ISA 60079-10-2-2013 Explosive Atmospheres C Part 10-2 Classification of areas - Combustible dust atmospheres (12 10 05).pdf

1、 AMERICAN NATIONAL STANDARD ANSI/ISA-60079-10-2 (12.10.05)-2013 Supercedes ANSI/ISA-61241-10 (12.10.05)-2004 Explosive Atmospheres Part 10-2: Classification of areas - Combustible dust atmospheres Approved 13 September 2013 ANSI/ISA-60079-10-2 (12.10.05)-2013, Explosive Atmospheres Part 10-2: Classi

2、fication of areas Combustible dust atmospheres ISBN: 978-0-876640-42-5 Copyright 2013 by IEC and ISA. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means

3、(electronic, mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 - 3 - ANSI/ISA-60079-10-2-2013 General Notes This is the ISA Standard for Explosive atmospheres P

4、art 10-2: Classification of areas Combustible dust atmospheres. It is the first edition of ANSI/ISA-60079-10-2. The document is a modification of the IEC document and includes U.S. deviations encompassing both additions and deletions of information. This Standard was prepared by the International So

5、ciety of Automation (ISA). Although the intended primary application of this Standard is stated in its Scope, it is important to note that it remains the responsibility of the users of the Standard to judge its suitability for their particular purpose. Level of harmonization This standard adopts the

6、 IEC text with deviations. The standard illustrates the national differences from the IEC text through the use of legislative text (strike-out and underline). This first edition of ANSI/ISA-60079-10-2 has been developed from ANSI/ISA-12.10.05-2004 (IEC 61241-10 Mod) which it now cancels and supersed

7、es. The significant changes with respect to the previous edition are listed below: the hazards presented by dust have been clarified; dust groups have been introduced; Annex D explaining Equipment Protection Levels (EPLs) has been introduced; 1 m of usual extent of zone 22 beyond zone 21 has been ex

8、panded to 3 m. - 5 - ANSI/ISA-60079-10-2-2013 Preface (ISA) This ISA standard is based on IEC Publication 60079-10-2, Edition 1. It is the intention of the ISA12 Committee to develop an ANSI standard that is harmonized with IEC 60079-10-2 to the fullest extent possible. This preface, as well as all

9、annexes, is included for informational purposes and is not part of ANSI/ISA-60079-10-2. The document is a modification of the IEC document and includes U.S. deviations encompassing both additions and deletions of information. The standards referenced within this document may contain provisions which

10、, through reference in this text, constitute requirements of this document. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this document are encouraged to investigate the possibility of applying the most recent

11、 editions of the standards indicated within this document. Members of IEC and ISO maintain registers of currently valid International Standards. ANSI maintains registers of currently valid U.S. Na tional Standards. This standard has been prepared as part of the service of ISA toward a goal of unifor

12、mity in the field of instrumentation. To be of real value, this standard should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and cr iticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexande

13、r Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549 -8411; Fax (919) 549-8288; E-mail: standardsisa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (

14、SI) in particular, in the preparation of instrumentation standards. The Department is further aware of t he benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end,

15、 this Department will endeavor to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. IEEE/ASTM SI 10, American National Standard for Metric Practice, and future revisions, will be the reference guide fo

16、r definitions, symbols, abbreviations, and conversion factors. It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards-making pr

17、ocess by an individual in no way constitutes endorsement by the employer of that individual, of ISA, or of any of the standards, recommended practices, and technical reports that ISA develops. CAUTION ISA DOES NOT TAKE ANY POSITION WITH RESPECT TO THE EXISTENCE OR VALIDITY OF ANY PATENT RIGHTS ASSER

18、TED IN CONNECTION WITH THIS DOCUMENT, AND ISA DISCLAIMS LIABILITY FOR THE INFRINGEMENT OF ANY PATENT RESULTING FROM THE USE OF THIS DOCUMENT. USERS ARE ADVISED THAT DETERMINATION OF THE VALIDITY OF ANY PATENT RIGHTS, AND THE RISK OF INFRINGEMENT OF SUCH RIGHTS, IS ENTIRELY THEIR OWN RESPONSIBILITY.

