IEC 60079-31:2022
(Main)Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
IEC 60079-31:2022 is available as IEC 60079-31:2022 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60079-31:2022 is applicable to equipment protected by enclosure and surface temperature limitation for use in explosive dust atmospheres. It specifies requirements for design, construction and testing of Ex Equipment and Ex Components. This document supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this document conflicts with a requirement of IEC 60079-0, the requirement of this document takes precedence. This document does not apply to dusts of explosives, which do not require atmospheric oxygen for combustion, or to pyrophoric substances. This document does not apply to Ex Equipment or Ex Components intended for use in underground parts of mines as well as those parts of surface installations of such mines endangered by firedamp and/or combustible dust. This document does not take account of any risk due to an emission of flammable or toxic gas from the dust. This third edition cancels and replaces the second edition published in 2013. This edition constitutes a technical revision. Main significant changes from the previous edition are:
1) Document has been restructured from edition 2
2) Fault current rating of interrupting contacts in clauses 4.3.1 and 4.4.1, major change type C1
3) Cells and batteries in clauses 4.3.5.1 and 4.4.5.1, major change type C2
4) Overload or malfunction condition for the determination of temperature class for "tb" converter fed rotating electric machines, major change type C3
5) Additional requirements for entry devices with dust ignition protection by enclosure "t", major change type C4
Information about the background of ‘Major Technical Changes’
C1 – Ex Equipment having Level of Protection "ta" shall be rated for connection to a circuit with a prospective short circuit current of not greater than 1.5 kA. For Ex Equipment having Level of Protection "tb" or "tc" which is intended for mains connection and intended to interrupt fault current above 10kA, the equipment shall have a rated maximum short circuit withstand current, be tested according to 6.1.1.1, and be marked according to Clause 7.
C2 – For Ex Equipment having Level of Protection "ta" which contains a cell or battery, only a sealed cell or battery shall be used. For Ex Equipment having Level of Protection "tb" and "tc" where there are sparking contacts or hot surfaces, and which contains a cell or battery, only a sealed cell or battery shall be used.
C3 – Table 2 now includes malfunction conditions for temperature class determination of Level of Protection "tb" converter-fed electric machines.
C4 – Annex A added for entry devices with Type of Protection "t" including cable transit devices.
The contents of the corrigendum of October 2023 have been included in this copy.
Atmosphères explosives - Partie 31: Protection contre l’inflammation de poussières par enveloppe "t" relative à l’appareil
IEC 60079-31:2022 est disponible sous forme de IEC 60079-31:2022 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 60079-31:2022 est applicable à l’appareil protégé par enveloppe et limitation de la température de surface, pour une utilisation en atmosphère de poussière explosive. Elle spécifie les exigences de conception, de construction et d'essai pour l’Appareil Ex et les Composants Ex. Le présent document complète et modifie les exigences générales de l’IEC 60079-0. Lorsqu'une exigence du présent document est en contradiction avec une exigence de l’IEC 60079-0, l’exigence du présent document prévaut. Le présent document ne s’applique pas aux poussières d’explosifs dont la combustion n’exige pas l’oxygène de l’air, ni aux substances pyrotechniques. Le présent document ne s’applique ni à l’Appareil Ex ni aux Composants Ex destinés à une utilisation dans les parties souterraines des mines, ni aux parties des installations de surface des mines où il existe des risques de grisou et/ou de poussières combustibles. Le présent document ne prend en compte aucun risque résultant d’une émission de gaz inflammable ou toxique provenant de la poussière.
Le contenu du corrigendum d'octobre 2023 a été pris en considération dans cet exemplaire.
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IEC 60079-31 ®
Edition 3.0 2022-01
REDLINE VERSION
INTERNATIONAL
STANDARD
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inside
Explosive atmospheres –
Part 31: Equipment dust ignition protection by enclosure "t"
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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About the IEC
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International Standards for all electrical, electronic and related technologies.
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IEC 60079-31 ®
Edition 3.0 2022-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Explosive atmospheres –
Part 31: Equipment dust ignition protection by enclosure "t"
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.260.20 ISBN 978-2-8322-4590-3
– 2 – IEC 60079-31:2022 RLV © IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 General . 10
