DIN EN 14034-3-2011 Determination of explosion characteristics of dust clouds - Part 3 Determination of the lower explosion limit LEL of dust clouds German version EN 14034-3 2006+.pdf

1、April 2011 Translation by DIN-Sprachendienst.English price group 13No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS

2、13.230!$n|g“1758968www.din.deDDIN EN 14034-3Determination of explosion characteristics of dust clouds Part 3: Determination of the lower explosion limit LEL of dust clouds(includes Amendment A1:2011)English translation of DIN EN 14034-3:2011-04Bestimmung der Explosionskenngren von Staub/Luft-Gemisch

3、en Teil 3: Bestimmung der unteren Explosionsgrenze UEG von Staub/Luft-Gemischen(enthlt nderung A1:2011)Englische bersetzung von DIN EN 14034-3:2011-04Dtermination des caractristiques dexplosion des nuages de poussire Partie 3: Dtermination de la limite infrieure dexplosivit LIE des nuages de poussir

4、e(Amendement A1:2011 inclus)Traduction anglaise de DIN EN 14034-3:2011-04SupersedesDIN EN 14034-3:2006-08See start of applicationwww.beuth.deDocument comprises pagesIn case of doubt, the German-language original shall be considered authoritative.2903.11 DIN EN 14034-3:2011-04 A comma is used as the

5、decimal marker. Start of application The start of application of this standard is 1 April 2011. National foreword This standard includes safety requirements. This standard has been prepared by Technical Committee CEN/TC 305 “Potentially explosive atmospheres Explosion prevention and protection” (Sec

6、retariat: DIN, Germany). The responsible German body involved in its preparation was the Normenausschuss Sicherheitstechnische Grundstze (Safety Design Principles Standards Committee), Working Committee NA 095-02-09 AA Kenngren fr Stube, Gase und Dmpfe. The DIN Standards corresponding to the Interna

7、tional Standards referred to in this document is as follows: ISO 4225 DIN ISO 4225 Amendments This standard differs from DIN EN 14034-3:2006-08 as follows: a) specifications relating to the use of barium nitrate have been deleted. Previous editions DIN EN 14034-3: 2006-08 National Annex NA (informat

8、ive) Bibliography DIN ISO 4225, Air quality General aspects Vocabulary 2 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14034-3:2006+A1 January 2011 ICS 13.230 Supersedes EN 14034-3:2006English Version Determination of explosion characteristics of dust clouds Part 3: Determination of the lower

9、 explosion limit LEL of dust clouds Dtermination des caractristiques dexplosion des nuages de poussire Partie 3: Dtermination de la limite infrieure dexplosivit LIE des nuages de poussire Bestimmung der Explosionskenngren von Staub/Luft-Gemischen Teil 3: Bestimmung der unteren Explosionsgrenze UEG v

10、on Staub/Luft-Gemischen This European Standard was approved by CEN on 20 April 2006 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 EuropeanStandard the status of a

11、national standard without any alteration. Up-to-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

12、 version in any other language made by translation 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, Cypr

13、us, Czech Republic, Denmark, Estonia,Finland, 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 COMI

14、T EUROPEN DE NORMALISATION EUROPISCHES KOMITEE 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 14034-3:2006+A1:2011: EEN 14034-3:2006+A1:2011 (E) 2 Contents Page

15、Foreword 4Introduction .51 Scope 62 Normative references 63 Terms and definitions .64 Test apparatus .74.1 General 74.2 Explosion vessel 74.3 Dust dispersion system (dust container, fast acting valve, connecting tube, dust disperser) 94.4 Ignition source 124.5 Control unit 124.6 Pressure measuring s

16、ystem 125 Dust sample . 126 Test procedure 127 Calibration and verification . 157.1 Calibration . 157.2 Verification 158 Safety precautions/instructions 169 Alternative test equipment/procedures 1610 Test report . 16Annex A (normative) Electro Pneumatic Valve . 18Annex B (normative) Dust disperser w

17、ith 5 mm holes . 20Annex C (normative) 20 l sphere 23C.1 General . 23C.2 Test apparatus 23C.3 Test conditions . 24C.4 Test procedure 24Annex ZA (informative) !Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC“ 26Bibliography . 27Figures Figure 1 1 m v

18、essel (schematic) . 8Figure 2 Dust container with blasting cap activated valve as commonly used for explosion suppression (schematic; it is commercially available) 9Figure 3 Location of the 6 mm holes in the dust disperser 11Figure 4 Dust dispersion and pressure-time curve . 14Figure 5 Determination

19、 of the lower explosion limit LEL . 15Figure A.1 Electro Pneumatic Valve (schematic) . 18Figure A.2 Discharge characteristic of dust dispersers (without dust) 19DIN EN 14034-3:2011-04 EN 14034-3:2006+A1:2011 (E) 3 Figure B.1 Location of the 5 mm holes in the dust disperser . 21Figure B.2 Rebound noz

