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# OAR Box 1128 Prepped by Ollie Stewart



### Document

Number: 

# 61)11-1-239
Docket Number: 

# A-83-2 2

Printed 4/21/2008 11:07:13 AM Sheet 61 of 198

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CHARACTERISTIC S O F AEROSO L SAMPLER S USE D I N

AMBIEN T AI RMONITORING



# C BY : Andre wR

. McFarlan d Carlo s A

. Orti z Civi l Engineerin g Departmen t Texa s A& M

Universit y Colleg e Station , Texa s 7784 3
Charle s E . Rode s Environmenta l Monitorin g and Suppor t Laborator y U.S . Environmenta l Protectio nAgenc y Researc hTriangl e Park , Nort hCarolin a 2771 1

Pape r Presente dA t 86t hNationa l Meetin g America nInstitut e o f Chemica l Engineer s

Houston , Texa s Apri l 1-5 , 197 9P. 3

ABSTRAC T



# c Aeroso l collectio ncharacteristic s o f th e 15 " x15 " (0.3 8 x0.3 8 m )

Hi-Vol , 11 V

x14 " (0.2 9 x0.3 6 m ) Hi-Vol , membrane , cascad e impactor , ER C dichotomou s (earl y model ) an

dBeckma ndichotomou s ambien t ai r sampler s wer e evaluate db

y win dtunne l testing . Th e system s wer e teste dt o determin e th e effect s o f typica l samplin g variable s suc ha s win dspee d(2 , 8 , an d2 4 km/hr ) anddirectio n(fo r sampler s wit hassymetri c inlets) , aerodynami c particl e siz e ove r th e rang e o f 1-3 0 ym , samplin g flo

w rate , andinterna l wal l losses . Win dvelocit y wa s a majo r caus e o f bia s fo r th e si xsampler s whe ncollectin g aeroso l particle s > 1 0 ym. . Characteristi c curve s wer e very simila r fo r th e 15 " x15 " Hi-Vo l an dth e 1 1 V x14 " Hi-Vol . A t 2 8 y m an dwin dspeed s o f 2 , 8 , and2 4 km/hr , samplin g effectivenes s value s respectivel y wer e 81 , 58 , 4 3 percen t fo r th e 15 " x15 " Hi-Vo l and72 , 50 , and4 3 percen t fo r th e 11% " x14 " Hi-Vol . Samplin g effectivenes s a t 2 4 km/h r whe nth e Hi-Vo l roo f ridg e wa s eithe r perpendicula r o r paralle l t o th e flo w fo r 23. 5 y

m wa s approximatel y

2 5 percen t les s tha n whe nth e roo f ridg e wa s oriente d45 ° t o th e flow . Determination s wer e mad e o f th e collectio no f win ddrive nparticulat e matte r b y a Hi-Vo l whe nth e sample r i s no t i noperation . Thi s depositio ni nth e standb y mod e wa s note d t o increas e wit hlarge r particl e size s andhighe r win dspeeds . Th e rainshiel dinle t o f th e membran e an dcascad e impacto r sampler s showe dles s tha n1 0 percen t collectio na t 2 4 km/h r a s compare dt o mor e tha n 7 5 percen t a t 2 km/h r fo r 2 8 y m particles . Wal l losse s as.higha s 9 5 per cen t fo r 1 0 y

m and5 0 percen t fo r 3.7 5 y m particle s wer e measure dfo r th e cascad e impacto r system .P. 4



### Collectio ncharacteristic s o f th e ER C dichotomou s sample r sho w tha t th e particl e siz e associate dwit h5 0 percen t effectivenes s i s reduce dfro m approximatel y

15. 5 t o 6. 3 y

m a s win dspee di s increase dfro m 2 t o 8 km/hr . For th e Beckma nsample r th e correspondin g value s o f particl e siz e fo r th e two win dspeed s ar e 15. 5 an d1 3 ym .

