EN 50381:2004
(Main)Transportable ventilated rooms with or without an internal source of release
Transportable ventilated rooms with or without an internal source of release
1.1 This European Standard contains the specific requirements for the construction and testing of transportable ventilated rooms (TVR's), such as skid mounted analyser houses with type of protection 'v' intended for use in potentially explosive atmospheres. Transportable in this sense means manufactured in one location (the manufacturer's premises) for trade and transportation to another location (the user's premises) for installation and use. This European Standard supplements European Standard EN 50014 or where appropriate EN 50021, the requirements of which apply to electrical apparatus with type of protection 'v' except as modified within this standard. This standard does not contain the requirements for equipment group II, category 1 or equipment group I, category M1. This standard does not contain the requirements for equipment group I, category M2 where there exists a potential source of release. This standard does not contain the requirements for group II where there exists a potential hazard from combustible dusts. NOTE It is not the intention of this European Standard to cover stationary analyzer houses according to EN 61285. 1.2 This European Standard includes the requirements for the construction of the TVR and its associated components including, the inlet and outlet apertures for the ventilation gas supply and for the safety provisions and devices necessary for the type of protection 'v'. 1.3 This European Standard specifies the requirements for TVR's with or without an internal source of release of potentially flammable or toxic, gas, liquid or vapour (for example analyzers placed within the TVR). 1.4 Due to the safety factors incorporated in the type of protection, the uncertainty of measurement inherent in good quality, regularly calibrated measurement equipment is considered to have no significant detrimental effect and need not be taken into account when making the measurements necessary to verify compliance of the apparatus with the requirements of this standard.
Transportable ventilierte Räume mit oder ohne innere Freisetzungsstelle
Caissons ventilés transportables avec ou sans source de dégagement interne
Premični prezračevani prostori z notranjim virom sproščanja ali brez njega + Popravek AC
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Transportable ventilierte Räume mit oder ohne innere FreisetzungsstelleCaissons ventilés transportables avec ou sans source de dégagement interneTransportable ventilated rooms with or without an internal source of release29.260.20Electrical apparatus for explosive atmospheresICS:Ta slovenski standard je istoveten z:EN 50381:2004SIST EN 50381:2005+AC:2005en01-december-2005SIST EN 50381:2005+AC:2005SLOVENSKI
STANDARD
EUROPEAN STANDARD
EN 50381 NORME EUROPÉENNE EUROPÄISCHE NORM
August 2004 CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50381:2004 E
ICS 29.260.20 Incorporates Corrigendum December 2005
English version
Transportable ventilated rooms
with or without an internal source of release
Caissons ventilés transportables
avec ou sans source de dégagement interne Transportable ventilierte Räume
mit oder ohne innere Freisetzungsstelle
This European Standard was approved by CENELEC on 2004-03-01. 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Foreword This European Standard was prepared by WG 31-73, of SC 31-7, Pressurization and other techniques, of the Technical Committee CENELEC TC 31, Electrical apparatus for explosive atmospheres. The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50381 on 2004-03-01. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2005-03-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2007-03-01 This standard covers the essential requirements for pressurized rooms without an internal source of release and the additional requirements when an internal source of release is present. This European Standard was prepared under mandate BC/CEN/CLC/08-92 given to CENELEC by the European Commission and the European Free Trade Association and covers essential requirements of the EC Directive 94/9/EC. See Annex ZZ. This European Standard is to be read in conjunction with EN 50014, Electrical apparatus for potentially explosive atmospheres – General requirements, or where appropriate, with EN 50021, Electrical apparatus for potentially explosive atmospheres – Type of protection “n”. This European Standard should not be considered in conjunction with any editions of these standards and their amendments published before 1997. The contents of the corrigendum of December 2005 have been included in this copy. SIST EN 50381:2005+AC:2005
