EN 60079-13:2010

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Explosionsfähige Atmosphäre - Teil 13: Geräteschutz durch überdruckgekapselte Räume (IEC 60079-13:2010)Atmosphères explosives - Partie 13: Protection du matériel par salle à surpression interne
p (CEI 60079-13:2010)Explosive atmospheres - Part 13: Equipment protected by pressurized rooms
p (IEC 60079-13:2010)29.260.20Electrical apparatus for explosive atmospheresICS:Ta slovenski standard je istoveten z:EN 60079-13:2010SIST EN 60079-13:2011en,fr,de01-januar-2011SIST EN 60079-13:2011SLOVENSKI
STANDARD
EUROPEAN STANDARD EN 60079-13 NORME EUROPÉENNE
EUROPÄISCHE NORM December 2010
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2010 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60079-13:2010 E
ICS 29.260.20
English version
Explosive atmospheres -
Part 13: Equipment protection by pressurized room "p" (IEC 60079-13:2010)
Atmosphères explosives -
Partie 13: Protection du matériel par salle à surpression interne "p" (CEI 60079-13:2010)
Explosionsfähige Atmosphäre -
Teil 13: Geräteschutz durch überdruckgekapselte Räume (IEC 60079-13:2010)
This European Standard was approved by CENELEC on 2010-12-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
at national level by publication of an identical
national standard or by endorsement
(dop)
2011-09-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2013-12-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 60079-13:2010 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 60079-17 NOTE
Harmonized as EN 60079-17. IEC 60079-20-1 NOTE
Harmonized as EN 60079-20-1. IEC 60079-29 series NOTE
Harmonized in EN 60079-29 series (partially modified). IEC 60529 NOTE
Harmonized as EN 60529. IEC 61285 NOTE
Harmonized as EN 61285. IEC 61511 series NOTE
Harmonized in EN 61511 series (not modified). __________ SIST EN 60079-13:2011

- 3 - EN 60079-13:2010 Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-426 - International Electrotechnical Vocabulary - Part 426: Equipment for explosive atmospheres - -
IEC 60079-0 - Explosive atmospheres -
Part 0: Equipment - General requirements EN 60079-0 -
IEC 60079-2 - Explosive atmospheres -
Part 2: Equipment protection by pressurized enclosure "p"
EN 60079-2 -
IEC 60079-10-1 - Explosive atmospheres -
Part 10-1: Classification of areas - Explosive gas atmospheres EN 60079-10-1 -
IEC 60695-11-10 - Fire hazard testing -
Part 11-10: Test flames - 50 W horizontal and vertical flame test methods EN 60695-11-10 -
IEC 60079-13Edition 1.0 2010-10INTERNATIONAL STANDARD NORME INTERNATIONALEExplosive atmospheres –
Part 13: Equipment protection by pressurized room “p”
Atmosphères explosives –
Partie 13: Protection du matériel par salle à surpression interne « p »
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE WICS 29.260.20 PRICE CODECODE PRIXISBN 978-2-88912-164-9
– 2 – 60079-13 © IEC:2010 CONTENTS FOREWORD.5 1 Scope.7 2 Normative references.10 3 Terms and definitions.10 4 Requirements for rooms.13 4.1 General.13 4.2 Construction.13 4.3 Mechanical strength.14 4.4 Openings, penetrations and seals.14 4.5 Doors.14 4.6 Inlets and outlets.14 4.7 Ducts.14 5 Clean air supply.14 5.1 Source of clean air.14 5.2 Environmental and air temperature conditions.15 5.3 Heating, ventilation and air conditioning services.15 5.4 Minimum flow rate.15 6 Purging and cleaning.15 6.1 General.15 6.2 Gases – Purging.15 6.2.1 General.15 6.2.2 Purge volume.15 6.2.3 Purging flow rate.15 6.2.4 Sequence of operations of the purging safety devices for type of protection px.16 6.2.5 Enclosures within the room.16 6.3 Dusts – Cleaning.16 7 Temperature limits.16 8 Minimum safety provisions, safety devices and electrical disconnects.16 8.1 Safety devices.16 8.2 Safety devices based upon type of protection.17 8.3 Gas detectors.18 8.4 Failure of the pressurization system.18 9 Pressurized room in a hazardous area and with no internal source of flammable substance.18 9.1 General.18 9.2 Protective gas.18 9.2.1 Type of protection px.18 9.2.2 Type of protection py.18 9.2.3 Type of protection pz.19 9.3 Pressurization system.19 9.3.1 Room pressure differential.19 9.3.2 Power for pressurization system.19 9.4 Preventing the explosive atmosphere from entering an open door.19 9.5 Airlock.19 9.6 Outward air velocity through a door.20 SIST EN 60079-13:2011

