oSIST prEN 50402:2013
(Main)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
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
2013-03-18 - Enquiry processing allocated to aclausse@cencenelec.eu * D139/C001: NWI approved * Will supersede EN 50402:2005 + A1:2008 * In hands of JWG CLC/SC 31-9/TC 216 * 2012-03-14: 9-month tolerance requested by SC 31-9
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
Električne naprave za odkrivanje in merjenje gorljivih ali strupenih plinov, hlapov ali kisika - Zahteve za funkcionalno varnost vgrajenih sistemov za odkrivanje plina
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 50402:2013
01-julij-2013
(OHNWULþQHQDSUDYH]DRGNULYDQMHLQPHUMHQMHYQHWOMLYLKDOLVWUXSHQLKSOLQRYKODSRY
DOLNLVLND=DKWHYH]DIXQNFLRQDOQRYDUQRVWYJUDMHQLKVLVWHPRY]DRGNULYDQMHSOLQD
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
oSIST prEN 50402:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 50402:2013
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
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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
8
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
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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
60
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
65
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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 chains . 71
st
78 Figure C.5 – Step 5 (1 loop) – Summarising of parallel chains . 71
79 Figure C.6 – Step 6 (1st loop) – Adaptation of block diagram structure . 73
nd
80 Figure C.7 – Step 4 (2 loop) – Summarising of single chains . 73
nd
81 Figure C.8 – Step 5 (2 loop) – Summarising of parallel chains . 73
nd
82 Figure C.9 – Step 6 (2 loop) – Adaptation of block diagram structure – No action required . 73
rd
83 Figure C.10 – Step 4 (3 loop) – Summarising of single chains . 74
rd
84 Figure C.11 – Step 5 (3 loop) – Summarising of parallel chains . 74
rd
85 Figure C.12 – Step 6 (3 loop) – Adaptation of block diagram structure – No action required . 74
th
86 Figure C.13 – Step 4 (4 loop) – Summarising of single chains – End of procedure . 74
87 Figure C.14 – Step 1 – Linkages between modules for the example . 75
88 Figure C.15 – Step 2 – Identification of modules with influence on the safety function . 75
89 Figure C.16 – Step 3 – Elimination of modules and linkages without influence on the safety
90 function . 76
91 Figure C.17 – Step 4 – Summarising of single chains . 76
92 Figure C.18 – Step 5 – Summarising of parallel chains – End of procedure . 76
93 Figure C.19 – Step 2 – Identification of modules with influence on the safety function . 76
94 Figure C.20 – Step 3 – Elimination of modules and linkages without influence on the safety
95 function . 77
st
96 Figure C.21 – Step 4 (1 loop) – Summarising of single chains . 77
st
97 Figure C.22 – Step 5 (1 loop) – Summarising of parallel chains . 77
st
98 Figure C.23 – Step 6 (1 loop) – Adaptation of block diagram structure – No action required . 78
nd
99 Figure C.24 – Step 4 (2 loop) – Summarising of single chains – End of procedure . 78
100
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101 Tables
102 Table 1 – Fault tolerance for simple modules according EN 61508–2:2010, Table 2 . 18
103 Table 2 - Fault tolerance for complex modules according EN 61508–2:2010, Table 3 . 18
104 Table 3 – Diagnostic measures for program sequence monitoring from EN 61508-2 . 34
105 Table 4 – Diagnostic measures for memory from EN 61508-2 . 35
106 Table 5 – List of replaced or not relevant clauses in EN 61508-3:2010 . 43
107 Table 6 – List of changes to clauses in EN 61508-3:2010. 43
108 Table 7 – EN 50402 required levels of rigour . 46
109 Table 8 – EN 50402 software requirements specification (from EN 61508-3:2010, Table A.1) . 47
110 Table 9 – Semi formal and formal methods (from EN 61508-3:2010, Table B.7) as applied to
111 Table A.1 . 48
112 Table 10 – EN 50402 software architecture design (from EN 61508-3:2010, Table A.2) . 49
113 Table 11 – EN 50402 software design (from EN 61508-3:2010, Table A.3) . 52
114 Table 12 – EN 50402 software detailed design (from EN 61508-3:2010, Table A.4) . 52
115 Table 13 – Semi formal methods (EN 61508-3:2010, Table B.7) as applied to Table A.4 . 53