- 3 - EN 50381:2004
Contents Page 1 Scope.6 2 Normative references.6 3 Definitions.7 4 Construction requirements for TVR's and ducting.10 4.1 General.10 4.2 Degree of ingress protection.10 4.3 Design and construction.11 4.4 Mechanical strength.11 4.5 Penetrations.11 4.6 Floor drains.11 4.7 Floors.11 4.8 Doors.11 4.9 Inspection window(s).12 4.10 Apertures.12 4.11 Enclosures.12 5 Requirements for TVR's, equipment group I, type of protection vM2.12 6 Ventilation requirements for TVR's, equipment group II.13 7 Additional ventilation requirements for TVR'S with an internal source of release.14 8 Temperature limits.14 9 Minimum safety provisions and devices.14 10 Additional safety provisions and devices for TVR's meeting the requirements of type of protection v2 and vM2.16 11 Additional requirements for TVR’s with an internal source of release.17 11.1 Assessment of containment systems.17 11.2 Release conditions.17 11.2.1 No release.17 11.2.2 Release of a flammable liquid.17 11.3 Design requirements for the containment system.17 11.3.1 Infallible parts of the containment system.18 11.3.2 Containment system with limited release.18 11.4 Ignition capable apparatus in the case of type of protection v2.18 11.5 Location of apparatus in the case of type of protection v3.18 11.6 Internal hot surfaces.19 11.6.1 Loss of minimum pressure differential, type of protection v2.19 11.6.2 Loss of ventilation flow, type of protection v2.19 11.6.3 Loss of ventilation flow, type of protection v3.19 11.7 Potential source of internal release.19 12 Requirements for gas detectors.19 13 Supply of protective gas.20 13.1 Ventilation.20 13.2 Leakage Compensation of a Breathable Atmosphere (LCBA).21 13.3 Density limits.21 SIST EN 50381:2005+AC:2005
14 Type verification and tests.21 14.1 Sequence of tests.21 14.2 Thermal tests.22 14.3 Overpressure test.22 14.4 Purging test.22 14.5 Verification of minimum pressure differential.23 14.6 Ventilation flow rate tests for TVR's with an internal source of release.23 14.7 Overpressure test for containment systems with limited release.23 14.8 Verification of sequence of operation of the safety devices.23 14.9 Additional tests.24 15 Routine tests.24 15.1 Test conditions.24 15.2 Verification of minimum pressure differential.24 15.3 Ventilation flow rate tests for TVR's with an internal source of release.24 15.4 Overpressure test for containment systems with limited release.24 15.5 Verification of sequence of operation of the safety devices.24 15.6 Additional tests.25 16 Marking.25 16.1 TVR's all cases.25 16.2 TVR's with a containment system.25 16.3 Safety related control systems.25 16.4 Additional marking.25 17 Instructions.26
Annex A (normative)
Method of protection of electrical apparatus containing a potential release of a flammable gas or vapour.27 A.1 Introduction.27 A.2 Definitions.27 A.3 Requirements.27 Annex B (normative)
Method of protection of electrical apparatus containing a potential release of a flammable liquid.30 B.1 Introduction.30 B.2 Definitions.30 B.3 Requirements.30 B.4 Flammable non-flashing liquids.31 B.5 Spark and particle barriers.32 B.6 Flashing liquids.33 Annex C (informative)
Determination of peak rise in enclosure pressure, resulting from an internal release of a flashing liquid.34 C.1 Introduction.34 C.2 Definitions.34 Annex D (informative)
Method of protection of electrical apparatus containing a potential release of a flammable gas or vapour.36 Annex E (informative)
Mathematical model of dilution of a source of release.38 Bibliography.41 Annex ZZ (informative)
Coverage of Essential Requirements of EC Directives.42 SIST EN 50381:2005+AC:2005
- 5 - EN 50381:2004
Introduction This is a new European Standard for transportable pressurized rooms with and without an internal source of release but is confined to those rooms which are transportable and should not apply to rooms constructed on site and not intended for resale. Pressurized rooms are locations intended for human occupation under normal operational circumstances. In such circumstances it is important to distinguish between pressurization, which may use air or inert gas and be applied to apparatus not required to support life, from ventilation. Ventilation in the context of this standard, taken together with other safety measures, ensures a safe (and breathable) atmosphere within the pressurized room.
