EN 1839-2012 9375 Determination of explosion limits of gases and vapours《气体和蒸气爆炸限值的测定》.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 1839:2012Determination of explosionlimits of gases and vapoursCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reprod

2、uction or networking permitted without license from IHS-,-,-BS EN 1839:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 1839:2012. It supersedes BS EN 1839:2003, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C

3、o m m i t t e e E X L / 2 3 , E x p l o s i o n a n d f i r e p r e c a u t i o n s i n industrial and chemical plant.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contr

4、act. Users are responsible for its correct application. The British Standards Institution 2012. Published by BSI Standards Limited 2012.ISBN 978 0 580 64619 5 ICS 13.230 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the aut

5、hority of the Standards Policy and Strategy Committee on 30 September 2012.Amendments issued since publicationDate T e x t a f f e c t e dCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from

6、IHS-,-,-BS EN 1839:2012EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1839 September 2012 ICS 13.230 Supersedes EN 1839:2003English Version Determination of explosion limits of gases and vapours Dtermination des limites dexposivit des gaz et vapeurs Bestimmung der Explosionsgrenzen von Gasen u

7、nd Dmpfen This European Standard was approved by CEN on 27 July 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-to-date lists and bibliographi

8、cal 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

9、 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, Former Yugoslav Republic of

10、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 COMIT EUROPEN DE NORMALISATION

11、 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 1839:2012: ECopyright European Committee for Standardization Provided by IHS under license wi

12、th CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E) 2 Contents Page Foreword 41 Scope 62 Normative references 63 Terms and definitions . 64 Test Methods 74.1 Method T (“tube” method) 74.1.1 Principle 74.1.2 Reagents and Materials .

13、 74.1.3 Apparatus . 84.1.4 Preparation of the test mixture . 104.1.5 Procedure . 104.2 Method B (“bomb“ method) 114.2.1 Principle 114.2.2 Reagents and materials 114.2.3 Apparatus . 114.2.4 Preparation of the test mixture . 134.2.5 Procedure . 134.3 Recording of results 154.4 Test report 15Annex A (n

14、ormative) Method for determination of the explosion limits of substances that are difficult to ignite . 17A.1 Background 17A.2 Explanation . 17A.3 Apparatus . 17A.4 Safety equipment . 18A.5 Preparation of the test mixture . 18A.6 Procedure . 18Annex B (informative) Examples to describe flame detachm

15、ent . 20Annex C (informative) Example of recommended evaporator equipment 21Annex D (normative) Safety measures . 23D.1 General 23D.2 General safety measures 23D.3 Additional safety measures concerning the tube method 23Annex E (informative) Example of a form expressing the results)Test report . 24A

16、nnex F (normative) Verification . 25Annex G (informative) Conversion of the values for the explosion limits 27G.1 Abbreviations and symbols 27G.2 Substance characteristics of air 27G.3 Definitions 28G.4 Mixture preparation . 28G.5 Conversion . 29Copyright European Committee for Standardization Provi

17、ded by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E) 3 Annex H (informative) Significant Changes between this European Standard and EN 1839:2003 31Annex ZA (informative) Relationship between this European

18、Standard and the Essential Requirements of EU Directive 94/9/EC . 32Bibliography 33Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E) 4 Foreword This

19、 document (EN 1839:2012) 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 status of a national standard, either by publication of an identica

20、l text or by endorsement, at the latest by March 2013, and conflicting national standards shall be withdrawn at the latest by March 2013. 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 respons

21、ible for identifying any or all such patent rights. This document supersedes EN 1839:2003. The significant changes between this European Standard and EN 1839:2003 are given in Table H.1. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Tra

22、de 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/CENELEC Internal Regulations, the national standards organisations of the following countries

23、 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, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,

24、 Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E)

25、 5 Introduction The hazard of an explosion can be avoided by preventing the formation of explosive mixtures of gases and/or vapours. To do so, the explosion limits (also known as “flammability limits“) of the flammable substance need to be known. These limits depend mainly on: the properties of the

26、flammable substance; temperature and pressure; size and shape of the test vessel; ignition source (type, energy); the criterion for self-propagating combustion. To obtain reliable and comparable results it is necessary to standardise the conditions for determining the explosion limits (i.e. apparatu

27、s and procedure). However, it is not possible to provide one single method that is suitable for all types of substances. For practical reasons, it is preferable to use apparatus that can also be used for the determination of other explosion characteristics. This European Standard, therefore, details

28、 two methods, namely, the tube method (method T) and the bomb method (method B). In general, the tube method gives a wider explosion range. Differences in the explosion limits determined by the two methods can vary by up to 10 % relative. For substances which are difficult to ignite with large quenc

