FprEN IEC 60079-31:2019
(Main)Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
Explosionsgefährdete Bereiche - Teil 31: Geräte-Staubexplosionsschutz durch Gehäuse „t“
Atmosphères explosives - Partie 31: Protection contre l’inflammation de poussières par enveloppe “t” relative au matériel
Eksplozivne atmosfere - 31. del: Zaščita opreme pred vžigom gorljivega prahu z ohišjem "t"
General Information
RELATIONS
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN 60079-31:2018
01-april-2018
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Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
Explosionsgefährdete Bereiche - Teil 31: Geräte-Staubexplosionsschutz durch Gehäuse
"t"Atmosphères explosives - Partie 31: Protection contre l’inflammation de poussières par
enveloppe “t” relative au matérielTa slovenski standard je istoveten z: prEN 60079-31:2018
ICS:
29.260.20 (OHNWULþQLDSDUDWL]D Electrical apparatus for
HNVSOR]LYQDR]UDþMD explosive atmospheres
oSIST prEN 60079-31:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 60079-31:2018
31/1358/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60079-31 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2018-01-12 2018-04-06
SUPERSEDES DOCUMENTS:
31/1320/CD,31/1335A/CC
IEC TC 31 : EQUIPMENT FOR EXPLOSIVE ATMOSPHERES
SECRETARIAT: SECRETARY:
United Kingdom Mr Mick Maghar
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel votingThe attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.TITLE:
Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
NOTE FROM TC/SC OFFICERS:Copyright © 2017 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
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IEC CDV 60079-31/Ed3 © IEC 2018 – 2 – 31/1358/CDV
1 CONTENTS
2 CONTENTS ................................................................................................................... 2
3 FOREWORD .................................................................................................................. 4
4 1 Scope ..................................................................................................................... 7
5 2 Normative references ............................................................................................... 7
6 3 Terms and definitions ............................................................................................... 8
7 4 General .................................................................................................................. 8
8 4.1 Levels of Protection ......................................................................................... 8
9 4.2 General requirements....................................................................................... 8
10 4.2.1 Equipment groups and ingress protection .................................................... 8
11 4.3 Requirements for Ex Equipment with Level of Protection “ta”................................ 9
12 4.3.1 Fault current ............................................................................................. 9
13 4.3.2 Maximum surface temperature ................................................................... 9
14 4.3.3 Overpressure............................................................................................ 9
15 4.3.4 Dust exclusion .......................................................................................... 9
16 4.3.5 Protective devices ..................................................................................... 9
17 4.3.6 Supplementary internal enclosure ............................................................. 10
18 4.4 Requirements for Ex Equipment with Level of Protection “tb” and “tc” .................. 10
19 4.4.1 Fault current ........................................................................................... 10
20 4.4.2 Maximum surface temperature ................................................................. 10
21 4.4.3 Overpressure.......................................................................................... 10
22 4.4.4 Dust exclusion ........................................................................................ 10
23 4.4.5 Thermal protection .................................................................................. 10
24 5 Construction.......................................................................................................... 11
25 5.1 Joints ........................................................................................................... 11
26 5.1.1 General.................................................................................................. 11
27 5.1.2 Threaded joints ....................................................................................... 11
28 5.1.3 Gaskets and seals .................................................................................. 11
29 5.1.4 Cemented joints ...................................................................................... 12
30 5.1.5 Operating rods, spindles and shafts .......................................................... 12
31 5.1.6 Windows ................................................................................................ 12
32 5.2 Entries into enclosures ................................................................................... 12
33 5.2.1 Cable glands .......................................................................................... 12
34 5.2.2 Entries ................................................................................................... 13
35 6 Verification and tests ............................................................................................. 13
36 6.1 Type tests ..................................................................................................... 13
37 6.1.1 Type tests for dust exclusion by enclosures ............................................... 13
38 6.1.2 Tests to determine maximum surface temperature ...................................... 14
39 6.2 Routine tests ................................................................................................. 15
40 7 Marking ................................................................................................................ 15
41 Annex A (Normative) Supplementary requirements for entry devices.................................. 16
42 A.1 General ........................................................................................................ 16
43 A.2 Construction requirements .............................................................................. 16
44 A.2.1 Cable glands, cable transit devices and conduit sealing devices .................. 16
