EN 14034-2:2006

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust cloudsDétermination des caractéristiques d'explosion des nuages de poussiere - Partie 2: Détermination de la vitesse maximale de montée en pression d'explosion (dp/dt)max des nuages de poussiereBestimmung der Explosionskenngrößen von Staub/Luft-Gemischen - Teil 2: Bestimmung des maximalen zeitlichen Druckanstiegs (dp/dt)max von Staub/Luft-GemischenTa slovenski standard je istoveten z:EN 14034-2:2006SIST EN 14034-2:2006en13.230ICS:SLOVENSKI
STANDARDSIST EN 14034-2:200601-september-2006

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14034-2
May 2006 ICS 13.230 English Version
Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds
Détermination des caractéristiques d'explosion des nuages de poussière - Partie 2: Détermination de la vitesse maximale de montée en pression d'explosion (dp/dt)max des nuages de poussière
Bestimmung der Explosionskenngrößen von Staub/Luft-Gemischen -Teil 2: Bestimmung des maximalen zeitlichen Druckanstiegs (dp/dt)max von Staub/Luft-Gemischen This European Standard was approved by CEN on 20 April 2006.
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-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN 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 CEN member into its own language and notified to the Central Secretariat has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, 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.
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B-1050 Brussels © 2006 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14034-2:2006: E

Electro Pneumatic Valve.17 Annex B (normative)
Dust dispenser with 5 mm holes.19 Annex C (normative)
20 l sphere.22 C.1 General.22 C.2 Test apparatus.22 C.3 Test conditions.23 C.4 Test procedure.23 C.5 Calculation of (dp/dt)max, 20 l, Kmax and KSt.24 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC.25 Bibliography.26 Figures Figure 1 — 1 m³ vessel (schematic).8 Figure 2 — Dust container with blasting cap activated valve as commonly used for explosion suppression (schematic; it is commercially available).9 Figure 3 — Location of the 6 mm holes in the dust disperser.10 Figure 4 — Dust dispersion and pressure-time curve.13 Figure 5 — Determination of the maximum rate of explosion pressure rise (dp/dt)max.14 Figure A.1 — Electro Pneumatic Valve (schematic).17

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 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 explosion effects. Therefore this document gives added values to the following clauses of the EU directives:  Directive 94/9/EC of the European Parliament and the Council of March 23, 1994 on the approximation of the laws of the member states concerning equipment and protective systems intended for use in potentially explosive atmospheres.
Annex II, Clause 1.0.1  Directive 98/37/EC of the European Parliament and the Council of June 22, 1998 on the approximation of the laws of the member states relating to machinery Annex I, Clause 1.5.7

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 about 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 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 which 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 µm. 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 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 ignition has occurred, combustion spreads to the entire unburned mixture 3.5 ignition delay tv time between the initiation of the dust dispersion and the activation of the ignition source 3.6 initial pressure pi pressure in the explosion vessel at the moment of ignition

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 m³ vessel (schematic) 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 dm³. Its aspect ratio is 3:1. It is designed to withstand an overpressure of at least 20 bar (see Figure 2).

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 (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 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). 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 than those described in this standard are used, a propagation of the explosion from the explosion vessel into the dust container, cannot be excluded. For this case, additional safety measures should be employed, e. g. higher pressure resistance of the dust container.
1) (e.g. EN ISO 1127, DN 20, 3/4")

Key 1 6 mm hole 2 end cap with 6 mm hole Figure 3 — Location of the 6 mm holes in the dust disperser 4.4 Ignition source The ignition source comprises two chemical igniters each having an energy of 5 kJ. The total mass of each igniter is 1,2 g and consists of 40 % by weight zirconium metal, 30 % by weight barium nitrate, and 30 % by weight barium peroxide. The igniters are fired by electrical
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