Table Of ContentHistoric, Archive Document
Do not assume content reflects current
scientific knowledge, policies, or practices.
aTD884
33
Laboratory
1999
Evaluationof
Two
Optical
2500Watershed
February 1999
9925-2806-MTDC Instruments for
^
40
X. 1
(
Laboratory
Evaluation of
Two
Optical
Instruments
for Rea||Ti
Particulate
Monitoring
Smoke
AndyTrent
ProjectLeader
HaroldThistle
ProgramLeader
Rich Fisher
AirResource Management, Washington Office
Ronald Babbitt
TheU.S. Departmentof Agriculture (USDA) prohibits Electronics Engineer, Fire Sciences Laboratory
discrimination inallitsprogramsandactivitiesonthe
basis of race, color, nationalorigin, gender, religion, Andria Holland-Sears
age, disability, political beliefs, sexual orientation, and
maritalorfamilystatus. (Notallprohibitedbasesapply Hydrologist, White RiverNational Forest
toallprograms.) Personswithdisabilitieswhorequire
alternative meansforcommunication of program USDAForestService
information (Braille, large print, audiotape, etc.) should
contact USDA’sTARGETCenterat 202-720-2600 Technologyand Development Program
(voiceandTDD). Missoula,Montana
Tofileacomplaintofdiscrimination,writeUSDA, —
Director,OfficeofCivil Rights, Room 326-W,Whitten 8E82F54 EvaluateTwoNephelometers
Building, 14th and IndependenceAvenue, SW,
W(vaosihciengortoTnD,D)D.CU2S0D2A50i-s9a4n10eqouralcalolpp(o2r0t2u)ni7ty20p-r5o9v6id4er February 1999
and employer.
Table of Contents
Introduction 1
Instruments 3
Methods 5
Results and Discussion 7
Conclusions 13
Additional Tests 13
Introduction
A
sland-managementagencies scattering,absorption,orextinction)are differencesbetweenthetwo
continueaggressivewildland- morepracticalandusefulfornearreal- measurementtechniques. Further
iburningprograms,theeffectsof timemeasurement. laboratorytestsinJulygathereddatato
increasedairborneparticulatematter developacorrectioncurvefortheoptical
becomemoreofaconcerntoland InMarchandJulyof1998,theMissoula instrumentsandtodetermineiftherewere
managers.Real-timemonitoringof TechnologyandDevelopmentCenter significantdifferencesintheoptical
airborneparticulatesiscriticaltotheland (MTDC)andtheFireSciences propertiesofsmokebasedonthetypeof
manager’sabilitytoprotecthumanhealth, Laboratory(FSL)evaluatedtworeal-time fuelgeneratingit.
publicsafety,andvisibility. Land opticalinstrumentsthatestimate
managersneedreliablemethodsto particulateconcentrationsbycomparing All results and conclusions were
measureparticulateconcentrationsatthe themwithtwogravimetricdevices.The based only on laboratory tests.
timeofthefiretohelpmakeoperational Marchlaboratorytestswereconductedto Furthertestingoftheinstruments
decisions. Gravimetrictechniquesrequire determinewhethertheopticaland in a field environment will be
thatfilterscollecttheparticulatematter. gravimetricinstrumentsshowed conducted to validate the labora-
Thefiltersarelaterweighedatspecial significantdifferenceswhenmeasuring toryresults.
facilitiesroutinelyusedinairquality smokeparticlesproducedfromburning
applications. Instrumentsthatinfer woodundercontrolledconditionsinan ThisevaluationwasfundedbytheUSDA
particulateconcentrationbymeasuring indoorchamber.Analysisofthedatafrom ForestService’sWatershed,Soil,andAir
opticalpropertiesoftheatmosphere(light thesetestsshowedconsiderable Program.