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20、OYALTY RATE AND FAIR AND REASONABLE TERMS AND CONDITIONS. FOR MORE ANSI/ISA-60079-10-2-2013 - 6 - INFORMATION ON SUCH DISCLOSURES AND LETTERS OF ASSURANCE, CONTACT ISA OR VISIT WWW.ISA.ORG/STANDARDSPATENTS. OTHER PATENTS OR PATENT CLAIMS MAY EXIST FOR WHICH A DISCLOSURE OR LETTER OF ASSURANCE HAS NO

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23、TIONALLY, THE USE OF THIS DOCUMENT MAY INVOLVE HAZARDOUS MATERIALS, OPERATIONS OR EQUIPMENT. THE DOCUMENT CANNOT ANTICIPATE ALL POSSIBLE APPLICATIONS OR ADDRESS ALL POSSIBLE SAFETY ISSUES ASSOCIATED WITH USE IN HAZARDOUS CONDITIONS. THE USER OF THIS DOCUMENT MUST EXERCISE SOUND PROFESSIONAL JUDGMENT

24、 CONCERNING ITS USE AND APPLICABILITY UNDER THE USERS PARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE APPLICABILITY OF ANY GOVERNMENTAL REGULATORY LIMITATIONS AND ESTABLISHED SAFETY AND HEALTH PRACTICES BEFORE IMPLEMENTING THIS DOCUMENT. THE USER OF THIS DOCUMENT SHOULD BE AWARE THAT THIS

25、DOCUMENT MAY BE IMPACTED BY ELECTRONIC SECURITY ISSUES. THE COMMITTEE HAS NOT YET ADDRESSED THE POTENTIAL ISSUES IN THIS VERSION. The following members of ISA Subcommittee ISA12.10 contributed to the development of this document: NAME COMPANY A. Engler, Chair* Det Norske Veritas DNV M. Coppler, Mana

26、ging Director* Det Norske Veritas Certification Inc. S. Arnold Ametek Drexelbrook S. Blais EGS Electrical Group E. Briesch UL LLC T. Crawford Intertek Testing Services R. Fontaine FM Approvals J. Kuczka Killark E. Leubner Cooper Crouse-Hinds R. Masek CSA Group E. Massey Baldor Electric Company T. Sc

27、hnaare Rosemount Inc. D. Wechsler American Chemistry Council R. Wigg E-x Solutions International Pty. Ltd. _ * One vote per company. - 7 - ANSI/ISA-60079-10-2-2013 The following members of ISA Committee ISA12 contributed to the development of this document: NAME COMPANY T. Schnaare, Chair Rosemount

28、Inc. W. Lawrence, Vice Chair FM Approvals LLC M. Coppler, Managing Director* Det Norske Veritas Certification Inc. R. Allen Honeywell Inc. D. Ankele UL LLC S. Bihler Zone Safe Solutions, Inc. K. Boegli Phoenix Contact Inc. D. Burns Shell P the formation of dust layers, which are not likely to form a

29、 dust cloud, but may ignite due to self-heating or exposure to hot surfaces or thermal flux and cause a fire hazard or over -heating of equipment. The ignited layer may also act as an ignition source for an explosive atmosphere (see Clause 7). Since explosive dust clouds and dust layers may exist, a

30、ny source of ignition should be avoided or otherwise protected. Subsequent to the completion of the area classification, a risk assessment may be carried out to assess whether the consequences of ignition of an explosive atmosphere requires the use of equipment of a higher or lower equipment protect

31、ion level (EPL) than normally required. The EPL requirements may be recorded, as appropriate, on the area classification drawings to allow proper assessment of ignition sources. A description of EPLs is given in Annex D. NOTE 1 If this cannot be donedust hazards cannot be avoided, then measures shou

32、ld be taken to reduce the likelihood of dust and/or ignition sources so that the likelihood of coincidence is so small as to be acceptable. NOTE 2 In some cases, where the risk of explosion cannot be completely avoided, it can be necessary to employ some form of explosion protection such as explosio