VP. 5



# I , INTRODUCTION

Characterizatio n o f th e concentratio n o f suspende d particle s i n th e ambien t atmospher e i s primaril yaccomplishe d throug h th e us e o f severa l thousan d Hi-Vo l sampler s sprea d acros s th e Unite d States

. Thes e sampler s have a n efficienc yapproachin g 10 0 percen t fo rparticle s fo rwhic h th e gravitationa l an d inertia l force s ar e smal l (les s tha n approximatel y5 ym) ; however , fo rlarger-size d particle s th e efficienc yi s quit e variabl e an d depend s no t onl yupo n particl e siz e bu t als o upo n win d spee d an d directio n (1) , an d t o a limite d exten t upo n ai rsamplin g rate
. I n fiel d applications , characterizatio n o f aeroso l concentratio n i s difficul t when th e uppe rsiz e limi t o f th e sample ri s variable

. Also , sinc e th e Hi-Vo l samplers ar e no t siz e segregate d nea rth e cente ro f th e atmospheri caeroso l distributio n (e.g. , fractionatio n o f respirable , <2. 5 ym , fro m non-respirabl e particles , >2.5) , lon g ter m particl e concentratio n trend s ma yb e misleading

. Publi c Healt h Servic e (2 ) studie s fo rth e perio d 1957 t o 196 6 showe d tha t i n urba n region s th e particl e concentratio n ha d decreased , whereas , a correspondin g increas e ha d occurre d i n non-urba n areas . Thi s ma ysimpl yreflec t a shif t i n particl e siz e distributio n i n urba n areas . I t i s possibl e tha t th e con centratio n o f respirabl e particle s actuall yincrease d i n urba n area s durin g th e period , bu t becaus e o f a decreas e i n th e emission s o f larg e particle s du e t o th e applicatio n o f abatemen t technology , th e overal l concentratio n measure d wit h th e Hi-Vo l approac h woul d sho wa decrease

. T

o enabl e interpre
tatio n o f bot h historica l dat a an d dat a whic h ar e currentl ybein g accumulate d wit h th e ai d o f Hi-Vols , i t i s highl ydesirabl e t o acquir e additiona l under
standin g o f th e inle t particl e transpor t characteristic s o f th e system
.P. 6



# I Analysi s o f dat a fro m mos t othe r ambien t ai r sampler s suffer s fro m th e same problem s a s th e Hi-Vol , tha t is , a lac k o f informatio no nth e inle t fractionatio ncharacteristic s a s function s o f th e environmental.conditions . I t woul db e expected , however , tha t system s whic hemplo y interna l classifi catio ndevice s (e.g. , impactor s o r th e dichotomou s sampler ) woul dyiel d informatio no nth e concentratio no f respirable-size dmateria l whic hwoul d
no t b e strongl y

influence db

y inle t design . Severa l investigator s (3-16 ) hav e examine dth e basi c flui dandpar ticulat e mechanic s modelin g fo r simpl e inle t configurations . However , suc h i s no t th e cas e fo r th e mor e comple xinle t configuration s tha t ar e use di n th e field . Davie s (3 ) conducte da stud y t o determin e theoreticall y andexperimen tall y th e condition s fo r efficien t samplin g wit hrespec t t o th e siz e o f inle t tube s i nrelatio nt o particl e size , samplin g flo w an dvelocity , an

d win dspeed . Agarwa l (5 ) studie dth e mechanic s o f aeroso l samplin g and transpor t wit hth e objectiv e o f characterizin g efficien t systems . Th e numerica l solutio no f th e Navier-Stoke s equatio nindicate dtha t th e samplin g efficienc y

o f a cylindrical-shape dinle t depend s primaril y onth e Stoke s numbe r an

dth e relativ e settlin g velocity . Samplin g efficiencie s fo r larg e windborn e particle s usin g 1 7 differen t samplin g device s i nth e fiel dwa s measure db y May et

_al_ . (7) . A

smal l por tabl e win dtunnel , 2 0 x2 0 cm square , wa s use dt o sampl e wit ha standar d knife-edge dorific e unde r isokineti c condition s fo r establishmen t o f tru e aeroso l concentration . McFarlan de_

t al_ . (15 ) develope danal l weathe r sample r inle t fo r a 2. 8 s,/mi n( 1 cfm ) out-of-door s ambien t ai r sample r tha t minimize s samplin g biase s from

suc hvariable s a s particl e size , win dvelocit y an ddirection , 2P. 7

an d turbulenc e intensity

. Th e collectio n efficienc ywa s examine d b

ygen eratin g monodispers e aeroso l particle s wit h th e ai d o f a vibratin g orific e atomize ran d introducin g th e aeroso l i n a 3.6 5 x1.8 3 m win d tunnel

