Comparison of Aspirated Smoke Detectors -Independent-Engineering-review
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Transcript of Comparison of Aspirated Smoke Detectors -Independent-Engineering-review
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AComparisonofAspiratedSmokeDetectors
HoneywellFAASTDetectorsandXtralisVESDAVLF(Laserfocus)
ConductedbyPackerEngineering,Inc
And
TheFireTestingandEvaluationCenterat
TheUniversityofMaryland,CollegePark
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AspiratedSmokeDetectionExperimentalSummary
1.0 OVERVIEWInthisexperimentalseries,theHoneywellFAASTaspiratedsmokedetection(ASD)systemwas
comparedtotheXtralisVESDAVLF(LaserFOCUS)aspiratingsmokedetectorthroughaseriesof
threetypesofexperiments.ThetestingwasperformedattheFireTestingandEvaluation
Center,partoftheFireProtectionEngineeringDepartmentattheUniversityofMaryland.The
scenariosconsistedofalargeroomwithsmokefromwireinsulation,anenclosedboxwith
directionalairflowcirculatingfinedust,andanenclosedboxwithdirectionalairflowcirculating
finedustandsmokefromwireinsulation.Theresponsetimetoalarmstateofeachsystemwas
recorded.Theobscurationduetodustorsmokeinsideoftheboxwasrecordedforthesecond
andthirdscenario.ThreeHoneywellFAASTmachines(H1,H2,andH3)andthreeXtralisVESDA
machines(V1,V2,andV3)werecomparedingroupsoftwo:H1wastestedwithV1,H2was
testedwithV2,andH3wastestedwithV3.Eachgroupwassubjectedtothesamethree
scenarios.Threetrialswereconductedpergroupperscenario.Obscurationwasmeasuredfor
theboxexperimentsonly.Obscurationisameasureoftheparticlepercentageperfoot.A
smokyroomwith100%/ftobscurationisfullofsmokeandnolightcanbetransmittedthrough
thesmoke.Theseexperimentsweredesignedtohaveanobscurationaround1.0%/ft.
Note:TheV#andH#labelscorrespondtothefollowingexistinglabelsfoundonthesystems:
V1:VLF5 H1:Chamber32
V2:VLF6 H2:Chamber12,9
V3:VLF7 H3:Chamber23,25
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TheresultsofeachtestaredefinedbythevariousresponsesoftheHoneywellFAASTand
XtralisVESDAVLFunits.TheFAASTsystemshavefivealarmlevelsandtenparticulatelevels.
ThealarmlevelsareAlert,Action1,Action2,Fire1,andFire2.Theparticulatelevelsare
numberedonethroughten.Asparticlesaredetected,thelevelsilluminateonthedisplay.Each
levelrepresentsa10%increaseintheparticulatelevelnecessarytoreachtheAlertalarmlevel.
Inotherwords,whenparticulatelevel10isreached,theAlertalarmlevelhasbeenreached.
TheFAASTunitsaresettoAlert:0.012%/ft,Action1:0.05%/ft,Action2:0.10%/ft,Fire1:
0.25%/ft,andFire2:0.50%/ft.
TheXtralisVESDAsystemshavefouralarmstateindicatorsandtenadditionalsmokelevel
indicators.ThealarmlevelsareAlert,Action,Fire1,andFire2.Thesmokelevelindicatorsare
comparabletothetenparticulatelevelsfoundontheHoneywellFAASTsystems.However,the
10particulatelevelsaretiedtotheFire1alarmlevel.Inotherwordseachparticulatelevel
correspondstoapproximately10%oftheFire1alarmlevel.TheXtralisVESDAunitsaresetto
Alert:0.5%/ft,Action:0.6%/ft,Fire1:0.625%/ft,andFire2:1.0%/ft.
Thegraphbelowsummarizestheaboveinformation.Whatisimportanttonoteisthateach
devicehasitsowninternalobscurationmeasurementthatistiedintothemeasuredactual
valueasobtainedinthesmokebox.Thus,thedeviceobscurationmeasurementsarenot
directlycomparable;theymustbenormalizedtothesmokeboxobscuration.Thealertand
actionlevelscanbecomparedwhenlookingatthesmokeboxobscurationmeasurements.For
instance,theXtralisVESDAdetectorreachesitsAlertlevelatapproximately0.23%/ft
obscurationwhiletheFAASTdetectorreachesanAlertlevelatapproximately0.10%/ft
obscuration.
