SIST EN ISO/IEC 80079-20-1:2020

SLOVENSKI STANDARD
oSIST prEN ISO/IEC 80079-20-1:2016
01-februar-2016
Eksplozivne atmosfere - 20-1. del: Lastnosti materiala in razvrstitev za pline in
hlape - Preskusne metode in podatki (ISO/IEC/DIS 80079-20-1:2015)
Explosive atmospheres - Part 20-1: Material characteristics for gas and vapour
classification - Test methods and data (ISO/IEC/DIS 80079-20-1:2015)
Atmosphères explosives - Partie 20-1: Caractéristiques des produits pour le classement
des gaz et des vapeurs - Méthodes et données d'essai (ISO/IEC/DIS 80079-20-1:2015)
Ta slovenski standard je istoveten z: prEN ISO/IEC 80079-20-1
ICS:
29.260.20 (OHNWULþQLDSDUDWL]D Electrical apparatus for
HNVSOR]LYQDR]UDþMD explosive atmospheres
oSIST prEN ISO/IEC 80079-20-1:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO/IEC 80079-20-1:2016
DRAFT INTERNATIONAL STANDARD
ISO/DIS 80079-20-1
ISO/TMBG Secretariat: ISO
Voting begins on: Voting terminates on:
2015-12-03 2016-03-03
Explosive atmospheres —
Part 20-1:
Material characteristics for gas and vapour classification —
Test methods and data
Atmosphères explosives —
Partie 20-1: Caractéristiques des produits pour le classement des gaz et des vapeurs — Méthodes et
données d’essai
ICS: 29.260.20
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the International Organization for
Standardization (ISO), and processed under the ISO lead mode of collaboration
as defined in the Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel five month enquiry.
Should this draft be accepted, a final draft, established on the basis of comments
received, will be submitted to a parallel two-month approval vote in ISO and
THIS DOCUMENT IS A DRAFT CIRCULATED
formal vote in CEN.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
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STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 80079-20-1:2015(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2015

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ISO/DIS 80079-20-1:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO/IEC 2015 – All rights reserved

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1 CONTENTS
2
3 FOREWORD . 5
4 1 Scope . 7
5 2 Normative references . 7
6 3 Terms and definitions . 7
7 4 Classification of gases and vapours. 9
8 4.1 General . 9
9 4.2 Classification according to the maximum experimental safe gaps (MESG) . 9
10 4.3 Classification according to the minimum igniting current ratio (MIC ratio) . 9
11 4.4 Classification according to a similarity of chemical structure . 10
12 4.5 Classification of mixtures of gases . 10
13 5 Data for flammable gases and vapours, relating to the use of equipment . 10
14 5.1 Determination of the properties . 10
15 5.1.1 General . 10
16 5.1.2 Equipment group . 10
17 5.1.3 Flammable limits . 10
18 5.1.4 Flash point FP . 11
19 5.1.5 Temperature class . 11
20 5.1.6 Minimum igniting current (MIC) . 11
21 5.1.7 Auto-ignition temperature (AIT) . 11
22 5.2 Properties of particular gases and vapours . 11
23 5.2.1 Coke oven gas . 11
24 5.2.2 Ethyl nitrite . 11
25 5.2.3 MESG of carbon monoxide . 12
26 5.2.4 Methane, Group IIA . 12
27 6 Method of test for the maximum experimental safe gap (MESG) . 12
28 6.1 Outline of method . 12
29 6.2 Test apparatus . 12
30 6.2.1 General . 12
31 6.2.2 Material and mechanical strength . 13
32 6.2.3 Interior chamber . 13
33 6.2.4 Exterior chamber . 13
34 6.2.5 Gap adjustment . 13
35 6.2.6 Injection of mixture . 13
36 6.2.7 Position of ignition source. 13
37 6.3 Procedure . 13
38 6.3.1 Preparation of gas mixtures . 13
39 6.3.2 Temperature and pressure . 13
40 6.3.3 Gap adjustment . 13
41 6.3.4 Ignition . 14
42 6.3.5 Observation of the ignition process . 14
43 6.4 Determination of maximum experimental safe gap (MESG) . 14
44 6.4.1 General . 14
45 6.4.2 Preliminary tests . 14

