EN 1839-2017 en Determination of the explosion limits and the limiting oxygen concentration(LOC) for flammable gases and vapours《测定可燃气体和蒸汽的爆炸极限和极限氧浓度(LOC)》.pdf

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1、BS EN 1839:2017Determination of the explosionlimits and the limiting oxygenconcentration(LOC) forflammable gases and vapoursBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 1839:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation

2、 of EN 1839:2017. It supersedes BS EN 14756:2006 and BS EN 1839:2012 which are withdrawn.The UK participation in its preparation was entrusted to Technical Committee EXL/23, Explosion and fire precautions in industrial and chemical plant.A list of organizations represented on this committee can be o

3、btained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 85555 9 ICS 13.230 Compliance w

4、ith a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2017.Amendments/corrigenda issued since publicationDate Text affectedBS EN 1839:2017EUROPEAN STANDARD NORME EUROPE

5、NNE EUROPISCHE NORM EN 1839 January 2017 ICS 13.230 Supersedes EN 14756:2006, EN 1839:2012English Version Determination of the explosion limits and the limiting oxygen concentration(LOC) for flammable gases and vapours Dtermination des limites dexplosivit des gaz et vapeurs et dtermination de la con

6、centration limite en oxygne (CLO) des gaz et des vapeurs inflammables Bestimmung der Explosionsgrenzen und der Sauerstoffgrenzkonzentration (SGK) fr brennbare Gase und Dmpfen This European Standard was approved by CEN on 7 November 2016. CEN members are bound to comply with the CEN/CENELEC Internal

7、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

8、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 version

9、s. CEN members are the national standards bodies of 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, Pol

10、and, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN All rights of expl

11、oitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1839:2017 EBS EN 1839:2017EN 1839:2017 (E) 2 Contents Page European foreword . 5 Introduction 6 1 Scope 7 2 Normative references 7 3 Terms and definitions . 7 4 Test methods 9 4.1 General 9 4.2 Method T (“

12、tube” method) 10 4.2.1 Detailed method . 10 4.2.2 Reagents and materials 10 4.2.3 Apparatus 11 Table 1 Maximum permissible uncertainty of measurement for the amount of test substance in the test mixture . 12 Figure 1 Scheme of the tube apparatus for determining the explosion limits respc. Limiting o

13、xygen concentration . 12 4.2.4 Preparation of the test mixture 13 4.2.5 Procedure 13 4.3 Method B (“bomb” method) 14 4.3.1 Principle 14 4.3.2 Reagents and materials 14 4.3.3 Apparatus 14 4.3.4 Preparation of the test mixture 16 4.3.5 Procedure 17 4.3.6 Determination of explosion limits . 17 4.3.7 De

14、termination of the limiting oxygen concentration . 18 4.4 Determination of the limiting oxygen concentration . 18 4.4.1 Metering devices and additional equipment . 18 4.4.2 Procedure 19 Figure 2 Short procedure scheme for the determination of the LAC . 20 Figure 3 Extended procedure scheme for the d

15、etermination of the LAC 21 4.5 Recording of results 22 4.5.1 General . 22 4.5.2 Determination of explosion limits . 22 4.5.3 Determination of the limiting oxygen concentration . 23 5 Verification . 23 6 Test report 23 Annex A (normative) Method for determination of the explosion limits and limiting

16、oxygen concentration of substances that are difficult to ignite . 25 A.1 Background 25 A.2 Explanation 25 A.2.1 Explosion criterion flame detachment 25 BS EN 1839:2017EN 1839:2017 (E) 3 A.2.2 Degree of halogenation . 25 A.3 Apparatus 25 A.3.1 Test vessel . 25 A.3.2 Reagents and materials 26 A.3.3 Ig

17、nition source . 26 A.3.4 Equipment for preparing the test mixture 26 A.4 Safety equipment 26 A.5 Preparation of the test mixture . 26 A.6 Procedure 27 A.6.1 Determination of LEL and UEL . 27 A.6.2 Determination of LOC 27 Annex B (informative) Conversion of the values for the explosion limits 28 B.1

18、Abbreviations and symbols . 28 B.2 Substance characteristics of air . 28 B.3 Definitions . 29 B.4 Mixture preparation 29 B.5 Conversion 30 Table B.1 Formulas for the conversion 31 Annex C (informative) Examples to describe flame detachment . 32 Annex D (informative) Example of recommended evaporator

19、 equipment 33 Figure D.1 Evaporator equipment for producing test mixtures from liquid flammable substances . 33 Annex E (normative) Safety measures . 35 E.1 General . 35 E.2 General safety measures 35 E.3 Additional safety measures concerning the tube method . 35 Annex F (informative) Examples of th

20、e determination of the LOC 36 F.1 Example 1: determination of the LOC short procedure . 36 Figure F.1 Determination of the LAC of a ternary system of n-hexane, air and nitrogen at 100 C and ambient pressure . 36 F.2 Example 2: determination of the LOC extended procedure . 36 Figure F.2 Determination

