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DSC.B1C1.DSC.B1CV..V;GB4075ISO2919CICICRF2.V..5V.0%/ft.V.pA.pFAm-241.uCi1234ABCD4321DCBATitleNumberRevisionSizeA4Date:20-Jan-2005SheetofFile:K:\LYG\\CICAM\JTY-LF-XKM01\JTY-LF-XKM01.DDBDrawnBy:Vin1GND3Vout2IC178L0912345678910111213141516MC145018PR2470RLED1R310MC10.1uFC21nFR41MR5220KC30.1uFX1R61MR71MSW1R9CAL.RR8CAL.RR14.8kTR1S9014RLY1123456D11N4148+12V0VBLUEBLUEGREENYELLOWR103.3KJTY-LF-XKM011.1212V-20VIC138.9V-9.1V2.3.4.ICMC145018P1416R8R9BVR8R95.3–5.59V5.60–5.89V5.90–6.19V6.20-6.5V5.86.4SmokedetectorionisationchambertypeDSCB1CGeneralDescriptionTheDSCB1C(fig1)isasmall,compactandrobustdualionisationchamberofadvanceddesigncontainingasingleradioisotopesourceproducingionisationinbothchambers.Thechamberhasauniqueinternalgeometry,whichallowsthedetectorchiptobepositionedbeneaththechamberwithinarecessinthemouldedplasticbase.Pin15ofthechipcanbeconnecteddirectlytothecollectorelectrodeinsidetheprotectiveRFshieldofthecover.Thisisolatesthehighlysensitiveconnectionbetweenthecollectorelectrodeandpin15fromotherpartsofthedetectioncircuitryanditprovidesahighdegreeofimmunityfromexternalelectricalinterference.TheexternaldesignfeaturesanddimensionsoftheDSCB1Ccanbeseeninfigures2and3.TheelectrodesandsourceholderaremadeofAISI316stainlesssteel.Theplasticinsulatormaterialisspeciallychosenforitsexceptionalmechanicalstabilityandresistancetomoistureandoxidisingchemicalsintheair.Theunitsaresuppliedassembledandreadytomountonasuitableprintedcircuitboardusingthepre-tinnedtagsprovided.Detailsofthesealedsourcedesigncanbefoundinthedatasheets'Americium-241alphafoilandsources'(4)and'SafetyandPackaging'(5).Bothoftheseareavailableonrequest.InaccordancewithOECDrequirements(6)thesourceactivityislessthan37kBq(1µCi)241Am.TheRecommendedWorkingLifeofthesourceis10years.TheBS/ISO/ANSIratingoftheionisationchamberisC64646.Thedesign,manufactureandtestingoftheDSCB1CismanagedwithinthescopeofAEATechnology'sQualitySystemwhichiscertifiedbyLloydsRegisterQualityAssuranceforcompliancewithBSENISO9001:1994(1)AEATechnologyexpertiseinthedesignandconstructionofionchambersiswellestablishedandwide-ranging.Aconsultancyserviceisavailabletoassistinthedesignofsystemsusingionchambersandintheprovisionoftestingandcomputationalmodellingservicestomeasureandmodeltheperformanceofcustomers'owndesigns.TheinternaldesignoftheDSCB1Cisshownschematicallyinfigure4.Thisfigurehighlightsthecompactinternaldesignfeaturesandthelocationoftheioncloudwithinthechamber.Fig1,DSCB1CFig2,SideviewFig3,BottomviewA.CollectorelectrodeB.CoverElectrodeC.SourceElectrodeFig4,DSCB1C-internaldesignThedesigniscompatiblewithcommerciallyavailableintegratedcircuits.ArecommendeddetectioncircuitforusewiththeDSCB1Ccanbefoundinfig5.Fig5RecommendedcircuitdesignforusewiththeMC1446detectorchipThesmokedetectionperformanceoftheDSCB1Cchamberhasbeenmeasuredusingavarietyofdifferenttypesofsmoke.Sensitivitytosmoulderingpaper,smokyparaffinandsmoulderingwickcanbefoundinfigures6a,6band6c.Fig6aDSCB1CsmoulderingpapersensitivityFig6bDSCB1CsmokyparaffinsensitivityFig6bDSCB1CsmoulderingwicksensitivityThesensitivityoftheDSCB1Ctohumidityisshowninfigure7.Fig7DSCB1Chumidityresponseat230C01234LightObscuration%dV(volts)01234ChangeinBalancevoltagevsLightObscurationSmoulderingWickTest00.511.522.5LightObscuration%dV(volts)01234ChangeinBalancevoltagevsLightObscurationSmoulderingPaperTest0123LightObscuration%dV(volts)0123ChangeinBalancevoltagevsLightObscurationSmokyParaffinTest01234567020406080100%RelativeHumidityBalanceVoltage(V)computermodelediondistributioncollectorsourcechiprecesssourcecollectorelectrodeelectrodeThesensitivityoftheDSCB1Ctotemperatureisshowninfigure8.Fig8DSCB1CTemperatureresponseat60%RHThesensitivityoftheDSCB1Ctoairpressurecanbeseeninfigure9Fig9DSCB1CAirpressureResponseThesensitivityoftheDSCB1Ctoairvelocitycanbeseeninfigure10.Fig10DSCB1CAirVelocityResponse(provisional)Theairvelocityresponseishighlydependentonthedesignofcustomers'owndetectorcircuitsanddetectorhousingandmayvarysignificantlyfromtheabovediagram.RegulatoryComplianceAEATechnologysealedfoilsourcesusedinthedetectorsmeettheregulatoryrequirementsofmostnationalauthoritiesworldwide.Virtuallyallionisationsmokedetectorsusesuchsealedsources.SpecificallyAEATechnologysourcescomplywith:-UnderwritersLaboratoriesInc.StandardUL217(2)-EuropeanNormEN5446(3)andGB4715-1993.-UKNationalRadiologicalProtectionBoard(NRPB)criteriaofacceptability(7)uponwhichUKgovernmentlegislationrelatingtosmokedetectorsisbased.-PerformancecriteriaofMassachusettsRadiationControlProgramwheretheyhavebeenregisteredundermodelnumberAMM.1001H.RegistrationsarerecognisedintheUSAasequivalenttoNRCregistrationandsohavenation-widevalidity.PrincipleofOperationBasicdesignsconsistofacoverelectrodewithlouverstoallowsmoketoenterandasourceelectrodeandcollectorelectrode,whichareconnectedbyhighlyinsulatingplasticsupportsasinfigure11.Aradioactivesourceemitsalphaparticlesintothechamber,throughanapertureinthecollectorelectrode.Alphaparticlespassingthroughtheinnerandouterregionsproducepositiveandnegativeionsthroughoutthechamber.Anioncur