazard<;>~ atmospheres, besides shall eonform to the stipulatiqn of this code, shall further coclorm to the stipulations of relevant national standards and codes. 1

9 2. Explosive gas atmosphere 2. 1 General provision The electrical design for explosive gas atmosphere shall be carried out, when one of the following explosive gas mixture atmospheres emerges or likely emerges in the procedure of production, processing, treatment, transferring or storing: 1. Under the atmospheric rondition, expl~ive gas mixture is formed by mixing of such laminable material as flammable gas, vapor or mist of flammable liquid, etc. with air; 2. Explosive &as mixture is formed by mixing of vapor or mist of combustible liquid having flash point lower tha~. or equal to the ambient temperature with air; 3. Under the case of material operating temperature higher than the flash point of combustible liquid, when the combustible liquid might leak out, explosive gas mixture is formed by mixing of its vapor with air~ The following conditions must exist simultaneously, when an explosion occurs in explosive gas atmosphere: 1. There exists vapour or mist of flammable gas or flammable liquid with its concentration within explosive limits; 2, There exists spark, electric arc or high temperature sufficient for ignition of explosive gas mixture The following explffion precautions shall be taken in explffive gas atmosphere: 1. First of all, the simultan 9US occurrence of the conditions producing an explosion shall be reduced to the least degree as far as possible. 2. In the process design, measures shall be adopted to eliminate or reduce the occurrence and accumulation of flammable material:, I (1) Relatively low pressure and temperature may be adopted in the process flow, and the flammable material is restricted, within an enclosed vessel; (2) The process layout shall restrict and reduce the scope of hazardous area, and may separate hazardous area of different classes, or hazardous and nonhazardou~ area, within individual production building or blocks; ( 3) The measure of blanketing with nitrogen or other inert gas can be used in the equipment; ( 4) The measure of safety interlocking or adding such chemicals as polymerization inhibitor on reaction during accider.t may be taken. 3. For prevention of explosive gas mixture from being formed, or shortening of detention time for explosive gas mixture, the followillg measures may be taken: 2 ( 1) The outdoor or open type layout may be adopted for the process installation;

10 (2) The mechanical ventilating installation is provided; ( 3) The positive pressure chamber is provided in the explosive hazardous atmosphere; ( 4) In the area where explosive gas nuxture is liable to be formed or accumulated, the automatic measuring instrumentation is provided so that when the gas or vapour concentration approaches 50%.of the lower limit, the signal shall be reliably emitted or the power source be cut off. 4. In hazardous area, measures shall be taken to eliminate or control spark, electric arc or high temperature produced in circt!-it of electrical equipment Classification o(.haz~rdous areas for explosive gas atm~phere Explosive gas atmospheres shall be zoned according to the following stipulations based on the occurrence frequency and time continuity of explosive gas mixture: 1. Zone 0 : An area in which an explosive gas atmosphere is present continuously or is present for long periods. 2. Zone 1 : An area in which an explosive gas atmosphere is likely to occur in normal operation. 3. Zo.ne 2: An area in whieh an explosive gas atmosphere is not likely to occur in.., normal o~ration,. and if it does occur, it will exist for a short period only. Note: Normal operation is referred to the normal start-up, running and shut-down, loading and unloading of flammable material and product, opening and closing of sealed vessel cover; safety valve, discharge valve, and all the equipme~ts in theplant are operated under status within their scopes of design parameters It can be zoned as non~hazardous area, when it conforms to one of the following conditions: 1. There is no source of release and no possibility of flammable material entering the 2. The highest concentration of flammable material which might occur does not exceed 10% of lower explosi()n limit; 3. The neighbourhood of ail equipment using open fire in production process, or the neighbourhood of an equipment whose component has a temperature on its red-hot surface that exceeds the ignition temperature of flammable material in the area; 4. Outside the production installation area, the zone of overhead pipeline installed outdoor or open for conveying flammable material, but its valve location is determined according to the specific conditio~. _ The source of release sha..j.l be classified aceording to. the release frequency and 3