Comparison of Aspirated Smoke Detectors -Independent-Engineering-review

7/27/2019 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


H1 Yes Yes 1000.9


H1 Yes Yes 1001.4

V2 Yes Yes 100

Trial1H2 No Yes 100

1.2


H2 No Yes 1000.8


H2 No Yes 1002.4


H3 No Yes 100

1.5


H3 No Yes 1001.1


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.

Documents

Comparison of Aspirated Smoke Detectors -Independent-Engineering-review