PREVENTIONOFDUST

EXPLOSIONS全面專業(yè)實(shí)用DUSTEXPLOSIONRISKDustexplosionisthemainprocesshazardinthepowdercoatingsindustryTheobjectiveofthistrainingistogiveyouthebasicknowledgeabouttheconditionfordustexplosionsandSafebehaviourstopreventdustexplosionsfromhappeningInordertopreventeventslikethis2011SBUEuropeWestHSEPolicy2DustexplosionatAluminiumWheelProducer2011SBUEuropeWestHSEPolicy32011SBUEuropeWestHSEPolicy4FiresandExplosionsofCombustibleDust

TheFireTriangelFireisachemicalreactionthatgeneratesenergyaslightandheat.Forfiretoigniteitrequiresthreeelements:fuel(combustibledust),Ignitionsource(spark),andtheoxidantagent(oxygen,air).DispersionFiresandExplosionsofCombustibleDust

ThedustexplosionpentagonAdustexplosioncouldbedefinedasthefastcombustion(fire)ofdustparticlessuspendedintheairinanenclosedlocation.Foracombustibledustexplosiontohappen,itrequiresthepresenceofallthesefactorsFuel(dust)OxidantIgnitionSourceConfinementDustExplosion-TermsandConditions

Technical

SafetyParametersofDusts

Sizeofparticle:Dustparticleslargerthan400μmarenotcombustible.Dustparticlesarecombustiblewhentheymeasurelessthan400μm.Combustibledustconcentration:dustiscombustiblewithincertain.Thelowercombustibilitylimitforourproductsisapprox.20…60g/m3airMinimumignitionenergy(MIE)Themin.energyofanelectricalsparkwhich,underdefinedconditions,isabletoignitetheexplosivedust/airmix.Noteverysparkiscapableofcausingignition.2011SBUEuropeWestHSEPolicy625wattlightbulbprobablycannotbeseenthroughsixfeetofamixtureofcombustibledustinair>MinimumExplosibleConcentrationDustCombustibilityWhatbulb?OSHA25watts2metersGlass40g/m3concentrationofcomb.dustsuspendedinairGlassHowDustExplodes2011SBUEuropeWestHSEPolicy8DustExplosion-TermsandConditions

ConfinementOccurswhenthefireoccursinaconfinedspaceThischangeinpressureorshockwavecanbemoreorlessdestructiveTheconfinementdoesnotnecessarilymeanthatthespaceorequipmentiscompletelyclosedMostofthetimeourproductsareconfinedduringtheproductionprocess2011SBUEuropeWestHSEPolicy9DustExplosion-TermsandConditions

DISPERIONItistheeffectofmovingthecloudofdustfromoneplacetoanother,mayitbebymechanicalprocesses(transport,ventilation,vibration,impropercleaning)orastheresultofaprimaryexplosion.2011SBUEuropeWestHSEPolicy10DustcloudisignitedandexplodesSomeeventdisturbsthesettleddustintoacloudDustsettlesonflatsurfacesDust2011SBUEuropeWestHSEPolicy11Therearemanysourcesofignitionandanakedflameneednotbetheonlyone!YoushouldKnow:Overonehalfofthedustexplosionswerefromnon-flamesources!Commonsourcesofignitionincludeelectrostaticdischargefrictionarcingfrommachineryorotherequipment;hotsurfaces,includinge.g.overheatedbearingsfireDustExplosion-TermsandConditions

SOURCESOFIGNITIONPreventionDustExplosions?WhatcanIdotopreventdustexplosions?MajorFactorsthatyouareabletocontroll:Preventdustaccumulationbyproperhousekeeping(Limitedfuel/nopossibledustdispersion)PreventPresenceofignitionsourcesDispersionFuel(dust)OxidantIgnitionSourceConfinementNoExplosionDUSTEXPLOSIONResultsfromthecombinationofthesefactors:Fire/Ignitionsourcedispersionofsolidparticulatematerialinamoreorlessenclosedspace++=firedispersionExplosionconfinementStatischeElektrizit?tAlsFolgevonTrennvorg?ngen,k?nnenunterbestimmtenBedingungenzündf?higeEntladungenstatischerElektrizit?tauftreten.DiefolgendenEntladungsformenk?nnenauftreten:Funkenentladungen:

Funkenentladungenk?nnendurchAufladungvonnichtgeerdeten,leitf?higenTeilenentstehen.Büschelentladungen:

