IEC TS 60079-40:2015

Explosive atmospheres - Part 40: Requirements for process sealing between flammable process fluids and electrical systems

IEC TS 60079-40:2015(E) provides specific requirements for process sealing between a flammable process fluid and an electrical system where a failure could allow the migration of the process fluid directly into the premises wiring system. This document contains requirements for evaluation, construction and testing of single process seal equipment, dual process seal equipment, and add-on secondary process seals. The requirements of this document do not apply to conduit sealing devices, cable glands and other wiring sealing methods addressed in the IEC 60079 series or other standards. Requirements for basic electrical safety and explosion protection are not addressed by this document, but may apply to the equipment under investigation. The effects of leakage to the environment are not addressed by this document. Keywords: process sealing between a flammable process fluid and an electrical system

General Information

• Status: Published
• Publication Date: 04-Feb-2015
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.260.20 - Electrical apparatus for explosive atmospheres
• Technical Committee: TC 31 - Equipment for explosive atmospheres
• Current Stage: PPUB - Publication issued
• Start Date: 05-Feb-2015
• Completion Date: 05-Feb-2015

Standards Content (sample)

IEC TS 60079-40
Edition 1.0 2015-02
TECHNICAL
SPECIFICATION
Explosive atmospheres –
Part 40: Requirements for process sealing between flammable process fluids
and electrical systems
IEC TS 60079-40:2015-02(en)
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IEC TS 60079-40
Edition 1.0 2015-02
TECHNICAL
SPECIFICATION
Explosive atmospheres –
Part 40: Requirements for process sealing between flammable process fluids
and electrical systems
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.260.20 ISBN 978-2-8322-2248-5

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 60079-40:2015 © IEC 2015
CONTENTS

FOREWORD ......................................................................................................................... 3

1 Scope ............................................................................................................................ 5

2 Normative references..................................................................................................... 5

3 Terms and definitions .................................................................................................... 5

4 General requirements .................................................................................................... 8

4.1 Basis for requirements .......................................................................................... 8

4.2 Single process seal equipment .............................................................................. 9

4.3 Dual process seal equipment ................................................................................. 9

4.4 Equipment with limited pressure at the electrical connections ................................. 9

4.5 Purged or pressurized equipment .......................................................................... 9

4.6 Add-on secondary process seals ........................................................................... 9

4.7 Annunciators ....................................................................................................... 10

5 Type verifications and tests ......................................................................................... 10

5.1 Test sample ........................................................................................................ 10

5.2 Single process seal equipment ............................................................................ 10

5.2.1 Order of conditioning .................................................................................... 10

5.2.2 Temperature cycling ..................................................................................... 10

5.2.3 Pressure cycling .......................................................................................... 11

5.2.4 Leakage test ................................................................................................ 12

5.2.5 Burst pressure test ....................................................................................... 12

5.3 Dual process seal equipment ............................................................................... 12

5.3.1 Primary process seal leakage test ................................................................ 12

5.3.2 Primary process seal burst pressure test ...................................................... 12

5.3.3 Venting pressure determination .................................................................... 12

5.3.4 Verification of annunciation effectiveness ..................................................... 13

5.3.5 Secondary process seal leakage test ............................................................ 13

5.4 Verification of limited pressure effectiveness ....................................................... 13

6 Marking ....................................................................................................................... 13

7 Instructions.................................................................................................................. 13

Annex A (informative) Conditioning and test flowchart ........................................................ 15

Bibliography ....................................................................................................................... 17

Figure 1 – Equipment process sealing components ................................................................ 6

Figure 2 – Examples of add-on secondary process seals ....................................................... 8

Figure 3 – Temperature cycle conditioning profile ................................................................ 11

Figure A.1 – Conditioning and test flowchart ........................................................................ 16

Table 1 – Leakage test pressures ........................................................................................ 12

Table 2 – Burst test pressures ............................................................................................ 12

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IEC TS 60079-40:2015 © IEC 2015 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLOSIVE ATMOSPHERES –
Part 40: Requirements for process sealing between
flammable process fluids and electrical systems
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

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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

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

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6) All users should ensure that they have the latest edition of this publication.

