prEN 50402:2013

SLOVENSKI STANDARD
01-julij-2013
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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
Elektrische Geräte für die Detektion und Messung von brennbaren oder toxischen Gasen
und Dämpfen oder Sauerstoff - Anforderungen an die funktionale Sicherheit von
ortsfesten Gaswarnsystemen
Appareils électriques pour la détection et la mesure des gaz ou vapeurs combustibles ou
toxiques ou de l'oxygène - Exigences relatives à la sécurité fonctionnelle des systèmes
fixes de détection de gaz
Ta slovenski standard je istoveten z: prEN 50402:2013
ICS:
13.230 Varstvo pred eksplozijo Explosion protection
13.320 Alarmni in opozorilni sistemi Alarm and warning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 50402
NORME EUROPÉENNE
May 2013
EUROPÄISCHE NORM
ICS 13.320 Will supersede EN 50402:2005 + corr. Jan.2009 + A1:2008

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

Appareils électriques pour la détection et la Elektrische Geräte für die Detektion und
mesure des gaz ou vapeurs combustibles Messung von brennbaren oder toxischen
ou toxiques ou de l'oxygène - Gasen und Dämpfen oder Sauerstoff -
Exigences relatives à la sécurité Anforderungen an die funktionale Sicherheit
fonctionnelle des systèmes fixes de von ortsfesten Gaswarnsystemen
détection de gaz
This draft European Standard is submitted to CENELEC members for CENELEC enquiry.
Deadline for CENELEC: 2013-10-18.

It has been drawn up by CLC/SC 31-9.

If this draft becomes a European Standard, 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.
This draft European Standard was established by CENELEC 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 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, 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they
are aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change
without notice and shall not be referred to as a European Standard.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Project: 23419 Ref. No. prEN 50402:2013 E

1 Contents Page
2 Foreword . 6
3 Introduction . 7
4 1 Scope . 8
5 2 Normative references . 9
6 3 Terms and definitions . 9
7 4 General requirements . 14
4.1 Specification of Safety functions . 14
9 4.2 Determination of Safety Function . 17
10 4.3 Functional safety characteristics of modules . 18
11 5 Functional modules and elements — Characterisation and requirements . 19
12 5.1 General . 19
13 5.2 Gas sampling . 24
14 5.3 Sensor . 26
15 5.4 Signal-transmission . 27
16 5.5 Input to signal processing . 29
17 5.6 Signal processing . 31
18 5.7 Output of the control unit . 38
19 6 Software . 41
20 6.1 General requirements . 41
21 6.2 Context of the Software Standard . 42
22 6.3 Requirements from EN 61508-3 . 42
23 6.4 List of Replaced or not Relevant Clauses in EN 61508-3:2010 . 43
24 6.5 List of Changes to Clauses in EN 61508-3 . 43
25 6.6 EN 50402 Required Levels of Rigour . 46
26 6.7 Tables of Techniques and Measures from EN 61508-3 Annex A . 46
27 7 Combining Functional Modules to Safety Functions . 59
28 7.1 SIL-capability . 59
29 7.2 Determination of SIL-capabilities for a safety function . 59
30 8 Determination of Hardware Failure Rates for each Safety Function . 62
31 9 Gas detection as Part of an overall Safety Function . 63
32 10 Information requirements . 64
33 11 Validation. 65
34 12 Functional safety management . 65
35 13 Functional safety assessment . 65
36 14 Documentation . 66
37 Annex A (normative) Transformation of the SIL-capabilities of gas detection systems . 67
38 A.1 Introduction . 67
39 A.2 Transformation of the SIL-capabilities of gas detection systems to the safety integrity
40 levels of EN 61508 (all parts) . 67
41 Annex B (normative) Transformation from generic standard requirements to modules . 68
42 B.1 General . 68
43 B.2 SIL-capability 1 . 68
44 B.3 SIL-capability 2 . 68
45 B.4 SIL-capability 3 . 69
46 Annex C (normative) Determination of SIL-capability of a safety function of the gas detection
47 system . 70
48 C.1 General . 70
49 C.2 Procedure of determination of SIL-capability . 70
50 C.3 Example: Determination of SIL-capability for a gas detection system . 74
51 Annex D (informative) Failure Modes for Specific Measuring Principles . 79
52 D.1 Introduction . 79
53 D.2 Failure modes relevant to most or all types of measuring principles and types of sensing
54 elements . 79
55 D.3 Catalytic Sensing Elements . 79
56 D.4 Thermal Conductivity Sensing Elements . 80
57 D.5 Infrared Sensing Elements . 80
58 D.6 Semiconductor Sensing Elements . 81
59 D.7 Electrochemical Sensing Elements . 81
D.8 FID Sensing Elements . 82
61 D.9 FTA Sensing Elements . 82
62 D.10 Paramagnetic Sensing Elements . 82
63 D.11 PID Sensing Elements . 84
64 Bibliography . 85
66 Figures
67 Figure 1 - Definitions of measuring point, measuring group and measuring location . 12
68 Figure 2 – Gas detection system and possible safety functions . 16
69 Figure 3 – Overview of safety-related system . 20
70 Figure 4 – Modules of a gas detection system . 22
71 Figure 5 - Single and parallel chains . 60
72 Figure 6 – Handling of complex modules in a redundant structure . 62
73 Figure C.1 – Step 1 – Linkage of modules . 70
74 Figure C.2 – Step 2 – Identification of modules necessary for the safety function . 71
75 Figure C.3 – Step 3 – Elimination of modules and linkages without influence on the safety
76 function . 71
st
77 Figure C.4 – Step 4 (1 loop) – Summarising of single
...