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2.0 ROOMDETECTIONTEST2.1 Set-upThedetectiontestwasconductedinalargeroomwiththeASDsystemslocatedinsidethe
room.Theroomhadminimalventilationtoensuremechanicalventsdidnotinterferewiththe
experiments.Eachsystemwasconnectedtoitsownpipenetworkforsmokeintake.Thepipe
networkswereparalleltoeachotherandthesamplingportswerelessthananinchapart.This
ensuredthesamesampleofairwasreceivedbyeachsystem.Thebranchpipeswereeach24.25feetlong.Theconnectingpipewas14feetlong,withtheASDsystemintakescenteredat
7feet.Theairsamplingportswerelocatedat17.75feetand24.25feetinthebranchpipes.
Fourdiameterportswerelocatedat17.75feetineachpipe.Theportsweresetevery90
FAAST&VESDAMeasuredObscurationvs.
SmokeBoxObscuration
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aroundthecircumferenceofthepipe.Onediameterportwaslocatedat24.25feetineach
pipe.Thisportwasdrilledintotheendcapofthepipe.EachASDsystemhadatotaloftenports
(fiveoneachside).Themaximumtransporttimeforthisconfigurationwascalculatedtobe
10.63seconds.Thesystemswereallowedtoexhaustbackintotheroom.Schematicsforthe
ASDsystemsandtheirlocationswithinthetestroomareshownbelow.
SamplingportlocationsforASDsystems
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Layoutofpipingandconfigurationofthetestroom
Thesmokecamefromsmolderingwireinsulationincompliancewiththehotwiretestfrom
NFPA761andUL268.Atwo-meterlongwirewascoiledaroundaone-inchdiameterpipe.The
coiledwirewasconnectedtoavariableACpowersource.Thewirewassubjectedtoahigh
currentatalowvoltage,whichresultedintheproductionofsmokefromthesmolderingwire
insulation.ThewirewaslocatedonacartbelowtheVESDAandFAASTsystems.Theclosest
samplingportsforeachsystemwereequidistantfromthewire.Thetestbeganwhenthewire
powerwasconnectedfor30secondsatthebeginningoftheexperiment.After30seconds,the
powertothesmolderingwirewasturnedoffandthewireremainedintheroom.Thevideo
camerawasconnectedtoaclosedcircuittelevisionformonitoringthesystemstatus.Thetest
wasallowedtocontinueuntilthesystemsalarmed.
2.2 ResultsOverall,theFAASTandVESDAASDsystemsalarmedwiththepresenceofsmoke.Inallcases,
theVESDAsystemalarmedfirst.TheFAASTsystemswouldgenerallyalarmwithinonetotwo
secondsaftertheVESDAsystems.Thefollowingchartsummarizesthereactionofeachmachineforeachtrial.Thetimeslistedrepresentthetimefromwhenthepowerwassuppliedtothe
wire.Thewirebegantosmokeabout4-6secondsaftertimezero.Notethatafaultsignaland
flowwarningoccurredinalltrialsforH1.
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Trial ASDSystems AlarmTime(sec) AverageTimes(sec)
V1 40Trial1
H1 42
V1 41Trial2
H1 42
V1 49Trial3
H1 51
V1:43.3seconds
H1:45seconds
V2 38
Trial1H2 39
V2 32Trial2
H2 36
V2 42Trial3
H2 43
V2:37.3seconds
H2:39.3seconds
V3 48Trial1
H3 49V3 45
Trial2H3 51
V3 41Trial3
H3 48
V3:44.7seconds
H3:49.3seconds
3.0 BOXWITHDUSTTEST3.1 Set-upTheboxwithdusttesthadtheASDsystemslocatedoutsideoftheboxwithintakeandexhaust
pipingconnectedtotheinsideofthebox.Afanwasplacedintheboxtodirecttheairflowina
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counterclockwisedirection.Portlandcementdustenteredtheboxforfourminutestosimulate
nuisanceparticles.Thedustwasdroppedintoafunnelequippedwithanaircompressor.The
compressoragitatedthedustintofineparticles,whichthenfellthroughascreenintothebox.
