1、BRITISH STANDARDBS EN 14034-4:2004Determination of explosioncharacteristics of dust clouds Part 4: Determination of the limiting oxygen concentration LOC of dust cloudsICS 13.230g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g5
2、4g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58+A1:2011National forewordThis British Standard is the UK implementation of EN 14034-4:2004+A1:2011. It supersedes BS EN 14034-4:2004 which is withdrawn.The start and finish of text introduced or altered by amendment is ind
3、icated in the text by tags. Tags indicating changes to CEN text carry the number of the CEN amendment. For example, text altered by CEN amendment A1 is indicated by !“.The UK participation in its preparation was entrusted to Technical Committee FSH/23, Fire precautions in industrial and chemical pla
4、nt.A list of organizations represented on this committee can be 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.Compliance with a British Standard cannot confer immunity fr
5、om legal obligations.BS EN 14034-4:2004+A1:2011This British Standard was published under the authority of the Standards Policy and Strategy Committee on 24 June 2005 BSI 2011Amendments/corrigenda issued since publicationDate Comments 31 July 2011 Implementation of CEN amendment A1:2011ISBN 978 0 580
6、 73583 7EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14034-4:2004+A1 January 2011 ICS 13.230 Supersedes EN 14034-4:2004English Version Determination of explosion characteristics of dust clouds - Part 4: Determination of the limiting oxygen concentration LOC of dust clouds Dtermination des ca
7、ractristiques dexplosion des nuages de poussire - Partie 4: Dtermination de la concentration limite en oxygne CLO des nuages de poussire Bestimmung der Explosionskenngren von Staub/Luft-Gemischen - Teil 4: Bestimmung der Sauerstoffgrenzkonzentration SGK von Staub/Luft-Gemischen This European Standar
8、d was approved by CEN on 9 July 2004 and includes Amendment 1 approved by CEN on 13 November 2010. CEN 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-t
9、o-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by transla
10、tion under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland,
11、 France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMIT
12、EE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14034-4:2004+A1:2011: E2 Contents page Foreword 31 Scope 52 Normative references 53 Terms and definitions .54 T
13、est apparatus .64.1 General 64.2 Explosion vessel 84.3 Dust dispersion system (dust container, fast acting valve, connecting tube, dust disperser) 84.4 Ignition source 124.5 Control unit 124.6 Pressure measuring system 124.7 Oxygen measuring system 124.8 System to create the inert gas/air-mixture .
14、125 Dust sample . 126 Test procedure 127 Calibration and verification . 157.1 Calibration . 157.2 Verification 158 Safety precautions / instructions for use . 159 Alternative test equipment / procedures 1610 Test report . 16Annex A (normative) Electro pneumatic valve 17Annex B (normative) Dust dispe
15、rser with 5 mm holes . 20Annex C (normative) 20 l sphere . 24C.1 General . 24C.2 Test apparatus 24C.3 Test conditions . 25C.4 System to create the inert gas/air-mixture . 26C.5 Test procedure 26Annex D (informative) Examples of procedures to determine the LOC 27Annex ZA (informative) !Relationship b
16、etween this European Standard and the Essential Requirements of EU Directive 94/9/EC“ 29Bibliography . 30BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)3 Foreword This document (EN 14034-4:2004+A1:2011) has been prepared by Technical Committee CEN/TC 305 “Potentially explosive atmospheres - Ex
17、plosion prevention and protection”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2011, and conflicting national standards shall be withdrawn at the
18、 latest by July 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document includes Amendment 1, approved by CEN on 2010-11-1
19、3. This document supersedes EN 14034-4:2004. The start and finish of text introduced or altered by amendment is indicated in the text by tags !“. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential re
20、quirements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. This document includes a Bibliography. This document is one of a series of standards as listed below: EN 14034-1,Determination of explosion characteristics of d
21、ust clouds - Part 1: Determination of the maximum explosion pressure pmaxof dust clouds; !EN 14034-2“, Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)maxof dust clouds; !EN 14034-3“, Determination of explosion c
22、haracteristics of dust clouds Part 3: Determination of the lower explosion limit LEL of dust clouds; EN 14034-4, Determination of explosion characteristics of dust clouds Part 4: Determination of the limiting oxygen concentration LOC of dust clouds. According to the CEN/CENELEC Internal Regulations,
23、 the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Net
24、herlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)4 Introduction This document specifies a method for experimental determination of the limiting oxygen concentration of dust/air/inert g
25、as mixtures. The limiting oxygen concentration is the maximum concentration of oxygen of a dust/air/inert gas mixture at which dust explosions cannot occur. The measurement of the limiting oxygen concentration forms the basis for explosion protection by ”Inerting“. This limiting oxygen concentration
26、 is a safety characteristic used for hazard identification and designing safety measures. This is done by avoidance or reduction of the amount of explosive atmosphere. !deleted text“ BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)5 1 Scope This document describes a test method for the determin
27、ation of the limiting oxygen concentration of dust clouds in a closed vessel under defined initial conditions of pressure and temperature. This method is not suitable for use with recognised explosives, like gunpowder and dynamite, substances which do not require oxygen for combustion, pyrophoric su
28、bstances, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Where any doubt exists about the existence of hazard due to explosive properties, expert advice should be sought. 2 Normative references The following referenced documents are indispensab