60079-13 © IEC:2010 – 3 – 9.7 Air consuming device.20 9.8 Action when pressurization system fails.20 9.8.1 Type of protection px.20 9.8.2 Types of protection py and pz.20 9.9 Re-energizing the room.21 10 Pressurized room in a hazardous area and containing an internal source of flammable substance.21 10.1 Evaluation of internal sources of a flammable substance.21 10.1.1 Flammable substance assessment.21 10.1.2 Assessment of release.21 10.1.3 Release – Additional requirements.21 10.1.4 Adequate dilution.21 10.2 Applicability of Clause 9.21 10.3 Containment system.21 10.4 Sample lines.21 10.5 Types of anticipated releases.22 10.5.1 General.22 10.5.2 No release.22 10.5.3 Negligible release.22 10.5.4 Limited release.22 10.5.5 Unlimited release.22 10.6 Safety measures.23 10.7 Minimum flow rate for dilution.23 10.8 Warning to prevent entry into a room.25 10.9 Air distribution.25 10.10 Protective gas.25 10.11 Additional pressurization system requirements when inert gas is used.25 11 Pressurized room in a non-hazardous area with internal source of flammable substance (type of protection pv).25 11.1 Applicability of Clause 9.26 11.2 Applicability of Clause 10.26 11.3 Loss of flow of the protective gas.26 11.4 Safety devices.26 12 Verification.26 12.1 General.26 12.2 Sequence of tests.26 12.3 Mechanical strength test.26 12.4 Overpressure test.27 12.5 Purging test.27 12.6 Minimum pressure differential test for types of protection px, py and pz.27 12.7 Minimum flow rate test.27 12.8 Overpressure test for containment systems with limited release.27 12.9 Confirmation of the ratings of the safety devices.27 12.10 Verification sequence of operation of the safety devices.27 13 Marking.28 14 Technical documentation.28 Annex A (normative)
Containment system.30 Annex B (informative)
Maintenance.33 SIST EN 60079-13:2011

– 4 – 60079-13 © IEC:2010 Annex C (informative)
Guidelines when pressurization not immediately restored.34 Annex D (normative)
Classification of the type of release within rooms.35 Bibliography.37
Table 1 – Exclusion of specific clauses of IEC 60079-0.8 Table 2 – Safety devices based on type of protection.17 Table 3 – Safety devices, loss of pressurization or use of inert protective gas.24 Table 4 – Protective gas requirements for a pressurized room
with an internal flammable substance.25
60079-13 © IEC:2010 – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________ EXPLOSIVE ATMOSPHERES –
Part 13: Equipment protection by pressurized room “p”
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, 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 60079-13 has been prepared by IEC technical committee 31: Equipment for explosive atmospheres. This first edition of this part of IEC 60079 cancels and replaces the original technical report issued in 1982. It constitutes a technical revision and now has the status of an International Standard. The significant technical changes with respect to the previous edition are listed below: – Addition of types of protection px, py, pz and pv based upon whether external area is classified as Zone 1, Zone 2 or non-hazardous and whether internal electrical equipment is ignition capable or not. – Addition of requirements related to Group III dusts. – Addition of equipment protection levels (EPL). – Expansion of requirements for various types of doors to prevent the entrance of a flammable atmosphere. – Allowance for air intake located in a Zone 2 under specific conditions. SIST EN 60079-13:2011

– 6 – 60079-13 © IEC:2010 – Addition of negligible release conditions and negligible release containment system, as well as conditions and containment for limited release and unlimited release. This part of IEC 60079 is to be read in conjunction with IEC 60079-0. The text of this part of IEC 60079 is based on the following documents: FDIS Report on voting 31/878/FDIS 31/891/RVD
Full information on the voting for the approval of this part of IEC 60079 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. The list of all parts of IEC 60079 series, 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 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.