116 Table 14 – EN 50402 software module testing and integration (from EN 61508-3:2010, Table A.5) . 54
117 Table 15 – EN 50402 PE integration (hardware + software) (from EN 61508-3:2010, Table A.6) . 55
118 Table 16 – EN 50402 software validation (from EN 61508-3:2010, Table A.7) . 56
119 Table 17 – EN 50402 modification (from EN 61508-3:2010, Table A.8) . 56
120 Table 18 – EN 50402 software verification (from EN 61508-3:2010, Table A.9) . 57
121 Table 19 – for low demand mode of operation (see EN 61508-1:2010, 7.6.2.9, Table 2) . 63
122 Table 20 – for high demand mode of operation or continuous mode of operation
123 (see EN 61508-1:2010, 7.6.2.9, Table 3) . 63
124 Table A.1 – Transformation of the SIL-capabilities of EN 50402 to SIL of EN 61508 (all parts) . 67
125 Table C.1 – Determination of SIL-capability for a parallel chain block . 72
126
127
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128 Foreword
129 This document [prEN 50402:2013] has been prepared by CLC/SC 31-9 "Electrical apparatus for the detection
130 and measurement of combustible gases to be used in industrial and commercial potentially explosive
131 atmospheres" of CLC/TC 31 "Electrical apparatus for potentially explosive atmospheres" and by CLC/TC 216
132 "Gas detectors".
133 This document is currently submitted to the Enquiry.
134 This document will supersede EN 50402:2005 and A1:2008.
135 Technical changes to the first edition:
136 – In General the standard is updated to consider the modifications in the second edition of EN 61508 for
137 hardware and software. Route 2 of the second edition of EN 61508 will not be permitted for gas detection
138 equipment.
139 – The standard is updated for the SIL 1 requirements to be in line with the second edition of EN 50271
140 specifying the minimum requirements for functional safety for performance approved gas detectors, gas
141 detection apparatus and complete gas detection systems.
142 – The latest revisions of the metrological standards have been considered.
143 – SIL 4 has been deleted as being not appropriate to gas detection.
144 – The Clauses 4 and 5 have been updated for more detailed specification.
145 – Clause 6 for software is new.
146 – Clauses 7 to 11 are restructured for clarification of requirements and relation to EN 61508.
147 – Clause 10 is specifying more details for the customer information.
148 – The former normative Annex D is now Clause 12.
149 – The former informative Annex A has been deleted. Relevant text was moved to Clauses 7 to 9.
150 – The new informative Annex D is providing information on failure modes of sensing elements
151
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152 Introduction
153 This European Standard specifies requirements for functional safety of gas detection systems and
154 encompasses criteria for reliability, avoidance of faults and fault tolerance. Functional safety is that part of the
155 overall safety related to the measures within the gas detection system to avoid or to handle failures in such a
156 manner that the safety function will be assured. This includes not only design requirements of the gas
157 detection system but also information requirements for planning, putting into operation, maintenance and
158 repair.
159 This European standard is dedicated to the manufacturer. Information important for the safe use of the device
160 (gas detection system) will be specified in the instruction manual.
161 Gas detection systems will fail to function if dangerous failures occur in the equipment used. Failure to function
162 will also occur if such systems are not installed or maintained in an appropriate manner. In some applications
163 failures of this type will dominate the functional safety achieved. This European Standard is only targeted at
164 reducing equipment failures to levels appropriate to the application. Users of gas detection systems will
165 therefore need to ensure installation and maintenance of such systems is carried out according to
166 requirements. This European Standard does not specify the physical positioning of measuring points /
167 locations.
168 Gas detection systems may differ strongly in structure, complexity and performance. They may not be handled
169 in a uniform manner like low complexity devices. A general specification of requirements is not possible on that
170 basis.
