1、BRITISH STANDARD BS EN 13821:2002 Potentially explosive atmospheres Explosion prevention and protection Determination of minimum ignition energy of dust/air mixtures The European Standard EN 13821:2002 has the status of a British Standard ICS 13.230 BS EN 13821:2002 This British Standard, having bee
2、n prepared under the direction of the Health and Environment Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 29 November 2002 BSI 29 November 2002 ISBN 0 580 40872 8 National foreword This British Standard is the official Engl
3、ish language version of EN 13821:2002. The UK participation in its preparation was entrusted to Technical Committee FSH/23, Fire precautions in industrial and chemical plant, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secr
4、etary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catal
5、ogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand t
6、he text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a fro
7、nt cover, an inside front cover, the EN title page, pages 2 to 16, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCH
8、ENORM EN13821 November2002 ICS13.230 Englishversion PotentiallyexplosiveatmospheresExplosionpreventionand protectionDeterminationofminimumignitionenergyofdust/air mixtures AtmosphresexplosiblesPrventionetprotectioncontre lexplosionDterminationdelnergieminimale dinflammationdesmlangespoussire/air Exp
9、losionsfhigeAtmosphrenExplosionsschutz BestimmungderMindestzndenergievonStaub/Luft Gemischen ThisEuropeanStandardwasapprovedbyCENon16October2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwitho
10、utanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCE
11、NmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Sweden,Switzerlanda
12、ndUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2002CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN13821:2002EEN13821:2002(E) 2 Contents pag
13、e Foreword3 1 Scope 3 2 Normativereferences 3 3 Termsanddefinitions. .3 4 Testapparatus 4 4.1 Sparkgenerationcircuit 4 4.2 Testvessel. .5 5 Testsample . .5 6 Testprocedure .5 6.1 Testdescription .5 6.2 Calibration 6 6.3 Conformity7 6.3.1 Conformitytests .7 6.3.2 Criteriaforconformity. .7 6.4 Testrep
14、ort . .8 AnnexA (normative) Descriptionsofsparkgeneratingsystems 9 A.1 General9 A.2 Triggeringbyhighvoltagerelay,usingatwoelectrodesystem .9 A.3 Triggeringbyelectrodemovement,usingatwoelectrodesystem .10 A.4 Triggeringbyauxiliaryspark,using3electrodesystem . .11 A.5 Triggeringbyvoltageincrease,using
15、twoelectrodesystem.1 2 A.6 Triggeringbytransformer,usingtwoelectrodesystem . 13 A.7 Exampleofatestapparatus . 14 AnnexZA (informative) ClausesofthisEuropeanStandardaddressingessentialrequirementsorother provisionsofEUDirectives. . 15 Bibliography 16EN13821:2002(E) 3 Foreword ThisdocumentEN13821:2002
16、hasbeenpreparedbyTechnicalCommitteeCEN/TC305“Potentiallyexplosive atmospheresExplosionpreventionandprotection“,thesecretariatofwhichisheldbyDIN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyMay2003,andconflictingnation
17、alstandardsshallbewithdrawnatthelatestby May2003. ThisdocumenthasbeenpreparedunderamandategiventoCENbytheEuropeanCommissionandtheEuropean FreeTradeAssociation,andsupportsessentialrequirementsofEUDirective(s). ForrelationshipwithEUDirective(s),seeinformativeannex ZA,whichisanintegralpartofthisdocumen
18、t. AnnexAisnormative. ThisdocumentincludesaBibliography. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg
19、Malta,Netherlands,Norway,Portugal,Spain, Sweden,SwitzerlandandtheUnitedKingdom. 1Scope ThisEuropeanStandardspecifiesamethodoftesttodeterminetheminimumignitionenergyofadust/airmixtureby anelectricallygeneratedspark. Thetestmethodisnotsuitableforusewithrecognisedexplosives,gunpowder,dynamite,explosiv
20、eswhichdonot requireoxygenforcombustion;pyrophoricsubstances,orsubstancesormixturesofsubstanceswhichcanunder somecircumstancesbehaveinasimilarmanner.Whereanydoubtexistsabouttheexistenceofahazarddueto explosiveproperties,expertadviceshouldbesought. WARNINGItisessentialthatprecautionsaretakentosafegua
