1、BS EN 50402:2017Electrical apparatus for thedetection and measurementof combustible or toxic gasesor vapours or of oxygen Requirements on the functionalsafety of gas detection systemsBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 50402:2017 BRITISH STANDARDNat
2、ional forewordThis British Standard is the UK implementation of EN 50402:2017. It supersedes BS EN 50402:2005+A1:2008 which is withdrawn .The UK participation in its preparation was entrusted to Technical Committee EXL/31/1, Gas detectors.A list of organizations represented on this committee can be
3、obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 .Published by BSI Standards Limited 2017ISBN 978 0 580 91961 9 ICS 13.320Compliance
4、with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS EN 50402:2017EUROPEAN STANDARD NO
5、RME EUROPENNE EUROPISCHE NORM EN 50402 March 2017 ICS 13.320 Supersedes EN 50402:2005 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 gas detection systems Matriel lectrique pour l
6、a dtection et la mesure des gaz ou vapeurs combustibles ou toxiques, ou de loxygne - Exigences relatives la fonction de scurit des systmes de dtection de gaz Elektrische Gerte fr die Detektion und Messung von brennbaren oder toxischen Gasen und Dmpfen oder Sauerstoff - Anforderungen an die funktiona
7、le Sicherheit von Gaswarnsystemen This European Standard was approved by CENELEC on 2017-02-04. 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-
8、to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by tr
9、anslation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic
10、, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingd
11、om. European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CENELEC All rights of exploitation in any form and by any means reserved
12、worldwide for CENELEC Members. Ref. No. EN 50402:2017 E BS EN 50402:2017Contents Page European foreword . 7 Introduction . 8 1 Scope 10 2 Normative references 11 3 Terms and definitions . 12 4 General requirements . 17 4.1 Specification of safety functions . 17 4.2 Determination of safety function .
13、 23 4.3 Functional safety characteristics of modules 24 5 Functional modules and elements Characterization and requirements . 25 5.1 General . 25 5.1.1 Structure of functional modules 25 5.1.2 General requirements . 29 5.2 Gas sampling . 30 5.2.1 Gas aspiration 30 5.2.2 Conditioning of measured gas
14、. 30 5.2.3 Gas multiplexer 31 5.2.4 Gas sampling by diffusion mode . 31 5.2.5 Automatic calibration and adjustment 31 5.3 Sensor 32 5.4 Signal-transmission 33 5.4.1 General requirements . 33 5.4.2 Signal-transmission between spatially separated modules . 33 5.4.3 Signal-transmission between modules
15、not spatially separated 35 5.5 Input to signal processing 36 5.5.1 General . 36 5.5.2 Interface for measured signal 36 5.5.3 Input system communication . 36 5.5.4 User interface . 36 5.5.5 Input from periphery . 37 5.5.6 Power supply . 37 5.6 Signal processing 37 5.6.1 General . 37 5.6.2 Calculation
16、 of measured values 39 5.6.3 Special state . 39 5.6.4 Signal assessment 40 5.6.5 Diagnostic means within a control unit 41 5.6.6 Reduced mode of operation . 43 5.6.7 Aspiration control 44 5.6.8 Gas multiplexer control 44 5.6.9 Control of automatic calibration 44 5.6.10 Control of automatic adjustmen
17、t . 45 5.7 Output of the control . 45 5.7.1 Visual indication 45 5.7.2 Switching output . 46 5.7.3 Output system communication 47 5.7.4 Output to periphery . 48 5.7.5 Data archives . 48 6 Software . 49 6.1 General requirements . 49 6.2 Context of the Software Standard . 49 6.3 Requirements from EN 6
18、1508-3 . 49 EN 50402:2017 (E)BS EN 50402:2017EN 50402:2017 (E) 3 6.4 List of replaced or not relevant clauses in EN 61508-3:2010 50 6.5 List of changes to clauses in EN 61508-3 . 51 6.6 EN 50402 Levels of rigour 54 6.7 Tables of techniques and measures from EN 61508-3:2010, Annex A 55 6.7.1 Explanat
19、ion of terms . 55 6.7.2 Writing conventions in the tables of techniques and measures 55 6.7.3 Software requirements specification 55 6.7.4 Software architecture design . 58 6.7.5 Software design and development Support tools and programming language 62 6.7.6 Software detailed design 62 6.7.7 Softwar
20、e module testing and integration 65 6.7.8 PE integration (hardware + software) 67 6.7.9 Software validation 68 6.7.10 Modification . 69 6.7.11 Software Verification . 70 7 Combining Functional Modules to Safety Functions 72 7.1 SIL-capability . 72 7.2 Determination of SIL-capabilities for a safety f
