EN 14034-2-2006 en Determination of explosion characteristics of dust clouds - Part 2 Determination of the maximum rate of explosion pressure rise (dp dt)max of dust clouds (Incorp.pdf

1、BRITISH STANDARDBS EN 14034-2:2006Determination of explosion characteristics of dust clouds Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)maxof dust clouds ICS 13.230g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g

2、38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58+A1:2011BS EN 14034-2:2006+A1:2011This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2006 BSI 2011ISBN 978 0 580 73581 3National forewordThis

3、 British Standard is the UK implementation of EN 14034-2:2006+A1:2011. It supersedes BS EN 14034-2:2006, which is withdrawn. The start and finish of text introduced or altered by amendment is indicated in the text by tags. Tags indicating changes to CEN text carry the number of the CEN amendment. Fo

4、r 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 plant.A list of organizations represented on this committee can be obtained on request to its secretary.This

5、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 from legal obligations.Amendments/corrigenda issued since publicationDate Comments 31 July 2011 Implementat

6、ion of CEN amendment A1:2011!“EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14034-2:2006+A1 January 2011 ICS 13.230 Supersedes EN 14034-2:2006English Version Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt

7、)maxof dust clouds Dtermination des caractristiques dexplosion des nuages de poussire - Partie 2: Dtermination de la vitesse maximale de monte en pression dexplosion (dp/dt)maxdes nuages de poussire Bestimmung der Explosionskenngren von Staub/Luft-Gemischen - Teil 2: Bestimmung des maximalen zeitlic

8、hen Druckanstiegs (dp/dt)maxvon 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 Euro

9、pean 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 CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official version

10、s (English, French, German). A 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, Be

11、lgium, Bulgaria, Croatia, Cyprus, 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 CO

12、MMITTEE FOR STANDARDIZATION COMIT 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 14034-2:2006+A1:2011: E2 Contents P

13、age Foreword 4Introduction .51 Scope 62 Normative references 63 Terms and definitions .64 Test apparatus .74.1 General 74.2 Explosion vessel 84.3 Dust dispersion system (dust container, fast acting valve, connecting tube, dust disperser) . 104.4 Ignition source 134.5 Control unit 134.6 Pressure meas

14、uring system 135 Dust sample . 136 Test procedure 137 Calibration and verification . 167.1 Calibration . 167.2 Verification 168 Safety precautions / instructions 179 Alternative test equipment / procedures 1710 Test report . 18Annex A (normative) Electro Pneumatic Valve . 19Annex B (normative) Dust

15、dispenser with 5 mm holes 22Annex C (normative) 20 l sphere 25C.1 General . 25C.2 Test apparatus 25C.3 Test conditions . 26C.4 Test procedure 26C.5 Calculation of (dp/dt)max, 20 l, Kmaxand KSt. 27Annex ZA (informative) !Relationship between this European Standard and the Essential Requirements of EU

16、 Directive 94/9/EC“ 28Bibliography . 29Figures Figure 1 1 m vessel (schematic) . 9Figure 2 Dust container with blasting cap activated valve as commonly used for explosion suppression (schematic; it is commercially available) 10Figure 3 Location of the 6 mm holes in the dust disperser 12Figure 4 Dust

17、 dispersion and pressure-time curve . 15Figure 5 Determination of the maximum rate of explosion pressure rise (dp/dt)max16Figure A.1 Electro Pneumatic Valve (schematic) . 20BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)3 Figure A.2 Discharge characteristic of dust dispersers (without dust) .

18、21Figure B.1 Location of the 5 mm holes in the dust disperser . 23Figure B.2 Rebound nozzle . 24Figure B.3 Dispersion cup 24Figure C.1 Test equipment 20 l sphere (schematic) . 26Tables Table 1 Maximum permissible deviations SEQ 17BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)4 Foreword This d

19、ocument (EN 14034-2:2006+A1:2011) has been prepared by Technical Committee CEN/TC 305 “Potentially explosive atmospheres - Explosion 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

20、an identical text or by endorsement, at the latest by July 2011, and conflicting national standards shall be withdrawn at the 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 hel

21、d responsible for identifying any or all such patent rights. This document includes Amendment 1, approved by CEN on 2010-11-13. This document supersedes EN 14034-2:2006. The start and finish of text introduced or altered by amendment is indicated in the text by tags !“. This document has been prepar

