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1、BRITISH STANDARD BS EN 50402:2005 Electrical apparatus for the detection and measurement of combustible or toxic gases or vapours or of oxygen Requirements on the functional safety of fixed gas detection systems The European Standard EN 50402:2005 has the status of a British Standard ICS 13.320 ? BS
2、 EN 50402:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 December 2005 BSI 30 December 2005 ISBN 0 580 46820 8 National foreword This British Standard is the official English language version of EN 50402:2005. The UK participation in
3、 its preparation was entrusted by Technical Committee GEL/31, Electrical apparatus for explosive atmospheres, to Subcommittee GEL/31/19, Gas detectors, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-referen
4、ces The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British S
5、tandards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to
6、the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside fron
7、t cover, the EN title page, pages 2 to 63 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments EUROPEAN STANDARD EN 50402 NORME EUROPENNE EUROPISCHE NORM August 2005 CENELEC Europe
8、an Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for
9、CENELEC members. Ref. No. EN 50402:2005 E ICS 13.320 English version Electrical apparatus for the detection and measurement of combustible or toxic gases or vapours or of oxygen Requirements on the functional safety of fixed gas detection systems Matriel lectrique pour la dtection et la mesure des g
10、az ou vapeurs combustibles ou toxiques, ou de loxygne Exigences relatives la fonction de scurit des systmes fixes de dtection de gaz Elektrische Gerte fr die Detektion und Messung von brennbaren oder toxischen Gasen und Dmpfen oder Sauerstoff Anforderungen an die funktionale Sicherheit von ortsfeste
11、n Gaswarnsystemen This European Standard was approved by CENELEC on 2005-07-01. 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 an
12、d 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 respon
13、sibility 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, Hunga
14、ry, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 50402:2005 2 Foreword This European Standard was prepared by SC 31-9, Electrical apparatus for the detection and measurement
15、 of combustible gases to be used in industrial and commercial potentially explosive atmospheres, of Technical Committee CENELEC TC 31, Electrical apparatus for explosive atmospheres and by the Technical Committee CENELEC TC 216, Gas detectors. The text of the draft was submitted to the formal vote a
16、nd was approved by CENELEC as EN 50402 on 200507-01. 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) 2006-07-01 latest date by which the national standards conflicting with th
17、e EN have to be withdrawn (dow) 2008-07-01 _ 3 EN 50402:2005 Contents Clause Page Introduction.5 1 Scope .6 2 Normative references .7 3 Definitions8 4 General requirements.12 4.1 Introduction.12 4.2 Functional safety characteristics of modules13 5 Modules and elements - Characterisation and requirem
18、ents 15 5.1 General requirements.19 5.2 Gas sampling21 5.3 Sensor.23 5.4 Signal-transmission 24 5.5 Input of control unit .27 5.6 Signal processing in the control unit.29 5.7 Output of the control unit 32 6 Characterisation of safety requirement35 6.1 General.35 6.2 Characterisation of safety functi
19、on .36 6.3 Characterisation of safety integrity37 6.4 Determination of SIL-capabilities for a safety function38 6.5 Determination of hardware failure rates for a safety function.41 6.6 Safety performance requirements 42 7 Information requirements 42 7.1 Information delivered by the manufacturer of t
20、he gas detection system 42 7.2 Information delivered by the user of the gas detection system.43 8 Validation.43 Annex A (informative) Gas detection systems as part of a safety-related system.44 Annex B (normative) Transformation of the SIL-capabilities of gas detection systems.49 Annex C (normative)
21、 Transformation from generic standard requirements to modules 50 Annex D (normative) Management of functional safety53 Annex E (informative) Determination of SIL-capability of a safety function of the gas detection system55 EN 50402:2005 4 Table 1 - Fault tolerance for complex modules according EN 6
22、1511-1, Table 5 .14 Table 2 - Fault tolerance for complex modules according EN 61508-2, Table 3 .14 Table 3 - Minimum hardware fault tolerance for simple modules according EN 61511-1, Table 615 Table 4 - Fault tolerance for simple modules according EN 61508-2, Table 2.15 Table 5 - Diagnostic measure
23、s for program sequence monitoring from EN 61508-219 Table 6 - Diagnostic measures for memory from EN 61508-2.20 Table 7 - Determination of SIL-capability for a parallel chain block40 Table B.1 - Transformation SIL-capability of EN 50402 to SIL of EN 6150849 Table B.2 - Transformation SIL-capability
24、of EN 50402 to Categories of EN ISO 13849-1 .49 Table E.1 - Determination of SIL-capability for a parallel chain block 57 Figure 1 - Definitions of measuring point, measuring group and measuring location.10 Figure 2 - Overview of safety-related system .16 Figure 3 - Modules of a gas detection system
25、18 Figure 4 - Implementation of a gas detection system in the overall safety life cycle (EN 61508-1: 7.1).36 Figure 5 - Single and parallel chains.38 Figure 6 Handling of complex modules in a redundant structure41 Figure A.1 - Functional safety of modules and systems (Proof test interval and mean ti
26、me to repair (MTTR) are not shown in the figure although they have to be included into the considerations) 47 Figure E.1 - Step 1 - Linkage of modules.55 Figure E.2 - Step 2 - Identification of modules necessary for the safety function.55 Figure E.3 - Step 3 - Elimination of modules and linkages wit
27、hout influence on the safety function56 Figure E.4 - Step 4 (1st loop) - Summarising of single chains 56 Figure E.5 - Step 5 (1st loop) - Summarising of parallel chains 56 Figure E.6 - Step 6 (1st loop) - Adaptation of block diagram structure58 Figure E.7 - Step 4 (2nd loop) - Summarising of single
28、chains58 Figure E.8 - Step 5 (2nd loop) - Summarising of parallel chains58 Figure E.9 - Step 6 (2nd loop) - Adaptation of block diagram structure No action required .58 Figure E.10 - Step 4 (3rd loop) - Summarising of single chains58 Figure E.11 - Step 5 (3rd loop) - Summarising of parallel chains59
29、 Figure E.12 - Step 6 (3rd loop) - Adaptation of block diagram structure No action required59 Figure E.13 - Step 4 (4th loop) - Summarising of single chains End of procedure.59 Figure E.14 - Step 1 - Linkages between modules for the example.60 Figure E.15 - Step 2 - Identification of modules with in
30、fluence on the safety function60 Figure E.16 - Step 3 - Elimination of modules and linkages without influence on the safety function.60 Figure E.17 - Step 4 - Summarising of single chains .61 Figure E.18 - Step 5 - Summarising of parallel chains End of procedure61 Figure E.19 - Step 2 - Identificati
31、on of modules with influence on the safety function61 Figure E.20 - Step 3 - Elimination of modules and linkages without influence on the safety function.62 Figure E.21 - Step 4 (1st loop) - Summarising of single chains 62 Figure E.22 - Step 5 (1st loop) - Summarising of parallel chains 62 Figure E.