. Effi
cienc ywa

s base d o n th e compariso n o f aeroso l collecte d b yth e sample rt o tha t o f a n isokineti c rake

. A566. 4 £/mi n (2 0 cfm ) ambien t aeroso l Hi-Vo l cascad e impacto rwa s fiel d teste d b

yBurto n et
. al_

. (16)

. I t wa s als o evaluate d b

ySehme l (17 ) fo rparticl e samplin g bia s cause d byinterstag e losse s an d b ynon-win d directio n sample rorientation

. Particl e samplin g bia s wa s decrease d by us e o f a win d oriente d inle t o n th e system
. Weddin g e t al_

. (1 ) conducte d a stud yt o determin e th e larg e particl e collectio n characteristic s o f ambien t aeroso l samplers

. O f th e fou rsamplers tested , th e two tha t ar e commerciall yavailabl e ar e a 23. 8 2,/mi n cascad e impacto ran d a Hi-Vo l sampler

. Studie s conducte d b

yStee n ej t a K(16 , 17 , 18 ) wer e focuse d o n deter
minatio n o f th e samplin g efficienc yo f samplers commonl yuse d i n Europe't o collec t ambien t aerosols

. T o investigat e inle t samplin g bias , Stee n an d co-worker s undertoo k

a progra m t o evaluat e sampler s i n th e fiel d an d i n a 0. 4 x0. 4 m win d tunnel

. Hi-Vo l sampler s wer e equippe d wit h symmetrica l inlets , on e o f thes e bein g a n isokineti cinle t use d a s a referenc e t o evaluat e a modifie d Hi-Vo l i n th e field

. Th e result s confirme d th e impor
tanc e o f inle t desig n t o samplin g efficiency

.

EXPERIMENTAL APPARATU S Th e win dtunne l testin g program wa s accomplishe dwit hth e us e o f thre e differen t siz e win dtunnels . A smal l win dtunnel , 1 5 c m diamete r b

y 18 0 c m

# I long , was use d t o obtai n hig h concentration s o f monodispers e aerosol s t o

facilitat e determinatio n o f wal l losse s an d fractionatio n efficienc yfo rth e dichotomou s sampler s an d cascad e impactor

. Amediu m size d win d tunnel , 6 1 x 6 1 c m b y3. 6 m long , was use d fo rth e evaluatio n o f th e inlet s an d sample r effectivenes s o f th e dichotomou s an d membran e sample rand , a larg e win d tunne l 1. 5 x1. 5 m cross-sectio n b y9. 8 m long , was use d t o accommodat e ful l siz e samplers , wher e environmenta l fiel d condition s o f win d velocit yan d directio n effect s coul d b e simulated

. Fo rth e latte rsystem , th e tes t sec tio n was se t u p wit h a on e RP M turntabl e t o evaluat e th e effec t o f win d directio n o n non-circula rinlets

. Avibratin g orific e monodispers e aeroso l generato rsyste m (20 , 21 ) wa s use d t o generat e uniformly-size d oi l droplet s fro m solution s o f ethano l an d olei caci d tagge d wit h uranine

. Sinc e particle s ma yposses s a n electrica l charg e afte rgeneration , th e freshl yforme d aeroso l wa s neutralize d wit h a 1 0 millicuri e Kr-8 5 radioactiv e source . Particl e siz e was determine d b ytakin g sample s o f th e aeroso l wit h th e ai d o f a Casell a impacto r(22)

. Th e particle s wer e collecte d o n clea n o i l phobi cmicroscop e slide s treate d b yimmersio n i n a fluorocarbo n sur factan t (23)

. Th e aeroso l sample s wer e checke d fo rsiz e an d homogeneit y unde ra Niko n LKE microscop e wit h fla t fiel d objective

. Particl e diamete r was measure d o n th e projecte d scree n o f a Mode l TV M 302 APuls e System , Inc

. televisio n monitor

. Th e imag e wa s transmitte d b ya n RC Atelevisio n camera , Mode l TCIOOO , mounted o n th e microscope

. Particl e diameter , measure d o n th e scree n wit h th e ai d o f a machinist' s comparator , was converte d t o equivalent
spherica l diamete rusin g a flattenin g facto r(23) , 0.69 0 o f th e measure d particle

. Also , particl e diamete ro f oi l droplet s was converte d t o aerodynami cparticl eP. 9

diamete r a s follows :

D a 2 " s '9-* D p 2
wher e D a -

aerodynami c particl e diamete r s.g . = particl e specifi c gravit y D = particl e diamete r o f oi l droolet s P I ncomputin g aerodynami c size , th e specifi c gravit y o f th e particl e wa s take nt o b e tha t o f olei c acid , 0.895 . 

