SIST EN 14034-4:2005+A1:2011
(Main)Determination of explosion characteristics of dust clouds - Part 4: Determination of the limiting oxygen concentration LOC of dust clouds
Determination of explosion characteristics of dust clouds - Part 4: Determination of the limiting oxygen concentration LOC of dust clouds
This document describes a test method for the determination 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 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 4: Bestimmung der Sauerstoffgrenzkonzentration SGK von Staub/Luft-Gemischen
Diese Norm legt ein Prüfverfahren für die Bestimmung der Sauerstoffgrenzkonzentration von Staubwolken in einem geschlossenen Behälter unter definierten Anfangsbedingungen von Druck und Temperatur fest.
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 poussière - Partie 4: Détermination de la concentration limite en oxygène CLO des nuages de poussière
La présente norme décrit une méthode d'essai permettant de déterminer la concentration limite en oxygène des nuages de poussière dans un récipient fermé, dans des conditions initiales définies de pression et de température.
Cette méthode ne convient pas aux explosifs reconnus, tels que la poudre, la dynamite, les explosifs dont la combustion ne nécessite pas d'oxygène, les substances pyrophoriques ou les substances ou mélanges de substances susceptibles de se comporter de manière similaire dans certaines conditions. Il convient de demander l'avis d'un expert lorsqu'un doute subsiste en ce qui concerne l'existence d'un phénomène dangereux dû aux propriétés explosives.
Ugotavljanje eksplozijskih značilnosti oblakov prahu - 4. del: Ugotavljanje mejne koncentracije kisika LOC oblakov prahu
Ta dokument opisuje preskusno metodo za ugotavljanje mejne koncentracije kisika oblakov prahu v zaprti posodi v opredeljenih začetnih razmerah glede tlaka in temperature.
Ta metoda ni primerna za uporabo s priznanimi eksplozivi, kot so smodnik in dinamit, snovi, ki za izgorevanje ne potrebujejo kisika, piroforne snovi ali snovi ali zmesi snovi, ki se lahko v nekaterih okoliščinah podobno obnašajo. Kadar obstaja kakršen koli dvom o nevarnosti zaradi eksplozivnih lastnosti, je treba poiskati strokovni nasvet.
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Bestimmung der Explosionskenngrößen von Staub/Luft-Gemischen - Teil 4: Bestimmung der Sauerstoffgrenzkonzentration SGK von Staub/Luft-GemischenDétermination des caractéristiques d'explosion des nuages de poussière - Partie 4: Détermination de la concentration limite en oxygène CLO des nuages de poussièreDetermination of explosion characteristics of dust clouds - Part 4: Determination of the limiting oxygen concentration LOC of dust clouds13.230Varstvo pred eksplozijoExplosion protectionICS:Ta slovenski standard je istoveten z:EN 14034-4:2004+A1:2011SIST EN 14034-4:2005+A1:2011en,fr,de01-maj-2011SIST EN 14034-4:2005+A1:2011SLOVENSKI
STANDARD
SIST EN 14034-4:2005+A1:2011
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE 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
Détermination des caractéristiques d'explosion des nuages de poussière - Partie 4: Détermination de la concentration limite en oxygène CLO des nuages de poussière
Bestimmung der Explosionskenngrößen von Staub/Luft-Gemischen - Teil 4: Bestimmung der Sauerstoffgrenzkonzentration SGK von Staub/Luft-Gemischen This European Standard 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-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 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, 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:
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: ESIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 2 Contents page Foreword .31Scope .52Normative references .53Terms and definitions .54Test apparatus .64.1General .64.2Explosion vessel .84.3Dust dispersion system (dust container, fast acting valve, connecting tube, dust disperser) .84.4Ignition source . 124.5Control unit . 124.6Pressure measuring system . 124.7Oxygen measuring system . 124.8System to create the inert gas/air-mixture . 125Dust sample . 126Test procedure . 127Calibration and verification . 157.1Calibration . 157.2Verification . 158Safety precautions / instructions for use . 159Alternative test equipment / procedures . 1610Test report . 16Annex A (normative)
Electro pneumatic valve . 17Annex B (normative)
Dust disperser with 5 mm holes . 20Annex C (normative)
20 l sphere . 24C.1General . 24C.2Test apparatus . 24C.3Test conditions . 25C.4System to create the inert gas/air-mixture . 26C.5Test procedure . 26Annex D (informative)
Examples of procedures to determine the LOC . 27Annex ZA (informative)
!!!!Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC"""" . 29Bibliography . 30 SIST EN 14034-4:2005+A1:2011
EN 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 - 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 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 held 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 14034-4:2004. 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 requirements 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 dust clouds - Part 1: Determination of the maximum explosion pressure pmax of 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)max of dust clouds; !EN 14034-3", Determination of explosion characteristics 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, 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, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
SIST EN 14034-4:2005+A1:2011
EN 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 gas 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 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" SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 5
1 Scope This document describes a test method for the determination 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 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 14034-1:2004+A1:2011"; Determination of explosion characteristics of dust clouds — Part 1: Determination of the maximum explosion pressure pmax of 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)max of dust clouds" !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 ignition delay tv time between the initiation of the dust dispersion and the activation of the ignition source 3.4 inert gas non-flammable gas which will not support combustion and does not react to produce a flammable gas SIST EN 14034-4:2005+A1:2011
EN 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 temperature 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 maximum 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 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 (ISO 6184-1) 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 limiting oxygen concentrations is an explosion pressure resistant vessel of 1 m³, as used for the determination of 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; 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). SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 7
Key 1 Pressure sensor 2 Chemical igniters 3 Inlet for purge 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 m³ vessel (schematic) SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+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 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. 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. 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). 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). SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 9
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) SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 10 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 these cases, 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") SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 11 Dimensions in millimetres
Key
1 6 mm hole 2 End cap with 6 mm hole Figure 3 — Location of the 6 mm holes in the dust disperser SIST EN 14034-4:2005+A1:2011
EN 14034-4:2004+A1:2011 (E) 12 4.4 Ignition source !The ignition source comprises two electrically activated pyrotechnical igniters, each having an ignition energy of 5 kJ. This is the nominal calorimetric energy based on the mass of pyrotechnic powder in the igniters. When activated, the igniters shall release a dense cloud of very hot particles with little gas. The igniters are fired by electrical fuse heads. The power supply circuit for the igniters shall be capable of firing the fuse heads in less than 10 ms. The two igniters shall be placed at the centre of the explosion vessel, firing in opposite directions (see Figure 1)." 4.5 Control unit The control unit sequences the start of the dust injection, the activation of the ignition source and the start of the recording system. 4.6 Pressure measuring system The pressure measuring system includes at least two pressure sensors and recording equipment. The pressure sensors shall be fitted in the test vessel, with their heads flush with the internal wall. Precautions to prevent temperature effects on the pressure sensors shall be taken. The pressure measuring system shall have an accuracy of ± 0,1 bar or better and a time resolution of 1 ms or better. 4.7 Oxygen measuring system The system used for measuring the oxygen concentration shall have an accuracy of ± 0,1 % V/V or better.
4.8 System to create the inert gas/air
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