171 Gas detection systems therefore need to be divided into functional modules for validation to ensure that
172 systems which have different structures are handled by appropriate procedures. A gas detection system will
173 not normally include all modules covered by this European Standard. Requirements are specified for each of
174 these modules in terms of hierarchical levels which represent one of the constituents of functional safety
175 performance. The hierarchical levels are termed as SIL-capabilities, with SIL-capability 1 representing the
176 minimum and SIL-capability 3 the maximum levels of performance to comply with this European Standard. The
177 SIL-capability of a module is related to the maximum safety integrity level that may be claimed for a safety
178 function which uses modules of that specified SIL-capability. Modules will be characterised in terms of the SIL-
179 capability. Information is also required on failure rate characteristics of modules or related physical
180 components to enable the overall performance of a gas detection system to be determined. In this way both
181 random failures of hardware components and systematic failures in hardware and software are taken account
182 of. This European standard also specifies the requirements that will enable determination of whether the gas
183 detection system have a low enough failure rate when used in conjunction with other equipment necessary for
184 functional safety.
185 This European Standard will enable the functional safety characteristics of the gas detection system to be
186 determined from the characteristics of its modules and components (see Annex C). This will enable a gas
187 detection system to be used as a part of an overall safety system.
188 The characterisation including the determination of a SIL-capability and failure rate data will only need to be
189 carried out once for a particular design.
190 After characterisation of each module and component the properties of the whole gas detection system will be
191 specified depending on the chosen safety function. The procedure for determining the SIL-capability of the
192 safety function of a gas detection system will only need to be repeated for each new combination of modules
193 and components. Different combination of equivalent modules may lead to gas detection systems which reach
194 different SIL-capabilities.
195 A flexible adoption of the gas detection system to different applications will be possible without repeating all
196 steps of the validation procedure for each new configuration.
197 This European Standard does not include requirements for availability which will need to be considered
198 separately.
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199 1 Scope
200 This European Standard is applicable to fixed gas detection systems for the detection and measurement of
201 flammable or toxic gases or vapours or oxygen.
202 NOTE 1 For the purpose of this standard the word ‘toxic’ covers ‘very toxic’, ‘toxic’, ‘harmful’, ‘corrosive‘, ‘irritating‘, ‘sensitising‘,
203 ‘carcinogenic‘, ‘mutagenic‘ and ‘teratogenic‘.
204 NOTE 2 This European Standard is dedicated to fixed apparatus. For portable gas detectors claiming a SIL higher than 1, this
205 European Standard may be applied.
206 This European Standard supplements the requirements of the European Standards for electrical apparatus for
207 the detection and measurement of flammable gases, vapours (e.g. EN 60079–29–1 or EN 60079–29–4), toxic
208 gases (e.g. EN 45544) or oxygen (e.g. EN 50104).
209 NOTE 3 These European Standards are mentioned in the text as "metrological standards".
210 NOTE 4 The examples above show the state of the standardisation for industrial applications at the time of publishing this European
211 Standard. There may be other metrological standards covering other application fields, for which this European Standard is also
212 applicable.
213 NOTE 5 This European Standard covers all SIL-capabilities (1, 2 and 3) however where SIL 1 capability is the only requirement then
214 EN 50271 may be applied.
215 Applying the above-mentioned metrological standards will ensure the measuring performance is adequate in
216 normal operation of a gas detection system. Additionally the requirements of this European Standard address
217 the functional safety of gas detection systems and encompass criteria for reliability, fault tolerance and
218 avoidance of systematic faults.
219 This European Standard will lead to the characterisation of the gas detection system by a SIL-capability and
220 related hardware failure rate representing a hierarchical order of safety levels. This will allow the user to
221 incorporate the gas detection system into an overall safety system according to the safety integrity levels of
222 EN 61508 (all parts).
223 This European Standard is a product standard which is based on EN 61508 (all parts) and for gas detection
224 systems covers SIL capabilities of 1, 2 or 3 only. It covers part of the phase 10 “realisation” of the overall safety
225 lifecycle defined in Figure 2 of EN 61508-1:2010.
226 NOTE 6 Applications requiring a SIL capability of
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