33、n venting or explosion suppression. NOTE 3 In this standard, explosive dust atmospheres and dust layers are treated separately. In this clause, area classification for explosive dust clouds is described, with dust layers acting as one of the possible sources of release. The hazard of dust layer igni

34、tion is described in Clause 7. ANSI/ISA-60079-10-2-2013 - 20 - NOTE 4 Additional i Information on EPLs is given in Annex D. 4.2 Area classification procedure for explosive dust atmospheres Area classification is based on a number of factors and may require informed input from a number of sources. Th

35、ese factors include: Whether or not the material is a combustible the dust is combustible or not. Dust combustibility explosibility can be confirmed by laboratory tests to the future IEC 60079-20-2 ANSI/ASTM E1226. Material characteristics for the process concerned. These should be obtained from a p

36、rocess specialist. Nature of release from particular items of the plant. Specialist engineering knowledge may be required for this information. Operational and maintenance regime procedures for the plant, including housekeeping. Other equipment and safety information. Close co-operation is necessary

37、 from specialists in safety and equipment. Although the definitions for zones deal only with the cloud risk, layers that can be disturbed to form a dust cloud shall also be considered. The procedure for identifying zones is as follows. a) The first step is to identify whether the material is combust

38、ible and, for the purpose of assessment of ignition sources, determine the material characteristics, such as particle size, moisture content, cloud and layer minimum ignition temperature and electrical resistivity, and the appropriate dust group, Group IIIA for combustible flyings, Group IIIB for no

39、n -conductive dust, or Group IIIC for conductive dust. NOTE The 2011 ANSI/NFPA 70 (NEC) does not differentiate selection and installation requirements based on dust groups for Zone 20, Zone 21 and Zone 22 installations. b) The second step is to identify where dust containment or sources of dust rele

40、ase can be present, as given in Clause 5. It may be necessary to consult process line diagrams and plant layout drawings. This step should include the identification of the possibility of the formation of dust layers as given in Clause 7. c) The third step is to determine the likelihood that dust wi

41、ll be released from those sources and thus, the likelihood of explosive dust atmospheres in various parts of the installation as given in 5.3. It is only after these steps that the zones can be identified and their extents define d. The decisions on the zone types and extent and the presence of dust

42、 layers shall be documented, usually on an area classification drawing. These documents are used subsequently as the basis for the assessment of ignition sources. The reasons for the decisions taken should be recorded in notes of the area classification study, to facilitate understanding at future a

43、rea classification reviews. Reviews of the area classification shall take place following changes to the process or changes to process materia ls or if dust emission becomes more common due to deterioration of the plant. It is expected that a review be made following the commissioning of a plant or

44、process, and thereafter on a periodic basis. Because this standard covers a wide range of circumstances, no exact identification of necessary measures can be given for each individual case. It is important, therefore, that the recommended procedure should be carried out by personnel having knowledge

45、 of the principles of area classification, the process material used, the plant involved and its functioning. - 21 - ANSI/ISA-60079-10-2-2013 5 Sources of release 5.1 General Explosive dust atmospheres are formed from sources of dust release. A source of dust release is a point or location from whic

46、h dust can be released or raised, such that an explosive dust atmosphere can be formed. This definition includes layers of dust capable of being dispersed to form a dust cloud. Depending on the circumstances, not every source of release will necessarily produce an explosive dust atmosphere. On the o

47、ther hand, a dilute or small continuous source of release in time can produce a potentially hazardous dust layer. The conditions need to be identified in which process equipment, process steps or other actions expected in plants, can form explosive dust atmospheres or create dust layers. It is neces

48、sary to consider separately the inside and outside of a dust containment. 5.2 Dust containment Inside a dust containment, dust is not released into the outside atmosphere but as part of the process, continuous dust clouds may form inside the containment. These clouds may exist continuously or may be

49、 expected to continue for long periods or for short periods. The frequency of their appearance depends on the process cycle. The equipment shall be studied for normal operation, abnormal operation and in the start up and shut-down conditions so that the incidence of cloud and layer presence can be identified and the results of this study shall be included in the verification dossier. Where thick layers are formed, these should be noted (see Clause 7 for dust layers). NOTE Requirements for a verification dossier are given in IEC 60079-14. 5.3 Id