1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 50495:2010Safety devices required for thesafe functioning of equipmentwith respect to explosion risksBS EN 50495:2010 BRITISH STANDARDNational forewordThis British Standard
2、 is the UK implementation of EN 50495:2010.The UK participation in its preparation was entrusted to TechnicalCommittee GEL/31, Equipment for explosive atmospheres.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to inc
3、lude all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 70994 4ICS 13.230; 29.260.20Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards
4、 Policy and Strategy Committee on 30 September 2010.Amendments issued since publicationDate Text affectedBS EN 50495:2010EUROPEAN STANDARD EN 50495 NORME EUROPENNE EUROPISCHE NORM February 2010 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotech
5、nique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: Avenue Marnix 17, B - 1000 Brussels 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 50495:2010 E ICS 13.230; 29.260.30 English version Safety devices
6、 required for the safe functioning of equipment with respect to explosion risks Dispositifs de scurit ncessaires pour le fonctionnement sr dun matriel vis-vis des risques dexplosion Sicherheitseinrichtungen fr den sicheren Betrieb von Gerten im Hinblick auf Explosionsgefahren This European Standard
7、was approved by CENELEC on 2009-12-01. 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 and bibliographical references concerning s
8、uch 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 responsibility of a CENELEC member into its own
9、 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, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Irela
10、nd, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 50495:2010EN 50495:2010 2 Foreword This European Standard was prepared by the Technical Committee CENELEC TC 31, Electrica
11、l apparatus for potentially explosive atmospheres. The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50495 on 2009-12-01. This European Standard is to be read in conjunction with the European Standards for the specific types of protection listed in EN 60079 or
12、EN 61241 series of standards. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date by which the EN
13、 has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2010-12-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2012-12-01 This European Standard has been prepared under a mandate given to CEN
14、ELEC by the European Commission and the European Free Trade Association and covers essential requirements of EC Directive 94/9/EC. See Annex ZZ. _ BS EN 50495:2010 3 EN 50495:2010 Contents Introduction . 4 1 Scope . 5 2 Normative references . 6 3 Terms and definitions . 7 4 Ignition prevention by sa
15、fety devices . 10 4.1 General concept of ignition risk reduction 10 4.2 Selection of a safety device 11 5 Functional requirements for a safety device . 11 5.1 General requirements . 11 5.2 Special requirements for safety components . 13 5.3 Requirements for achieving the Safety Integrity Level (SIL)
16、 13 6 Tests . 15 6.1 Type tests . 15 6.2 Routine tests . 16 6.3 Regular functional proof tests . 16 7 Marking 16 8 Safety instructions 17 Annex A (informative) Example of an assessment procedure for a simple safety device 18 Annex B (informative) Example of an assessment procedure for the hardware s
17、afety integrity of a safety device . 19 Annex C (informative) Example of determining the hardware safety integrity level 24 Annex D (informative) Examples for safety devices 33 Annex E (informative) Basic concept for safety devices 34 Annex ZZ (informative) Coverage of Essential Requirements of EC D
18、irectives. 36 Bibliography 37 Tables Table 1 Requirements for Safety Integrity Level and Fault Tolerance of a safety device . 11 Table B.1 Failure rates assuming a series failure model 20 Table B.2 Safety Integrity Levels: Target failure measures for a safety function 22 Table B.3 Hardware safety in
19、tegrity: Architectural constrains on Type A or B safety-related subsystems . 23 Table C.1 Total hardware failure rates 31 Table E.1 Increase of the failure tolerance of equipment by the control of a safety device 34 Table E.2 Classified area, in which the ignition probability of controlled equipment
20、 would lead to a tolerable risk . 35 Table E.3 Required SIL and HFT of a safety device for the control of equipment 35 BS EN 50495:2010EN 50495:2010 4 Introduction Safety devices, controlling devices and regulating devices which are used for the protection concept of equipment for explosive atmosphe
21、res, shall function reliably for the intended purpose. This shall be expressed in terms of some measure of confidence that the devices will be able to maintain a required level of safety at all times. This measure of confidence needs to be in conformity with 1, CENELEC standards of the series EN 600
22、79 and EN 61241 for apparatus for use in explosive atmospheres and relevant control standards. CENELEC identified the need for research to determine whether existing and proposed standards in the field of safety-related control systems were suitable for this purpose. Research proposals on this topic
23、 were invited under the Standardisation, Measurement and Testing (SMT) Programme of the EU-commission and the SAFEC project was selected for funding (contract SMT4-CT98-2255). The project was a 12 month project which began in January 1999. The SAFEC partners were the Health and Safety Laboratory (HS
24、L) of the Health and Safety Executive in the UK (the project coordinator), the Deutsche Montan Technologie (DMT) in Germany, the National Institute for Industrial Environment and Risks (INERIS) in France and the Laboratorio Oficial J.M. Madariaga (LOM) in Spain. The result of this project is summari
25、sed in 2 and recommends the application of Safety Integrity Levels as specified in EN 61508-1 for safety devices. A short description of the basic concept is provided in Annex E of this standard. BS EN 50495:2010 5 EN 50495:2010 1 Scope This European Standard specifies the requirements of electrical
26、 safety devices, which are used to avoid potential ignition sources of equipment in explosive atmospheres. This also includes safety devices, which are operated outside areas with explosive atmospheres, to guarantee the safe function of equipment with respect to explosion hazards. NOTE 1 This Europe
27、an Standard can also be used to design and assess safety devices for protective systems. Electrical equipment, which is intended for use in explosive atmospheres, may rely on the correct operation of safety devices which for example maintain certain characteristics of the equipment within acceptable
