1、 AMERICAN NATIONAL STANDARD ANSI/ISA-60079-18 (12.23.01)-2009 Supercedes ANSI/ISA-60079-18 (12.23.01)-2005 Electrical Apparatus for Use in Class I, Zone 1 Hazardous (Classified) Locations: Type of Protection - Encapsulation “m” Approved 31 July 2009 Commitment for Amendments This standard is issued
2、jointly by the International Society of Automation (ISA) and Underwriters Laboratories Incorporated (UL). Comments or proposals for revisions on any part of the standard may be submitted to ISA or UL at any time. Revisions to this standard will be made only after processing according to the standard
3、s development procedures of ISA and UL. ISA and UL will issue revisions to this standard by means of a new edition or revised or additional pages bearing their date of issue. ISBN: 978-1-936007-15-8 Copyright 2009 By ISA These materials are subject to copyright claims of IEC, ANSI, and ISA. All righ
4、ts reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced in any form, including an electronic retrieval system, without the prior written permission of ISA. All requests pertaining to this standard should be submitted to ISA. ISBN Copyright
5、2009 Underwriters Laboratories Incorporated ULs Standards for Safety are copyrighted by UL. Neither a printed nor electronic copy of a Standard should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive
6、property of UL. This ANSI/UL Standard for Safety consists of the Second edition. The most recent designation of ANSI/UL 60079-18 as an American National Standard (ANSI) occurred on 31 July 2009. ANSI approval for a standard does not include the Cover Page, Transmittal Pages, Title Page (front and ba
7、ck), or the Preface. The National Difference Page and IEC Foreword are also excluded from the ANSI approval of IEC-based standards. Comments or proposals for revisions on any part of the Standard may be submitted to UL at any time. Proposals should be submitted via a Proposal Request in ULs On-Line
8、Collaborative Standards Development System (CSDS) at http:/. To purchase UL Standards, visit Comm 2000 at http:/m- or call toll-free 1-888-853-3503. ISA Underwriters Laboratories Inc. ANSI/ISA60079-18 ANSI/UL 60079-18 Second Edition Second Edition Electrical Apparatus for Use in Class I, Zone 1 Haza
9、rdous (Classified) Locations: Type of Protection Encapsulation “m” This page intentionally left blank. 31 July 2009 ANSI/ISA-60079-18 ANSI/UL 60079-18 5 General Notes This is the common ISA and UL standard for Electrical Apparatus for Explosive Gas Atmospheres Part 18: Construction, testing and mark
10、ing of type of protection encapsulation “m” electrical apparatus. It is the second edition of ANSI/ISA-60079-18 and the second edition of ANSI/UL 60079-18. The ISA suffix “Mod” indicates the document is a modification of the IEC document and includes U.S. deviations encompassing both additions and d
11、eletions of information. ANSI/ISA-60079-18 and ANSI/UL 60079-18 contain identical requirements, and identical publication dates. The presentation and format of the standards material may differ between the two published standards. This common standard was prepared by The International Society of Aut
12、omation (ISA) and Underwriters Laboratories Inc. (UL). 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 harmonizat
13、ion This standard adopts the IEC text with deviations. The requirements are presented in different formats. The ISA version of the standard illustrates the national differences from the IEC text through the use of legislative text (strike-out and underline). The UL version of the standard illustrate
14、s national differences immediately following the IEC text. National differences between the UL version and the ISA version shall be word for word except for editorial changes. Interpretations The interpretation by the SDO of an identical or equivalent standard shall be based on the literal text to d
15、etermine compliance with the standard in accordance with the procedural rules of the SDO. If more than one interpretation of the literal text has been identified, a revision shall be proposed as soon as possible to each of the SDOs to more accurately reflect the intent. UL Effective Date As of 31 Ju
16、ly 2009, all products Listed or Recognized by UL must comply with the requirements in this Standard. This page intentionally left blank. 31 July 2009 ANSI/ISA-60079-18 ANSI/UL 60079-18 7 Preface This ISA standard is based on IEC Publication 60079-18. It is the intention of the ISA12 Committee to dev
17、elop an ANSI Standard that is harmonized with IEC 60079-18 to the fullest extent possible. This preface is included for informational purposes and is not part of ANSI/ISA 60079-18. The document is a modification of the IEC document and includes U.S. deviations encompassing both additions and deletio
18、ns of information. The standards referenced within this document may contain provisions which, 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 bas
19、ed on this document are encouraged to investigate the possibility of applying the most recent 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. National Stan
20、dards. This document has been prepared as part of the service of ISA, toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and a
21、sks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander 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
22、attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric
23、system) in their business and professional dealings with other countries. Toward this end, this Department will endeavour to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the In
24、ternational System of Units (SI): The Modern Metric System, published by the American Society for Testing b) incorporation of two levels of protection. This page intentionally left blank. 31 July 2009 ANSI/ISA-60079-18 ANSI/UL 60079-18 17 1 Scope This part of IEC 60079 standard gives the specific re
25、quirements for the construction, testing, and marking of electrical apparatus, parts of electrical apparatus and Ex components with the type of protection encapsulation “m”. This part of IEC 60079 standard only applies for encapsulated electrical apparatus, encapsulated parts of electrical apparatus
26、 and encapsulated Ex components (hereinafter always referred to as “m” apparatus) where the rated voltage does not exceed 10 kV with a relative tolerance of +10 %. This standard supplements and modifies the general requirements in ANSI/ISA-60079-0 IEC 60079-0. Where a requirement of this standard co
27、nflicts with a requirement of ANSI/ISA-60079-0, the requirement of this standard will take precedence. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the l