60079-13 © IEC:2010 – 7 – EXPLOSIVE ATMOSPHERES –
Part 13: Equipment protection by pressurized room “p”
1 Scope This part of IEC 60079 gives requirements for the design, construction, assessment and testing and marking of rooms protected by pressurization in: • a room located in an explosive gas atmosphere or explosive dust atmosphere hazardous area that does not include an internal source of a flammable substance; • a room located in an explosive gas atmosphere or explosive dust atmosphere hazardous area that includes an internal source of a flammable substance; • a room located in a non-hazardous area that includes an internal source of a flammable substance. NOTE If ventilation is used and pressurization is not used, then this part of IEC 60079 does not apply.
The situation is covered by the requirements of IEC 60079-10-1. A room may be a single room, multiple rooms, a complete building or a room contained within a building and includes inlet and outlet ducts. This part of IEC 60079 also includes requirements for associated equipment, safety devices and controls necessary to ensure that pressurization is established and maintained. This part of IEC 60079 covers rooms or buildings that are constructed or assembled on site, which may be either on land or off-shore, designed to facilitate the entry of personnel and primarily intended for installation by an end-user and verification on site.
The room may be located in an explosive gas atmosphere or a explosive dust atmosphere requiring equipment protection levels (EPL) Gb, Db, Gc or Dc. This part of IEC 60079 does not specify the methods that may be required to ensure adequate air quality for personnel with regard to toxicity and temperature within the room. NOTE 1 Whilst the scope of this part of IEC 60079 does not address toxicity it is vital that proper consideration is given to this aspect to ensure the safety of personnel.
National regulations and requirements should be observed in this regard.
NOTE 2 There is a related standard IEC60079-2 (Equipment protection by pressurized enclosure) covering the different conditions encountered when using the pressurization technique. NOTE 3 Maintenance needs are contained in Annex B until they are included IEC 60079-17. NOTE 4 For the purposes of this part of IEC 60079, the terms "lower flammable limit (LFL)" and "lower explosive limit (LEL)" are deemed to be synonymous, and likewise the terms "upper flammable limit (UFL)" and "upper explosive limit (UEL)" are deemed to be synonymous. For ease of reference, the two abbreviations LFL and UFL may be used hereinafter to denote these two sets of terms. It should be recognized that particular authorities having jurisdiction may have overriding requirements that dictate the use of one of these sets of terms and not the other. This part of IEC 60079 supplements and modifies the general requirements of IEC 60079-0, except as indicated in Table 1.
Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of this standard takes precedence. SIST EN 60079-13:2011

– 8 – 60079-13 © IEC:2010 Table 1 – Exclusion of specific clauses of IEC 60079-0 Clause of IEC 60079-0 Ed. 4.0 (2004) (Informative)Ed. 5.0 (2007) (Informative) Clause / subclause title (Normative)
4 4 Equipment grouping Applies 4.1 4.1 Group I Applies 4.2 4.2 Group II Applies 4.3 4.3 Group III Applies 4.4 4.4 Equipment for a particular explosive atmosphere Applies 5.1 5.1 Environmental influences Applies 5.1.1 5.1.1 Ambient temperature Applies 5.1.2 5.1.2 External source of heating or cooling Applies 5.2 5.2 Service temperature Applies 5.3.1 5.3.1 Determination of maximum surface temperature Applies 5.3.2.1 5.3.2.1 Group I electrical equipment Applies 5.3.2.2 5.3.2.2 Group II electrical equipment Applies 5.3.2.3 5.3.2.3 Group III electrical equipment Applies 5.3.3 5.3.3 Small component temperature for Group I and Group II electrical equipment Applies 6.1 6.1 General Applies 6.2 6.2 Mechanical strength
Excluded 6.3 6.3 Opening times
Excluded 6.4 6.4 Circulating currents Excluded 6.5 6.5 Gasket retention Excluded 6.6 6.6 Electromagnetic and ultrasonic radiating equipment Excluded 7 7 Non-metallic enclosures and parts of enclosure Excluded 8 8 Metallic enclosures and metallic parts of enclosures Excluded 9 9 Fasteners Excluded 10 10 Interlocking devices Excluded 11 11 Bushings Excluded 12 12 Materials used for cementing Excluded 13 13 Ex components Excluded 14 14 Connection facilities and termination compartments Excluded 15 15 Connection facilities for earthing and bonding conductors Excluded 16 16 Entries into enclosures Excluded 17 17 Supplementary requirements for rotating electrical machines Excluded 18 18 Supplementary requirements for switchgear Excluded 19 19 Supplementary requirements for fuses Excluded SIST EN 60079-13:2011

60079-13 © IEC:2010 – 9 – Clause of IEC 60079-0 Ed. 4.0 (2004) (Informative)Ed. 5.0 (2007) (Informative) Clause / subclause title (Normative)
20 20 Supplementary requirements for plugs and sockets Excluded 21 21 Supplementary requirements for luminaires Excluded 22 22 Supplementary requirements for caplights and handlights Excluded 23 23 Equipment incorporating cells and batteries Excluded 24 24 Documentation Applies 25 25 Compliance of prototype or sample with documents Excluded 26 26 Type tests Excluded 27 27 Routine tests Applies 28 28 Manufacturers responsibility Applies 29.1 29.1 Location Applies 29.2 29.2 General Applies NR 29.3 Ex marking for explosive gas atmospheres Applies NR 29.4 Ex marking for explosive dust atmospheres Applies 29.3 29.5 Combined types of protection Applies NR 29.6 Multiple types of protection Applies NR 29.7 Ga using two independent Gb types of protection Excluded 29.5 29.8 Ex components Excluded 29.6 29.9 Small equipment and small Ex components Excluded 29.7 29.10 Extremely small equipment and extremely small Ex components Excluded 29.8 29.11 Warning markings Applies NR 29.12 Alternate marking of equipment protection levels (EPLs) Applies 29.9 29.13 Cells and batteries Excluded 29.10 29.14 Examples of marking Applies 30 30 Instructions Applies Annex A Annex A Supplementary requirements for Ex cable glands Excluded Annex B Annex B Requirements for Ex components Excluded Annex C Annex C Example of rig for resistance to impact test Applies NR Annex D Introduction to an alternative risk assessment method encompassing “equipment protection levels” for Ex equipment Applies Applies – This requirement of IEC 60079-0 is applied without change. Excluded – This requirement of IEC 60079-0 does not apply. SIST EN 60079-13:2011

– 10 – 60079-13 © IEC:2010 Clause of IEC 60079-0 Ed. 4.0 (2004) (Informative)Ed. 5.0 (2007) (Informative) Clause / subclause title (Normative)
NOTE The applicable requirements of IEC 60079-0 are identified by the clause title which is normative. This table was written against the specific requirements of IEC 60079-0, Ed 6.0. The clause numbers for the 6th and previous edition are shown for information only. This is to enable the General Requirements IEC 60079-0, Ed 5.0, to be used where necessary with this part of IEC 60079.