29、hing distances, only a modified tube method is suitable. This is described in Annex A. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E) 6 1 Scope T

30、his European Standard specifies two test methods (method T and method B) to determine the explosion limits of gases, vapours and their mixtures, mixed with air. An air/inert gas mixture (volume fraction of the oxygen 2 0,2 4.1.3.4 Temperature regulating system. For measurements at temperatures above

31、 ambient temperature, the apparatus requires a temperature regulating system. When this is used, it has to be ensured that the temperature difference inside the test vessel is not more than 10 K. This has to be checked when initially setting up the apparatus, whenever parts are renewed and at every

32、verification. Key 1 test vessel 7 timer 2 electrodes 8 facility for keeping the temperature 3 three-way valve 9 flammable substance 4 mixing vessel 10 air 5 metering devices 11 power supply 6 high-voltage transformer Figure 1 Scheme of the tube apparatus for determining the explosion limits Copyrigh

33、t European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E) 10 4.1.3.5 Safety equipment. The safety measures specified in Annex D shall be followed. 4.1.4 Preparation

34、 of the test mixture When evaporating liquid samples, it is important to remember that the mixture composition of the gaseous phase in equilibrium with a liquid phase (”vapour”) generally differs from the mixture composition of the liquid phase itself. Furthermore, the mixture compositions of the li

35、quid and the vapour phases may change when removing material from the vapour phase. Allowance for this is necessary when determining explosion limits for flammable liquids, when handling liquid samples and when preparing test mixtures by evaporating liquid samples. To avoid error, the method of dyna

36、mic total evaporation is used. An example of a suitable evaporator set up is described in Annex C. When liquids are metered, it has to be ensured that bubbles are not formed in any component carrying the liquid (e.g. pipes). To achieve complete homogenization, the test mixture flows through a mixing

37、 vessel, preferably made of glass. For a mixing vessel with no built-in elements, a volume of at least 600 ml is recommended. It is expedient to introduce the test mixture tangentially. The mixing vessel is not necessary if homogenization is effectively achieved by the metering device. The temperatu

38、re of the mixing vessel and of all parts carrying the test mixture is kept constant to prevent the test substance from condensing. It is recommended that the components carrying the test mixture are heated along with the test vessel. 4.1.5 Procedure If the explosion limits are to be determined at el

39、evated temperature, preheat the test vessel and all parts carrying the test mixture to the required temperature. For liquid samples, the temperature of the test mixture shall be at least 25 K higher than the condensation temperature. Prior to each ignition attempt, it has to be ensured that the temp

40、erature in the test vessel differs by no more than 5 K from the required value. The determination of the explosion limits consists of a series of ignition tests which are carried out with test mixtures whose test substance content is varied. For safety reasons, the initial ignition tests are carried

41、 out using a test mixture with test substance content which, if possible, lies outside the expected explosion range. For organic substances which consist exclusively of carbon, hydrogen and oxygen (with the exception of peroxides), the LEL can be roughly estimated. At 20 C, the LEL, in many cases, i

42、s approximately half the test substance content of the stoichiometric composition. The temperature dependence of the LEL has to be taken into account. Up to 200 C, the LEL decreases more or less linearly between 30 % and 50 % of the value estimated for 20 C. There is currently no method which readil

43、y estimates the UEL. Prior to each ignition attempt, the test vessel is purged with the test mixture. The purging volume has to be at least ten times the volume of the test vessel. When purging is complete, the inlet to the test vessel is sealed. The test mixture then by-passes the test vessel and f

44、lows directly into the exhaust system. An ignition is attempted using the induction spark under quiescent conditions (i.e. after a 6 s to 10 s delay). It is observed whether a flame detaches from the ignition source (see Annex B). It is recommended that the ignition testing is carried out without in

45、terruption of the production of the test mixture. If restarting, it will take a finite time to produce a test mixture of constant composition even if the adjustment has not been changed. If an ignition is observed, the test substance content in the test mixture is iteratively varied until no further

46、 flame detachment follows. Close to the explosion limits, the incremental change of test substance content is selected so that it is almost equal to the relative deviation given in Table 1. The test mixture with which a further flame detachment just fails has to be repeated four times. The determina

47、tion is terminated when all five tests have taken place with no observed flame detachment. If flame detachment does occur, the test substance content has to be further changed, i.e. for determination of the LEL, the test substance content has to be reduced by one increment; for the UEL, it has to be

48、 increased by one increment. Five tests are carried out at the new test substance content. When it is established that a given test mixture will not ignite, it is recommended that the composition of the non-Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 1839:2012EN 1839:2012 (E) 11 ignited test mixture flowing o