28、atest edition of the referenced document (including any amendments) applies. IEC 60079-0: , Electrical apparatus for explosive gas atmospheres Part 0: General requirements ANSI/ISA-60079-0 (12.00.01)-2005, Electrical Apparatus for Use in Class I, Zones 0, 1 b) any specified abnormal conditions; c) i
29、n defined failure conditions. For level of protection “ma”, the working voltage at any point in the circuit shall not exceed 1 kV. For level of protection “ma”, components without additional protection shall only be used if they cannot damage the encapsulation mechanically or thermally in the case o
30、f any fault. Alternatively, where a fault of an internal component may lead to failure of the encapsulation system due to increasing temperature, the requirements of 6.2 shall apply. NOTE Certain components whose application is allowed according to this standard for level of protection “mb” can poss
31、ibly make the protective measure encapsulation ineffective by mechanical or thermal damage as a consequence of internal reactions. This risk should be excluded for level of protection “ma” apparatus. 4.4 Level of protection “mb” “m” apparatus of level of protection “mb” shall not be capable of causi
32、ng ignition in each of the following circumstances: a) in normal operation and installation conditions; b) in defined failure conditions. 4.5 Supply specifications The limiting values of the supply (rated voltage and the prospective short circuit current) shall be stated to ensure that, under the re
33、levant level of protection “ma” or “mb”, the limiting temperature is not exceeded. Any protective device used shall comply with the requirements of 7.9. 31 July 2009 ANSI/ISA-60079-18 ANSI/UL 60079-18 21 5 Requirements for compounds 5.1 General The documentation shall specify the compound(s) used an
34、d the processing method(s). As a minimum, those properties of the compound(s) on which the encapsulation “m” depends shall be provided. Due consideration shall be given in the selection of encapsulating materials to allow for the expansion of components during operation and in the event of allowable
35、 faults. 5.2 Specification The manufacturer shall attest on his own responsibility that the material complies with the compound specification. The material specification shall include: a) the name and address of the manufacturer of the compound, b) the exact and complete reference of the material, a
36、nd, if relevant percentage of fillers and any other additives, the mixture ratios and the type designation, c) if applicable, any treatment of the surface of the compound(s), for example varnishing, d) if applicable, to obtain correct adhesion of the compound to a component any requirement for pre-t
37、reating of the component, for example cleaning, etching, e) if appropriate, the result of the water absorption test in accordance with 8.1. Where this test has not been performed, to indicate this special condition of use the apparatus shall be marked “X” in accordance with item i) of 29.2 of ANSI/I
38、SA-60079-0 IEC 60079-0, f) the dielectric strength in accordance with IEC 60243-1 at the maximum temperature of the apparatus determined according to 8.2.2, g) temperature range of the compound(s) (upper and lower continuous operating temperature), h) in the case of “m” apparatus where the compound
39、is part of the external enclosure the temperature index TI value as defined by 7.1.3 d) of ANSI/ISA-60079-0 IEC 60079-0. As an alternative to the TI, the relative thermal index (RTI-mechanical impact) may be determined in accordance with UL 746B1, i) the colour of the compound used for the test samp
40、les where the compound specification will be influenced by changing the colour. 6 Temperatures 6.1 General The maximum surface temperature and the maximum value of the continuous operating temperature of the compound shall not be exceeded during normal operation. The “m” apparatus shall be protected
41、 in such a way that the encapsulation “m” is not adversely affected under specified fault conditions. 1UL 746B, Polymeric Materials Long-Term Property Evaluations 22 ANSI/ISA-60079-18 ANSI/UL 60079-18 31 July 2009 6.2 Temperature limitation When a protective device is required to limit temperatures
42、for safety reasons, it shall be a non-resetting internal or external, electrical or thermal device. One device is required for level of protection “mb” and two devices for level of protection “ma”. The thermal coupling of the device to the component being monitored shall be sufficient. For functiona
43、l reasons, the “m” apparatus may also contain an additional resettable protective device. If the non-resetting protective device complies with IEC 60127UL 248-1 or IEC 60691, only one device is necessary for both levels of protection. Where the apparatus may be subject to fault, see 7.2.1, or where
44、there is the possibility of an increased temperature, for example by an unfavourable input voltage in accordance with 7.2.1 or an unfavourable load, these shall be taken into account in determining the limiting temperature. 6.3 Determination of the limiting temperature 6.3.1 Maximum surface temperat
45、ure of the test sample The maximum surface temperature shall be determined using the test method given in 8.2.2 in accordance with the supply conditions specified in 4.5. This temperature shall be used to determine the temperature class. 6.3.2 Temperature of the components in the compound The hottes
46、t component(s) shall be determined. The maximum temperature in the compound, adjacent to the hottest component(s), shall be determined using the test method given in 8.2.2 for normal operation. NOTE The determination of the hottest component may be done by calculation or manufacturers specification
47、or by a practical test prior to encapsulating the components. 7 Constructional requirements 7.1 General Where the encapsulation forms part of the external enclosure, it shall comply with the requirements for non metallic enclosures and parts of non metallic enclosures of ANSI/ISA-60079-0. If additio
48、nal protective measures are required by the user in order to satisfy the requirements of this standard, for example, additional mechanical protection, to indicate this special condition of use the apparatus shall be marked “X” in accordance with item i) of 29.2 of ANSI/ISA-60079-0 IEC 60079-0. Appro
49、priate action shall be taken to accommodate the expansion of components during normal operation and in the event of faults according to 7.2. In 7.2 to 7.9 the requirements differ according to whether the compound adheres to the enclosure. Where adhesion is specified, the aim is to prevent the ingress of explosive atmospheres and moisture at the boundary surfaces (for example enclosure-compound, compound-parts that are not completely embedded in the compound, such as printed wiring boards, connect
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