45 A.2.2 Blanking elements and thread adapters ..................................................... 16
46 A.3 Type tests ..................................................................................................... 16
47 A.3.1 Cable glands, cable transit devices and conduit sealing devices .................. 16
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48 A.3.2 Blanking elements and thread adapters ..................................................... 16
49 A.4 Marking ........................................................................................................ 17
50 Bibliography ................................................................................................................. 18
52 Table 1 – Level of Protection, equipment group and ingress protection (IP) relationship ........ 8
53 Table 2 – Overload or malfunction conditions for Level of Protection “tb” ............................ 14
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56 INTERNATIONAL ELECTROTECHNICAL COMMISSION
57 ____________
59 EXPLOSIVE ATMOSPHERES –
61 Part 31: Equipment dust ignition protection by enclosure "t"
63 FOREWORD
64 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
65 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
66 international co-operation on all questions concerning standardization in the electrical and electronic fields. To
67 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
68 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
69 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
70 in the subject dealt with may participate in this preparatory work. International, governmental and non-
71 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
72 with the International Organization for Standardization (ISO) in accordance with conditions determined by
73 agreement between the two organizations.74 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
75 consensus of opinion on the relevant subjects since each technical committee has representation from all
76 interested IEC National Committees.77 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
78 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
79 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
80 misinterpretation by any end user.81 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
82 transparently to the maximum extent possible in their national and regional publications. Any divergence
83 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
84 the latter.85 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
86 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
87 services carried out by independent certification bodies.88 6) All users should ensure that they have the latest edition of this publication.
89 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
90 members of its technical committees and IEC National Committees for any personal injury, property damage or
91 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
92 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
93 Publications.94 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
95 indispensable for the correct application of this publication.96 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
97 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
98 International Standard IEC 60079-31 has been prepared by IEC technical committee 31:
99 Equipment for explosive atmospheres.100 This third edition cancels and replaces the second edition published in 2013. This edition
101 constitutes a technical revision.102
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103 The significance of changes between IEC 60079-31, Edition 3 and IEC 60079-31, Edition 2
104 (2013) is as listed below:Type
Changes Clause Minor and Extension Major technical
changes
editorial
changes
Document has been restructured from edition 2 Numerous X
Fault current rating of interrupting contacts 4.3.1 and C1
4.4.1
Cells and batteries 4.3.5.1 and C2
4.4.5.1
Overload or malfunction condition for the Table 2 C3
determination of temperature class for “tb” converter
fed rotating electric machines
Additional requirements for entry devices with dust Annex A C4
ignition protection by enclosure "t"
Thermal tests are relocated to IEC 60079-0. Formerly See “Information about the background
6.1.2of Changes”
105 NOTE The technical changes referred to include the significance of technical changes in the revised IEC
106 Standard, but they do not form an exhaustive list of all modifications from the previous version. More guidance may
107 be found by referring to the Redline Version of the standard.108 Explanations:
109 A) Definitions
110 Minor and editorial changes
111 clarification
112 decrease of technical requirements
113 minor technical change
114 editorial corrections
115 These are changes which modify requirements in an editorial or a minor technical way. They
116 include changes of the wording to clarify technical requirements without any technical change,
117 or a reduction in level of existing requirement.118 Extension addition of technical options
119 These are changes which add new or modify existing technical requirements, in a way that
120 new options are given, but without increasing requirements for equipment that was fully
121 compliant with the previous standard. Therefore, these will not have to be considered for
122 products in conformity with the preceding edition.123 Major technical changes
124 addition of technical requirements
125 increase of technical requirements
126 These are changes to technical requirements (addition, increase of the level or removal)
127 made in a way that a product in conformity with the preceding edition will not always be able
128 to fulfil the requirements given in the later edition. These changes have to be considered for
129 products in conformity with the preceding edition. For these changes additional information is
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131 NOTE These changes represent current technological knowledge. However, these changes should not normally
132 have an influence on equipment already placed on the market.133 B) Information about the background of ‘Major Technical Changes’
134 C1 –Ex Equipment having Level of Protection “ta” shall be rated for connection to a circuit
135 with a prospective short circuit current of not greater than 1.5 kA. For Ex Equipment having
136 Level of Protection “tb” or “tc” which is intended for mains connection and intended to
137 interrupt fault current above 10kA, the equipment shall have a rated maximum short circuit
138 withstand current, be tested according to 6.1.1.1, and be marked according to Clause 7.