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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.

The main task of IEC technical committees is to prepare International Standards. In

exceptional circumstances, a technical committee may propose the publication of a technical

specification when

• the required support cannot be obtained for the publication of an International Standard,

despite repeated efforts, or

• the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

Technical specifications are subject to review within three years of publication to decide

whether they can be transformed into International Standards.

IEC 60079-40, which is a technical specification, has been prepared by IEC technical

committee 31: Equipment for explosive atmospheres.
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– 4 – IEC TS 60079-40:2015 © IEC 2015
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
31/1134/DTS 31/1170/RVC

Full information on the voting for the approval of this technical specification can be found in

the report on voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 60079 series, published under the general title Explosive

atmospheres, can be found on the IEC website.

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 standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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IEC TS 60079-40:2015 © IEC 2015 – 5 –
EXPLOSIVE ATMOSPHERES –
Part 40: Requirements for process sealing between
flammable process fluids and electrical systems
1 Scope

This document provides specific requirements for process sealing between a flammable

process fluid and an electrical system where a failure could allow the migration of the process

fluid directly into the premises wiring system.

NOTE Some definitions differentiate the terms “flammable” and “combustible” liquids on the basis of their

flashpoints. Combustible liquids under conditions of elevated pressure and/or temperature can lead to the

formation of flammable mists and aerosols which are within the scope of this technical specification.

This document contains requirements for evaluation, construction and testing of single

process seal equipment, dual process seal equipment, and add-on secondary process seals.

The requirements of this document do not apply to conduit sealing devices, cable glands and

other wiring sealing methods addressed in the IEC 60079 series or other standards.

Requirements for basic electrical safety and explosion protection are not addressed by this

document, but may apply to the equipment under investigation. The effects of leakage to the

environment are not addressed by this document.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements

IEC 60079-2, Explosive atmospheres – Part 2: Equipment protection by pressurized enclosure

"p"
3 Terms and definitions
For the purposes of this document the following terms and definitions apply.

NOTE See Figure 1 for a graphical representation of the various process seal components.

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– 6 – IEC TS 60079-40:2015 © IEC 2015
Premises
Wiring
System
Secondary
Process
Seals
Vent
(when provided)
Electrical Equipment
Electrical Equipment
Primary
Process
Seal
Process Fluid
IEC
Figure 1 – Equipment process sealing components
3.1
dual process seal equipment

equipment which incorporates, along any single potential leakage path, a primary process

seal and one or more secondary process seals such that the failure of two or more

independent process seals is required to allow migration of process fluids from their designed

containment into the premises wiring system
3.2
process connected equipment

electrical equipment that contains a process seal and is intended for connection to an external

system that contains the process fluid
3.3
process fluid

gas, liquid or vapour that is used in or is a by-product of an industrial process

Note 1 to entry: For the purposes of this technical specification, use of the term process fluid refers to a

flammable process fluid. For further information, refer to IEC 60079-0, IEC 60079-10-1, and IEC 60079-20-1.

3.4
process seal

seal between the electrical system and a flammable process fluid where a failure could allow

the migration of the process fluid into the premises wiring system

Note 1 to entry: Although an entire containment system may constitute a potential source of release under

unusual conditions, this technical specification recognizes the concept of infallible containment as defined in

IEC 60079-2.
3.5
single process seal equipment

equipment that incorporates, along any single potential leakage path, a single sealing

structure such that a failure of the seal would result in the migration of the process fluid from

the designed containment into the premises wiring system

Note 1 to entry: Single process seal equipment in compliance with this document is considered to have a

negligible probability of failure when used in accordance with the manufacturer's specification.

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IEC TS 60079-40:2015 © IEC 2015 – 7 –
3.6
primary process seal

process seal that is directly in contact with process fluids under conditions of normal

operation
3.7
secondary process seal

process seal that comes into contact with process fluids only in the case of a primary process

seal failure
3.8
process seal with moving parts

process seal containing mechanical parts that, under conditions of normal operation, are

capable of motion relative to other parts of the s
...