## ( D



# L METHODOLOG Y

Fo r th e evaluatio no f a sample r i nth e 1. 5 x1. 5 m windtunnel , th e devic e wa s place di nth e tes t section . Inth e cas e o f th e Hi-Vol , th e uni t
wa s eithe r mounte donth e on e RPM turntabl e o r se t stationar y i nth e appro priat e direction . Durin g a test , aeroso l wa s introduce da t th e win dtunne l entrance , mixe dan

duniformize dwit hth e ai do f a turbulenc e gri dlocate da t th e entranc e o f th e win dtunnel , andtransporte dt o th e tes t section . Aero so l concentratio nprofile s wer e determine dwit hth e ai do f nin e isokineti c samplers , positione da t 2 5 c m interval s i nbot hthe horizonta l an dvertica l directions . Thes e wer e mounte do na rak e a t th e downwin dendo f th e tes t section , andth e flow i neac hsample r wa s monitore dwit ha separat e rotameter . Fo r smok e particles , an dsmal l an

dlarg e monodispers e aeroso l particle s th e concentratio nprofile s prove dt o b e a valuabl e too l fo r checkin g th e mixin g a t th e tes t section . Collectio neffectivenes s o f th e sample r wa s determine db y comparin g the concentratio ndetermine dwit hth e aeroso l sample r t o tha t determine dwit h th e ai do f a 8. 5 m 3 /h r ( 5 cfm ) isokineti c sample r (9 , 10 , 12 , 24) .P.1 0

( Test s o f th e small-size dinlet s o f th e dichotomou s an dth e membran e sample r wer e conducte di nth e 6 1 x6 1 cm win dtunnel . Th e sam e testin g pro cedur e a s tha t use dwit hth e 1. 5 x1. 5 m tunne l wa s employe dwit honl y mino r differences . Th e mixin g o f th e aeroso l particle s wa s accomplishe dwit hth e ai do f a Stairman ddis c a t th e entranc e o f th e windtunne l andthe nuniform ize dwit ha turbulenc e gri d1. 2 m downstream . Also , onl y the inlet s wer e place di nth e tes t sectio nwhil e th e sample r se t underneat hth e win dtunnel . T o determin e wal l losse s o f th e cascad e impacto r andt o determin e wal l losse s andfractionatio nefficienc y o f th e dichotomou s sampler , test s wer e conducte di nth e 1 5 cm diamete r win dtunnel . Freshl y generate daeroso l wa s transporte dt o th e tes t sectio nwher e a portio no f th e flo w wa s draw

nthroug h
a sampl e intak e tub e t o th e fractionatin g units . A vacuu m blowe r wit ha cleanin g filte r wa s use dt o maintai na slightl y negativ e pressur e i nth e tunne l Fo r th e analysi s o f aeroso l collecte db y th e sample r o

nth e filter , an

d particle s deposite do nth e wall s o f th e sampler , a fluorescenc e techniqu e wa s use dt o quantif y

concentration s o f uranine . Filter s andany

component s o f th e sample r t o b e analyze dwer e place di n solution s o f ethano l t o extrac t olei c aci danduranine . Th e volume o f ethano l
was hfo r th e filter s range dfro m 2 0 t o 25 0 md , an

dth e filter s wer e lef t i n solutio nfo r a t leas t on e hou r befor e dilutio nwit ha nequivalen t volum e o f distille dwater . Sample r component s t o b e analyze dfo r particl e collectio n wer e thoroughl y

washe di na detergen t solution , rinse dwit hta pwate r an d rerinse dwit hdistille dwate r andethanol . Afte r th e test , th e sample r wa s take napart ; eac hcomponen t t o b e analyze dwa s place di na separat e containe r anda measure dvolum e o f ethano l wa s added . B y mil dagitatio no f th e con taine r fo r severa l minutes , th e olei c aci dandfluorescen t materia l wer e re move dandth e solutio nwa s dilute dwit hdistille dwater . 6P.1 1



# I Fro

m well-mixed , ethanol-disti l le dwate r solutions , abou t 4 m! , o f the was hwa s poure dint o a cuvett e an dduplicat e reading s o f fluorescenc e wer e taken . T o stabiliz e an dmaximiz e th e fluorescenc e o f sodiu m fluorescei non e dro po f 1 N

NaO H wa s adde dt o th e solutio ni nth e cuvette .

