SIST-TP CLC/TR 60079-33:2015

SLOVENSKI STANDARD
SIST-TP CLC/TR 60079-33:2015
01-julij-2015
Eksplozivne atmosfere - 33. del: Zaščita opreme s posebno zaščito "s" (IEC 60079-
33:2012)
Explosive atmospheres - Part 33: Equipment protection by special protection 's '(IEC
60079-33:2012)
Explosionsgefährdete Bereiche - Teil 33: Geräteschutz durch Sonderschutz "s" (IEC
60079-33:2012)
Atmosphères explosives - Partie 33: Protection du matériel par protection spéciale "s"
(IEC 60079-33:2012)
Ta slovenski standard je istoveten z: CLC/TR 60079-33:2015
ICS:
29.260.20 Električni aparati za Electrical apparatus for
eksplozivna ozračja explosive atmospheres
SIST-TP CLC/TR 60079-33:2015 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CLC/TR 60079-33:2015

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SIST-TP CLC/TR 60079-33:2015


TECHNICAL REPORT CLC/TR 60079-33

RAPPORT TECHNIQUE

TECHNISCHER BERICHT
April 2015
ICS 29.260.20

English Version
Explosive atmospheres - Part 33: Equipment protection by
special protection 's'
(IEC 60079-33:2012)
Atmosphères explosives - Partie 33: Protection du matériel Explosionsgefährdete Bereiche - Teil 33: Geräteschutz
par protection spéciale "s" durch Sonderschutz "s"
(IEC 60079-33:2012) (IEC 60079-33:2012)


This Technical Report was approved by CENELEC on 2014-06-02.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.



European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. CLC/TR 60079-33:2015 E

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Foreword
This document (CLC/TR 60079-33:2015) consists of the text of IEC 60079-33:2012 prepared by
IEC/TC 31 "Equipment for explosive atmospheres ".

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.

Endorsement notice
The text of the International Standard IEC 60079-33:2012 was approved by CENELEC as a European
Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60079-26 NOTE Harmonized as EN 60079-26.
IEC 60079-1 NOTE Harmonized as EN 60079-1.
IEC 60079-11 NOTE Harmonized as EN 60079-11.
IEC 60079-29-3 NOTE Harmonized as EN 60079-29-3.
IEC 60079-15 NOTE Harmonized as EN 60079-15.
IEC 60079-2 NOTE Harmonized as EN 60079-2.
IEC 60079-18 NOTE Harmonized as EN 60079-18.
IEC 60079-7 NOTE Harmonized as EN 60079-7.
IEC 60228 NOTE Harmonized as EN 60228.
IEC 60079-10-1 NOTE Harmonized as EN 60079-10-1.
IEC 60079-10-2 NOTE Harmonized as EN 60079-10-2.
IEC 60079-14 NOTE Harmonized as EN 60079-14.
IEC 60079-1 NOTE Harmonized as EN 60079-1.
IEC 60300 (Series) NOTE Harmonized as EN 60300 (Series).
ISO/IEC 80079 (Series) NOTE Harmonized as EN ISO/IEC 80079 (Series).

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Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year

IEC 60079-0 -  Explosive atmospheres -- Part 0: EN 60079-0 -
Equipment - General requirements
- -  +A11 -
IEC 60079 series Explosive atmospheres EN 60079 series
IEC 60079-29-1 -  Explosive atmospheres -- Part 29-1: Gas EN 60079-29-1 -
detectors - Performance requirements of
detectors for flammable gases
IEC 60079-29-2 2007 Explosive atmospheres -- Part 29-2: Gas EN 60079-29-2 2007
detectors - Selection, installation, use and
maintenance of detectors for flammable
gases and oxygen
- -  +corrigendum Dec. 2007
IEC 61508-1 -  Functional safety of EN 61508-1 -
electrical/electronic/programmable
electronic safety-related systems -- Part 1:
General requirements
IEC 61508 series Functional safety of EN 61508 series
electrical/electronic/programmable
electronic safety-related systems
IEC 61511 series Functional safety - Safety instrumented EN 61511 series
systems for the process industry sector
IEC 62061 -  Safety of machinery - Functional safety of EN 62061 -
safety-related electrical, electronic and
programmable electronic control systems
- -  +corrigendum Feb. -
ISO 13849-1 2006 Safety of machinery - Safety-related parts EN ISO 13849-1 2008
of control systems -- Part 1: General
principles for design
ISO 13849-2 -  Safety of machinery_- Safety-related parts EN ISO 13849-2 -
of control systems_- Part_2: Validation

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SIST-TP CLC/TR 60079-33:2015



IEC 60079-33

®


Edition 1.0 2012-09




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Explosive atmospheres –

Part 33: Equipment protection by special protection “s”




Atmosphères explosives –

Partie 33: Protection du matériel par protection spéciale "s"
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX W