139 C2 – For Ex Equipment having Level of Protection “ta” which contains a cell or battery, only a
140 sealed cell or battery shall be used. For Ex Equipment having Level of Protection “tb” and “tc”
141 where there are sparking contacts or hot surfaces, and which contains a cell or battery, only a
142 sealed cell or battery shall be used.143 C3 – Table 2 now includes malfunction conditions for temperature class determination of
144 Level of Protection “tb” converter-fed electric machines.145 C4 – Annex A added for entry devices with Type of Protection "t" including cable transit
146 devices.147 Thermal test formerly located in Clause 6.1.2 are relocated to IEC 60079-0 Ed 7.
148 The text of this standard is based on the following documents:FDIS Report on voting
31//FDIS 31//RVD
149
150 Full information on the voting for the approval of this standard can be found in the report on
151 voting indicated in the above table.152 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
153 This International Standard is to be used in conjunction with IEC 60079-0.154
155 A list of all parts of the IEC 60079 series, under the general title Explosive atmospheres, can
156 be found on the IEC website.157 The committee has decided that the contents of this publication will remain unchanged until
158 the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
159 the data related to the specific publication. At this date, the publication will be
160 • reconfirmed,161 • withdrawn,
162 • replaced by a revised edition, or
163 • amended.
164
165
166
167
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168 EXPLOSIVE ATMOSPHERES –
169
170 Part 31: Equipment dust ignition protection by enclosure "t"
171
172
173 1 Scope
174 This part of IEC 60079 is applicable to equipment protected by enclosure and surface
175 temperature limitation for use in explosive dust atmospheres. It specifies requirements for
176 design, construction and testing of Ex Equipment and Ex Components.177 This standard supplements and modifies the general requirements of IEC 60079-0. Where a
178 requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of
179 this standard takes precedence.180 This standard does not apply to dusts of explosives, which do not require atmospheric oxygen
181 for combustion, or to pyrophoric substances.182 This standard does not apply to Ex Equipment or Ex Components intended for use in
183 underground parts of mines as well as those parts of surface installations of such mines
184 endangered by firedamp and/or combustible dust.185 This standard does not take account of any risk due to an emission of flammable or toxic gas
186 from the dust.187 2 Normative references
188 The following documents are referred to in the text in such a way that some or all of their
189 content constitutes requirements of this document. For dated references, only the edition
190 cited applies. For undated references, the latest edition of the referenced document (including
191 any amendments) applies.192 IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements
193 IEC 60127 (all parts), Miniature fuses194 IEC 60691, Thermal-links – Requirements and application guide
195 IEC 60529, Degrees of Protection Provided by Enclosures
196 IEC 60034-5, Rotating electrical machines – Part 5: Degrees of protection provided by the
197 integral design of rotating electrical machines (IP code) – Classification198 ISO 965-1, ISO general-purpose metric screw threads – Tolerances – Part 1: Principles and
199 basic data200 ANSI/ASME B1.20.1, Pipe threads, general purpose (inch)
201 ANSI/UL 248 (all parts), Standard for Low-Voltage Fuses
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202 3 Terms and definitions
203 For the purposes of this document, the terms and definitions given in IEC 60079-0 and the
204 following apply.205 ISO and IEC maintain terminological databases for use in standardization at the following
206 addresses:207 • IEC Electropedia: available at http://www.electropedia.org/
208 • ISO Online browsing platform: available at https://www.iso.org/obp/ui
209 3.1
210 dust ignition protection by enclosure “t”
211 Type of Protection for explosive dust atmospheres where equipment is provided with an
212 enclosure providing dust ingress protection and a means to limit surface temperatures
213 4 General214 4.1 Levels of Protection
215 Type of Protection “t” is divided into three Levels of Protection based on the risk of the Ex
216 Equipment becoming an ignition source in an explosive dust atmosphere. Ex Equipment with
217 Type of Protection “t” shall be one of the following:218 • Level of Protection “ta” for EPL “Da”;
219 • Level of Protection “tb” for EPL “Db”;
220 • Level of Protection “tc” for EPL “Dc”.