This text is based upon the scope of EN 61285, IEC/TR 61831, IEC 60079-13 and IEC 60079-16 and the essential safety requirements of Directive 94/9/EC. SIST EN 50381:2005+AC:2005
1 Scope 1.1 This European Standard contains the specific requirements for the construction and testing of transportable ventilated rooms (TVR's), such as skid mounted analyser houses with type of protection 'v' intended for use in potentially explosive atmospheres. Transportable in this sense means manufactured in one location (the manufacturer's premises) for trade and transportation to another location (the user's premises) for installation and use. This European Standard supplements European Standard EN 50014 or where appropriate EN 50021, the requirements of which apply to electrical apparatus with type of protection 'v' except as modified within this standard. This standard does not contain the requirements for equipment group II, category 1 or equipment group I, category M1. This standard does not contain the requirements for equipment group I, category M2 where there exists a potential source of release. This standard does not contain the requirements for group II where there exists a potential hazard from combustible dusts. NOTE It is not the intention of this European Standard to cover stationary analyzer houses according to EN 61285. 1.2 This European Standard includes the requirements for the construction of the TVR and its associated components including, the inlet and outlet apertures for the ventilation gas supply and for the safety provisions and devices necessary for the type of protection 'v'. 1.3 This European Standard specifies the requirements for TVR's with or without an internal source of release of potentially flammable or toxic, gas, liquid or vapour (for example analyzers placed within the TVR). 1.4 Due to the safety factors incorporated in the type of protection, the uncertainty of measurement inherent in good quality, regularly calibrated measurement equipment is considered to have no significant detrimental effect and need not be taken into account when making the measurements necessary to verify compliance of the apparatus with the requirements of this standard. 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.
EN 954-1
Safety of machinery - Safety related parts of control systems EN 50014
Electrical apparatus for potentially explosive atmospheres – General requirements EN 50015
Electrical apparatus for potentially explosive atmospheres – Oil immersion 'o' EN 50016
Electrical apparatus for potentially explosive atmospheres – Pressurized apparatus 'p' EN 50017
Electrical apparatus for potentially explosive atmospheres – Powder filling 'q' EN 50018
Electrical apparatus for potentially explosive atmospheres – Flame proof enclosures 'd' EN 50019
Electrical apparatus for potentially explosive atmospheres – Increased safety 'e' EN 50020
Electrical apparatus for potentially explosive atmospheres – Intrinsic safety 'i' SIST EN 50381:2005+AC:2005
- 7 - EN 50381:2004
EN 50021
Electrical apparatus for potentially explosive atmospheres – Type of protection ‘n’ EN 50028
Electrical apparatus for potentially explosive atmospheres – Encapsulation 'm' EN 50039
Electrical apparatus for potentially explosive atmospheres – Intrinsically safe electrical systems ‘i’ EN 60034-5
Rotating electrical machines -- Part 5: Degrees of protection provided bythe integral design of rotating electrical machines (IP code) – Classification (IEC 60034-5) EN 60079-10 1996 Electrical apparatus for explosive gas atmospheres – Part 10: Classification of hazardous areas (IEC 60079-10:1995) EN 60079-15 2003 Electrical apparatus for explosive gas atmospheres – Part 15: Type of protection “n” (IEC 60079-15:2001, modified) EN 60529
Degrees of protection provided by enclosures (IP Code) (IEC 60529) EN 61285
Industrial-process control – Safety of analyser houses (IEC 61285) EN 61779-1
Electrical apparatus for the detection and measurement of flammable gases – Part 1: General requirements and test methods (IEC 61779-1:1998, modified) EN 61779-2
Electrical apparatus for the detection and measurement of combustible gases – Part 2: Performance requirements for Group I apparatus indicating
a volume fraction up to 5 % methane in air (IEC 61779-2:1998, modified) EN 61779-3
Electrical apparatus for the detection and measurement of flammable gases – Part 3: Performance requirements for Group I apparatus indicating a volume fraction up to 100 % methane in air (IEC 61779-3:1998, modified) EN 61779-4
Electrical apparatus for the detection and measurement of combustible gases – Part 4: Performance requirements for Group II apparatus indicating a volume fraction up to 100 % lower explosive limit (IEC 61779-4:1998, modified) EN 61779-5
Electrical apparatus for the detection and measurement of combustible gases – Part 5: Performance requirements for Group II apparatus indicating a volume fraction up to 100 % gas (IEC 61779-5:1998, modified) 3 Definitions For the purpose of this standard, the following definitions apply: 3.1 purging – the operation of passing a specified quantity of air through the TVR, or apparatus as defined in Annex A, and its associated ducts, so that any explosive gas or vapour is reduced to a safe concentration; or – the operation of passing a quantity of inert gas through apparatus as defined in Annex B, and its associated ducts, so that any oxygen, as a component of air that may be present is reduced to a safe concentration SIST EN 50381:2005+AC:2005
NOTE Purging may also be used for other purposes such as:
– to ensure that the air quality of the atmosphere within the TVR is acceptable; or
– to ensure that any toxic gas or vapour that may be present is reduced to a safe concentration; or
– to account for the potential depletion of oxygen, accumulation of carbon dioxide or potential release of any asphyxiant gas.