RESULT S Th e dat a acquire dfro m th e experimenta l stud y ar e assimilate di ngraphica l form . Th e collectio neffectivenes s fo r eac ho f th e aeroso l sampler s i s plotte d
a s a functio no f samplin g variables : aerodynami c particl e size , win dvelocity , an dwin ddirectio nfo r assymetri c inlets . Her e effectiveness , E , i s define da s

C . E = sa

m 'iso x100 % 

### (2 )

wher e C„, „ = concentratio ndetermine dwit hthe tes t

s a m sample r C = concentratio ndetermine dwit hth e isokineti c

sample r
Fo r device s whic hhav e highaeroso l losse s i nth e interna l components , (e.g. , the cascad e impacto r an dth e dichotomou s sampler) , th e tota l wal l losse s (percen t o f tota l aeroso l enterin g the syste m whic hi s deposite do n interna l surface s othe r tha nth e actua l collectio nsurfaces ) ar e plotte da s a functio no f aerodynami c particl e size . Duplicat e test s wer e performe dfo r mos t o f th e experimenta l conditions . Additiona l dat a wa s acquire di f th e averag e valu e o f E , T , wa s greate r tha n 5 0 percen t an dth e rati o o f th e rang e o f values , Rt o E wa s

> 15 %P.1 2

Also , fo r th e cas e o f E < 50% , i f



## i- r > 15 %

additiona l test s wer e conducted

.



# I Hi-Vo l Sampler s

Th e Hi-Vol s wer e operate d a t a flo wrat e o f 1.4 1 m 3 /mi n (5 0 cfm ) t o determin e th e samplin g effectivenes s a s a functio n o f particl e siz e an d win d velocity

. Th e result s o f thes e test s fo ra rang e o f particl e size s fro m 1-3 0 y

m an d fo rwin d speed s o f 2 , 8 , an d 2 4 km/h rwit h th e sample r rotatin g a t on e RP

M ar e show n i n Figure s 1 an d 2

. Th e characteristi c curve s ar e ^ery

simila rfo rth e 15 " x15 " an d th e 11% " x14 " Hi-Vols

. Fo r particle s <1 0 y

m samplin g effectivenes s i s ove r9 0 percen t fo rth e thre e win d speeds

. Fo rparticle s large rtha n 1 0 y m th e collectio n depend s o n win d velocity

. A t 2 8 y

m th e 15 " x15 " Hi-Vo l (Figur e 1 ) ha s samplin g effec
tivenes s value s o f 81 , 5 8 an d 4 3 percen t fo r2 , 8 , an d 2 4 km/hr ; an d fo rth e 11% " x14 " Hi-Vo l (Figur e 2 ) th e correspondin g effectivenes s value s ar e 72 , 5 0 an d 4 3 percent , respectively

. T o determin e th e influenc e o f th e flo wrat e o n samplin g effectiveness , th e 11% " x14 " Hi-Vo l was teste d wit h 2 9 y m particle s a t a win d spee d o f 2 km/h rwit h thre e level s o f flo wrate : 0.57 , 1.41 , an d 1.9 2 m 3 /mi n (20 , 5 0 an d 6 8 cfm)

. Th e result s (Figur e 3 ) sho w flo wrat e ha s littl e influenc e upo n performanc e o f th e sample ra t th e condition s tested

. However , fo r flo wrate s lowe rtha n thos e tested , th e samplin g effectivenes s ma yincreas e du e t o th e sedimentatio n o f win d drive n particle s o n th e samplin g filter

.P.1 3



# L 100 -

£ 80 - U J 

# o c r U J 

# °-6 0

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# £ 4 0 o U J 

# fc 2 C

c , 1—— i r iii' ' 

### n 

# o

0 *"^^ ^



# o 2 Km/h rV o 8 Km/h r\ ® 2 4 Km/h r^

> • "

i * — '
•i i •* - 1 —•—•—* •• — 

# >j 3 ^

7 1 0 3 0 AERODYNAMI C PARTICL E DIAMETER , }xm

FIGUR E 1

. SAMPLIN G EFFECTIVENESS O F 15 " x15 " HI-VOL

.