Where there were no requirements for the 5th edition but there are for the 6th edition (indicated by NR against the 5th edition only), or where is a conflict between requirements, the 6th edition requirements should be considered.
2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050(426), International Electrotechnical Vocabulary – Part 426: Equipment for explosive atmospheres IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements
IEC 60079-2, Explosive atmospheres – Part 2: Equipment protection by pressurized enclosure “p” IEC 60079-10-1, Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres IEC 60695-11-10, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and vertical flame test methods 3 Terms and definitions For the purposes of this document, the terms and definitions given in IEC 60050(426) and IEC 60079-0 as well as the following terms and definitions apply NOTE Unless otherwise specified, the terms “voltage” and “current” mean the r.m.s. values of an alternating, direct or composite voltage or current. 3.1
airlock means of egress, consisting of two interdependent doors designed to maintain the internal pressure of the room in order to prevent the entry of a surrounding explosive atmosphere 3.2
alarm piece of apparatus that generates a visual or audible signal that is intended to attract attention 3.3
clean air air that is essentially free of contaminants or foreign matter and contains no more than trace amounts of flammable vapour or gas SIST EN 60079-13:2011

60079-13 © IEC:2010 – 11 – 3.4
containment system parts within the room or building containing the flammable substance that may constitute an internal source of release NOTE The containment system may extend beyond the room or building. 3.5
dilution continuous supply of a clean air, after purging, at such a rate that the concentration of a flammable mixture inside the room is maintained at a value below the explosive limits except in a dilution area NOTE For safety reasons, dilution to a level lower than the LEL may be required if associated with the potential release there is an additional toxic or asphyxiant risk. Further guidance can be found in IEC 61285. 3.6
dilution area area in the vicinity of a source of release where it cannot be demonstrated that the concentration of flammable gas or vapour is diluted to a safe concentration 3.7
flammable substance
gases, vapours, liquids or mixtures thereof that are capable of being ignited 3.8
ignition-capable equipment ICE
equipment which in normal operation constitutes a source of ignition for a specified explosive gas atmosphere
3.9
internal source of flammable substance point or location from which a flammable substance may be released into the room or building such that an explosive gas atmosphere could be formed 3.10
limited release release of flammable gas or vapour, the maximum flow rate of which can be predicted 3.11
limiting value lowest concentration value of the lower flammable limit (LFL) of each component involved, taking account of the most onerous conditions of concentration that may occur from every source of release within the room 3.12
lower flammable limit LFL
volume fraction of flammable gas or vapour in air below which an explosive gas atmosphere will not form, expressed as a percentage (see IEC 60079-20-1) NOTE This is also known as Lower Explosive Limit (LEL). 3.13
upper flammable limit UFL
volume fraction of flammable gas or vapour in air above which an explosive gas atmosphere will not form, expressed as a percentage (see IEC 60079-20-1) SIST EN 60079-13:2011

– 12 – 60079-13 © IEC:2010 NOTE This is also known as Upper Explosive Limit (UEL). 3.14
opening inlet, outlet, door or non-airtight fixed panel 3.15
pressurization technique of guarding against the ingress of the external atmosphere into a room by maintaining a protective gas therein at a pressure above that of the external atmosphere and guarding against the affects of an internal release within the room by dilution or inerting, or only guarding against the affects of an internal release within the room by dilution or inerting NOTE Pressurization as used in this part of IEC 60079 applies to a room. 3.16
pressurization system grouping of components used to pressurize and monitor a pressurized room 3.17
pressurized room enclosed volume protected by pressurization and of sufficient size to permit the entry of a person who may be expected to work or remain inside NOTE The term “room” is employed without distinction to designate rooms, groups of rooms or buildings. 3.18
protective gas clean air or inert gas used for purging and maintaining an overpressure and, if required, dilution 3.19
purging
operation of passing a quantity of clean air through the room and ducts, so that the concentration of the explosive gas atmosphere is brought to a safe level 3.20
room volume volume of the empty room NOTE The term “room” is employed without distinction to designate rooms, groups of rooms or buildings. 3.21