221 The construction and marking requirements apply to all Ex Equipment, and in addition, the
222 requirements for "ta" as given in 4.3 and the requirements for "tb" and "tc" as given in 4.4.
223 Failure modes as defined in the industrial standard for particular internal components
224 affecting the temperatures of the equipment shall be taken into account when considering
225 applicable malfunctions.226 When a resistor is used for current limiting, it shall not be considered to fail as short circuit if it
227 is of metal film or of wire wound construction. The resistor shall be rated for the maximum
228 rated voltage of the equipment.229 4.2 General requirements
230 4.2.1 Equipment groups and ingress protection
231 The relationship between the Level of Protection, the group, and ingress protection required is
232 shown in Table 1.233 Table 1 – Level of Protection, equipment group and ingress protection (IP) relationship
Level of Protection Group IIIC Group IIIB Group IIIA“ta” IP6X IP6X IP6X
“tb” IP6X IP6X IP5X
“tc” IP6X IP5X IP5X
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234 4.3 Requirements for Ex Equipment with Level of Protection “ta”
235 4.3.1 Fault current
236 Ex Equipment shall be rated for connection to a circuit with a prospective short circuit current
237 of not greater than 1,5 kA, unless marked according to Clause 7.238 4.3.2 Maximum surface temperature
239 These requirements modify and supplement the requirements of IEC 60079-0.
240 The marked maximum surface temperature shall be determined based upon measurements of
241 the surfaces of the internal components in accordance with 6.1.2. The highest of the
242 measured temperatures shall be the basis for the marked maximum surface temperature. If
243 the equipment includes a supplementary internal enclosure, the temperature shall be
244 measured on the external surfaces of the supplementary internal enclosure.245 NOTE 1 Partial rupture of the external enclosure is considered to be a potential rare malfunction and is considered
246 in the temperature determination for “ta” equipment.247 NOTE 2 Due to the limited thermal dissipation available to Level of Protection “ta” equipment, the maximum normal
248 power dissipation is generally limited to a few watts.249 4.3.3 Overpressure
250 A positive internal pressure of 4 kPa shall be applied to the enclosure in accordance with
251 6.1.1.3 prior to the dust exclusion test.252 4.3.4 Dust exclusion
253 Dust exclusion by enclosure shall be carried out in accordance with 6.1.1.
254 4.3.5 Protective devices
255 4.3.5.1 General
256 If the Ex Equipment is capable of exceeding the marked maximum surface temperature as a
257 result of the temperature test of 6.1.2 under expected malfunction or for rare malfunction
258 conditions, a protective device is required. The protective device may be directly integrated
259 into the Ex Equipment or be external to the Ex Equipment.260 Where the external protective device is not provided by the manufacturer as part of the Ex
261 Equipment, the marking shall include the symbol “X” in accordance with IEC 60079-0, and the
262 Specific Conditions of Use shall detail the required ratings and characteristics of the
263 protective device. The protective device shall be capable of interrupting the maximum current
264 of the circuit in which it is installed. If the Ex Equipment contains a cell or battery, only a
265 sealed cell or battery shall be used. A control device shall be provided to prevent overheating
266 of the cell or battery. The control device may also be considered as a protective device,
267 provided it also protects the complete Ex Equipment from exceeding the maximum surface