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46 6.4.3 Confirmatory tests . 14
47 6.4.4 Reproducibility of maximum experimental safe gaps (MESG) . 14
48 6.4.5 Tabulated values . 14
49 6.5 Verification of the MESG determination method . 14
50 7 Method of test for auto-ignition temperature (AIT) . 15
51 7.1 Outline of method . 15
52 7.2 Apparatus . 15
53 7.2.1 General . 15
54 7.2.2 Test vessel and support . 16
55 Thermocouples . 16
7.2.3
56 7.2.4 Oven . 16
57 7.2.5 Metering devices . 17
58 7.2.6 Mirror . 17
59 7.2.7 Timer . 17
60 7.2.8 Equipment for purging the test vessel with air . 17
61 Automated apparatus . 17
7.2.9
62 7.3 Sampling, preparation and preservation of test samples . 17
63 7.3.1 Sampling . 17
64 7.3.2 Preparation and preservation . 17
65 7.4 Procedure . 18
66 7.4.1 General . 18
67 Sample injection . 18
7.4.2
68 7.4.3 Determination of the auto ignition temperature (AIT) . 19
69 7.5 Auto-ignition temperature (AIT) . 20
70 7.6 Validity of results . 20
71 7.6.1 Repeatability . 20
72 7.6.2 Reproducibility . 20
73 Data . 20
7.7
74 7.8 Verification of the auto-ignition temperature determination method . 20
75 Annex A (normative) Ovens of test apparatus for the tests of auto-ignition
76 temperature . 22
77 “IEC oven” . 22
A.1
78 A.2 “DIN oven” . 22
79 Annex B (informative) Tabulated values . 30
80 Annex C (informative) Determination of cool flames . 78
81 Annex D (informative) Volume dependence of auto ignition temperature . 79
82 Bibliography . 80
83
84 Figure 1 – Test apparatus . 12
85
Figure A.1 – Test apparatus: assembly . 23
86 Figure A.2 – Section A-A (flask omitted) . 24
87
Figure A.3 – Base heater (board made of refractory material) . 24
88 Figure A.4 – Flask guide ring (board made of refractory material) . 25
89
Figure A.5 – Neck heater (board made of refractory material) . 26
90 Figure A.6 – Oven . 27
91
Figure A.7 – Lid of steel cylinder . 28
92 Figure A.8 – Lid of steel cylinder . 29

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93 Figure A.9 – Injection of gaseous sample . 29
94 Figure C.1 – Additional thermocouple to detect cool flames . 78
95 Figure C.2 – ‘Negative temperature coefficient’ shown for butyl butyrate as an example . 78
96 Figure D.1 – Volume dependence of auto ignition temperature . 79
97
98 Table 1 – Classification of temperature class and range of auto-ignition temperatures . 11
99 Table 2 – Values for verification of the apparatus . 15
100 Table 3 – Values for verification of the apparatus . 20
101
102

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103 INTERNATIONAL ELECTROTECHNICAL COMMISSION
104 ____________
105
106 EXPLOSIVE ATMOSPHERES –
107
108 Part 20-1: Material characteristics for gas
109 and vapour classification –
110 Test methods and data
111
112
113 FOREWORD
114 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
115 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
116 international co-operation on all questions concerning standardization in the electrical and electronic fields. To
117 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
118 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
119 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
120 in the subject dealt with may participate in this preparatory work. International, governmental and non-
121 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
122 with the International Organization for Standardization (ISO) in accordance with conditions determined by
123 agreement between the two organizations.
124 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
125 consensus of opinion on the relevant subjects since each technical committee has representation from all
126 interested IEC National Committees.
127 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
128 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
129 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
130 misinterpretation by any end user.
131 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
132 transparently to the maximum extent possible in their national and regional publications. Any divergence
133 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
134 the latter.
135 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
136 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
137 services carried out by independent certification bodies.
138 6) All users should ensure that they have the latest edition of this publication.
139 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
140 members of its technical committees and IEC National Committees for any personal injury, property damage or
141 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
142 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
143 Publications.
144 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
145 indispensable for the correct application of this publication.
146 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
147 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
148 International Standard IEC 80079-20-1 has been prepared by IEC technical committee
149 SC31M: Non-electrical equipment and protective systems for explosive atmospheres.
150 This first edition of ISO/IEC 80079-20-1 cancels and replaces the first edition of IEC 60079-
151 20-1(2010). It constitutes a technical revision. No significant changes with respect to the other
152 edition were done.
153
154

