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2、combustible or toxicgases or vapours or ofoxygen Requirements on thefunctional safety offixed gas detectionsystemsICS 13.320Electrical apparatus fothe detection andmeasurement ofBRITISH STANDARD BS EN50402:2005+A1:2008Incorporating corrigendum October 2010BS EN 50402:2005+ALicensed Copy: Wang Bin, I
3、SO/EXCHANGE CHINA STANDARDS, 10/02/2011 02:44, Uncontrolled Copy, (c) BSIThis British Standard waspublished under the authorityof the Standards Policy andStrategy Committee on 30 December 2005 BSI 2010ISBN 978 0 580 73240 9Amendments/corrigenda issued since publicationDate Comments30 June 2009 Imple
4、mentation of CENELC amendment A1: 200831 October 2010 Correction of print file errors and addition of page numberingGEL/31, Electrical apparatus for explosive atmospheres, to SubcommitteeGEL/31/19, Gas detectors.A list of organizations represented on this subcommittee can be obtained onrequest to it
5、s secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity fromlegal obligations.1:2008National forewordThis British Standard is the UK implementation
6、of EN 50402:2005+A1:2008.It supersedes BS EN 50402:2005 which is withdrawn.The start and finish of text introduced or a ltered by amendment is indicated inthe text by tags. Tags indicating changes to CENELEC text carry the numberof the CENELEC amendment. For example, text altered by CENELECamendment
7、 A1 is indicated by !“.The UK participation in its preparation was entrusted by Technical CommitteeEUROPEAN STANDARD EN 50402:2005+A1 NORME EUROPENNE EUROPISCHE NORM May 2008 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches K
8、omitee 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 CENELEC members. Ref. No. EN 50402:2005 E ICS 13.320 English version Electrical apparatus for the detection and
9、 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 gaz ou vapeurs combustibles ou toxiques, ou de loxygne Exigences relatives la fonction de scurit des systmes fix
10、es 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 ortsfesten Gaswarnsystemen This European Standard was approved by CENELEC on 2005-07-01. CENELEC members are bound to co
11、mply 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 S
12、ecretariat 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
13、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, Slova
14、kia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 10/02/2011 02:44, Uncontrolled Copy, (c) BSIForeword This European Standard was prepared by SC 31-9, Electrical apparatus for the detection and measurement of combustible gases to be
15、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 and was approved by CENELEC a
16、s 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 the EN have to be withdrawn (d
17、ow) 2008-07-01 _ Foreword to amendment A1 This amendment was prepared by SC 31-9, Electrical apparatus for the detection and measurement of combustible gases to be used in industrial and commercial potentially explosive atmospheres, of Technical Committee CENELEC TC 31, Electrical apparatus for expl
18、osive atmospheres. The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as amendment A1 to EN 50402:2005 on 2008-03-01. The following dates were fixed: latest date by which the amendment has to be implementedat national level by publication of an identic
19、al national standard or by endorsement (dop) 2009-03-01 latest date by which the national standards conflicting with the amendment have to be withdrawn (dow) 2011-03-01 _ BS EN 50402:2005+A1:2008 EN 50402:2005+A1:2008Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 10/02/2011 02:44, Uncontroll
20、ed Copy, (c) BSIContents 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 requirements 15 5.1 General requirements .19 5.2 Gas
21、 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 requirement 35 6.1 General .35 6.2 Characterisation of safety function .36 6.3 Characterisation of safety in
22、tegrity37 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 the gas detection system 42 7.2 Informat
23、ion 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) Transformation from generic standard
24、 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 BS EN 50402:2005+A1:2008 EN 50402:2005+A1:2008- -3Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 10/02/20
25、11 02:44, Uncontrolled Copy, (c) BSITable 1 - Fault tolerance for complex modules according EN 61511-1, 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 -
26、Fault tolerance for simple modules according EN 61508-2, Table 2.15 Table 5 - Diagnostic measures for program sequence monitoring from EN 61508-2 19 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 - Transfor
27、mation SIL-capability of EN 50402 to SIL of EN 6150849 Table B.2 - Transformation SIL-capability 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
28、.10 Figure 2 - Overview of safety-related system .16 Figure 3 - Modules of a gas detection system 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
29、structure 41 Figure A.1 - Functional safety of modules and systems (Proof test interval and mean time 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 module
30、s necessary for the safety function.55 Figure E.3 - Step 3 - Elimination of modules and linkages without influence on the safety function56 Figure E.4 - Step 4 (1stloop) - Summarising of single chains 56 Figure E.5 - Step 5 (1stloop) - Summarising of parallel chains 56 Figure E.6 - Step 6 (1stloop)
31、- Adaptation of block diagram structure58 Figure E.7 - Step 4 (2ndloop) - Summarising of single chains58 Figure E.8 - Step 5 (2ndloop) - Summarising of parallel chains58 Figure E.9 - Step 6 (2ndloop) - Adaptation of block diagram structure No action required .58 Figure E.10 - Step 4 (3rdloop) - Summ
32、arising of single chains 58 Figure E.11 - Step 5 (3rdloop) - Summarising of parallel chains 59 Figure E.12 - Step 6 (3rdloop) - Adaptation of block diagram structure No action required59 Figure E.13 - Step 4 (4thloop) - Summarising of single chains End of procedure.59 Figure E.14 - Step 1 - Linkages
33、 between modules for the example.60 Figure E.15 - Step 2 - Identification of modules with influence 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 - S
34、tep 5 - Summarising of parallel chains End of procedure61 Figure E.19 - Step 2 - Identification 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 (1stloop) - Summarising of s
35、ingle chains 62 Figure E.22 - Step 5 (1stloop) - Summarising of parallel chains 62 Figure E.23 - Step 6 (1stloop) - Adaptation of block diagram structure No action required 63 Figure E.24 - Step 4 (2ndloop) - Summarising of single chains End of procedure 63 BS EN 50402:2005+A1:2008 EN 50402:2005+A1:
36、2008 -4-Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 10/02/2011 02:44, Uncontrolled Copy, (c) BSIIntroduction This European Standard specifies requirements for functional safety of gas detection systems and encompasses criteria for reliability, avoidance of faults and fault tolerance. Func
37、tional 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 requirements of the gas detection system but also information requirements
38、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 installed or maintained in an appropriate manner. In some applications failures of
39、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 ensure installation and maintenance of such systems is carried out according
40、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 like low complexity devices. A general specification of requirements is not po
41、ssible 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 system will not normally include all modules covered by this European Standard
42、. 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-capability 1 representing the minimum and SIL-capability 4 the maximum lev
43、els 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. Modules will be characterised in terms of the SIL-capability. Information is
44、 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 and systematic failures in hardware and software are taken account of. The st
45、andard 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 European Standard will enable the functional safety characteristics of the gas
46、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 including the determination of a SIL-capability and failure rate data will only need
47、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 for determining the SIL-capability of the safety function of a gas detection s
48、ystem 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 adoption of the gas detection system to different applications will be possible wit
49、hout 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. BS EN 50402:2005+A1:2008 EN 50402:2005+A1:2008-5-Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 10/02/2011 02:44, Uncontrolled Copy, (c) BSI1 Scope This 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 su