type of protection pv pressurization that reduces and maintains by adequate dilution the equipment protection level (EPL) within the pressurized room to none, where leakage from an abnormal internal source of release might occur infrequently and for a short period 3.22
type of protection px pressurization that allows for the required Gb or Db equipment protection level (EPL) within the pressurized room to be reduced to none by maintaining an internal overpressure and diluting when there is an internal source of release 3.23
type of protection py pressurization that allows for the required Gb equipment protection level (EPL) within the pressurized room to be reduced to Gc by maintaining an internal overpressure and diluting when there is an internal source of release SIST EN 60079-13:2011

60079-13 © IEC:2010 – 13 – 3.24
type of protection pz pressurization that allows for the required Gc or Dc equipment protection level (EPL) within the pressurized room to be reduced to none by maintaining an internal overpressure and diluting when there is an internal source of release 3.25
volume fraction ratio of the volume of a component to the volume of the gas mixture under specified conditions of temperature and pressure 4 Requirements for rooms 4.1 General
This international standard addresses pressurized rooms, with the term “room” applying equally to a single room, multiple rooms or to a building, which allows for full bodily personnel access. Types of protection px, py, pz, and pv are included. Type of protection px allows for the required Gb or Db equipment protection level (EPL) within the pressurized room to be reduced to permit the use of non-explosion protected equipment by maintaining an internal overpressure and diluting when there is an internal source of release. NOTE 1 This permits unprotected equipment to be installed within the pressurized room except for pressurization defined safety devices (see 8.1). NOTE 2 Because type of protection px reduces the EPL to none (a nondefined EPL) there are more onerous requirements concerning its application with respect to interlocks, alarms, etc. Type of protection py allows for the required Gb equipment protection level (EPL) within the pressurized room to be reduced to Gc by maintaining an internal overpressure and diluting when there is an internal source of release, NOTE 3 For pressurization defined safety devices (see 8.1).
Type of protection pz allows for the required Gc or Dc equipment protection level (EPL) within the pressurized room to be reduced to permit the use of non-explosion protected equipment by maintaining an internal overpressure and diluting when there is an internal source of release. NOTE 4 This permits unprotected equipment to be installed within the pressurized room except for pressurization defined safety devices (see 8.1). Type of protection pv is in essence protection by dilution, and allows for the required Gb or Gc equipment protection level (EPL) within the pressurized room to be reduced to, permit the use of non-explosion protected equipment where there is only an internal source of release and the pressurized room is located in an non-hazardous area. 4.2 Construction The pressurized room shall, at a minimum, be designed to allow pressurization to be used in accordance with Clause
9 or Clause
10 or
Clause
11.
NOTE The pressurized room construction requirements may be affected by the location, occupancy requirements, and functionality. Dead air spaces created within the room, that may allow a gas or vapour accumulation, for example by suspended ceilings, trenches, raised floors, shall be avoided unless otherwise monitored or protected to assure that an explosive atmosphere cannot persist during normal operation.
– 14 – 60079-13 © IEC:2010 4.3 Mechanical strength The room and any ducts and their connecting parts shall be designed to withstand the maximum pressure of the pressurization system.
This shall be verified by the design documentation or by the overpressure test of 12.3.
The room, including windows, shall withstand the mechanical strength test of
12.3. NOTE Test for mechanical strength need not be carried out on the completed room but may instead be applied to all parts such as windows, gland plates, penetrations, doors, inlets or outlets of the room which are not made of steel or concrete but which are integral to the type of protection. In which case the tests may be carried out on the parts themselves, appropriately mounted for the test. 4.4 Openings, penetrations and seals
The entry of cables, electrical conduits and other penetrations into the room shall be sealed so that the necessary pressure differential can be maintained. If floor drainage facilities are provided, measures shall be taken to minimize the exchange of atmosphere between the inside and the outside of the room. NOTE Barriers may need to be considered for certain room designs to prevent ingress of gases or vapours from potential external sources at atmospheric pressure. 4.5 Doors All doors shall open outwards.