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155 It is published as a double logo standard.
156 The text of this standard is based on the following documents:
FDIS Report on voting
31M/xxx/xxx 31M/xxx/xxx
157
158 Full information on the voting for the approval of this standard can be found in the report on
159 voting indicated in the above table.In ISO, the standard has been approved by xx P members
160 out of xx having cast a vote.
161 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
162 A list of all parts of the IEC 60079 respectively ISO/IEC 80079 series, under the general title:
163 Explosives atmospheres can be found on the IEC website.
164 The committee has decided that the contents of this publication will remain unchanged until
165 the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
166 related to the specific publication. At this date, the publication will be
167 • reconfirmed,
168 • withdrawn,
169 • replaced by a revised edition, or
170 • amended.
171
172 The National Committees are requested to note that for this publication the stability date
173 is 2020
174 THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE
175 DELETED AT THE PUBLICATION STAGE.
176
177

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178 EXPLOSIVE ATMOSPHERES –
179
180 Part 20-1: Material characteristics for gas
181 and vapour classification –
182 Test methods and data
183
184
185
186 1 Scope
187 This part of ISO/IEC 80079 provides guidance on classification of gases and vapours. It
188 describes a test method intended for the measurement of the maximum experimental safe
189 gaps (MESG) for gas-air mixtures or vapour-air mixtures under normal conditions of
1
190 temperature and pressure (20 °C, 100 kPa) so as to permit the selection of an appropriate
191 group of equipment. The standard describes also a test method intended for use in the
192 determination of the auto-ignition temperature (AIT) of a vapour-air mixture or gas-air mixture
193 at atmospheric pressure, so as to permit the selection of an appropriate temperature class of
194 equipment.
195 Values of chemical properties of materials are provided to assist in the selection of equipment
196 to be used in hazardous areas. Further data may be added as the results of validated tests
197 become available.
198 The materials and the characteristics included in a table (see Annex B) have been selected
199 with particular reference to the use of equipment in hazardous areas. The data in this
200 standard have been taken from a number of references which are given in the bibliography.
201 These methods for determining the MESG or the AIT may also be used for gas-air-inert
202 mixtures or vapour-air-inert mixtures. However, data on air-inert mixtures are not tabulated.
203 2 Normative references
204 The following referenced documents are indispensable for the application of this document.
205 For dated references, only the edition cited applies. For undated references, the latest edition
206 of the referenced document (including any amendments) applies.
207 IEC 60079-11, Explosive atmospheres – Part 11: Equipment protection by intrinsic safety "i"
208 IEC 60079-14, Explosive atmospheres – Part 14: Electrical installations design, selection and
209 erection
210 3 Terms and definitions
211 For the purposes of this document, the following terms and definitions apply.
212 Note 1 to entry: For the definitions of any other terms, particularly those of a more general nature, reference should
213 be made to IEC 60050-426 or other appropriate parts of the IEV (International Electrotechnical Vocabulary).
214 3.1
215 ignition by hot surface (auto-ignition)
216 a reaction which is evidenced by a clearly perceptible flame and/or explosion, and for which
217 the ignition delay time does not exceed 5 min
218
219 Note 1 to entry: See 7.2.2 for a test method
—————————
1 An exception is made for substances with vapour pressures which are too low to permit mixtures of the required
concentrations to be prepared at normal ambient temperatures. For these substances, a temperature 5 K above that
needed to give the necessary vapour pressure or 50 K above the flash point is used.