29、le for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. !EN 14034-1:2004+A1:2011“; Determination of explosion characteristics of dust clouds Part 1: Determ
30、ination of the maximum explosion pressure pmaxof dust clouds !EN 14034-2:2006+A1:2011; Determination of explosion characteristics of dust clouds Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)maxof dust clouds“ !EN 14460“, Explosion resistant equipment 3 Terms and defini
31、tions For the purposes of this document, the following terms and definitions apply. 3.1 dust small solid particles in the atmosphere which settle out under their own weight, but which may remain suspended in air for some time (includes dust and grit, as defined in ISO 4225). NOTE Generally maximum p
32、article size will not exceed 500 m. 3.2 combustible dust dust able to undergo an exothermic reaction with air when ignited NOTE The terms “flammable” and “combustible” are used synonymously. 3.3 ignition delay tv time between the initiation of the dust dispersion and the activation of the ignition s
33、ource 3.4 inert gas non-flammable gas which will not support combustion and does not react to produce a flammable gas BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)6 3.5 initial pressure pi the pressure in the explosion vessel at the moment of ignition 3.6 initial temperature Ti the temperatu
34、re in the explosion vessel at the moment of ignition 3.7 limiting oxygen concentration of dust clouds (LOC) maximum oxygen concentration in mixture of a combustible dust and air and an inert gas, in which an explosion will not occur, determined under test conditions specified by this document 3.8 ma
35、ximum explosion pressure pmax maximum overpressure occurring in a closed vessel during the explosion of an explosive atmosphere determined under specified test conditions and standard atmospheric conditions 3.9 maximum rate of explosion pressure rise (dp/dt)max maximum value of the pressure rise per
36、 unit time during explosions of all explosive atmospheres in the explosion range of a combustible substance in a closed vessel under specified test conditions and standard atmospheric conditions NOTE This parameter when determined in the 1 m3vessel is numerically identical with the parameters Kmax(I
37、SO 6184-1) and KSt(VDI 2263-1) but the units of the latter are bar m s-1whereas the unit of the (dp/dt)maxis bar s-1. 4 Test apparatus 4.1 General The standard test apparatus to determine limiting oxygen concentrations is an explosion pressure resistant vessel of 1 m, as used for the determination o
38、f the maximum explosion pressure, the maximum rate of explosion pressure rise (KSt-value) and the lower explosion limit of dust clouds. The main components of the test apparatus are the explosion vessel; the dust dispersion system; the ignition source; the control unit; the pressure measuring system
39、; the oxygen measuring system; the system to create the inert gas/air-mixture. NOTE The 20 l sphere apparatus is an alternative explosion vessel for these determinations (see annex C). BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)7 Key 1 Pressure sensor 2 Chemical igniters 3 Inlet for purge
40、air / inert gas 4 Dust disperser 5 Dust container 6 Fast acting valve 7 Connecting tube 8 Outlet for exhaust gas 9 Oxygen analyser Figure 1 1 m vessel (schematic) BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)8 4.2 Explosion vessel The standard explosion vessel is an explosion pressure resist
41、ant, spherical or cylindrical vessel having a volume of 1 m in accordance with !EN 14460“. The aspect ratio of the cylindrical vessel shall be 1:1 10 % (see Figure 1). NOTE It is recommended that the explosion vessel be designed to withstand an overpressure of at least 20 bar. The apparatus shall be
42、 fitted with electrical and/or mechanical cut-offs as far as possible to ensure that any openings in the vessel (e.g. main door, instrument ports, inlet or outlet) are properly closed before a test procedure can start. The apparatus shall also be equipped as far as possible to ensure that any residu
43、al pressure inside the vessel is vented before the vessel can be opened. 4.3 Dust dispersion system (dust container, fast acting valve, connecting tube, dust disperser) The dust to be dispersed is charged into a dust container having a volume of 5,4 dm. Its aspect ratio is 3:1. It is designed to wit
44、hstand an overpressure of at least 20 bar (see Figure 2). The dust container has an outlet at the base, through which the dust leaves the container. This outlet is closed by a fast acting valve activated by a blasting cap. The valve has a mushroom-shaped seal. The seal is held in position against th
45、e pressure in the dust container by a small ring. The ring is destroyed by firing a blasting cap and the valve opens due to the pressure inside the dust container (see Figure 2). The valve shall be designed so that it opens in less than 10 ms. For alternative valves see annex A. The fast acting valv
46、e is connected to the side of the explosion vessel. The connecting tube between the fast acting valve and the dust disperser shall be not longer than 350 mm (see Figure 1). BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)9 Key 1 Dust container 5 Protective hood 2 Mushroom shaped seal 6 Protecti
47、ve hood 3 Seal housing 7 Blasting cap 4 Support ring 8 Connecting tube Figure 2 Dust container with blasting cap activated valve as commonly used for explosion suppression (schematic; it is commercially available) BS EN 14034-4:2004+A1:2011EN 14034-4:2004+A1:2011 (E)10 For dispersing the dust, a per
48、forated semicircular spray pipe (dust disperser) is mounted inside the explosion vessel, concentric with its wall. The spray pipe, with an internal diameter of 21,7 mm1)is fitted with 13 holes of a diameter of 6 mm (incl. one hole in each end cap) which are located as shown in Figure 3 (see also Fig
49、ure 1). For coarse, voluminous, fibrous or poorly flowing dust samples, it may not be possible to properly discharge the dust through the dust dispersers detailed in Figures 3 and B.1. It may, therefore, be necessary to use special dust dispersers, examples of which are given in Figures B.2 and B.3. In such cases, the dust disperser used shall be described in the test report. NOTE If other dust dispersing systems