268 temperature.269 4.3.5.2 Thermal protective devices
270 The Ex Equipment shall be protected by one or more integral thermal protective devices.
271 Thermal protective devices shall not be of a self-resettable type and shall be duplicated
272 unless conforming to the IEC 60127 series, IEC 60691 or ANSI/UL 248 series, in which case
273 only one device is necessary.274 Alternatively, if it can be demonstrated that an overcurrent protective device can be used to
275 provide thermal protection, such a device may be used. When an overcurrent protective
276 device is not also used as a thermal protective device, it is permissible for the overcurrent
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277 protective device to be located outside the enclosure of the Ex Equipment. In this case, the
278 marking shall include the symbol "X" in accordance with IEC 60079-0 and the Specific
279 Conditions of Use shall detail the required overcurrent protective device.280 The response time of the thermal protective devices should be taken into account and be
281 adequate for the necessary over temperature protection.282 4.3.6 Supplementary internal enclosure
283 Where normally arcing and sparking parts are incorporated, these parts shall have a
284 supplementary enclosure inside the main enclosure and the maximum surface temperature of
285 that enclosure is used to determine the marked surface temperature of the equipment in
286 accordance with 4.3.2.287 When hot internal components are enclosed in a supplementary enclosure, the maximum
288 surface temperature of that enclosure is used to determine the marked surface temperature of
289 the equipment in accordance with 4.3.2.290 The supplementary enclosure shall meet the following requirements which replace the
291 requirements of IEC 60079-0 for such an enclosure:292 • A COT of at least equal to the lower specified ambient temperature and at least 20 K
293 greater than the maximum service temperature applies for non-metallic materials,
294 • Resistance to impact test is performed in accordance with 6.1.1.2 with no hot and cold
295 impact testing required,296 • IP6X in accordance with IEC 60529 following the resistance to impact without thermal
297 endurance to heat and cold.298 4.4 Requirements for Ex Equipment with Level of Protection “tb” and “tc”
299 4.4.1 Fault current
300 For Ex Equipment having Level of Protection “tb” or “tc” which is intended for mains
301 connection and intended to interrupt fault current above 10 kA, the equipment shall have a
302 rated maximum short circuit current, be tested according to 6.1.1.1, and be marked according
303 to Clause 7.304 4.4.2 Maximum surface temperature
305 The marked maximum surface temperature shall be measured on the external surfaces of the
306 enclosure for Ex Equipment with Types of Protection “tb” and “tc" in accordance with 6.1.2.
307 4.4.3 Overpressure308 A positive internal pressure of 2 kPa shall be applied to the enclosure in accordance with
309 6.1.1.3 prior to the dust exclusion test, except where the design of the Ex Equipment is such
310 that gaskets or seals are physically constrained from moving e.g. an “O” ring in a groove.
311 4.4.4 Dust exclusion312 Dust exclusion by enclosure shall be carried out in accordance with 6.1.1.
313 4.4.5 Thermal protection
314 4.4.5.1 General
315 For Level of Protection “tb”, if the Ex Equipment is capable of exceeding the marked
316 maximum surface temperature as a result of the temperature test of 6.1.2, a protective device
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317 is required. The protective device may be directly integrated into the Ex Equipment or be
318 external to the Ex Equipment.319 Where the external protective device is not provided by the manufacturer as part of the Ex
320 Equipment, the marking shall include the symbol “X” in accordance with IEC 60079-0, and the
321 Specific Conditions of Use shall detail the required ratings and characteristics of the
322 protective device. The protective device shall be capable of interrupting the maximum current
323 of the circuit in which it is installed. If the Ex Equipment contains a cell or battery and a
324 control device is provided to prevent overheating of the cell or battery, the control device can
325 also be considered as a protective device, provided it also protects the complete Ex
326 Equipment from exceeding the maximum surface temperature. For Ex Equipment having Level
327 of Protection “tb” or “tc”, only a sealed cell or battery shall be used where there are sparking
328 contacts or hot surfaces.329 4.4.5.2 Thermal
...
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