IEC 60079-31:2013

Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"

IEC 60079-31:2013 is applicable to electrical equipment protected by enclosure and surface temperature limitation for use in explosive dust atmospheres. It specifies requirements for design, construction and testing of electrical equipment and Ex Components. This standard supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of this standard takes precedence. This standard does not apply to dusts of explosives, which do not require atmospheric oxygen for combustion, or to pyrophoric substances. This standard does not apply to electrical 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 standard does not take account of any risk due to an emission of flammable or toxic gas from the dust. Consideration of additional protective measures is required where the application of electrical equipment is in atmospheres, which can contain combustible dust as well as explosive gas, whether simultaneously or separately. Where the electrical equipment has to meet other environmental conditions, for example, protection against ingress of water and resistance to corrosion, additional measures can be necessary. The measures used should not adversely affect the integrity of the enclosure. This second edition cancels and replaces the first edition published in 2008. This edition constitutes a technical revision. The major technical changes include:
- The marked maximum surface temperature shall be measured on the external surfaces of the enclosure and the surfaces of the internal components for equipment with types of protection "ta";
- Additional protection for arcing and sparking parts for "ta";
- Test for internal enclosure for level "ta" added. Keywords: explosive dust atmospheres
The contents of the Interpretation Sheet 1 of February 2022 have been included in this copy.
This publication is to be read in conjunction with IEC 60079-0:2011.

Atmosphères explosives - Partie 31: Protection du matériel contre l'inflammation de poussières par enveloppe "t" relative au matériel

L'IEC 60079-31:2013 est applicable au matériel électrique 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 le matériel électrique et les composants Ex. La présente norme complète et modifie les exigences générales de l'IEC 60079-0. Lorsqu'une exigence de la présente norme est en conflit avec une exigence de l'IEC 60079-0, l'exigence de la présente norme prévaut. La présente norme ne s'applique pas aux poussières d'explosifs qui ne nécessitent pas l'oxygène de l'air pour leur combustion, ni aux substances pyrotechniques. La présente norme ne s'applique ni au matériel électrique 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. La présente norme ne prend en compte aucun risque résultant d'une émission de gaz inflammable ou toxique provenant de la poussière. La considération des mesures de protection complémentaires est exigée en cas d'utilisation d'un matériel électrique dans des atmosphères, pouvant contenir de la poussière combustible ainsi que du gaz explosif, que ce soit simultanément ou séparément. Lorsque le matériel électrique doit satisfaire à d'autres conditions environnementales, par exemple, la protection contre la pénétration de l'eau ou la résistance à la corrosion, des mesures supplémentaires peuvent être nécessaires. Il convient que les mesures utilisées ne dégradent pas l'intégrité de l'enveloppe. Cette deuxième édition annule et remplace la première édition parue en 2008. Cette édition constitue une révision technique. Les modifications techniques majeures suivantes:
- La température maximale de surface marquée doit être mesurée sur les surfaces externes de l'enveloppe et les surfaces des composants internes pour les matériels avec des modes de protection "ta";
- Protection supplémentaire pour les parties produisant des arcs et des étincelles pour "ta";
- Protection supplémentaire pour les parties produisant des arcs et des étincelles pour "ta". Mots clés : atmosphère de poussière explosive
Cette publication doit être lue conjointement avec la CEI 60079-0:2011.

General Information

• Status: Published
• Publication Date: 26-Nov-2013
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.260.20 - Electrical apparatus for explosive atmospheres
• Technical Committee: TC 31 - Equipment for explosive atmospheres
• Drafting Committee: MT 60079-31 - TC 31/MT 60079-31
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 17-Jan-2022

Relations

• Revised: IEC 60079-31:2013/ISH1:2022 - Interpretation Sheet 1 - Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
• Effective Date: 05-Sep-2023
• Revises: IEC 60079-31:2008/COR1:2009 - Corrigendum 1 - Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
• Effective Date: 05-Sep-2023
• Revises: IEC 60079-31:2008/ISH1:2022 - Interpretation Sheet 1 - Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
• Effective Date: 05-Sep-2023
• Revised: IEC 60079-31:2022 - Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
• Effective Date: 05-Sep-2023
• Revises: IEC 60079-31:2008 - Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60079-31 ®
Edition 2.0 2013-11
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 au matériel
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IEC 60079-31 ®
Edition 2.0 2013-11
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 au matériel
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX N
ICS 29.260.20 ISBN 978-2-8322-1185-4

– 2 – 60079-31 © IEC:2013
CONTENTS
FOREWORD . 3
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General . 7
4.1 Levels of protection . 7
4.2 Equipment groups and ingress protection. 7
4.3 Requirements for electrical equipment with level of protection “ta” . 8
4.3.1 Fault current . 8
4.3.2 Maximum surface temperature . 8
4.3.3 Overpressure . 8
4.3.4 Dust exclusion . 8
4.3.5 Protective devices . 8
4.3.6 Protection for arcing and sparking parts . 9
4.4 Requirements for electrical equipment with Level of Protection “tb” and
“tc” . 9
4.4.1 Maximum surface temperature . 9
4.4.2 Over pressure . 9
4.4.3 Dust exclusion . 9
5 Construction . 9
5.1 Joints . 9
5.1.1 General . 9
5.1.2 Threaded joints . 10
5.1.3 Gaskets and seals . 10
5.1.4 Cemented joints . 10
5.1.5 Operating rods, spindles and shafts . 10
5.1.6 Windows . 10
5.2 Cable glands . 11
5.3 Entries . 11
5.3.1 Plain entries . 11
5.3.2 Threaded entries . 11
6 Verification and tests . 11
6.1 Type tests . 11
6.1.1 Type tests for dust exclusion by enclosures . 11
6.1.2 Thermal tests . 12
6.2 Routine tests . 12
7 Marking . 12
Bibliography . 14

Table 1 – Level of Protection, equipment group and ingress protection (IP) relationship . 7

60079-31 © IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLOSIVE ATMOSPHERES –
Part 31: Equipment dust ignition protection by enclosure "t"

FOREWORD
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International Standard IEC 60079-31 has been prepared by IEC technical committee 31:
Equipment for explosive atmospheres.
This second edition cancels and replaces the first edition published in 2008. This edition
constitutes a technical revision.

– 4 – 60079-31 © IEC:2013
The significance of changes between IEC 60079-31, Edition 2.0 (2012) and IEC 60079-31,
Edition 1.0 (2008) (including Corrigendum) is as listed below:
Type
Changes Clause Minor and Extension Major technical
changes
editorial
changes
Document has been restructured from the first edition Numerous X
The marked maximum surface temperature shall be 4.3.2  C1
measured on the external surfaces of the enclosure and
the surfaces of the internal components for equipment
with types of protection “ta”
Additional protection for arcing and sparking parts for “ta” 4.3.6  C2
Limiting the internal pressure test to enclosures where 4.4.2 X
the seal is not physically constrained from moving.
Requirements for tapered threaded joints without an 5.1.2 X
additional seal or gasket added.

Requirements for cable gland aligned for all levels and 5.2 X
Groups the only difference is now the required IP
protection
Requirements for plain entries added 5.3.1 X
5 threads for parallel threads only required when no 5.3
...