ICS 29.260.20 ISBN 978-2-83220-359-0



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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 General . 11
4.1 Application . 11
4.2 Equipment group and temperature classification . 11
4.3 Level of protection (equipment protection level (EPL)) . 11
4.4 Manufacturer’s justification . 12
4.5 Verification . 12
5 Independent verifier . 12
5.1 General . 12
5.2 Competence . 12
5.3 Duties. 13
5.4 Acceptance . 13
5.5 Independence. 13
6 Design and construction . 13
6.1 Principles of an integrated approach to explosion safety . 13
6.2 Design and construction . 14
6.3 Overloading of equipment . 14
6.4 Potential ignition sources . 14
6.4.1 Hazards arising from different ignition sources . 14
6.4.2 Hazards arising from overheating . 14
6.4.3 Hazards arising from pressure compensation operations . 14
6.5 Requirements in respect of safety-related devices . 14
7 Application of equipment protection levels (EPL) . 15
7.1 Equipment with EPL Ma . 15
7.2 Equipment with EPL Mb . 15
7.3 Equipment with EPL Ga . 16
7.4 Equipment with EPL Gb . 17
7.5 Equipment with EPL Gc . 17
7.6 Equipment with EPL Da . 17
7.7 Equipment with EPL Db . 18
7.8 Equipment with EPL Dc . 18
8 Preparation of assessment and test specification . 18
8.1 General . 18
8.2 Assessment and test specification . 19
8.3 Assessment and testing. 19
8.4 Reporting results of the assessment and test specification . 19
9 Ignition hazard assessment . 19
9.1 General . 19
9.2 Protective measures . 19
9.3 Explanation of the ignition hazard assessment procedure . 20
9.4 Examples of ignition hazard assessment . 20
10 Application of special protection “s” . 20

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10.1 General . 20
10.2 Justification for the application of special protection “s” . 20
10.2.1 Application . 20
10.2.2 Equipment substantially meeting the requirements for the recognized
types of protection . 21
10.2.3 Equipment outside the scope of recognized types of protection . 21
10.2.4 Protection technique with no alignment to the recognized types of
protection . 21
10.2.5 Enhanced EPL through additional means of protection . 22
10.2.6 Combination of approaches . 22
10.3 Adaption of recognized types of protection . 22
10.4 Other innovative means of ensuring safety . 22
10.5 Connection of conductor and cables . 22
11 Type verification and tests . 23
11.1 General . 23
11.2 Temperature measurement test . 23
12 Routine verification and test . 23
13 Documentation . 23
14 Ex components . 23
15 Marking . 23
15.1 General . 23
15.2 Marking for Ex “s” only . 23
15.3 Marking for Ex “s” with other recognized types of protection . 23
16 Certificate information . 24
16.1 Certificate for Ex “s” only . 24
16.2 Certificate for Ex “s” with other recognized types of protection . 24
16.3 Specific conditions of use . 24
16.4 Schedule of limitations . 24
17 Instructions . 24
Annex A (informative) Explanation of the ignition hazard assessment procedure. 25
Annex B (informative) Examples of ignition hazard assessment . 31
Bibliography . 37

Figure A.1 – Relationship between ignitions source definitions . 26

Table A.1 – Recommended documentation of initial assessment of equipment related
ignition sources. 27
Table A.2 – Example for reporting identification of ignition hazards (step 1) and first
assessment (step 2). 28
Table A.3 – Example for reporting determination of preventive or protective measures
(step 3) and concluding estimation and EPL assignment (step 4) . 29
Table B.1 – Common cases demonstrating the use of the reporting method –
Electrostatic discharge . 33
Table B.2 – Ignition hazard assessment report for a linear motor with permanent
magnets in the table-track, EPL Gb, in addition to the basic requirements of
IEC 60079-0 (for example material characteristics, electrostatic, earthing). 35

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

EXPLOSIVE ATMOSPHERES –

Part 33: Equipment protection by special protection “s”

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
Publications.
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.
International Standard IEC 60079-33 has been prepared by IEC technical committee 31:
Equipment for explosive atmospheres.
The text of this standard is based on the following documents:
FDIS Report on voting
31/997/FDIS 31/1011/RVD

Full information on the voting for the approval of this standard 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.