21、unction . 73 7.2.1 General . 73 7.2.2 Summarizing of single chains 74 7.2.3 Summarizing of parallel chains . 74 8 Determination of hardware failure rates for each safety function . 75 9 Gas detection as part of an overall safety function . 76 10 Information requirements . 77 11 Validation . 78 12 Fu
22、nctional safety management 79 13 Functional safety assessment . 79 14 Documentation 79 Annex A (normative) Transformation of the SIL-capabilities of gas detection systems . 80 A.1 Introduction 80 A.2 Transformation of the SIL-capabilities of gas detection systems to the safety integrity levels of EN
23、 61508 (all parts) 80 Annex B (normative) Transformation from generic standard requirements to modules 81 B.1 General . 81 B.2 SIL-capability 1 81 B.3 SIL-capability 2 81 B.4 SIL-capability 3 82 Annex C (informative) Determination of SIL-capability of a safety function of the gas detection system 83
24、 C.1 General . 83 C.2 Procedure of determination of SIL-capability 83 C.3 Example: Determination of SIL-capability for a gas detection system 89 C.3.1 General . 89 C.3.2 Example: Characterization of relay outputs of control units A and B . 89 C.3.3 Example: Characterization of relay output of common
25、 alarm 91 Annex D (informative) Failure modes for specific measuring principles 93 BS EN 50402:2017D.1 Introduction 93 D.2 Failure modes relevant to most or all types of measuring principles and types of sensing elements . 93 D.2.1 Generic failure modes . 93 D.2.2 Failure modes identified in the met
26、rological standards 93 D.3 Catalytic sensing elements 94 D.4 Thermal conductivity sensing elements . 94 D.5 Infrared sensing elements 94 D.5.1 Point detectors 94 D.5.2 Open path detectors 95 D.5.3 TDLAS (e.g. for oxygen) 95 D.6 Semiconductor sensing elements . 95 D.7 Electrochemical sensing elements
27、 95 D.7.1 Galvanic Lead based oxygen 95 D.7.2 Amperometric with organic or aqueous electrolyte 96 D.8 FID sensing elements 96 D.9 FTA sensing elements 96 D.10 Paramagnetic sensing elements 97 D.10.1 General . 97 D.10.2 Principle using a dumbbell . 97 D.10.3 Microflow Measuring Principle 97 D.10.4 Me
28、asurement of magnetic susceptibility 98 D.10.5 Paramagnetic thermal effect 98 D.11 PID sensing elements . 98 Figures Figure 1 Definitions of measuring point, measuring group and measuring location. 14 Figure 2a Gas detection system plus actuator for safety function 18 Figure 2b Gas detection system
29、plus actuator for safety function 19 Figure 2c Gas detector with relay output plus actuator for safety function 20 Figure 2d Gas detection system plus actuator for safety function 20 Figure 2e Gas detection system plus actuator for safety function 21 Figure 2f Gas detection system plus actuator for
30、safety function . 22 Figure 2 Examples for the overall safety function of gas detection systems . 22 Figure 3 Overview of safety-related system . 26 Figure 4 Modules of a gas detection system 28 Figure 5 Architectures for data communication . 35 Figure 6 Single and parallel chains 73 Figure 7 Handli
31、ng of complex modules in a redundant structure 75 EN 50402:2017 (E)BS EN 50402:2017EN 50402:2017 (E) 5 Figure C.1 Step 1 Linkage of modules 83 Figure C.2 Step 2 Identification of modules necessary for the safety function . 84 Figure C.3 Step 3 Elimination of modules and linkages without influence on
32、 the safety function 84 Figure C.4 Step 4 (1st loop) Summarizing of single chains . 84 Figure C.5 Step 5 (1st loop) Summarizing of parallel chains . 85 Figure C.6 Step 6 (1st loop) Adaptation of block diagram structure . 87 Figure C.7 Step 4 (2nd loop) Summarizing of single chains 87 Figure C.8 Step
33、 5 (2nd loop) Summarizing of parallel chains 87 Figure C.9 Step 6 (2nd loop) Adaptation of block diagram structure No action required . 88 Figure C.10 Step 4 (3rd loop) Summarizing of single chains . 88 Figure C.11 Step 5 (3rd loop) Summarizing of parallel chains 88 Figure C.12 Step 6 (3rd loop) Ada
34、ptation of block diagram structure No action required 88 Figure C.13 Step 4 (4th loop) Summarizing of single chains End of procedure . 89 Figure C.14 Step 1 Linkages between modules for the example . 89 Figure C.15 Step 2 Identification of modules with influence on the safety function . 90 Figure C.