28、 limits. Examples of such safety devices are motor protection devices (to limit temperature rise during stall conditions) and controlling devices for pressurisation protection. By means of control or monitoring devices, sources of ignition can be avoided. Therefore these devices shall execute the ap
29、propriate measures in the appropriate reaction time, for example the initiation of an alarm or an automatic shut down. NOTE 2 Some potential ignition sources might not be controllable by safety devices, e.g. electrostatic discharges, ignition sparks caused by mechanical impact. Also some protection
30、measures might not be controllable by safety devices, e.g. flameproof enclosures. Safety devices, whose safety function can not adequately be specified under the existing EN 60079 or EN 61241 series of standards, shall additionally be designed according to the requirements of this standard. Generall
31、y for complex safety devices appropriate design requirements are not provided in the existing types of protection (see 3.13 for the definition of a complex device). NOTE 3 In general the levels of safety required by this standard are considered to be equivalent to those provided by conformity to EN
32、60079-0 or EN 61241-0. No increase or decrease of safety is intended or required. Similarly neither increase nor decrease of safety with respect to EN 61508 series is intended. Safety devices can be classified in 2 types: a) devices, which are included as component in the equipment under control (se
33、e 3.8). The combined apparatus is considered as equipment. EXAMPLES - thermal switch or thermistor to avoid overheating, - temperature monitoring devices to control the surface temperature. b) devices, which are installed separately from the equipment under control and considered as associated appar
34、atus exclusively for a specific type of protection or specific equipment under control. The combined apparatus is considered as a system. EXAMPLES - external control devices or safety related parts of a control system for type of protection pressurisation, - overload protective device for electric m
35、otors of type of protection Ex e Increased Safety, - control devices for battery charging equipment (protection against overcharging or deep discharging), - level detectors for the control of submersible pumps. Exclusions from this standard: Safety devices, where the safety function is adequately co
36、vered in the existing standards of EN 60079 and EN 61241 series do not need any additional assessment according to this standard. EXAMPLES Intrinsically safe associated apparatus, fuses, electromechanical overload protection, simple thermal protection devices (e.g. thermal fuses, thermal switches).
37、The standard does not include devices or systems to prevent the occurrence of explosive atmospheres, e.g. inerting systems, ventilation in workplaces and containers/vessels. BS EN 50495:2010EN 50495:2010 6 Gas detectors, which are covered under EN 61779 series, EN 50271 or EN 50402 are also excluded
38、 from the scope of this standard. This standard does not deal with protection by control of ignition source b for non-electrical equipment as defined in EN 13463-6. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references,
39、 only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13237 Potentially explosive atmospheres Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres EN 13
40、463-6 Non-electrical equipment for use in potentially explosive atmospheres Part 6: Protection by control of ignition source b EN 50271 Electrical apparatus for the detection and measurement of combustible gases, toxic gases or oxygen Requirements and tests for apparatus using software and/or digita
41、l technologies EN 50402 + A1 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 EN 60079 series Explosive atmospheres (IEC 60079 series) EN 60079-0 Electrical apparatus for
42、explosive gas atmospheres Part 0: General requirements (IEC 60079-0, mod.) EN 60079-10-1 Explosive atmospheres Part 10-1: Classification of areas Explosive gas atmospheres (IEC 60079-10-1) EN 60079-30-1 Explosive atmospheres Part 30-1: Electrical resistance trace heating General and testing requirem
43、ents (IEC 60079-30-1) EN 60079-30-2 Explosive atmospheres Part 30-2: Electrical resistance trace heating Application guide for design, installation and maintenance (IEC 60079-30-2) EN 60812 Analysis techniques for system reliability Procedure for failure mode and effects analysis (FMEA) (IEC 60812)
44、EN 61010-1 Safety requirements for electrical equipment for measurement, control, and laboratory use Part 1: General requirements (IEC 61010-1) EN 61025 Fault tree analysis (FTA) (IEC 61025) EN 61165 Application of Markov techniques (IEC 61165) EN 61241 series Electrical apparatus for use in the pre
45、sence of combustible dust (IEC 61241 series) EN 61241-0 Electrical apparatus for use in the presence of combustible dust Part 0: General requirements (IEC 61241-0, mod.) EN 61496-1 Safety of machinery Electro-sensitive protective equipment Part 1: General requirements and tests (IEC 61496-1, mod.) E
46、N 61508 series Functional safety of electrical/electronic/programmable electronic safety-related systems (IEC 61508 series) BS EN 50495:2010 7 EN 50495:2010 EN 61508-1 Functional safety of electrical/electronic/programmable electronic safety-related systems Part 1: General requirements (IEC 61508-1)
47、 EN 61508-2:2001 Functional safety of electrical/electronic/programmable electronic safety-related systems Part 2: Requirements for electrical/electronic/programmable electronic safety-related systems (IEC 61508-2:2000) EN 61508-3 Functional safety of electrical/electronic/programmable electronic sa
48、fety-related systems Part 3: Software requirements (IEC 61508-3) EN 61508-4 Functional safety of electrical/electronic/programmable electronic safety-related systems Part 4: Definitions and abbreviations (IEC 61508-4) EN 61508-7:2001 Functional safety of electrical/electronic/programmable electronic
49、 safety-related systems Part 7: Overview of techniques and measures (IEC 61508-7:2000) EN 61511 series Functional safety Safety instrumented systems for the process industry sector (IEC 61511 series) EN 61511-1:2004 Functional safety Safety instrumented systems for the process industry sector Part 1: Framework, definitions, system, hardware and software requirements (IEC 61511-1:2003) EN 61779 series Electrical apparatus for the detection and measurement of flammable