These and other like issues are the responsibility of the user and the test house is not required to verify compliance. 3.2 internal source of flammable release a point or location from which a flammable substance in the form of a flammable gas or vapour or liquid may be released into the TVR such that an explosive gas atmosphere could be formed 3.3 ignition capable apparatus apparatus which in normal or abnormal operation constitutes a source of ignition for a specified explosive atmosphere by being capable of
producing sparks or generating ignition capable hot surfaces. Apparatus which meets the requirements of one or more of the types of protection listed in EN 50014 for the specified atmosphere is considered not ignition capable 3.4 non-incendive apparatus apparatus which in normal operation does not produce sparks or generate hot surfaces capable of igniting
a specified explosive atmosphere. Apparatus which meets the requirements of one or more of the types of protection in EN 50021 or EN 60079-15 and/or by the methods outlined in Annex A or Annex B is considered non-incendive 3.5 limited toxic release a release of toxic gas, vapour or liquid, the maximum flow rate of which can be predicted by the use of limiting devices and/or by calculation NOTE This standard does not specify the necessary safety criteria for dealing with toxic release. Some guidance is given in EN 61285. 3.6 limiting value the limiting value is the lowest concentration value of the lower explosive limit (LEL) of each component involved, taking account of the most onerous conditions of concentration that may occur from every potential source of release within the TVR 3.7 protective gas – air used for purging and maintaining a pressure differential and, if required, dilution within the TVR or an enclosure meeting the requirements of Annex A; or – an inert gas used for maintaining a pressure differential within an enclosure meeting the requirements of Annex B 3.8 ventilation the maintenance of a pressure differential between the external atmosphere and that within the TVR with continuous flow of the protective gas. The purpose is to dilute any potential limited release to a safe level within the TVR. This concept is only applicable to type of protection v2, v3 and v4 NOTE The term 'ventilation' is used in this text as a means of explosion protection. It is recognised that ventilation may also be used to ensure adequate air quality for personnel and also to maintain a specific temperature regime within the TVR; these latter requirements are out with the scope of this document. SIST EN 50381:2005+AC:2005
- 9 - EN 50381:2004
3.9 Leakage Compensation of a Breathable Atmosphere (LCBA) the maintenance of a pressure differential between the external atmosphere and that within the TVR with a supply of air which, after purging, when the outlet apertures are closed, is sufficient to maintain the required positive pressure differential whilst compensating for any loss due to leakage and maintaining an internal atmosphere of breathable quality. This concept is only applicable to type of protection vM2 NOTE Additional measures, such as the use of oxygen deficiency detectors may be required to ensure an equable environment within the TVR. Such measures are not within the scope of this standard. 3.10 containment system those parts of the apparatus associated with the TVR containing the flammable gas, vapour or liquid that may constitute an internal source of release NOTE The containment system may extend out with the enclosure walls of the TVR. 3.11 dilution the continuous supply of a protective gas, after purging, at such a rate that the concentration of a flammable mixture inside the TVR 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 EN 61285. 3.12 dilution area an 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 NOTE A dilution area may be extended to include locations where it is not necessary for the test house to carry out assessments, for example where no apparatus is located. 3.13 limited release a release of flammable gas or vapour the maximum flow rate of which, can be predicted by the use of limiting devices and/or by calculation 3.14 unlimited release a release of flammable gas or vapour the maximum flow rate of which cannot be predicted arising from the release of a flammable liquid 3.15 Lower Explosive Limit (LEL) the volume ratio of flammable gas or vapour in air below which an explosive gas atmosphere will not be formed 3.16 Upper Explosive Limit (UEL) volume ratio of flammable gas or vapour in air above which an explosive gas atmosphere will not be formed 3.17 volume ratio (v/v) ratio of the volume of a component to the volume of the gas mixture under specified conditions of temperature and pressure SIST EN 50381:2005+AC:2005
