1、 IEC TS 60079-32-1 Edition 1.0 2017-03 TECHNICAL SPECIFICATION Explosive atmospheres Part 32-1: Electrostatic hazards, guidance IEC TS 60079-32-1:2013-08/AMD1:2017-03(en) AMENDMENT 1 THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2017 IEC, Geneva, Switzerland All rights reserved. Unless otherwise
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10、If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csciec.ch. IEC TS 60079-32-1 Edition 1.0 2017-03 TECHNICAL SPECIFICATION Explosive atmospheres Part 32-1: Electrostatic hazards, guidance INTERNATIONAL ELECTROTECHNICAL CO
11、MMISSION ICS 29.260.20 ISBN 978-2-8322-4107-3 AMENDMENT 1 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. 2 IEC TS 60079-32-1:2013/AMD1:2017 IEC 2017 FOREWORD This amendment has been prepared
12、by IEC technical committee 31: Equipment for explosive atmospheres. The text of this amendment is based on the following documents: DTS Report on voting 31/1237/DTS 31/1253/RVC Full information on the voting for the approval of this amendment can be found in the report on voting indicated in the abo
13、ve table. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC website under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be transformed into an International
14、 standard, reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. _ 2 Normative references Replace the following two references: IEC 60079-0, Explosive atmospheres Part 0: Equipment General requirements IEC 60079-32-2
15、, Explosive atmospheres Part 32-2: Electrostatics hazards Tests with the following two new references: IEC 60079-0:2011, Explosive atmospheres Part 0: Equipment General requirements IEC 60079-32-2:2015, Explosive atmospheres Part 32-2: Electrostatics hazards Tests IEC TS 60079-32-1:2013/AMD1:2017 3
16、IEC 2017 Insert, after Clause 13, a new Clause 14 as follows: 14 Special requirements for equipment according to IEC 60079-0 14.1 General In this document, threshold limits are given for electrostatic testing of products which differ from the threshold limits in IEC 60079-0:2011. The threshold limit
17、s specified in this document are in some cases more conservative, as they apply to a broad range of industrial applications where the physical situation may be quite different to that in which electrical equipment complying with IEC 60079-0 is used. The more conservative limits are based on theoreti
18、cal modeling supported by empirical data. In order to have all relevant electrostatic requirements accessible in one place, the requirements from IEC 60079-0:2011 are included for information in this clause of this document, with the addition of helpful explanatory material and cross-references to o
19、ther text in this document. The test methods in IEC 60079-32-2:2015 are equivalent to those cited in IEC 60079-0:2011, but in some cases climatic conditions are different. Equipment within the scope of IEC 60079-0 may be tested in the climatic conditions specified in IEC 60079-0. NOTE The use in app
20、aratus of products and materials conforming to the threshold limits specified in IEC 60079-0:2011 is not known to have resulted in any accidental ignition. 14.2 Electrostatic charges on external non-metallic materials 14.2.1 Applicability The requirements of this subclause only apply to external non
21、-metallic materials of electrical equipment, including non-metallic parts which are applied to the external surface of an enclosure. NOTE 1 Non-metallic paints, films, foils, and plates are typically attached to external surfaces of enclosures to provide additional environmental protection. Their ab
22、ility to store an electrostatic charge is addressed by this subclause. NOTE 2 It is generally acknowledged that glass is not susceptible to storing an electrostatic charge. 14.2.2 Avoidance of a build-up of electrostatic charge on Group I or Group II electrical equipment Electrical equipment should
23、be so designed that under normal conditions of use, maintenance and cleaning, danger of ignition due to electrostatic charges are avoided. This requirement should be satisfied by one or more of the following: a) By suitable selection of the material so that surface resistance shall meet at least one
24、 of the criteria given below (see 6.2.1) when measured in accordance with IEC 60079-32-2: 100 G measured at (30 5) % relative humidity 1 G measured at (50 5) % relative humidity NOTE 1 For more information see 6.1. b) By limitation of the surface area of non-metallic parts of enclosures, determined
25、according to 6.3.2, to the values of Table 23. The values for surface area can be increased by a factor of four if the exposed area of non-metallic material is surrounded by and in contact with conductive earthed frames (see 6.3.3). Alternatively, for long parts with non-metallic surfaces, such as t
26、ubes, bars, or ropes, the surface area need not be considered, but the diameters or widths should not exceed the values shown in Table 23. 4 IEC TS 60079-32-1:2013/AMD1:2017 IEC 2017 NOTE 2 Electric cables for connection of external circuits are not in the scope of Clause 14. Information on external
27、 cables can be found in IEC 60079-14. NOTE 3 Requirements for pipes and hoses for liquids are not in the scope of Clause 14. Requirements for pipes and hoses for liquids are given in 7.7, and for solids in 9.3.3. c) By provision of an insulating layer bonded to a conductive surface. This layer shoul
28、d meet at least one of the following criteria: 1) the layer is not expected to be subject to high charging processes stronger than manual rubbing (see 3.13) and has a thickness 2 mm for Groups I, IIA, IIB or 0,2 mm for Group IIC (see Table 23 and 6.3.4.2). 2) the breakdown voltage measured through t
29、he thickness of the insulating material is 4 kV (see 6.3.4.3) when measured as described in IEC 60079-32-2. NOTE 4 According to IEC 60243-2, insulating materials stressed by DC have their breakdown voltage tested with DC and the method described in IEC 60243-1 with the additional requirements in IEC