22、ed under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directives. 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 on

23、e of a series of standards as listed below: EN 14034 “Determination of explosion characteristics of dust clouds“ Part 1: Determination of the maximum explosion pressure pmaxof dust clouds; Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)maxof dust clouds; Part 3: Determin

24、ation of the lower explosion limit LEL of dust clouds; Part 4: Determination of the limiting oxygen concentration LOC of dust clouds. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Aust

25、ria, Belgium, Bulgaria, Croatia, Cyprus, 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. BS E

26、N 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)5 Introduction This European Standard specifies a method for experimental determination of the maximum rate of explosion pressure rise of dust clouds. The maximum rate of explosion pressure rise is the maximum value of the pressure rise per unit time

27、during explosions of explosive atmospheres in the explosion range of a combustible dust in a closed vessel. The measurement of the maximum rate of explosion pressure rise forms the basis for explosion protection by design and construction of equipment, protective systems and components to reduce the

28、 explosion effects. !deleted text“ BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)6 1 Scope This standard describes a test method for the determination of the maximum rate of explosion pressure rise of dust clouds in a closed vessel under defined initial conditions of pressure and temperature.

29、 This method is not suitable for use with recognised explosives, 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 ab

30、out the existence of hazard due to explosive properties, expert advice 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

31、of the referenced document (including any amendments) applies. EN 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 w

32、hich may remain suspended in air for some time (includes dust and 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 syn

33、onymously. 3.3 explosion pressure pexhighest overpressure occurring 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 ign

34、ition has occurred, combustion spreads to the entire unburned mixture 3.5 ignition delay tvtime between the initiation of the dust dispersion and the activation of the ignition source BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)7 3.6 initial pressure pi pressure in the explosion vessel at t

35、he moment of ignition 3.7 initial temperature Ti temperature in the explosion vessel at the moment of ignition 3.8 Kmax, KSt dust specific, volume independent characteristic which is calculated using the cubic law equation ()maxSt3/1maxconst.d/d KKVtp = 3.9 rate of explosion pressure rise (dp/dt)ex

36、the maximum slope of the pressure/time curve during an explosion of a dust cloud in a closed vessel 3.10 maximum rate of explosion pressure rise (dp/dt)max maximum value of the pressure rise per unit time during explosions of all explosive atmospheres in the explosion range of a combustible substanc

37、e 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(EN 26184-1) and KSt(VDI 2263-1) but the units of the latter are bar m s-1whereas the unit of the (dp/dt)max

38、is bar s-1. 4 Test apparatus 4.1 General The standard test apparatus to determine the maximum rate of explosion pressure rise (dp/dt)maxof dust clouds is an explosion pressure resistant vessel of 1 m, as used for the determination of the maximum explosion pressure and the lower explosion limit of du

39、st clouds as well as the limiting oxygen concentration of dust/air/inert gas mixtures. The main components of the test apparatus are explosion vessel; dust dispersion system; ignition source; control unit; pressure measuring system. NOTE The 20 l sphere apparatus is an alternative explosion vessel f

40、or these determinations (see Annex C). BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)8 4.2 Explosion vessel The standard explosion vessel is an explosion pressure resistant, spherical or cylindrical vessel having a volume of 1 m in accordance with EN 14460. The aspect ratio of the cylindrical

41、 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 mechanical cut-offs as far as possible to ensure that any openings in the vessel (e.g. main doo

42、r, 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 vented before the vessel can be opened. BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)

43、9 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) BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)10 4.3 Dust dispersion system (dust container, fast

44、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 20 bar (see Figure 2). The dust container has an outlet at the base, through which the

45、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 a small ring. The ring is destroyed by firing a blasting cap and the valve opens due t

46、o 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 explosion vessel. The connecting tube between the fast acting valve and the dust dispers

47、er 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 container with blasting cap activated valve as commonly used for explosion suppression (sche

48、matic; 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 diameter of 21,7 mm1)is fitted with 13 holes of a diameter of 6 mm (incl. one hole in

49、 each end cap) which are located as shown in Figure 3 (see also Figure 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 1) (e.g. EN ISO 1127, DN 20, 3/4“) BS EN 14034-2:2006+A1:2011EN 14034-2:2006+A1:2011 (E)11 special dust dispersers,