3.18 type of protection v a type of protection intended to reduce the risk of explosion to an appropriate level by the prevention of the formation of an explosive atmosphere in the vicinity of a source of ignition 3.18.1 type of protection vM2 suitable for use in underground parts of mines and to those parts of surface installations of such mines, liable to be endangered by firedamp and/or combustible dust. Type of protection vM2 ensures the requisite level of protection, even in the event of frequently occurring disturbances or equipment faults which normally have to be taken into account by maintaining a positive pressure differential between the atmosphere within the TVR and that external 3.18.2 type of protection v2 suitable for areas in which explosive atmospheres caused by gases, vapours or mists are likely to occur Type of protection v2 ensures the requisite level of protection, even in the event of frequently occurring disturbances or equipment faults which normally have to be taken into account by maintaining a positive pressure differential between the atmosphere within the TVR and that external, and where appropriate adequate ventilation 3.18.3 type of protection v3 suitable for areas in which explosive atmospheres caused by gases, vapours or mists are unlikely to occur or if they do occur, are likely to do so infrequently and for a short period only. Type of protection v3 ensures the requisite level of protection during normal operation by maintaining a positive pressure differential between the atmosphere within the TVR and that external, and where appropriate adequate ventilation 3.18.4 type of protection v4 suitable for areas normally considered safe but in which a risk of an explosive atmosphere caused by gases, vapours or mists might occur due to the operation of equipment within the TVR and if they do occur, are likely to do so infrequently and for a short period only. Type of protection v4 ensures the requisite level of protection during normal operation by maintaining a negative pressure differential between the atmosphere within the TVR and that external, and where appropriate adequate ventilation 4 Construction requirements for TVR's and ducting 4.1 General The size of the TVR depends on the number, size and access requirements of the equipment to be housed. Except for type of protection vM2 the absolute minimum unobstructed headroom shall be 2,0 m. Suspended ceilings, cable trenches and other dead air spaces shall be avoided. NOTE 1 NOTE 1
An additional allowance of 30 % should be made for the addition of further equipment. Recommended minimum dimensions are 2,5 m length and width and 2,3 m headroom. NOTE 2 NOTE 2
If the electrical apparatus has to withstand particularly adverse service conditions (e.g. rough handling, humidity, effects of ambient temperature variations, effects of chemical agents, corrosion) these should be specified by the user to the manufacturer and are not the responsibility of the testing house. 4.2 Degree of ingress protection The TVR, including any apertures for moving parts but excluding apertures for the inlet and outlet of the protective gas, shall have a degree of protection in accordance with at least IP40 of EN 60529. In the case of equipment group I, type of protection vM2 the TVR shall have a degree of protection in accordance with at least IP44 of EN 60529. SIST EN 50381:2005+AC:2005
- 11 - EN 50381:2004
4.3 Design and construction The exterior of the TVR shall be designed and constructed to minimize the accumulation of dust and provide easy facility for cleaning, for example by the use of a pitched roof with extended eaves and the fitment of external pitched canopies.