Doors shall be automatically self closing, close fitting and designed to close and latch against the normal pressure differential.
Doors shall be capable of being opened from within, even if locked (for example by the use of a panic bar). NOTE A second door or emergency exit remote from the first should be considered, if access to the main door may be impeded either internally or externally.
4.6 Inlets and outlets The location of inlets and outlets shall be arranged to ensure even distribution of the clean air flow so as to avoid pockets where gases or vapours could accumulate, taking into account the density of those gases and vapours. Design parameters and constraints shall be documented. Exterior air intakes and outlets shall be arranged to minimize the effect of outside conditions. 4.7 Ducts Ducts for the pressurization system shall be constructed of metal or of a non-metallic material with a minimum flame resistance of V-0 according to IEC 60695-11-10.
NOTE In order to minimize the entrance of contamination into the duct, the fan suction duct should be free of leaks and protected against foreseeable mechanical damage. 5 Clean air supply 5.1 Source of clean air The source of the clean air shall be determined from the nature of the process and the physical layout and shall be preferably from a non-hazardous area.
Under certain conditions as prescribed in
9.2, the source may be from a Zone 2 hazardous area.
60079-13 © IEC:2010 – 15 – 5.2 Environmental and air temperature conditions The appropriate environmental and air temperature conditions for design as determined at the inlet to the room shall be documented. 5.3 Heating, ventilation and air conditioning services The clean air supply may include heating, ventilation, and air conditioning equipment.
Any outdoor air used by heating, ventilation and air conditioning equipment shall be provided from the clean air supply. NOTE Inlet filtering should be considered where conditions of dust, smoke, toxics or corrosive vapours or fumes may exist. 5.4 Minimum flow rate The continuous flow of clean air through the room shall be a minimum of 5 air changes per hour.
This may need to be increased for an air consuming device in accordance with
9.7 and where dilution is necessary in accordance with
10.7. 6 Purging and cleaning 6.1 General Purging of flammable gases or removal of combustible dusts from the pressurized room is required at both the initial commissioning of the room and following loss of pressurization.
NOTE Loss of pressurization refers to complete loss of pressure differential and not a partial reduction in pressure differential. 6.2 Gases – Purging 6.2.1 General Before energizing any electrical equipment in the pressurized room which is not suitable for the equipment protection level external to the room, it is necessary to ensure the concentration of flammable gas is less than 25 % of the limiting value (see 3.11) either by purging or by checking the atmosphere in the room with a combustible gas detector.
The pressurized room shall be purged by clean air, except where otherwise permitted or required by this part of IEC 60079.
NOTE For example, see
10.11. 6.2.2 Purge volume The purge volume shall be a minimum of 10 room volumes unless a reduced purge volume can be verified by 12.5 or determined from criteria, such as that defined in IEC 60079-2. 6.2.3 Purging flow rate The purging flow rate shall be a minimum of 5 air changes per hour. The flow rate shall be monitored. Verification shall be according to 12.7. If the room has a dedicated outlet, the flow shall be monitored at the outlet.
Where there is not a dedicated outlet, gas detectors shall be used to ensure that the air within the room is at or below 25 % of the limiting value. SIST EN 60079-13:2011

– 16 – 60079-13 © IEC:2010 6.2.4 Sequence of operations of the purging safety devices for type of protection px The sequence of operations of the safety devices shall be as follows: a) Following the initiation of the sequence, the purging flow through and the pressure differential between the internals of the room and the external atmosphere shall be monitored in accordance with this part of IEC 60079. b) The purge timer shall start once the minimum specified purging flow rate through the room is verified and the pressure differential is within the specified limits. c) When the purge time has elapsed, the purging flow rate may be reduced to th
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