21、 of the LAC of a ternary system of hydrogen, air and nitrogen at 20 C and ambient pressure 37 Annex G (normative) Verification 38 Table G.1 Data for verification of the apparatus with respect to the lower explosion limit 38 Table G.2 Data for verification of the apparatus with respect to the upper e

22、xplosion limit 38 Annex H (informative) Example of a form expressing the results . 40 BS EN 1839:2017EN 1839:2017 (E) 4 Annex I (informative) Significant Changes between this European Standard and EN 1839:2012 and EN 14756:2006 42 Table I.1 The significant changes with respect to EN 1839:2012 and EN

23、 14756:2006 42 Annex ZA (informative) Relationship between this European Standard and the essential requirements of Directive 2014/34/EU aimed to be covered . 43 Table ZA.1 Correspondence between this European Standard and Annex II of Directive 2014/34/EU . 43 Bibliography . 44 BS EN 1839:2017EN 183

24、9:2017 (E) 5 European foreword This document (EN 1839:2017) 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 document supersedes EN 14756:2006, and EN 1839:2012. This European

25、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 2017, and conflicting national standards shall be withdrawn at the latest by January 2018. Attention is drawn to the possibility that some of the elements of

26、 this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. 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

27、 EU Directive(s). For relationship with EU Directives, 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 are bound to implement this European Standard: Austria, Belg

28、ium, 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, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden

29、, Switzerland, Turkey and the United Kingdom. BS EN 1839:2017EN 1839:2017 (E) 6 Introduction The hazard of an explosion can be avoided by preventing the formation of explosive mixtures of gases and/or vapours with air. To do so, the explosion limits (also known as “flammability limits”) or the limit

30、ing oxygen concentration of the flammable substance need to be known. These limits depend mainly on: the properties of the flammable substance; temperature and pressure; size and shape of the test vessel; ignition source (type, energy); the criterion for self-propagating combustion; the inert gas (i

31、n case of the limiting oxygen concentration). To obtain reliable and comparable results it is necessary to standardize the conditions for determining the explosion limits resp. the limiting oxygen concentration (i.e. apparatus and procedure). However, it is not possible to provide one single method

32、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 two methods, namely, the tube method (method T) and the bomb method (metho

33、d B). In general, the tube method gives a wider explosion range. Differences in the explosion limits and limiting oxygen concentration determined by the two methods can vary by up to 10 % relative. For substances which are difficult to ignite, only a modified tube method is suitable. This is describ

34、ed in Annex A. BS EN 1839:2017EN 1839:2017 (E) 7 1 Scope This 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 or an air / inert gas mixture (volume fraction of the oxygen 2 0,2 4.2.3.4 Tempera

35、ture regulating system For measurements at temperatures above 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 setti

36、ng up the apparatus, whenever parts are renewed and at every 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 inert gas 6 high-voltage transformer 12 power supply Figure 1

37、Scheme of the tube apparatus for determining the explosion limits respc. Limiting oxygen concentration BS EN 1839:2017EN 1839:2017 (E) 13 4.2.3.5 Safety equipment The safety measures specified in Annex E shall be followed. 4.2.4 Preparation of the test mixture When evaporating liquid samples, it is

38、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 liquid and the vapour phases may change when removing material

39、 from the vapour phase. It is necessary to account for these possible changes in composition when determining explosion limits for flammable liquids, when handling liquid samples and when preparing test mixtures by evaporating liquid mixtures. To avoid error, the method of dynamic total evaporation

40、is used. An example of a suitable evaporator set up is described in Annex D. 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 vessel, preferably ma

41、de 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 temperature of the mixing vesse

42、l 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. 4.2.5 Procedure 4.2.5.1 General The characterization of explosion limits consists of det

43、ermining the amount of test substance in the mixture with which the test mixture no longer ignites (according the explosion criterion in 3.10). Close to the explosion limits, the incremental change of test substance content is selected such that it is almost equal to the relative uncertainty of meas

44、urement given in Table 1. If the explosion limits or the limiting oxygen concentration are to be determined at elevated 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

45、25 K higher than the condensation temperature. Prior to each ignition attempt, it has to be ensured that the temperature in the test vessel differs by no more than 5 K from the required value. 4.2.5.2 Determination of explosion limits For safety reasons, the initial ignition tests are carried out us

46、ing a test mixture with test substance content which, if possible, lies outside the expected explosion range 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 i

47、nlet to the test vessel is sealed. The test mixture then by-passes the test vessel and flows 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 sou

48、rce (see Annex C). It is recommended that the ignition testing is carried out without interruption 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 observe

49、d, the test substance content in the test mixture is iteratively varied until no further 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 concentration at which an ignition just fails (just no flame detachment) has to be confirmed with four additional tests. The determination is terminated when with all five tests a flame detachment is not observed. If flame detachment d