4.4 Mechanical strength The TVR, ducts, if any, and their connecting parts shall withstand a pressure equal to 1,5 times the maximum pressure differential specified by the manufacturer for normal service with a minimum of 200 Pa (2 mbar). In the case of type of protection v2 and v3 all outlets shall be closed and in the case of v4 all inlets shall be closed. If a pressure differential can occur in service that can cause a deformation of the TVR, ducts, if any, or connecting parts, a safety device shall be fitted by the manufacturer to limit the maximum pressure differential to a level below that which could adversely affect the type of protection. 4.5 Penetrations Penetrations shall be via devices such as bulkhead panels and gland plates with appropriate bulkhead fittings and/or glands or 1) fire wall transit and shall maintain the required degree of ingress protection. 4.6 Floor drains Where there is a source of internal release of liquid cleaning facilities such as a slight slope and drain to a common collecting point, shall be provided. Where a floor drain is installed it shall, except for type of protection vM2, be free draining to the outside. Provision shall be made to prevent exchange of the atmosphere between the interior and exterior of the TVR. 4.7 Floors Floors shall be non-slip. Non-slip finishes shall be resistant to any material likely to come into contact with the floor. Floors shall be non porous and impervious to hydrocarbon vapours. The test house is not required to verify compliance. NOTE It is the user's responsibility to ensure that measures shall be taken to prevent ingress of extraneous liquids for example by raising the floor above ground and/or providing a step or ramp at the door entrance. Where the TVR is intended to be positioned on a concrete plinth this should be impervious to hydrocarbons and raised at least 0,1 m above the surrounding area. 4.8 Doors A minimum of one door shall be provided. All doors shall open outwards. Except for vM2, doors shall be fitted with an automatic self closing mechanism to close and latch (regardless of the extent to which the door was initially open) even against the maximum overpressure specified in normal service.
4.8.1 Door(s) shall be fitted with lock(s) to control unauthorized access. Door(s) shall be capable of being opened from within, even when locked (for example by the use of a panic bar). 4.8.2 Doors shall be fitted with a position switch to operate when the door is closed.
1) See Annex J of IEC/TR 61831. SIST EN 50381:2005+AC:2005
4.9 Inspection window(s) Where inspection window(s) are fitted in doors they shall be sealed, not be capable of being opened and shall be shatter resistant for example by wire reinforcing.
NOTE Recommendations for the requirements for inspection windows are given in EN 61285. 4.10 Apertures The location, size and number of apertures shall be suitable for effective purging. NOTE The number of apertures should be chosen in regard to the design and disposition of the apparatus particular consideration being given to the needs of sub-compartments into which the apparatus might be divided. 4.10.1 Apertures shall be designed to be self closing in the event of ventilation failure or failure of maintenance of pressure differential. 4.10.1.1 In the case of equipment group I, type of protection vM2, apertures shall be self closing and sealed to at least IP44 of EN 60529. in the event of failure of maintenance of pressure differential. 4.10.1.2 In the case of equipment group II apertures shall be self closing in the event of ventilation failure. 4.10.2 Aperture closures shall be fitted with a switch or device to operate when open.