21、rdthehealthofpersonnelconductingthe testsagainsttheriskoffire,explosionand/ortoxiceffects,ofcombustionproducts. 2 Normativereferences Therearenonormativereferences. 3 Termsanddefinitions ForthepurposesofthisEuropeanStandard,thefollowingtermsanddefinitionsapply. 3.1 dust smallsolidparticlesthatareabl
22、etoremainsuspendedinairforsometime NOTE Normallymaximumparticlesizeswillnotexceed500m.Thisdefinitionincl udeswhataredefinedinISO4225as dustandgritEN13821:2002(E) 4 3.2 combustibledust dustabletoundergoanexothermicreactionwithairwhenignited 3.3 explosivedust/airmixture mixtureofdustwithairinwhich,aft
23、erignitionhasoccurred,combustionspreadstotheentireunburnedmixture 3.4 sparkdischarge transientdiscreteelectricdischargewhichtakesplacebetweentwoelectrodeswhichareatdifferentpotentials.The dischargebridgesthegapbetweentheconductorsintheformofasingleionisationchannel 3.5 minimumignitionenergyofanexplo
24、sivedust/airmixture lowestelectricalenergystoredinacapacitorwhichupondischargeisjustsufficienttoeffectignitionofthemostignit ablemixtureofagivendustunderspecifictestconditions 3.6 ignition propagationofasustainableflameawayfromthesparkdischargeposition 3.7 ignitiondelaytime timebetweentheonsetofdisp
25、ersionofthedustsampleintoacloudandtheoccurrenceofthesparkdischarge 3.8 testconditions (temperature,pressure) airhavingatemperatureintherangefrom20Cto25Candapressureintherangefrom0.8barto1.1bar, absolute 4 Testapparatus 4.1 Sparkgenerationcircuit AnnexAdescribessomesuitableformsofcircuitforsparkgener
26、ationallofwhichshallhavethefollowingcharac teristics: a) inductanceofdischargecircuit:from1mHto2mHexceptwhenthedataistobeusedfortheassessmentof electrostatichazards.Thenthetotalinductanceofthedischargecircuitshallnotexceed25H; b) ohmicresistanceofdischargecircuit:aslowaspossibleandnotmorethan5 W ; c
27、) electrodematerial:tungsten,stainlesssteel,brass,orcopper; d) electrodeshaftdiameter:2.0 0.5mm; e) electrodeshape:pointed; f) electrodegap: 6mm(minimum); g) capacitanceofelectrodearrangement:aslowaspossible.Iftheparasiticcapacitanceoftheelectrodesystem issignificantcomparedwiththedischargecapacitan
28、ce,itshallbetakenintoaccount; h) insulationresistancebetweenelectrodes:sufficientlyhightopreventleakagecurrents. NOTE Forlowsparkenergiestogetherwithpointedelectrodesasignificantfractionoftheenergyinthecapacitancecan drainawayascoronadischargespriortothesparkdischarge.EN13821:2002(E) 5 4.2Test vesse
29、l TherecommendedtestequipmentistheHartmannapparatusdescribedinreferences7,8and10inbibliography.This apparatusisshowninA.7. NOTE Theminimumignitionenergyisindependentofthevolume(V 1l).Thereforeitcanalsobedeterminedinthe20l sphereorinthe1m 3 vessel. Othervesselsmaybeusedprovidedthattheconformityrequir
30、ementsaccordingto6.3aremet. 5 Testsample Theminimumignitionenergydecreaseswithdecreasingparticlesize.Thereforetheparticlesizedistributionshallbe determinedforthesampleastestedandshallbeindicatedinthetestreport. Theminimumignitionenergydecreaseswithdecreasingmoisturecontent.Thereforethemoistureconten
31、tshallbe determinedforthesampleastestedandshallbeindicatedinthetestreport. NOTE1 Wheretheparticlesizesofthematerialintheplantarenotknown,testsshouldbecarriedoutondustsamplesof particlesizese.g.lessthan63 m m. NOTE2 Thesizeofthedustparticlescanbereducedbythedispersionprocess.Incases,wherethiseffectca
32、nbe important,itsmagnitudecanbeevaluatedbymeasuringtheparticlesizedistributionafterdispersion(withoutignition). NOTE3 Grinding can alter the particle shape and surface condition, and sieving can alter the proportion of inert in the sample.Aroughclassificationoftheshapeofthedustparticlesmayalsobenece
33、ssary(spherical“,flat“orfibrous“). NOTE4 Wherethemoisturecontentintheplantisnotknown,thesampleshouldbecarefullydried,e.g.at50 Cunder vacuum,orat75 Candatmosphericpressureuntilthesampleweighthasreachedaconstantvalue. 6 Testprocedure 6.1Test description Thedusttobetestedisdispersedinairattestcondition
34、s(specifiedin3.8)inthetestapparatus,andthedustcloudis subjectedtoasparkdischargefromacapacitor. Theenergyvalueofthedischargeiscalculatedfromtheequation E=0,5 C U 2 (1) where: E isthestoredenergyinjoulesJ; C isthetotalcapacitanceofthedischargecircuitinfaradsFand U isthevoltageofthecapacitorinvoltsV.