32、23 - Step 6 (1st loop) - Adaptation of block diagram structure No action required63 Figure E.24 - Step 4 (2nd loop) - Summarising of single chains End of procedure63 5 EN 50402:2005 Introduction This European Standard specifies requirements for functional safety of gas detection systems and encompas
33、ses criteria for reliability, avoidance of faults and fault tolerance. Functional safety is that part of the overall safety related to the measures within the gas detection system to avoid or to handle failures in such a manner that the safety function will be assured. This includes not only design
34、requirements of the gas detection system but also information requirements for planning, putting into operation, maintenance and repair. Gas detection systems will fail to function if dangerous failures occur in the equipment used. Failure to function will also occur if such systems are not installe
35、d or maintained in an appropriate manner. In some applications failures of this type will dominate the functional safety achieved. This European Standard is only targeted at reducing equipment failures to levels appropriate to the application. Users of gas detection systems will therefore need to en
36、sure installation and maintenance of such systems is carried out according to requirements. This European Standard does not specify the physical positioning of sensors. Gas detection systems may differ strongly in structure, complexity and performance. They may not be handled in a uniform manner lik
37、e low complexity devices. A general specification of requirements is not possible on that basis. Gas detection systems therefore need to be divided into functional modules for validation to ensure that systems which have different structures are handled by appropriate procedures. A gas detection sys
38、tem will not normally include all modules covered by this European Standard. Requirements are specified for each of these modules in terms of hierarchical levels which represent one of the constituents of functional safety performance. The hierarchical levels are termed as SIL-capabilities, with SIL
39、-capability 1 representing the minimum and SIL-capability 4 the maximum levels of performance to comply with this standard. The SIL- capability of a module is related to the maximum safety integrity level that can be claimed for a safety function which uses modules of that specified SIL-capability.
40、Modules will be characterised in terms of the SIL- capability. Information is also required on failure rate characteristics of modules or related physical components to enable the overall performance of a gas detection system to be determined. In this way both random failures of hardware components
41、and systematic failures in hardware and software are taken account of. The standard also specifies the requirements that will enable determination of whether the gas detection system have a low enough failure rate when used in conjunction with other equipment necessary for functional safety. This Eu
42、ropean Standard will enable the functional safety characteristics of the gas detection system to be determined from the characteristics of its modules and components (see Annex C). This will enable a gas detection system to be used as a part of an overall safety system. The characterisation includin
43、g the determination of a SIL-capability and failure rate data will only need to be carried out once for a particular design. After characterisation of each module and component the properties of the whole gas detection system will be specified depending on the chosen safety function. The procedure f
44、or determining the SIL-capability of the safety function of a gas detection system will only need to be repeated for each new combination of modules and components. Different combination of equivalent modules may lead to gas detection systems which reach different SIL-capabilities. A flexible adopti
45、on of the gas detection system to different applications will be possible without repeating all steps of the validation procedure for each new configuration. This European Standard does not include requirements for availability which will need to be considered separately. EN 50402:2005 6 1 Scope Thi
46、s European Standard is applicable to fixed gas detection systems for the detection and measurement of flammable or toxic1) gases or vapours or oxygen. This European Standard supplements the requirements of the European Standards for electrical apparatus for the detection and measurement of flammable
47、 gases, vapours (e.g. EN 61779 or EN 50241), toxic gases (e.g. EN 45544) or oxygen (e.g. EN 50104). NOTE 1 These European Standards will be mentioned in the text as “metrological standards“. NOTE 2 The examples above show the state of the standardisation for industrial applications at the time of pu
48、blishing this European Standard. There may be other metrological standards covering other application fields, for which this standard is also applicable. NOTE 3 For fixed apparatus used for safety applications with a SIL requirement up to 1 and for portable apparatus the European Standard EN 50271 m
49、ay be applied instead of this European Standard. Applying the above mentioned metrological standards will ensure the measuring performance is adequate in normal operation of a gas detection system. Additionally the requirements of this European Standard address the functional safety of gas detection systems and encompass criteria for reliability, fault tolerance and avoidance of systematic faults. This European Standard will lead to the