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1、BRITISH STANDARD BS EN 50281-3:2002 Equipment for use in the presence of combustible dust Part 3: Classification of areas where combustible dusts are or may be present The European Standard EN 50281-3:2002 has the status of a British Standard ICS 29.100.01 ? Licensed Copy: sheffieldun sheffieldun, n
2、a, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 50281-3:2002 This British Standard, having been prepared under the direction of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 18 Oc
3、tober 2002 BSI 18 October 2002 ISBN 0 580 40602 4 National foreword This British Standard is the official English language version of EN 50281-3:2002. It partially supersedes BS 6467-2:1988 which will be withdrawn when the relevant CENELEC standards covering selection, installation and maintenance f
4、or electrical apparatus for use in the presence of combustible dust are published. The UK participation in its preparation was entrusted by Technical Committee GEL/31, Electrical apparatus for explosive atmospheres, to Subcommittee GEL/31/20, Apparatus for use in the presence of combustible dust, wh
5、ich has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the
6、section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applicatio
7、n. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor
8、 related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 24, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the
9、 document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARDEN 50281-3 NORME EUROPENNE EUROPISCHE NORMSeptember 2002 CENELEC European Committee for Ele
10、ctrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2002 CENELEC -All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref.
11、 No. EN 50281-3:2002 E ICS 29.100.01 English version Equipment for use in the presence of combustible dust Part 3: Classification of areas where combustible dusts are or may be present Appareils pour utilisation en prsence de poussires combustibles Partie 3: Classement des emplacements o des poussir
12、es combustibles sont ou peuvent tre prsentes Betriebsmittel zur Verwendung in Bereichen mit brennbarem Staub Teil 3: Einteilung von staubexplosionsgefhrdeten Bereichen This European Standard was approved by CENELEC on 2002-03-05. CENELEC members are bound to comply with the CEN/CENELEC Internal Regu
13、lations 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 Secretariat or to any CENELEC member. Th
14、is 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 as the official versions. CENELEC membe
15、rs are the national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: sheffieldun shef
16、fieldun, na, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50281-3:2002 - 2 - Foreword This European Standard was prepared by a joint Working Group (JWG 17) from CENELEC TC 31, Electrical apparatus for explosive atmospheres - General requirements, and CEN TC 305. The text of the
17、draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50281-3 on 2002-03-05. This European Standard was prepared under a mandate given to CENELEC by the European Commission and the European Free Trade Association and supports the essential safety requirements of th
18、e EC Directive 94/9/EC. 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)2003-03-01 -latest date by which the national standards conflicting with the EN have to be withdrawn(dow
19、)2005-03-01 Annexes designated “informative“ are given for information only. In this standard, annexes A to C are informative. _ Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI - 3 -EN 50281-3:2002 Contents Introduction.4 1Scope.5 2Normative
20、 references.5 3Definitions.6 4Area classification for combustible dusts.7 5Sources of release for explosive dust atmospheres9 6Zones for explosive dust atmospheres .10 7Dust layer hazard .13 8Documentation .13 Annex A (informative) Examples of area classification16 Annex B (informative) Risk of fire
21、 from hot surface ignition of dust layer.20 Annex C (informative) Housekeeping .23 Figure 1 Identification of zones on drawings.15 Figure A.1 Area classification for a bag emptying station within a building and without exhaust ventilation.16 Figure A.2 Area classification for a bag emptying station
22、within a building and with exhaust ventilation17 Figure A.3 Area classification for cyclone and filter with clean outlet outside building.18 Figure A.4 Area classification for a drum tipper within a building without exhaust ventilation19 Figure B.1 Reduction in the maximum permissible surface temper
23、ature of apparatus for increasing depth of dust layers.21 Table 1 - Designation of zones depending on presence of combustible dust.10 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50281-3:2002 - 4 - Introduction Combustible dusts are ha
24、zardous because when they are dispersed in air by any means they form potentially explosive atmospheres. Further, layers of combustible dust may ignite and act as ignition sources for an explosive atmosphere. Therefore, equipment placed in an environment where dust clouds can form should be dust ign
25、ition protected and have a surface temperature limitation below the temperature at which a dust cloud or layer will ignite. This standard gives guidance on the identification of areas where hazards from combustible dust can arise. The purpose is to permit selection of appropriate equipment for use i
26、n such areas. General and special criteria are given, with examples, for the procedure used to identify areas. By exercising ingenuity in the layout of equipment, it is frequently possible to locate much of the equipment in less hazardous or in non-hazardous locations and thus, to reduce the amount
27、of special equipment required. This standard contains an informative annex giving practical examples for classifying areas. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI - 5 -EN 50281-3:2002 1 Scope This standard is concerned with the clas
28、sification of areas where explosive dust/air mixtures and combustible dust layers are present, in order to permit the proper selection of equipment for use in such areas. In this standard, explosive dust atmospheres and combustible dust layers are treated separately. In Clause 4 area classification