35、16 Step 3 Elimination of modules and linkages without influence on the safety function 90 Figure C.17 Step 4 Summarizing of single chains 90 Figure C.18 Step 5 Summarizing of parallel chains End of procedure 90 Figure C.19 Step 2 Identification of modules with influence on the safety function . 91 F
36、igure C.20 Step 3 Elimination of modules and linkages without influence on the safety function 91 Figure C.21 Step 4 (1st loop) Summarizing of single chains . 92 Figure C.22 Step 5 (1st loop) Summarizing of parallel chains . 92 Figure C.23 Step 6 (1st loop) Adaptation of block diagram structure No a
37、ction required . 92 Figure C.24 Step 4 (2nd loop) Summarizing of single chains End of procedure 92 Tables Table 1 Fault tolerance for simple modules according to EN 615082:2010, (Table 2) 24 Table 2 Fault tolerance for complex modules according to EN 615082:2010, (Table 3) 25 Table 3 Diagnostic meas
38、ures for program sequence monitoring and clock from EN 615082 41 Table 4 Diagnostic measures for memory from EN 615082 42 Table 5 List of replaced or not relevant clauses in EN 615083:2010 50 Table 6 List of changes to clauses in EN 615083:2010 51 Table 7 EN 50402 levels of rigour . 54 Table 8 EN 50
39、402 software requirements specification (from EN 615083:2010, Table A.1) . 55 Table 9 Semi formal and formal methods (from EN 615083:2010, Table B.7) as applied to Table A.1 . 57 Table 10 EN 50402 software architecture design (from EN 615083:2010, Table A.2) . 58 Table 11 EN 50402 software design (f
40、rom EN 615083:2010, Table A.3) . 62 Table 12 EN 50402 software detailed design (from EN 615083:2010, Table A.4) 62 BS EN 50402:2017Table 13 Semi-formal methods (EN 615083:2010, Table B.7) as applied to Table A.4 . 64 Table 14 EN 50402 software module testing and integration (from EN 615083:2010, Tab
41、le A.5) 65 Table 15 EN 50402 PE integration (hardware + software) (from EN 615083:2010, Table A.6) . 67 Table 16 EN 50402 software validation (from EN 615083:2010, Table A.7) 68 Table 17 EN 50402 modification (from EN 615083:2010, Table A.8) . 69 Table 18 EN 50402 software verification (from EN 6150
42、83:2010, Table A.9) . 70 Table 19 For low demand mode of operation (see EN 615081:2010, 7.6.2.9, Table 2) 76 Table 20 For high demand mode of operation or continuous mode of operation (see EN 615081:2010, 7.6.2.9, Table 3) 76 Table A.1 Transformation of the SIL-capabilities of EN 50402 to SIL of EN
43、61508 (all parts) 80 Table C.1 Determination of SIL-capability for a parallel chain block (applicable for hardware only) 86 EN 50402:2017 (E)BS EN 50402:2017EN 50402:2017 (E) 7 European foreword This document (EN 50402:2017) has been prepared by CLC/SC 31-9 “Electrical apparatus for the detection an
44、d measurement of combustible gases to be used in industrial and commercial potentially explosive atmospheres” of CLC/TC 31 “Electrical apparatus for potentially explosive atmospheres” and by CLC/TC 216 “Gas detectors”. The following dates are fixed: latest date by which this document has to be imple
45、mented at national level by publication of an identical national standard or by endorsement (dop) 2018-02-04 latest date by which the national standards conflicting with this document have to be withdrawn (dow) 2020-02-04 This document supersedes EN 50402:2005. Attention is drawn to the possibility
46、that some of the elements of this document may be the subject of patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights. EN 50402:2017 includes the following significant technical changes with respect to EN 50402:2005: In general, the standard is updated t
47、o consider the modifications in the second edition of EN 61508 for hardware and software. Route 2 of the second edition of EN 61508 will not be permitted for gas detection equipment. The standard is updated for the SIL 1 requirements to be in line with the second edition of EN 50271 specifying the m
48、inimum requirements for functional safety for performance approved gas detectors, gas detection apparatus and complete gas detection systems. The latest revisions of the metrological standards have been considered. SIL 4 has been deleted as being not appropriate to gas detection. Clauses 4 and 5 hav
49、e been updated for more detailed specification. Clause 6 for software is new. Clauses 7 to 11 are restructured for clarification of requirements and relation to EN 61508. Clause 10 is specifying more details for the customer information. The former normative Annex D is now Clause 12. The former informative Annex A has been deleted. Relevant
