1、October 2012 Translation by DIN-Sprachendienst.English price group 18No 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).IC
2、S 13.230!$=“1919726www.din.deDDIN EN 14491Dust explosion venting protective systems;English version EN 14491:2012,English translation of DIN EN 14491:2012-10Schutzsysteme zur Druckentlastung von Staubexplosionen;Englische Fassung EN 14491:2012,Englische bersetzung von DIN EN 14491:2012-10Systmes de
3、protection par vent contre les explosions de poussires;Version anglaise EN 14491:2012,Traduction anglaise de DIN EN 14491:2012-10SupersedesDIN EN 14491:2007-08 andDIN EN 14491 Corrigendum1:2009-03www.beuth.deDocument comprises 42 pagesIn case of doubt, the German-language original shall be considere
4、d authoritative.09.12 DIN EN 14491:2012-10 2 A comma is used as the decimal marker. 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 (Secretariat: DIN
5、, Germany). The responsible German body involved in its preparation was the Normenausschuss Sicherheitstechnische Grundstze (Safety Design Principles Standards Committee), Working Committee NA 095-02-01 AA Explosionsschutzeinrichtungen (auer Flammendurchschlagsicherungen). Amendments This standard d
6、iffers from DIN EN 14491:2007-08 and DIN EN 14491 Corrigendum 1:2009-03 as follows: a) additional explanations and clarification of hybrid mixtures have been included; b) Subclause 6.2.3 has been restructured; c) a new formula (24) has been introduced; d) formula (17) has been modified and moved to
7、the new Subclause 6.2.3.3; e) the former Subclause 6.2.5 “Effects of flameless explosion venting devices” has been replaced by a reference to an upcoming standard on flameless explosion venting devices; f) Annex A (informative) on the influence of the filter elements on the explosion venting has bee
8、n added; g) Annex B (informative) on the design of explosion venting of cyclones has been added; h) the former Annex A is now Annex C and the examples have been recalculated; i) a new example and Figure C.8 have been added; j) the former Subclause 5.5 has been moved to a new informative Annex D “Pro
9、tection of buildings”; k) the former Subclause 7.2.4 has been moved to a new informative Annex E “Deflectors” with editorial modifications; l) Annex F with the significant changes with regard to the previous version has been added; m) a new bibliography has been added. Previous editions DIN EN 14491
10、: 2006-07, 2007-08 DIN EN 14491 Corrigendum 1: 2009-03 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14491 August 2012 ICS 13.230 Supersedes EN 14491:2006English Version Dust explosion venting protective systems Systmes de protection par vent contre les explosions de poussires Schutzsysteme z
11、ur Druckentlastung von StaubexplosionenThis European Standard was approved by CEN on 30 June 2012. 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-t
12、o-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 transla
13、tion 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,
14、 Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION C
15、OMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14491:2012: EEN 14491:2012 (E) 2 Contents Page Foreword 31 Scope
16、 42 Normative references 43 Terms and definitions .44 Venting of enclosures .65 Sizing of vent areas .75.1 General 75.2 Venting of isolated enclosures .85.3 Special dust cloud conditions 95.3.1 General 95.3.2 Pneumatic conveying of product with axial introduction into vessels and silos .95.3.3 Pneum
17、atic conveying of the product with tangential introduction into vessels and silos. 105.3.4 Free fall filling 115.4 Protection of interconnected enclosures . 115.5 Protection of pipes . 125.6 Influences of vent ducts . 135.7 Design of vent ducts 145.8 Hybrid mixtures . 156 Supplementary design consid
18、erations 166.1 General . 166.2 Explosion effects external to the vent 166.2.1 General . 166.2.2 Flame effects . 166.2.3 Pressure effects 176.2.4 Effects of flameless explosion venting devices 186.2.5 Recoil forces . 186.2.6 Vacuum breakers 197 Marking 208 Information for use . 20Annex A (informative
19、) Explosion venting of dust filters 21Annex B (informative) Explosion venting of cyclones . 23Annex C (informative) Estimating the L/D ratio when calculating vent areas for elongated enclosures . 24Annex D (informative) Protection of buildings 31D.1 General . 31D.2 Calculating the vent area . 31D.3
20、Calculation of internal surface area 32Annex E (informative) Deflectors 33Annex F (informative) Significant changes between this European Standard and EN 14491:2006 35Annex ZA (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC . 38Bibliog
21、raphy . 39DIN EN 14491:2012-10 EN 14491:2012 (E) 3 Foreword This document (EN 14491:2012) 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 st
22、atus of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2013, and conflicting national standards shall be withdrawn at the latest by February 2013. Attention is drawn to the possibility that some of the elements of this document may be the
23、 subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 14491:2006. Annex F provides details of significant technical changes between this European Standard and the previous edition. This document has been
24、 prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive 94/9/EC. For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. According to the CEN/CE
25、NELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary,
26、Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. DIN EN 14491:2012-10 EN 14491:2012 (E) 4 1 Scope This European Standard specifies the basic requirements of de
27、sign for the selection of a dust explosion venting protective system. This European Standard is one of a series including EN 14797, Explosion venting devices and EN 14460, Explosion resistant equipment. The three standards together represent the concept of dust explosion venting. To avoid transfer o