4.10.3 Apertures shall be fitted with mesh or screen meeting IP20, to prevent foreign material such as rodents or leaves impairing the proper operation of the closure devices. 4.10.4 In the case of equipment group II, the distribution of inlet and outlet apertures shall be arranged so as to be unaffected by outside weather conditions such as wind, rain or snow. TVR's intended for use outdoors shall have several apertures distributed on opposite faces so that at least 50 % are effective even during adverse weather conditions. 4.11 Enclosures Where within the TVR, there may exist enclosures, such as junction boxes or distribution panels which are protected by one or more of the methods listed in Clause 2, excluding EN 50016, the total volume of such enclosures shall not exceed 10 % of the internal volume of the room or chamber in which they are fitted. NOTE The test house is not required to verify that the internals of such enclosures are purged during the TVR purge sequence. 5 Requirements for TVR's, equipment group I, type of protection vM2 5.1 The leakage compensation system shall ensure a positive pressure differential of 25 Pa (0,25 mbar) between the external atmosphere and that within the TVR (except within the immediate vicinity of the outlet aperture during purging). The manufacturer shall specify the minimum and maximum over pressure differential in service. NOTE It is essential for the safety of a TVR that the installation of the associated ducts and of the compressor or fan does not introduce a hazard. 5.2 The minimum flow rate of protective gas required for purging is the rate specified by the manufacturer. The minimum purging duration is the duration also specified by the manufacturer and verified by the type tests. The purging flow rate shall be monitored at the inlet to the TVR. SIST EN 50381:2005+AC:2005
- 13 - EN 50381:2004
NOTE To determine the free space of the associated ducts and to set up the additional purging time for the given minimum flow rate is the responsibility of the user. The purge duration shall be increased by the time necessary to purge the free volume of those associated ducts which are not part of the certified apparatus by at least five times their volume at the minimum flow rate specified by the manufacturer. 5.2.1 The design and arrangement of inlet ducts and the outlet apertures shall be arranged to ensure even distribution of the purge air flow so as to avoid pockets where gases could accumulate. 5.2.2 If additional equipment is required to ensure adequate distribution of purge air it shall be incorporated as part of the essential safety system and shall be protected by one of the means listed in Clause 2. NOTE The circulation fans may form part of a heating cooling system. 6 Ventilation requirements for TVR's, equipment group II 6.1 Ventilation shall provide a minimum of 5 air changes per hour. NOTE Ventilation may also be used to ensure an equable environment for personnel and/or equipment. For that reason heating and/or cooling facilities may be incorporated in the ventilation system. 6.2 The ventilation system shall ensure a minimum pressure differential of 25 Pa (0,25 mbar) between the external atmosphere and that within the TVR except within the immediate vicinity of the outlet aperture in the case of v2 and v3 and the inlet apertures in the case of v4. The manufacturer shall specify the minimum and maximum pressure differential in service. NOTE 1 It is essential for the safety of a TVR that the installation of the associated ducts and of the compressor or fan does not introduce a hazard. NOTE 2 Local wind conditions shall always be taken into consideration when overpressures are being set.
6.3 The minimum flow rate of protective gas required for purging is the rate specified by the manufacturer. The minimum purging duration is the duration also specified by the manufacturer and verified by test or calculation in the case of v2, v3 and v4. The purging flow rate shall be monitored at the inlet to the TVR in the case of v2 and v3 and at the outlet in the case of v4. NOTE To determine the free space of the associated ducts and to set up the additional purging time for the given minimum flow rate is the responsibility of the user. The purge duration shall be increased by the time necessary to purge the free volume of those associated ducts which are not part of the certified apparatus by at least five times their volume at the minimum flow rate specified by the manufacturer. 6.3.1 The design and arrangement of ducts and the apertures shall be arranged to ensure even distribution of the ventilation air flow so as to avoid pockets where gases or vapours could accumulate. NOTE 1 Guidance on the installation and location of ducts is given in Annex B and Annex C of IEC 60079-16. If additional circulation fans or equipment are required to ensure adequate distribution of air they shall be incorporated as part of the essential safety system and shall, if fitted within the TVR and/or associated ducts, be protected by one of the means listed in Clause 2. NOTE 2 The circulation fans may form part of a heating cooling system. 6.4 The ventilation flow rate shall be monitored at the inlet to the TVR in the case of v2 and v3 and at the outlet in the case of v4. The minimum ventilation flow rate specified by the manufacturer shall be achieved with 50 % of the flaps closed. SIST EN 50381:2005+AC:2005