30、 60243-2. This method and the additional requirements are also given in IEC 60079-32-2. d) By provision of a conductive coating (see 6.3.5). Non-metallic surfaces may be covered with a bonded durable conductive coating. The resistance between the coating and either the bonding point (in the case of
31、fixed equipment) or the farthest point of possible contact with the enclosure (in the case of portable equipment) should not exceed 1 G. The resistance should be measured in accordance with IEC 60079-32-2 but using the 100 mm 2electrode at the worst case position of the surface and either the bondin
32、g point or the farthest point of possible contact. NOTE 5 The environmental conditions that have an effect on the coating material can include influences from small particles in an air stream, solvent vapours, and the like. e) By using any other safety measure in this Technical Specification to avoi
33、d the danger of ignition due to electrostatic charges. f) By testing that the maximum transferred charge measured according to IEC 60079-32-2 under worst case conditions is within the threshold limits of Table 23. g) In specific cases, IEC 60079-0 allows the use of fixed equipment which does not ful
34、fill the requirements a) to f) and may have a risk from electrostatic discharges by marking them with “X”. In this case, the instruction manual should provide guidance for the user to minimize the risk from electrostatic discharges by operational measures. Where practicable, the equipment should als
35、o be marked with the electrostatic charge warning given in IEC 60079-0. However, this alternative should not be used if hazardous electrostatic charging is expected during use (e.g. for hand-held equipment or for constantly charging fixed installations). NOTE 6 X-marking is used e.g. for insulating
36、housings of electrical equipment that are touched by the operator only during cleaning, maintenance and repair. IEC TS 60079-32-1:2013/AMD1:2017 5 IEC 2017 Table 23 Alternative restrictions on insulating solid materials and isolated conductive or dissipative parts in hazardous areas for equipment wi
37、thin the scope of IEC 60079-0 Group I Group II Group III EPL Ma, Mb Sub group EPL Ga EPL Gb EPL Gc EPL Da EPL Db EPL Dc A) Surface area 10 000 mm 2A 5 000 mm 210 000 mm 210 000 mm 2No limits B 2 500 mm 210 000 mm 210 000 mm 2C 400 mm 2 2 000 mm 2 2 000 mm 2B) Width of bars, rods 30 mm A 3 mm 30 mm 3
38、0 mm No limits B 3 mm 30 mm 30 mm C 1 mm 20 mm 20 mm C) Thickness of insulating coatings to avoid brush discharges 2 mm A 2 mm No limits B 2 mm C 0,2 mm Thickness of insulating coatings to avoid any incendive discharge Not permitted Not per mitted Not permitted 8 mm if area 500 mm 2D) Transferred ch
39、arge 60 nC A 60 nC No limits for insulating solids 200 nC aB 25 nC C 10 nC E) Capacitance of unearthed metal parts 10 pF A 3 pF 10 pF 10 pF 10 pF bB 3 pF 10 pF 10 pF C 3 pF aValue only valid for spark discharges from unearthed conductive or dissipative parts bFor equipment intended for use in ducts
40、or pipes subject to the presence of fast moving dust a lower limiting value of capacitance is under consideration NOTE 1 The width criterion in B) applies to thin pipes, cable sheaths, and other insulating materials having small widths or diameters. NOTE 2 The limits in A) and B) are not absolute va
41、lues that prevent incendive discharges, they merely reduce it to a generally accepted low level. NOTE 3 The limits in C) apply to insulating coatings and layers on conductive or dissipative materials. NOTE 4 The limits in D) ensure that incendive discharges do not occur. NOTE 5 All of the values in
42、D) contain a certain safety margin. Recent work indicates that the value hitherto used for IIB contains a lower safety margin than all other values. To equalize all safety margins the values for IIB have been reduced from 30 nC to 25 nC. This does not mean that the former value was unsafe or retesti
43、ng is necessary. NOTE 6 The subgroups are based on the maximum experimental safe gap (MESG) or the minimum ignition current ratio (MIC ratio) of the explosive gas atmosphere in which the equipment may be installed (see IEC 60079-20-1). More details can be found in C.6 and D.3. NOTE 7 The values in E
44、PL Gc do not exclude the possibility of high charging processes. Manual rubbing is usually not considered to be a high charging process (see 3.13). NOTE 8 It is generally accepted that an unearthed metal fastener such as a cover screw will present a capacitance of not more than 3 pF. 6 IEC TS 60079-
45、32-1:2013/AMD1:2017 IEC 2017 14.2.3 Avoidance of a build-up of electrostatic charge on equipment for Group III It is not possible to create electrostatic discharges from insulating surfaces that are incendive for dust clouds or dust layers just by manual rubbing. However, if high charging processes
46、(see 3.13) are not excluded, painted/coated metal equipment and equipment of plastic material should be so designed that under normal conditions of use, ignition caused by propagating brush discharges is avoided. Enclosures of plastic material cannot be charged to such a critical charge density that
47、 propagating brush discharges can be generated. However, no extended flat conductive surfaces should be installed inside the enclosure within a distance of 8 mm to the outer surface. NOTE 1 An internal printed circuit board can be considered to be an extended flat conductive surface, though this nee
48、d not be applied in small hand-held equipment unless the equipment is likely to be subjected to a prolific charge generating mechanism (such as might occur in pneumatic transfer of powders or charge spraying in a powder coating process). Charging through normal handling of hand-held equipment is not
49、 considered to lead to a prolific charge generating mechanism and therefore would not lead to a situation where a propagating brush discharge might occur. NOTE 2 A single flat conductive surface not exceeding 500 mm 2is not considered to be an extended flat surface. This allows for the standoffs or brackets used for the mounting of conductive flat plates inside of an enclosure. Using external insulation of at least 8 mm in thickness on metal par