28、f explosions to other communicating equipment, one should also consider applying EN 15089 Explosion Isolation Systems. This European Standard covers: vent sizing to protect an enclosure against the internal pressure effects of a dust explosion; flame and pressure effects outside the enclosure; recoi
29、l forces; influence of vent ducts; hybrid mixtures. This European Standard is not intended to provide design and application rules against effects generated by detonation reactions or runaway exothermic reactions. This European Standard does not cover fire risks arising from materials either process
30、ed, used or released by the equipment or from materials that make up equipment and buildings. This European Standard does not cover the design, construction, testing and certification of explosion venting devices that are used to achieve explosion venting1). 2 Normative references The following docu
31、ments, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13237:2003, Potentiall
32、y explosive atmospheres Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres EN 14460:2006, Explosion resistant equipment EN 14797:2006, Explosion venting devices EN 15089, Explosion isolation systems 3 Terms and definitions For the purpose
33、s of this document, the terms and definitions given in EN 13237:2003, EN 14460:2006 and the following apply. 3.1 building enclosed, roofed space that contains a working environment that may include process plant, offices and personnel, either separately or together, but is not, in itself, an item of
34、 process plant 1) This is covered in EN 14797. DIN EN 14491:2012-10 EN 14491:2012 (E) 5 3.2 enclosure vessel that forms a distinct and identifiable part of a process plant and to which explosion protection by explosion venting can be applied as described in this European Standard 3.3 hybrid mixture
35、mixture of flammable substances with air in different physical states SOURCE: EN 13237:2003 3.4 dust explosion constant KStmaximum value of the pressure rise per unit time (dp/dt)maxduring the explosion of a specific explosive atmosphere involving dust in a closed vessel under specified test conditi
36、ons normalised to a vessel volume of 1 m3multiplied by V1/3Note 1 to entry: See EN 14034-2. 3.5 gas explosion constant KGmaximum value of the pressure rise per unit time (dp/dt)maxduring the explosion of a specific explosive atmosphere involving gas or vapour in a closed vessel under specified test
37、conditions normalised to a vessel volume of 1 m3multiplied by V1/3SOURCE: EN 14994:2007, 3.8, modified 3.6 geometric vent area Avratio of required vent area A and venting efficiency Effor the venting device Note 1 to entry: The geometric vent area is the minimum cross-sectional flow area of the vent
38、 opening, taking into consideration the possible reduction of the cross section, e.g. by back pressure supports, retaining devices and parts of the explosion venting device which remain after bursting or venting. 3.7 required vent area A vent area required for the explosion venting assuming optimum
39、venting efficiency 3.8 overpressure required vent area pressure above ambient pressure 3.9 maximum explosion overpressure pmaxmaximum overpressure occurring in a closed vessel during the explosion of an explosive atmosphere and determined under specified test conditions Note 1 to entry: See EN 14034
40、-1. DIN EN 14491:2012-10 EN 14491:2012 (E) 6 3.10 pipe connection between two or more enclosures Note 1 to entry: A pipe cannot be explosion protected by the explosion venting methods for enclosures described in this European Standard. 3.11 explosive atmosphere mixture with air, under atmospheric co
41、nditions, 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 3.12 maximum reduced explosion overpressure pred,maxresulting maximum overpressure generated by an explosion of an e
42、xplosive atmosphere in a vessel at optimum fuel concentration, after effective explosion venting or explosion suppression 3.13 maximum rate of explosion pressure rise (dp/dt)maxmaximum value of the pressure rise per unit time during explosions of all explosive atmospheres in the explosion range of a
43、 combustible substance in a closed vessel determined under specified test conditions Note 1 to entry: This parameter is numerically identical with the parameter KSt, if the test vessel is 1 m3in volume, but the unit of the latter is barms1whereas the unit of the (dp/dt)maxis bars1. Note 2 to entry:
44、See EN 14034-2. 3.14 maximum external overpressure pext,maxexternal maximum value of the overpressure generated by vented dust explosion 3.15 static activation overpressure pstatdifferential pressure at which the retaining element activates such that the venting element is able to open SOURCE: EN 14
45、797:2006, 3.11 3.16 vacuum breaker device which prevents damage to a vessel when the internal pressure falls below atmospheric pressure 4 Venting of enclosures Explosion venting is a protective measure for enclosures by which unacceptably high internal explosion overpressures are prevented. Weak are
46、as in the walls of the enclosure open at an early stage of the explosion, burning and/or un-burnt material and combustion products are released and the overpressure inside the enclosure is reduced. Information required for calculation of the vent area includes the explosion resistance of the enclosu
47、re, the explosion characteristics of the dust, the shape and size of the enclosure, the static activation overpressure and other characteristics of the vent closure, and the condition of the dust cloud inside the enclosure. Explosion venting shall not be performed if unacceptable amounts of material
48、s that are classified as poisonous, corrosive, irritant, carcinogenic, teratogenic or mutagenic can be released. Either the dust or the DIN EN 14491:2012-10 EN 14491:2012 (E) 7 combustion products can present a hazard to the immediate environment. If there is no alternative to explosion venting, an endangered area shall be specified. NOTE 1 There is no direct guidance for estimating an endangered area for toxic or other harmful emissions, but the