20、zle . 22Figure B.3 Dispersion cup 22Figure C.1 Test equipment 20 l sphere (schematic) . 24DIN EN 14034-3:2011-04 EN 14034-3:2006+A1:2011 (E) 4 Foreword This document (EN 14034-3:2006+A1:2011) has been prepared by Technical Committee CEN/TC 305 “Potentially explosive atmospheres Explosion prevention

21、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 latest by July 201

22、1. 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 2010-11-13. This document su

23、persedes EN 14034-3:2006. 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 requirements of EU Di

24、rectives. For relationship with the EU Directive 94/9/EC, see informative Annex ZA, which is an integral part of this document. This European Standard is one of a series of standards as listed below: EN 14034 “Determination of explosion characteristics of dust clouds“ Part 1: Determination of the ma

25、ximum explosion pressure pmaxof dust clouds; Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)maxof dust clouds; Part 3: Determination of the lower explosion limit LEL of dust clouds; Part 4: Determination of the limiting oxygen concentration LOC of dust clouds. According

26、to the CEN/CENELEC Internal Regulations, 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, L

27、atvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. DIN EN 14034-3:2011-04 EN 14034-3:2006+A1:2011 (E) 5 Introduction This European Standard specifies a method for experimental determination of the lo

28、wer explosion limit of dust clouds. The lower explosion limit is the lowest concentration of a combustible dust in mixture with air at which an explosion occurs. The measurement of the lower explosion limit forms the basis for hazard identification and explosion prevention. !deleted text“ DIN EN 140

29、34-3:2011-04 EN 14034-3:2006+A1:2011 (E) 6 1 Scope This standard describes a test method for the determination of the lower explosion limit 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,

30、like gunpowder and dynamite, explosives which do not require oxygen for combustion, pyrophoric substances, 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 a

31、dvice should be sought. 2 Normative references The following referenced documents are indispensable 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

32、 14460, Explosion resistant equipment 3 Terms and definitions 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

33、 grit, as defined in ISO 4225) NOTE Generally maximum particle 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 explosion pressure pex highest overpressure occurr

34、ing during an explosion of a dust cloud in a closed vessel 3.4 explosive atmosphere mixture with air, under atmospheric conditions, of flammable (combustible) substances in the form of gases, vapours, mists or dusts, in which, after ignition has occurred, combustion spreads to the entire unburned mi

35、xture 3.5 ignition delay tvtime between the initiation of the dust dispersion and the activation of the ignition source DIN EN 14034-3:2011-04 EN 14034-3:2006+A1:2011 (E) 7 3.6 initial pressure pipressure in the explosion vessel at the moment of ignition 3.7 initial temperature Ti temperature in the

36、 explosion vessel at the moment of ignition 3.8 lower explosion limit (LEL) lowest concentration of a combustible dust in mixture with air at which an explosion occurs 4 Test apparatus 4.1 General The standard test apparatus to determine the lower explosion limit of dust clouds is an explosion press

37、ure resistant vessel of 1 m, as used for the determination of the maximum explosion pressure and the maximum rate of explosion pressure rise of dust clouds as well as the limiting oxygen concentration of dust/air/inert gas mixtures. The main components of the test apparatus are explosion vessel; dus

38、t dispersion system; ignition source; control unit; pressure measuring system. NOTE The 20 l sphere apparatus is an alternative explosion vessel for these determinations (see Annex C). 4.2 Explosion vessel The standard explosion vessel is an explosion pressure resistant, spherical or cylindrical ves

39、sel 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 fitted with electrical and/or mech

40、anical 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 residual pressure inside the vessel is ve

41、nted before the vessel can be opened. DIN EN 14034-3:2011-04 EN 14034-3:2006+A1:2011 (E) 8 Key 1 pressure sensor 5 dust container 2 chemical igniters 6 fast acting valve 3 inlet for purge air 7 connecting tube 4 dust disperser 8 outlet for exhaust gas Figure 1 1 m vessel (schematic) DIN EN 14034-3:2

42、011-04 EN 14034-3:2006+A1:2011 (E) 9 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 withstand an overpressure of at least 2

43、0 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 the pressure in the dust container by

44、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 valve is connected to the side of the ex

45、plosion vessel. The connecting tube between the fast acting valve and the dust disperser shall be not longer than 350 mm (see Figure 1). Key 1 dust container 5 protective hood 2 mushroom shaped seal 6 protective hood 3 seal housing 7 blasting cap 4 support ring 8 connecting tube Figure 2 Dust contai

46、ner with blasting cap activated valve as commonly used for explosion suppression (schematic; it is commercially available) For dispersing the dust, a perforated semicircular spray pipe (dust disperser) is mounted inside the explosion vessel, concentric with its wall. The spray pipe, with an internal

47、 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 Figure 1). 1) (e.g. EN ISO 1127, DN 20, 3/4“) DIN EN 14034-3:2011-04 EN 14034-3:2006+A1:2011 (E) 10 For coarse, voluminous, fibrous or poorly flowing

48、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 than those des