SIST EN 14034-2:2006
(Main)Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds
Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds
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.
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.
Bestimmung der Explosionskenngrößen von Staub/Luft-Gemischen - Teil 2: Bestimmung des maximalen zeitlichen Druckanstiegs (dp/dt)max von Staub/Luft-Gemischen
Diese Norm legt ein Prüfverfahren fest für die Bestimmung des maximalen zeitlichen Druckanstiegs von
Staubwolken in einem geschlossenen Behälter unter definierten Anfangsbedingungen von Druck und
Temperatur.
Dieses Verfahren ist nicht geeignet für Sprengstoffe, wie Schießpulver und Dynamit sowie Stoffe, die ohne
Sauerstoff verbrennen, pyrophore Stoffe oder Stoffe bzw. Stoffgemische, die sich unter bestimmten
Umständen ähnlich verhalten. Wenn Zweifel über eventuell vorhandene Gefährdungen durch die Explosions-wirkung
bestehen, sollten Fachleute zu Rate gezogen werden.
Détermination 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 poussiere
La présente Norme spécifie une méthode d’essai pour déterminer la vitesse maximale de montée en pression
lors de l’explosion de nuages de poussiere dans un récipient fermé, dans des conditions initiales de pression
et de températures définies.
Cette méthode ne convient pas aux explosifs reconnus comme tels, comme la poudre et la dynamite, aux
explosifs dont la combustion ne nécessite pas d’oxygene, aux substances pyrophoriques ou aux substances
et mélanges de substances pouvant, dans certaines circonstances, se comporter de maniere similaire.
Lorsqu’il existe un doute sur l’existence d’un phénomene dangereux en raison de propriétés explosives, il
convient de faire appel a l’avis d’experts.
Ugotavljanje eksplozijskih značilnosti oblakov prahu - 2. del: Ugotavljanje največje hitrosti naraščanja tlaka eksplozije (dp/dt)max oblakov prahu
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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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
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
EN 14034-2:2006 (E) 2 Contents Page Foreword.4 Introduction.5 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Test apparatus.7 4.1 General.7 4.2 Explosion vessel.7 4.3 Dust dispersion system (dust container, fast acting valve, connecting tube, dust disperser).8 4.4 Ignition source.10 4.5 Control unit.11 4.6 Pressure measuring system.11 5 Dust sample.11 6 Test procedure.11 7 Calibration and verification.14 7.1 Calibration.14 7.2 Verification.14 8 Safety precautions / instructions.15 9 Alternative test equipment / procedures.15 10 Test report.16 Annex A (normative)
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
EN 14034-2:2006 (E) 3 Figure A.2 — Discharge characteristic of dust dispersers (without dust).18 Figure B.1 — Location of the 5 mm holes in the dust disperser.20 Figure B.2 — Rebound nozzle.21 Figure B.3 — Dispersion cup.21 Figure C.1 — Test equipment 20 l sphere (schematic).23 Tables Table 1 — Maximum permissible deviations SEQ.15 Table ZA.1 — Correspondence between this European Standard and Directive 94/9/EC.25
EN 14034-2:2006 (E) 4 Foreword This document (EN 14034-2:2006) 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 an identical text or by endorsement, at the latest by November 2006, and conflicting national standards shall be withdrawn at the latest by November 2006. 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 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 one 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 pmax of dust clouds; – Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of 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 to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: 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.
EN 14034-2:2006 (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 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
EN 14034-2:2006 (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.
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
EN 14034-2:2006 (E) 7 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/dKKVtp===⋅ 3.9 rate of explosion pressure rise (dp/dt)ex 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 substance in a closed vessel under specified test conditions and standard atmospheric conditions NOTE This parameter when determined in the 1 m3 vessel 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-1 whereas the unit of the (dp/dt)max 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)max of dust clouds is an explosion pressure resistant vessel of 1 m³, as used for the determination of the maximum explosion pressure and the lower explosion limit 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; dust 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 vessel having a volume of 1 m³ 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.
EN 14034-2:2006 (E) 8 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 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 vented before the vessel can be opened.
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).
EN 14034-2:2006 (E) 9 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 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 explosion 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 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")
EN 14034-2:2006 (E) 10 Dimensions in millimeters
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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