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220 3.2
221 ignition delay time
222 time between the completed injection of the flammable material and the ignition
223 3.3
224 auto-ignition temperature
225 AIT
226 lowest temperature (of a hot surface) at which under specified test conditions an ignition of a
227 flammable gas or vapour in mixture with air or air-inert gas occurs
228 Note 1 to entry: See Clause 7 for a test method.
229 3.4
230 maximum experimental safe gap
231 MESG
232 maximum gap of a joint of 25 mm in width which prevents any transmission of an explosion
233 during the tests made under specified conditions
234 Note 1 to entry: See Clause 6 for a test method.
235 3.5
236 minimum igniting current
237 MIC
238 minimum current in a specified test circuit that causes the ignition of the explosive test mixture
239 in the spark-test apparatus according to IEC 60079-11
240 Note 1 to entry: See 5.1.6 for the test circuit.
241 3.6
242 flammable limits
243 the flammable limits of a gas or vapor are the lower (LFL) and upper (UFL) flammable limit, stated in
244 percent by volume or in g/m³ of gas in a gas-air mixture, between which a flammable mixture is formed
245 Note 1 to entry: In the past, flammable and explosive have been used interchangeably in many texts, but the trend
246 is to avoid the confusion that this causes. The term flammable relates to the properties of the material that
247 determine its ability to produce self-sustaining flame propagation in any direction (upwards, sideways or
248 downwards). The term explosive relates to flame propagation that is accompanied by pressure and temperature
249 rise and noise (usually higher-speed propagation) and is significantly affected by (non-material related) test-
250 chamber conditions (geometry, degree of confinement…). LFL concentrations are typically lower than LEL
251 concentrations for the same material and UFL concentrations are typically higher than UEL concentrations for the
252 same material.
253 3.7
254 equipment grouping
255 classification system of equipment related to the explosive atmosphere for which they are intended to
256 be used
257 Note 1 to entry: IEC 60079-0 identifies three equipment groups:
258 Group I, equipment for mines susceptible to fire damp;
259 Group II, which is divided into sub-groups, equipment for all places with an explosive gas atmosphere
260 other than mines susceptible to fire damp
261 Group III, which is divided into sub-groups, equipment for all places with an explosive dust atmosphere
262 other than mines susceptible to fire damp
263 3.8
264 flash point
265 FP
266 lowest liquid temperature at which, under specified test conditions, a liquid gives off vapours in
267 quantity such as to be capable of forming an ignitable vapour-air mixture
268 3.9
269 gas
270 gaseous phase of a substance that cannot reach equilibrium with its liquid or solid state in the
271 temperature and pressure range of interest
272 Note 1 to entry: This is a simplification of the scientific definition, and merely requires that the substance is above
273 its boiling point or sublimation point at the ambient temperature and pressure.

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274 3.10
275 vapour
276 gaseous phase of a substance that can reach equilibrium with its liquid or solid state in the
277 temperature and pressure range of interest
278 Note 1 to entry: This is a simplification of the scientific definition, and merely requires that the substance is below
279 its boiling point or sublimation point at the ambient temperature and pressure.
280 4 Classification of gases and vapours
281 4.1 General
282 Group I addresses mines susceptible to firedamp.
283 Note Firedamp consists mainly of methane, but always contains small quantities of other gases, such as nitrogen,
284 carbon dioxide, and hydrogen, and sometimes ethane and carbon monoxide. The terms firedamp and methane are
285 used frequently in mining practice as synonyms.
286 Group II addresses flammable gases and vapours other than in mines susceptible to
287 firedamp. Group II gases and vapours are classified according to their MESG and/or MIC ratio
288 into subgroups.
289 All flammable materials are classified according to their AIT into temperature classes.
290 4.2 Classification according to the maximum experimental safe gaps (MESG)
291 Gases and vapours may be classified according to their MESG into Groups IIA, IIB or IIC,
292 based on the determination method described in this standard. This method does not take into
2
293 account the possible effects of obstacles on the safe gaps .
294 NOTE 1 The standard method for determining MESG is described in 6.2, but where determinations have been
295 undertaken only in an 8 l spherical vessel with ignition close to the flange gap these can be accepted provisionally.
296 For the purpose of classification the MESG limits are:
297 Group IIA: MESG ≥ 0,90 mm.
298 Group IIB: 0,50 mm < MESG < 0,90 mm.
299 Group IIC: MESG ≤ 0,50 mm.
300 Determination of both the MESG and MIC ratio is required when 0,50 < MESG < 0,55. Then
301 the Group is determined by MIC ratio,
302 NOTE 2 For gases and highly volatile liquids, the MESG is determined at 20 °C.
303 NOTE 3 If it was necessary to do the MESG determination at temperatures higher than ambient temperature a
304 temperature 5 K above that needed to give the necessary vapour pressure or 50 K above the flash point is used
305 and this value of MESG is given in the table
...