35、NOTE1 FurtherinformationrelevanttothecalculationofsparkenergiesiscontainedinannexA. NOTE2 Thefollowingpossibleinfluencesonthetestshouldbeconsidered: dust/airmixturedynamics/turbulence(afunctionofignitiondelaytimeanddispersingpressureetc.); dust concentration; voltageofthecapacitor; capacitanceofthed
36、ischargecircuitcapacitor; inductanceofthedischargecircuit;EN13821:2002(E) 6 ohmicresistanceofthedischargecircuit; materialsanddimensionsoftheelectrodesandthegapbetweentheelectrodes. Theminimumignitionenergyisafunctionofthedust/airmixturedynamics/turbulenceandthedustconcentration.The minimumignitione
37、nergyshallbemeasuredattheoptimumdustconcentrationandthelowestturbulencelevel experimentallyattainable.Theturbulencelevelisreducedbyextendingtheignitiondelaytimeuntilaslongadelay timeasisfeasiblefortheapparatusisdetermined. Theoptimumdustconcentrationandthelowestturbulencelevelcannotbeobtainedinonest
38、ep.Thereforean iterativeprocedureisrequiredofwhichthemainstepsareasfollows: Step1 Startwithavalueofignitionenergythatwillreliablycauseignitionofagivenconcentrationinairofthedustbeing tested.Reducethesparkenergyinsteps(e.g.by50%)atthegivendustconcentrationuntilthedustclouddoesno longerigniteinanyof10
39、testsatagivenenergy. Step2 Continuetheprocedurevarying thedustconcentrationatthelowestenergyfoundinStep 1.Ifforanydust concentrationanignitionoccurs,thenrepeatStep1atthatconcentration. Step3 Repeattheprocedurebythiscombinationofsparkenergyanddustconcentrationvaryingthedelaytime(turbulence) untilthem
40、aximumenergy(E 1 )isfoundwherenoignitionoccurs. TheminimumignitionenergyMIEliesbetweenthehighestenergy, E 1 ,atwhichignitionfailstooccurin10successive attemptstoignitethedust/airmixture,andthelowestenergy, E 2 ,atwhichignitionoccurswithinupto10successive attempts. E 1 MIE E 2 (2) 6.2Calibration Atre
41、gularintervals(atleastevery12months,orfollowinganysignificantmaintenanceorrepair)theapparatusshall becalibratedby: a)checksofcomponents 1) energyofthedischarge:capacitanceofcapacitorsandvoltageapplied/generated; 2) inductanceofthecircuit; 3) ohmicresistanceofthecircuit; 4) capacitanceofthecircuit; 5
42、) thedustdispersionsystems:delaytimeanddispersionpressure. b)calibrationoftotalsystem Calibrationshallbecarriedoutusingoneofthefollowingtests: internalcalibrationwithatleastonereferencedusttheMIEofwhichisknown.Theresultsofthe E S value(see section6.3)shalldifferbylessthanafactorof3toprovethepositive
43、outcomeofthecalibration. comparativemeasurementofminimumignitionenergywithatleastoneotherlaboratorywithatleastone referencedust.Theresultsofthe E S value(seesection6.3)shalldifferbylessthanafactorof3.EN13821:2002(E) 7 Forthepurposesofinternalcalibrationdustsshallbechosenonthebasisofevidencethattheirminimumignition energydoesnotchangesignificantlyovertheperiodbetweencalibrations. 6.3Conformity 6.3.1 Conformitytests Theminimumignitionenergymaybedeterminedusingalterna