9P.1 4

( 

## I0 0 l- o

a
8 0 U J 

# o c r u i O L 

## 6 0 C O C O U J 

# £ 40 o U J U L 

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o 2 Km/h r © 8 Km/h r ® 2 4 Km/h r

| il l I 1—L_ l 

## 3 5 7 1 0 AERODYNAMI C PARTICL E DIAMETER , M m

FIGUR E 2 . SAMPLIN

GEFFECTIVENES S O F lUs " x14 " HI-VOL .

1 0P.1 5



# c 0 ^

* 

# t *



## C D I N

^s » do

N § 

# fr

•s

v S

r JP.1 6

( 

### 100 -

0. 5 1. 0 1.

5 2. 0 VOLUMETRI C FLO

W RATE , m 3



### /mi n

FIGUR E 3 . EFFEC T O F FLOW RAT E O NPERFORMANC E

O F 11 V x 14 " HI-VOL . AERODYNAMI C PARTICL E DIAMETE R = 2 9 ym .



### 1 1P.1 7

Figur e 4 illustrate s th e depositio n o f win d drive n particle s o n th e filte rwhe n th e sample rwa s no t i n operation

. A n H V x14 " Hi-Vo l wa s se t i n th e win d tunne l i n th e standb ymod e an d subjecte d t o monodispers e aerosol s (4-3 0 ym ) a t win d speed s o f 2 an d 8 km/hr

. Adepositio n parameter , m/ c , i s plotte d a

s a functio n o f aerodynami cparticl e size , where :

m = depositio n rat e o n Hi-Vo l filter , yg/da y c = mea

n aeroso l concentratio n collecte d b yisokineti c sampler , yg/m 3

( Th e rat e o f deposition , yg/day , o f win ddrive nparticle s ca nb e determine d

fo r a specifi c particl e siz e b y knowin g the ambien t ai r concentration , c , yg/m 3 . Fro

m Figur e 4 , th e depositio nparameter , m , m 3 /day , i s define db y th e particl e siz e and th e win dspeed . Rat e o f depositio no f a give nparticl e siz e i s th e produc t o f th e depositio nparamete r and th e ambien t ai r concen tration . Win dvelocit y

an d directio neffect s o nsamplin g effectivenes s ar e plotte d i nFigur e 5 . Test s wit hth e 11V ' x!4 " Hi-Vo l yielde dresult s whic hsho w a variatio no f samplin g effectivenes s wit hsample r orientation . Th e sample r wa s teste da t fou r differen t positions : 0 ° (Hi-Vo l roo f ridg e paralle l t o th e flow) , 45° , 90 ° an d rotatin g on e RPM . Whe nth e Hi-Vo l i s operate di n th e rotationa l mode , on e RPM , th e samplin g effectivenes s i s approximatel y th e averag e o f th e effectivenes s value s fo r th e variou s orientation s tested . Th e sample r i s les s sensitiv e t o win dvelocit y effect s fo r th e roo f ridg e a t 45 ° t o th e flow , and <15 % differenc e fo r win dspeed s o f 2 and 2 4 km/hr . Thi s i s no t th e cas e fo r th e 90 ° orientatio nwher e th e differenc e i s >50?S .



### 1 2P.1 8



# e 1000 1 I I I 111 1 1 —I I I 11 1



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### E o a 

### 10 0

hi h 

## u < < C L 

## o C O O 

## a. U J 

## o 1 0



## 1.0 . 1. 0 O 2 Km/h r

•8 Km/h r

1 i « i i m 

## 3 1 0 i i i.ii n 

### 3 0 10 0 AERODYNAMI C PARTICL E DIAMETER , /i m

FIGUR E 4 . DEPOSITION I N STANDB YMODE , 11% " x14 " HI-VOL . 1 3

### 100 Tr 1—r—n r 

# *m . 8 0
U J o c c U J 

### Q - 6 0 C O C O U l U J 

## > 4 0 r 

## o U J 

### u _ u _ U J 

### 2 0 

# G

0 0 © SAMPLE R POSITIO N 0 ° 45 ° 90 ° 1 RP M

' I I I I I 

### 2 4 6 8 1 0 WIN D VELOCITY , Km/h r 2 0

FIGUR E 5 . EFFEC T O F WIN D VELOCIT YAN D DIRECTION O N PERFORMANC E O F 11 V

x14 " HI-VOL . AERODYNAMI C PARTICL E DIAMETE R= 23. 5 y m

• o c oP.2 0

Membran e Sample r Th e evaluatio no f aeroso l penetratio nint o th e rainshiel dinle t o f the membran e system