Büschelentladungenk?nnenanaufgeladenenTeilenausnichtleitf?higenStoffen,zuihnengeh?rendiemeistenKunststoffe,entstehen.Gleitstielbüschelentladungen:

SogenannteGleitstielbüschelentladungenk?nnenbeischnellablaufendenTrennvorg?ngenauftreten.Schüttkegelentladungen:

Schüttkegelentladungenk?nnenbeispielweisebeiderpneumatischenBefüllungvonSilosauftreten.Staub/Luft-Gemischek?nnendurchdieo.g.Entladungsformenentzündetwerden,allerdingssindBüschelentladungennuralsm?glicheZündquellebeizündf?higenSt?ubenanzusehen.ProcessSafetyNetwork-AssetIntegrityTraining15ChargeGenerationStaticelectricityisgeneratedwhenmaterialscometogetherandthenseparate,orwhentheyrubagainstoneanother.ChargeAccumulationAstaticchargeaccumulatesuntilitislargeenoughtodischargeChargeDissipationAfterChargeishighenoughitwilldischargeinacontrolledwayviaagroundedstructureoraearthingcableorinanuncontrolledwaybyanenergeticsparkthatcouldhaveenoughenergytoigniteanexplosiveatmosphereBigBaggroundedbyEarthingcableSourcesofIgnition-

ElectrostaticProcessSafetyNetwork-AssetIntegrityTraining16ElectrostaticChargeGenerationWhenpowdersarepouredfrombags,achargewillbegeneratedonthebagandanoppositechargewillbegeneratedinthepowder.TheoperatorwillalsobecomechargedProcessSafetyNetwork-AssetIntegrityTraining17ElectrostaticChargeGenerationPersonwalkingoninsulatingfloorwearinginsulatingshoesDustcyclonesPneumatictransportofpowderintubesConveyourbeltsPlasticshrinkwrappingcancarryacharge.Anoperatorworkingwiththeseorstandingclosetothiscanbecomechargedbyinduction.SpraynozzlesforpowdercoatingapplicationPouringRawmaterialsformBagsProcessSafetyNetwork-AssetIntegrityTraining18StaticChargeAccumulationThemorebagstheoperatoremptiesthemorehewillbecomechargedunlessheisgrounded.Forexamplethroughanti-staticshoesDustiscontinuallydrawnintotheductedextractionsystem.Ifthisisnotgrounded,chargewillaccumulateontheductingandwilleventuallydischargeintheformofasparkifagroundedconductorisnearby.2011SBUEuropeWestHSEPolicy19Thedissipationofelectrostaticchargefrommetalplantmaybeachievedby:i)Bonding:connectingtheplantitemsaccumulatingpositiveandnegativechargebyalowresistancelink.ii)Earthing:connectingallplantitemstoacommonearthpathbyalowresistancelink.Staticelectrificationprocessesarecurrentgeneratorsandthecurrentsproducedinindustrialoperationsdonotexceed10-4Aandforthemostpartthecurrentislessthan10-6A.Inthesesituationsaresistancetoearthoflessthan106(megohm)willpreventaccumulationofdangerouslevelsofcharge.ProcessSafetyNetwork-AssetIntegrityTraining20InsulatingMaterials

Thehumanbodycanbecomecharged…..Personwearinginsulatingshoesbecomeschargedbyinductionwhenapproachinganinsulated,chargedcontainerduring,orimmediatelyafterfilling.Adischarge(propagatingbrushdischarge)canoccurbetweenthepersonandthecontaineriftheaccumulatedchargeonthecontainerishighenoughandheisclose.2011SBUEuropeWestHSEPolicy21ProcessSafetyNetwork–AssetIntegrityTraining22ZoneDefinitions-DustZone20Aplaceinwhichanexplosiveatmosphereintheformofacloudofcombustibledustinairispresentcontinuously,orforlongperiodsorfrequently.Zone21AplaceinwhichanexplosiveatmosphereintheformofacloudofcombustibledustinairisislikelytooccurinnormaloperationoccasionallyZone22Aplaceinwhichanexplosiveatmosphereintheformofacloudofcombustibledustinairisnotlikelytooccurinnormaloperation,but,ifitdoesoccurwillpersistforashortperiodonly.NB-Mostpowdersusedinpowdercoatingsplantsarecombustibleexceptsomeanorganicfillersandpigments

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Housekeeping2011SBUEuropeWestHSEPolicy23

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