1
(
2
0
Instruments
Several ForestServiceRegions opticalchamber. Inthesetests,thePM measurementrangefromapproximately1
havealreadypurchasedoptical 2.5impactorheadwasused. Forcustom to 1000 ug/m3whenconvertedfrom
instrumentstomeasureairborne calibrations,particulatecanbecollected Bscat.Theinstrumenthasaninternaldata
particulatelevels.Twotypesofthese onafilterlocatedinthebaseofthe loggerthatwillstorescatteringcoefficient
instrumentsaretheMIEDataRAM instrument.Anin-lineheatermayalsobe averagesandtheoperatingparameters
portablereal-timeaerosolmonitoring installedformonitoringinconditionsof thatareusedtoestimatetheBscat.The
systemandtheRadianceResearch highhumidity(typicallyabove70% storeddatacanberetrievedusinga
M903nephelometer. Bothinstruments relativehumidity)orfog.Thetubular personalcomputerthroughanRS232
measuretheextinctioncoefficientoflight heaterisdesignedtoraisethe port.Differentaveragingtimesandlog
duetolightbackscattering(Bscat). temperatureofthesampledairstreamto intervalsmaybeset.Theinstrumentcan
Aerosollevelsarecommonlyreportedin evaporateliquidwaterfromairborne storeapproximately2weeksof5-minute
massconcentration,usuallyexpressedin particlesortoeliminatefogdroplets. averages.
microgramspercubicmeter(ug/m3 The
).
massconcentrationisestimatedfrom TheM903RadianceResearchportable Weinvestigatedathirdinstrument,the
Bscatbyapplyingaconversionfactor. nephelometer(Figure2) isalightweight, DustLite,manufacturedbyRupprechtand
low-powerinstrumentdesignedfor Patachnick.TheDustLiteestimatesmass
TheDataRAM (Figure 1) isacompact, portableoperationaswellasgeneral concentrationmuchliketheMIE
self-containedinstrumentthatinternally environmentalmonitoring. Itmeasures DataRAM, butthe purchase price isa
estimatesmassconcentrationfromthe anddisplays
measured Bscat(particulate Bscat, notmass
measurementrangesfrom0.1 ug/m3to concentrationlike
400,000ug/m3). Itcontinuouslydisplays theDataRam.
thecurrentandtime-weightedaverage Mass
massconcentrationwhileloggingupto concentrations
10,000datapoints.Optionally,the mustbecalculated
DataRAMcanbeconfiguredwitheithera byhandfromthe
PM-2.5orPM-10impactorheadto Bscatreadings.
preventparticleslargerthan2.5or1 Theinstrument
microns,respectively,fromenteringthe hasaparticulate
Figure1-TheMIEDataRam.
Figure2-TheRadianceResearchnephelometer.
3
fractionoftheDataRAM’sprice.However, gatherthegravimetricsamples.Onewas airbornesmokestudies.Thisinstrument’s
afteraninitialevaluation,weconcluded anEnvironmentalProtectionAgency 37-mmdiameterfilterswereweighedina
thatthisinstrumentwouldnotbe (EPA)ReferenceMethodPM2.5sampler specialenvironmentallycontrolledfacility
satisfactoryforForestServicefielduse. manufacturedbyRupprecht&Patachnick locatedattheFireSciencesLaboratory.
Co., Inc. (R&P). IMLAirSciencein Concentrationsofparticulatein
Gravimetricfiltersamplesof2.5urnand Sheridan,WY,weighedthe47-mm microgramspercubicmeterwere
smallerwerecollectedconcurrentlywith diameterTeflonfiltersusedbythis calculatedfromflowandgravimetricdata.
theopticalinstrumentstodetermineactual instrument.Thesecondinstrumentwasa FortheJulyseriesoftests, onlythe
particulatelevels. FortheMarchtests, PM2.5samplerdevelopedbytheFire RMFSLfiltersystemwasavailable.
twodifferentinstrumentswereusedto SciencesLaboratory(FSL)forconducting
4