7 Additional ventilation requirements for TVR'S with an internal source of release 7.1 Ventilation shall provide that air flow necessary to dilute escaping vapours from the rupture or failure of the most hazardous sample or service line to less than 20 % of the limiting value except in a dilution area. Where one fault or rupture automatically precipitates another, they shall be treated together as a single fault. NOTE For most fluids, the major constraint is that the concentration of vapours, which are hazardous for personnel, is lower than the LEL, and additional ventilation may be required. Additional safety measures for the safe handling and disposal of gases or vapours emerging from the ventilation system are the responsibility of the user. 7.2 A minimum of two gas detectors shall be fitted. They shall be positioned according to the nature of the gases expected either from the external atmosphere or potentially released within the TVR. Where a set of detectors is required to ensure adequate response to the range of flammable gases specified, a minimum of two sets of detectors shall be fitted. 8 Temperature limits 8.1 The TVR shall be classified in accordance with the temperature classification requirements of EN 50014 or EN 50021 or EN 60079-15. The maximum surface temperature shall be determined as follows: a) in the case of v2 and v3 either by the temperature of the hottest point of the external surface of the TVR; or b) by the T rating of the internal parts which are protected by any of the types of protection listed in EN 50014 or EN 50021 or EN 60079-15, and which remain energized even when the supply of protective gas is removed (e.g. electrical heaters) which ever is the hotter. 8.1.1 Normally the temperature of the protective gas to be taken into consideration is 40 K at the inlet to the TVR. In special circumstances a higher temperature may be permitted or a lower temperature may be required, for example for cooling purposes, in which case the maximum inlet temperature of the protective gas shall be marked on the TVR and stated in the manufacturer's documentation. 8.2 If during normal service the temperature of any surface within the TVR exceeds the value determined in 8.1 b for the temperature class, appropriate measures shall be taken to prevent if ventilation ceases, any explosive atmosphere coming into contact with the hot surface. NOTE This may be achieved either by the design and construction of the TVR, e.g. air locks or by bringing auxiliary ventilation systems into operation or by arranging that the hot surface within the TVR is in a gas tight or encapsulated housing. 9 Minimum safety provisions and devices 9.1 All safety devices used to prevent electrical apparatus protected by type of protection 'v' from causing an explosion shall themselves not be capable of causing an explosion or shall be mounted outside the hazardous area. 9.2 The safety devices required by this standard form safety related parts of a control system. It is the responsibility of the manufacturer to assess that the safety and integrity of the control system is consistent with the level of safety required by this standard. NOTE See EN 954-1, Safety of machinery - Safety related parts of a control system. 9.3 The safety devices shall be provided by the manufacturer of the TVR or by the user. In the latter case the apparatus shall be marked "X" and the description documents shall contain all necessary information required by the user to ensure conformity with the requirements of this standard. SIST EN 50381:2005+AC:2005
- 15 - EN 50381:2004
9.4 Where the safety related control system forms part of the apparatus, a functional sequence diagram shall be provided by the manufacturer, for example truth table, state diagram, flow chart, etc., to define the action of the control system. The sequence diagram shall clearly identify and show the operational states of the safety devices and ensuing actions. Functional tests shall be required to verify conformity to the diagram. These tests need only be carried out under normal conditions of atmospheric temperature and pressure (NTP) unless otherwise specified by the manufacturer. 9.5 The manufacturer shall specify the maximum and minimum action levels and tolerances of the safety devices. The safety devices shall be used within the normal operational limits as specified by the manufacturer (of those devices) taking due account of the most onerous conditions specified for normal service. 9.6 Safety devices, such as time delay relays and devices for monitoring the pressure differential and the flow of protective gas, shall be provided to prevent ignition capable apparatus, in the case of category 2 and equipment not meeting the requirements for non-incendive apparatus in the case of category 3 , within the TVR, becoming energized until purging has been completed. The sequence of operations of the safety devices shall be as follows: – following the initiation of the sequence, the purging flow through and the pressure differential between the internals of the TVR and the external atmosphere shall be monitored in accordance with this standard; – in the case of v4 the inlet apertures shall indicate closure prior to commencement of purge in all other cases the outlet apertures shall indicate closure prior to commencement of purge when: a) in the case of vM2, the minimum specified purge rate or in the case of v2, v3 or v4 the minimum specified ventilation flow rate of protective gas through the TVR is achieved;
and b) the pressure differential is within the specified limits;
and c) in the case of category M2 all of the outlet apertures are open or in the case of v2, v3 and v4 ≥ 50 % of the apertures are open;
and d) the minimum prescribed purge flow rate for equipment protected by the methods described in Annex A or Annex B, if fitted, has been achieved, the purge timer can be started. – when the pur
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...