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The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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INTRODUCTION
This part of IEC 60079 was created in response to a request from the IECEx certification
system to provide a set of requirements to be used for certification within the IECEx product
certification scheme when the standards for existing types of protection were not applicable.
The present standard refers to the use of one or more independent verifiers, in accordance
with ISO/IEC rules on the writing of standards that mitigate against specifying particular forms
of conformity assessment. The IECEx system will specify how the term "independent verifier"
will be interpreted for the purposes of the scheme. For example, it may specify that in the
case of three independent verifiers they shall all be certification body members of the
scheme, each accepted specifically for the purpose of assessing special protection
applications and each from a separate member country of the system.
The purpose of IEC 60079-33 special protection “s” for any equipment protection level (EPL)
is to allow design, assessment and testing of equipment or parts of equipment that cannot be
fully assessed within a recognized type of protection or combination of recognized types of
protection because of functional or operational limitations and where the desired equipment
protection level can be achieved by the use of this standard.
Special protection “s” allows a design concept that cannot comply in full with recognized types
of protection, or where the design concept is not covered by recognized types of protection.
When specification for the equipment includes aspects as given above, additional information
and data may be required from
• technical research,
• evaluation of existing data and information.
Manufacturers should first consider the possibilities for design to the recognized types of
protection, or to combinations of recognized type of protection, before proceeding to special
protection “s”.
This standard is intended to provide a framework to demonstrate how essential safety
requirements can be met if not covered by established standards, thus allowing for innovation
and dealing with unknowns.
When equipment intended to meet a recognized type of protection does not comply with all
the provisions of the relevant standard, it is not to be considered under this standard unless:
• it can be clearly demonstrated that complete compliance with the type of protection is not
practicable; and
• additional measures have been applied to establish an equivalent protection level.
Special protection “s” is based on identification of failure modes and ignition hazard
assessment in the identified modes. In this regard, the assessed safety of the assigned EPL
of the equipment will satisfy the EPL requirements and, where appropriate, be at least
equivalent to the EPL provided by the defined levels for the recognized types of protection.
1
provides for requirements for equipment with EPL Ga and Ga/Gb but
IEC 60079-26 [1]
depends on combining types of protection already described in other parts of the IEC 60079
series.
The responsibility of initially demonstrating the need to design for special protection “s” and
establishing the criteria for verification lies with the manufacturer. The specification defines
—————————
1
 Figures in square brackets refer to the Bibliography.

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the safety concepts and shows how the essential safety requirements are to be achieved. It is
likely this will be done in consultation with experts in the assessment of explosion protection
techniques.
The requirements in this standard take into account:
• allowance for first, second or third party verification;
• the use of EPLs;
• the use of equipment groups for mining, gas and dust;
• alignment with existing temperature requirements;
• compatibility with the marking requirements given in IEC 60079-0.
Where requirements for a product/design concept are developed and intended for repeated
use in subsequent designs, they should be reviewed and, provided the manufacturer is
prepared to release the intellectual property, be included initially in an annex of this standard
with the intention of being removed and relocated to an appropriate place at a later time, e.g.
in an existing or new type of protection standard.
Unlike other recognized types of protection, special protection “s” may require the application
of reliability engineering tools and procedures such as failure modes and effects analysis
(FMEA), fault tree analysis (FTA) and failure modes, effects and criticality analysis (FMECA)
to identify the failure modes of the equipment being tested. This type of analysis will ensure
that the failure modes and corresponding mitigation designs are addressed by the most
appropriate testing strategies, which simulate the environment in which the equipment will be
operated, with appropriate factors of safety applied.
The probability of failure of the identified failure modes may need to be demonstrated to be of
a similar likelihood as the failures expected in recognized types of protection.
Full life cycle conditions may need to be considered and any restrictions may form part of the
mandatory directions for use of the equipment to ensure EPLs are maintained during the
operational life of the equipment.
By its very nature, assessment and testing to special protection “s” cannot be as prescriptive
as for the recognized types of protection. It is anticipated that considerable dialogue is
required between the manufacturer and an independent verifier. Additional assessment and
testing may be identified by the independent verifier to ensure the relevant EPL is achieved.
When undertaking verification, it is strongly recommended the guidance provided in this
standard is followed including:
• applying different levels of verification to match the EPL (similar in concept to the
approach given in the IEC 61508 series);
• always involving at least one independent person/organization (an independent verifier);
• not using personnel who have had any involvement in research or determining the criteria
for establishing the essential safety requirements in conjunction with the manufacturer.
Where it is intended to apply the requirements of this standard within a certification
system/scheme, the following recommendations are made:
• the requirements laid down in EN 50495 [2] for safety devices are observed;
• an assessment should be performed by independent certification bodies (as the
independent verifier) according to the requirements in this standard before issuing a
certificate of conformity;
• a certification body performing an assessment for equipment not covered by recognized
types of protection should have demonstrated expertise in the field under question.

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The need for a standard to address special protection “s” can be justified on the basis that:
• provision has been in IEC 60079-0 for many years with reference Ex “s” in a note in the
marking requirements or elsewhere. This reference goes back to IEC standards that pre-
date 1957;
• there have been standards used on a national basis for many years for certification to
special protection “s”. Examples are SFA 3009 in the UK and AS/NZS 1826 in Australia
and New Zealand;
• it is necessary to have an
...