29、for explosive dusts clouds is described, with dust layers acting as one of the possible sources of release. In Clause 7 the hazard of dust layer ignition is described. The standard assumes effective housekeeping based on a system of cleaning for the plant. The principles of the standard can also be
30、followed when combustible fibres or flyings may cause a hazard. This standard is intended to be applied where there can be a risk due to the presence of explosive dust/air mixtures or combustible dust layers under normal atmospheric conditions. It does not apply to ? underground mining areas, ? area
31、s where a risk can arise due to the presence of hybrid mixtures, ? dusts of explosives which do not require atmospheric oxygen for combustion, or to pyrophoric substances, ? catastrophic failures, which are beyond the concept of abnormality dealt with in this standard (see NOTE 1), ? any risk arisin
32、g from an emission of flammable or toxic gas from the dust. This standard does not take into account the effects of consequential damage following a fire or an explosion. NOTE 1 Catastrophic failure in this context is applied, for example, to the rupture of a storage silo or a pneumatic conveyor. NO
33、TE 2 In any process plant, irrespective of size, there can be numerous sources of ignition apart from those associated with equipment. Appropriate precautions will be necessary to ensure safety in this context, but these are outside the scope of this standard. 2 Normative references This European St
34、andard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply
35、to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN 1127-1 Explosive atmospheres - Explosion prevention and protection Part 1: Basic concepts and methodology EN 13
36、237-11)Potentially explosive atmosphere Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres EN 50281-1-1 Electrical apparatus for use in the presence of combustible dust Part 1-1: Electrical apparatus protected by enclosures - Construction
37、 and testing 1) At draft stage. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 06 07:23:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50281-3:2002 - 6 - EN 50281-1-2 Electrical apparatus for use in the presence of combustible dust Part 1-2: Electrical apparatus protected by enclosures - Sele
38、ction, installation and maintenance EN 50281-2-1 Electrical apparatus for use in the presence of combustible dust Part 2-1: Test methods - Methods for determining the minimum ignition temperatures of dust IEC 61241-3Electrical apparatus for use in the presence of combustible dust Part 3: Classificat
39、ion of areas where combustible dusts are or may be present. ISO 4225 Air quality - General aspects Vocabulary 3 Definitions For the purpose of this standard the following definitions apply. 3.1 area a three-dimensional region or space 3.2 atmospheric conditions (surrounding conditions) conditions th
40、at include variations in pressure and temperature above and below reference levels of 101,3 kPa (1 013 mbar) and 20 C (293 K), provided that the variations have a negligible effect on the explosive properties of the combustible dust (IEC 61241-3) 3.3 hybrid mixture mixture of flammable substances in
41、 different physical states, with air (EN 1127-1) NOTE An example of a hybrid mixture is a mixture of methane, coal dust and air. 3.4 dust small solid particles including fibres and flyings in the atmosphere which settle out under their own weight, but which may remain suspended in air for some time
42、(includes dust and grit as defined in ISO 4225) 3.5 explosive dust atmosphere a mixture with air, under atmospheric conditions, of flammable substances in the form of dust or fibres in which, after ignition, combustion spreads throughout the unconsumed mixture (IEV 426-02-04) 3.6 combustible dust du
43、st that can burn or glow in air and could form explosive mixtures with air at atmospheric pressure and normal temperatures 3.7 hazardous area (dust) area in which combustible dust in cloud form is, or can be expected to be, present in quantities such as to require special precautions for the constru
44、ction, installation and use of equipment in order to prevent ignition of an explosive dust/air mixture. Hazardous areas are divided into zones based upon the frequency and duration of the occurrence of explosive dust/air mixture Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 06 07:23:21 GMT+00:
45、00 2006, Uncontrolled Copy, (c) BSI - 7 -EN 50281-3:2002 3.8 non-hazardous area (dust) area in which combustible dust in cloud form is not expected to be present in quantities such as to require special precautions for the construction, installation and use of apparatus 3.9 dust containment those pa
46、rts of the process equipment inside which materials are handled, processed, transported or stored e.g. to prevent the release of dust to the surrounding atmosphere 3.10 source of dust release a point or location from which combustible dust can be released to the atmosphere. This can be either from a
47、 dust containment or a dust layer. Sources of release will be divided into the following grades depending on the order of decreasing severity: ? continuous formation of a dust cloud: Locations in which a dust cloud may exist continuously, or may be expected to continue for long periods or for short
48、periods which occur frequently; ? primary grade of release: A source can be expected to release combustible dust in normal operation occasionally; ? secondary grade of release: A source which is not expected to release combustible dust during normal operation but if it releases, is likely to do so o
49、nly infrequently and for short periods only 3.11 extent of zone distance in any direction from the edge of a source of release to the point where the hazard associated with the release is considered to exist no longer 3.12 normal operation the situation when the process equipment is operating within its design parameters. Minor releases of dust which may form a cloud or layer (e.g. releases from filters) can be part of normal operation 3.13 abnormal operation expected
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