SIZING OF EXPLOSION RELIEF VENTS

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1、SHAPATechnicalBulletinNo.10SizingofExplosionReliefVentsSHAPATechnicalBulletinNo.10SIZINGOFEXPLOSIONRELIEFVENTSPage1of6Nov.2004SHAPATechnicalBulletinNo.10SizingofExplosionReliefVentsSizingofExplosionReliefVentsByMikeWardFikeUKLtdOnbehalfofTheSHAPATechnicalCommittee

2、IntroductionManyindustrieshandlematerialswiththepotentialforadustexplosionandtherearestatutoryrequirementstotakebothpreventativeandprotectivemeasurestoprotectpersonnelandplantequipment.Formanyyearsthemostcommonandpopularmethodofprotectionhasbeenexplosionventing.In

3、itssimplestform,aventisanapertureinthetoporsideofavesseltoprovideameansofpressurereliefduringanexplosion.Aswellasprovidingsufficientreliefarea,theventaperturemustbesealedwithawater/dusttightcoverorburstingpanelofsuitableconstructionandATEXcertification–seePicture1

4、.Althoughcalculatingthesizeoftheventrequiredisrelativelystraightforward,caremustbetakentoensuresafeandreliabledesign.TheGermancodeofpracticeVDI3673(2002)“PressureventingofDustExplosions”anddraftENstandardprEN14491arewidelyused.Picture1Page2of6Nov.2004SHAPATechnica

5、lBulletinNo.10SizingofExplosionReliefVentsCalculationsThebasicsizingequationsforareducedexplosionpressureoflessthan1.5barare:A=B(1+Cxlog10(L/DE))with-5–0.569–0.50.753B=(3.264x10xPmaxxKstxPred+0.27x(Pstat–0.1)xPred)xVandC=(-4.305xlog10Pred+0.758)where2A=Areaofventi

6、nm333V=Volumeofvesselinm(between0.1mand1000m)Kst=explosionpressurerateofriseinbar.m/sec*Pmax=Maximumexplosionpressureinbar*(between5and10barforKst<300bar.m/secandbetween5and12barforKstupto800bar.m/sec)Pred=reducedexplosionpressureinbarPstat=staticopeningpressureof

7、burstpanelinbar(between0.1and1.0bar)L/DE=lengthtodiameterratio(upto20)*TestdatafromexplosiontestingofmaterialbeinghandledL/DEisameasureofthe‘shape’ofavesselandturnsouttobeanimportantdesignparameter.Vesselsthatareneartocubic(L/DEapproximately1)requirerelativelylitt

8、leventarea,whilstelongatedvesselsmayneeddouble,trebleorperhapsevenmoreventareaincomparison.Forrectangularorcylindricalvessels,L/DEcanbecalculateddirectl