Intakepipeswerepositionednexttoeachotherintheboxtoensurethesamesampleofair
wastakenbyeachsystem.Thesepipeswereorientedinthedirectionofairflowinthetop
portionofthebox.Thisorientationallowedonlyairbornedustparticlestobesampled.The
timedelayfortheparticlestoreachthedetectionsystemswasthesamefortheFAASTandthe
VESDAsystems.Afteranalysis,thesampledairwasreturnedtotheinterioroftheboxthrough
exhaustpiping.AvideocamerarecordedtheresponseoftheASDsystems.Theobscuration
(%/ft)ofthedustwasalsomeasured.Alaserdiagnosticwasusedtomeasuretheobscuration
oftheairdirectlybeforeitenteredtheintake(asseeninthefollowingimage).Thislaserwas
positionedinthetopportionoftheboxclosetotheASDsystemintaketubesbutfarfromthe
airre-entryanddustentrylocations.Throughoutallofthetrials,theobscurationvariedfrom
0.07%/ftto0.9%/ft.Thefollowingimageshowstheoverallset-up.Notethelaserfor
obscurationmeasurementsandthefunneltodropthedustintothebox.
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3.2 ResultsInmosttrials,theVESDAASDsystemsalarmedforthedustwhiletheFAASTASDsystemsdid
not.Thetablebelowdescribesthealarmstateforeachsystemthroughoutthetrials.The
maximumsignalthresholdnotestheparticulatelevel(1-10)reachedbyeachsystemduring
testing.Insometrials,theASDsystemsdidnotreach100%bytheendoftheexperiment.The
obscurationprovidedisanaverageoverthecourseofeachtrial.Additionally,theresponseto
dustisnoted.Generally,theFAASTsystemsdidnotreachanAlarmstatewhenonlynuisance
dustwaspresentinthebox.
Laser
IntakeExhaust
DustFunnel
Airflow
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TrialASD
Systems
Alarmedfor
Dust?
MaximumSignal
Threshold(%)
DustObscuration
%/ft
V1 Yes 80Trial1
H1 Yes 1000.18
V1 Yes 90Trial2
H1 Yes 1000.11
V1 Yes 100Trial3
H1 Yes 1000.96
V2 Yes 80Trial1
H2 No 600.51
V2 Yes 80Trial2
H2 No 600.07
V2 Yes 100Trial3
H2 No 400.25
V3 Yes 100Trial1
H3 No 400.13
V3 Yes 100Trial2
H3 No 500.40
V3 Yes 100Trial3
H3 No 20
0.25
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4.0 BOXWITHDUSTANDSMOKETEST
4.1
Set-upTheboxwithdustandsmokehadthesameset-upastheboxwithdustexperiments.Afterthe
dustwasinsertedintotheboxforfourminutes,smokefromsmolderingwireinsulationwas
introduced.ThesmolderingwirewasincompliancewithNFPA761andwasidenticaltotheset-
upusedintheroomdetectiontests.ThesmolderingwireiscomparabletoUL268,whichused
cottonlampwickstointroducegraysmokeintothebox2.Aslightlylowercurrentandvoltage
thantheroomdetectortestswereusedinordertoachievesmokeobscurationlevelsofless
than1%/ft.Thewirewasallowedtosmolderfor20seconds,thenpowerwascutofffromthewirefor30seconds.Thison/offpatternwasrepeatedthroughoutthetest.Thispatternwas
experimentallydiscoveredtomaintainaconstantobscurationfromthewire.Thedispersionof
smokeintheboxwasdrivenbythecounterclockwiseflow.After30secondsofnopower(no
smokeproduction),theobscurationintheboxbegantodecrease.Asteadyobscuration
behaviorispreferredoveranobscurationthatincreasesanddecreasesasafunctionoftime.In
ordertokeeptheobscurationconstant,additionalsmokeneededtobeintroducedinsidethe
box,thereforethepowerwasturnedbackon.Thiswasnecessarytomaintainanobscurationof
0.7%/ftduetosmokeinsideofthebox.Theon/offpatternoccurreduntilbothsystems
alarmed.Incaseswhereonesystemalarmedduetothepresenceofdust,thesmokewas
introduceduntilthesecondsystemalarmed.Throughoutallofthetrials,theobscurationofthe
dustvariedfrom0.8%/ftto2.6%/ftandtheobscurationofthewirewasconstantaround
0.7%/ft.AvideocamerarecordedtheresponseoftheASDsystemsthroughoutthetest.The
followingimagesshowtheinsideofthebox.Thehotwireisseenontheleft.Theintakeand
exhaustportsfortheASDsystemsareseenontheright.