4.1 Levels of protection. 10
4.2 Equipment groups and ingress protection . 11
4.3 Requirements for electrical equipment Ex Equipment with Level
of Protection "ta" . 11
4.3.1 Fault current . 11
4.3.2 Maximum surface temperature . 11
4.3.3 Overpressure .
4.3.3 Dust exclusion . 12
4.3.4 Protective Devices . 12
4.3.5 Supplementary internal enclosure . 13
4.3.6 Protection for arcing and sparking parts.
4.3.6 Cells and batteries . 13
4.4 Requirements for electrical equipment Ex Equipment with Level of Protection
"tb" and "tc" . 14
4.4.1 Fault current . 14
4.4.2 Maximum surface temperature . 14
4.4.3 Dust exclusion . 14
4.4.4 Thermal protection . 14
4.4.5 Cells and batteries . 15
4.4.6 External plug and socket connections for field wiring connection . 15
5 Construction . 15
5.1 Joints . 15
5.1.1 General . 15
5.1.2 Threaded joints . 15
5.1.3 Gaskets and seals . 16
5.1.4 Cemented joints. 16
5.1.5 Operating rods, spindles and shafts . 16
5.1.6 Windows . 17
5.2 Cable glands, cable transit devices and conduit sealing devices . 17
5.3 Entries . 17
5.3.1 Plain entries . 17
5.3.2 Threaded entries . 17
6 Verification and tests . 18
6.1 Type tests . 18
6.1.1 Type tests for dust exclusion by enclosures . 18
6.1.2 Thermal tests.
6.1.2 Tests to determine maximum surface temperature . 19
6.2 Routine tests . 20
7 Marking . 20
Annex A (normative) Supplementary requirements for entry devices . 21
A.1 General . 21
A.2 Construction requirements . 21
A.2.1 Cable glands, cable transit devices and conduit sealing devices . 21
A.2.2 Blanking elements and thread adapters . 21
A.3 Type tests . 21
A.3.1 Cable glands, cable transit devices and conduit sealing devices . 21
A.3.2 Blanking elements and thread adapters . 21
A.4 Marking . 21
Bibliography . 22
Table 1 – Level of Protection, equipment group and ingress protection (IP) relationship . 11
Table 2 – Overload or malfunction conditions for Level of Protection "tb" . 20
– 4 – IEC 60079-31:2022 RLV © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLOSIVE ATMOSPHERES –
Part 31: Equipment dust ignition protection by enclosure "t"
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made to
the previous edition IEC 60603-7:2013. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.
International Standard IEC 60079-31 has been prepared by IEC technical committee 31:
Equipment for explosive atmospheres.
This third edition cancels and replaces the second edition published in 2013. This edition
constitutes a technical revision.
The significance of changes between IEC Standard, IEC 60079-31, Edition 3.0 and
IEC 60079-31, Edition 2.0, are as listed below:
Type
Minor and Major technical
Changes Clause Extension
editorial changes
changes
Document has been restructured from edition 2 Numerous X
Withstand of prospective short-circuit current 4.3.1 X
Fault current rating of interrupting contacts rated 4.4.1 and C1
greater than 10 kA for mains connected circuits 6.1.1.1
Thermal protective device can include a thermal 4.4.4.1 X
protective circuit with an appropriate sensor.
Cells and batteries 4.3.6 and C2
4.4.5
Joints employing parallel threads with an additional 5.1.2 X
seal or gasket are permitted to have less than five
threads.
Gasket joints that interlock (not a butt joint) and are
5.1.3 X
designed such that un
...
IEC 60079-31 ®
Edition 3.0 2022-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 31: Equipment dust ignition protection by enclosure "t"
Atmosphères explosives –
Partie 31: Protection contre l’inflammation de poussières par enveloppe "t"
relative à l’appareil
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
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les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.
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CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
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The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 19 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
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If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
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IEC 60079-31 ®
Edition 3.0 2022-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 31: Equipment dust ignition protection by enclosure "t"
Atmosphères explosives –
Partie 31: Protection contre l’inflammation de poussières par enveloppe "t"
relative à l’appareil
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.260.20 ISBN 978-2-8322-1062-5
– 2 – IEC 60079-31:2022 © IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 General . 9
4.1 Levels of protection. 9
4.2 Equipment groups and ingress protection . 9
4.3 Requirements for Ex Equipment with Level of Protection "ta" . 10
4.3.1 Fault current . 10
4.3.2 Maximum surface temperature . 10
4.3.3 Dust exclusion . 10
4.3.4 Protective Devices . 10
4.3.5 Supplementary internal enclosure . 11
4.3.6 Cells and batteries . 11
4.4 Requirements for Ex Equipment with Level of Protection "tb" and "tc" . 11
4.4.1 Fault current . 11
4.4.2 Maximum surface temperature . 12
4.4.3 Dust exclusion . 12
4.4.4 Thermal protection . 12
4.4.5 Cells and batteries . 12
4.4.6 External plug and socket connections for field wiring connection . 13
5 Construction . 13
5.1 Joints . 13
5.1.1 General . 13
5.1.2 Threaded joints . 13
5.1.3 Gaskets and seals . 13
5.1.4 Cemented joints. 14
5.1.5 Operating rods, spindles and shafts . 14
5.1.6 Windows . 14
5.2 Cable glands, cable transit devices and conduit sealing devices . 14
5.3 Entries . 14
5.3.1 Plain entries . 14
5.3.2 Threaded entries . 14
6 Verification and tests . 15
6.1 Type tests . 15
6.1.1 Type tests for dust exclusion by enclosures . 15
6.1.2 Tests to determine maximum surface temperature . 16
6.2 Routine tests . 17
7 Marking . 17
Annex A (normative) Supplementary requirements for entry devices . 18
A.1 General . 18
A.2 Construction requirements . 18
A.2.1 Cable glands, cable transit devices and conduit sealing devices . 18
A.2.2 Blanking elements and thread adapters . 18
A.3 Type tests . 18
A.3.1 Cable glands, cable transit devices and conduit sealing devices . 18
A.3.2 Blanking elements and thread adapters . 18
A.4 Marking . 18
Bibliography . 19
Table 1 – Level of Protection, equipment group and ingress protection (IP) relationship . 10
Table 2 – Overload or malfunction conditions for Level of Protection "tb" . 16
– 4 – IEC 60079-31:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLOSIVE ATMOSPHERES –
Part 31: Equipment dust ignition protection by enclosure "t"
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest ed
...
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