ThistestmethodologyissimilartoatestdevelopedbytheNationalInstituteofStandardsand
Technology3.IntheNISTexperiments,titledFire-emulator/detectorEvaluatorExperiments,a
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smokesourceisintroducedatonesideofanarrowbox.TheNISTsmokesourceusedwood
sticksonahotplate,intendedtoproducesmokegrayincolor.Theboxisequippedwithafan
todirecttheairflow.Thedetectorsarelocatedatthetopofthebox.Alaserisdirectedthrough
theboxattheheightofthedetectorsslightlyaheadofthedetectorinlets.Thelightextinction
ofthelaserismeasuredthroughouttheexperiment.Dust(clayparticles)isalsoinsertedinto
theboxtotestthedetectorresponsetonuisancesources.Thedustisinjectedintotheboxby
passingitthroughasmallairjet,similartotheset-upusedintheexperimentsattheUniversity
ofMarylandFireTEClab.
4.2 ResultsThefirstportionofthisexperimenthadthesameresultsastheboxwithdustonlyexperiments.
TheVESDAsystemsalarmedwiththepresenceofdustandtheFAASTsystemsinmostcasesdid
not.Whenthesmokewasintroducedintothebox,theFAASTsystemsthatdidnotalarmfor
dustalarmed.Thisbehaviorissummarizedinthefollowingchart.WhentheVESDAsystems
alarmedfordust,thealarmremainedwiththenotedsignalthresholduntiltheendoftheexperiment.Thedustobscurationmeasurementsareslightlyhigherforthisexperiment.In
mostcases,theFAASTASDstilldoesnotalarmfortheseelevatedlevelsofdust.
Intake
Exhaust
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TrialASD
Systems
Alarmedfor
Dust?
Alarmedfor
Smoke?
MaximumSignal
Threshold(%)
DustObscuration
%/ft
V1 Yes Yes 100Trial1
H1 Yes Yes 1000.8
V1 Yes Yes 100Trial2
H1 Yes Yes 1000.9
V1 Yes Yes 100Trial3
H1 Yes Yes 1001.4
V2 Yes Yes 100
Trial1H2 No Yes 100
1.2
V2 Yes Yes 100Trial2
H2 No Yes 1000.8
V2 Yes Yes 100Trial3
H2 No Yes 1002.4
V3 Yes Yes 100Trial1
H3 No Yes 100
1.5
V3 Yes Yes 100Trial2
H3 No Yes 1001.1
V3 Yes Yes 100Trial3
H3 No Yes 1002.6
5.0 CONCLUSIONSTheroomdetectiontestsdisplayedthattheXtralisVESDAandHoneywellFAASTASDsystems
havesimilaralarmtimeswhensubjectedtosmokefromwireinsulation.Theprogressionof
alarmlevelswascomparablebetweenthetwoasthesystemsdetectedsmoke.Intheboxtests,
itwasobservedthattheHoneywellFAASTASDsystemgenerallydidnotalarminthepresence
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ofanuisancesource(dust)whiletheXtralisVESDAsystemalarmedalmostimmediately.Once
smokewasintroducedintothebox,theHoneywellFAASTsystemsthatdidnotalarmfordust
alarmed.Therefore,itcanbeconcludedthattheHoneywellFAASTASDsystemhasahigher
capabilitytodiscriminateagainstnuisancesources,therebyloweringthefrequencyofnuisance
alarmswhencomparedtotheXtralisVESDAsystem.
6.0 REFERENCES1. NFPA76:StandardfortheFireProtectionofTelecommunicationsFacilities,NationalFire
ProtectionAssociation,Quincy,MA,2002.
2. UL268:StandardforSmokeDetectorsforFireProtectiveSignalingSystems,UnderwritersLaboratories,Inc.,Northbrook,IL,1989.
3. Cleary,T.,W.Grosshandler,andA.Chernovsky,SmokeDetectorResponsetoNuisanceAerosols,NationalInstituteofStandardsandTechnology,Gaithersburg,MD,1999.