i s show

ni nFigur e 6 fo r a samplin g rat e o f 11 9 fc/min(4. 2 cfm) . I t ma y

b e note dtha t win dvelocit y doe s hav e a pronounce deffec t on th e effectivenes s o f collection . Fo r particle s < 5 y m collectio ni s greate r tha n9 0 percen t regardles s o f th e win dspeed . Fo r win dvelocit y u pt o 8 km/hr , th e effec t i s no t noticeabl e fo r particle s smalle r than1 0 ym . Particl e siz e associate dwit h5 0 percen t effectivenes s i s reduce dfro m 2 1 y m a t 8 km/h r t o 1 0 y

m a t 2 4 km/h4 . 

# C Cascad e Impacto r (25 , 26 , 27 )

Durin g preliminar y

testin g wit h1 0 y

m particle s a t 2 an

d8 km/hr , effec tivenes s value s o f approximatel y 1 0 percen t wer e observe dwit hth e cascad e impacto r a s oppose dt o 9 0 percen t fo r th e membran e sample r whic hha s a n identica l inle t configuration . Base do nthi s observatio nan dknow nfact s fro m othe r studie s (27 , 28 , 29 , 30) , a detaile dstud y wa s mad e t o determin e th e wal l losse s o f th e impacto r a s a functio no f particl e size . Fo r th e cascad e impacto r operatin g a t 11 2 i/mi n(3.9 4 cfm ) th e result s showin g tota l wal l losse s a s a functio no f aerodynami c particl e siz e ar e give ni nFigur e 7 . I t ma y b e note dtha t fo r aeroso l particle s greate r tha n2 ym , wal l losse s increas e rapidl y fro m 2 percen t t o 9 5 per cen t fo r 1 0 y

m andtha t 5 0 percen t wal l losse s correspon dt o 3.7 5 ym . Thes e dat a suppor t th e result s o f onl y 1 0 percen t collectio neffectivenes s fo r 1 0 ym .



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FIGUR E 7 . WAL L LOSSE S O F CASCAD E IMPACTOR .

FLO W RAT E =11 2 £/mi n

1 7P.2 3



### ERC Dichotomou s Sample r Th e performanc e o f a

naeroso l fractionato r i s generall y characterize d i nterm s o f th e fractiona l collectio nefficienc y a s a functio no f particl e siz e an dth e interna l wal l losse s a s a functiono f particl e siz e (31) . Th e fractiona l efficienc y curv e fo r th e earl y

versiono f a

nERC dichotomou s sampler , Figur e 8 , wa s determine db y testing th e fractionato r headseparate l y i nth e smal l aeroso l win dtunnel . Th e quantit y o f particulat e matte r collecte donth e larg e an dsmal l collectio nfilter s wa s determine dan dth e efficiency , n , calculate da s follows :



# I m .

n = m £ + m s + m w 

### wher e m= aeroso l collecte d o n larg e filte r m= aeroso l collecte d o n smal l filte r m= aeroso l collecte d o n interna l wall s w (3 )



### Th e result s o f thes e test s sho wa cutpoin t (particl e siz e fo r whic h th e efficienc yi s 5 0 percent ) o f 2. 7 ym . Wal l losses , WL , wer e determine d i n a simila r manne r an d wer e compute d from :
m.

W L = w

m 

### w + 

### \ + m 

### s (4 )
Wal l losse s a s a functio n o f particl e siz e ar e als o show n i n Figur e 8 . Fo r particle s betwee n 2. 8 an d 1 0 ym , wal l losse s ar e S 7 percent . Hig h losse s fo r large r particle s ar e du e t o depositio n o f aeroso l i n th e upstrea m regio n o f th e acceleratio n nozzle . Thi s coul d b e reduce d .b ymakin g mino r modification s i n th e nozzl e geometry . 1 8P.2 4



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AERODYNAMI C PARTICL E DIAMETER , /* m 10 0

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### 2 0

FIGUR E 8 . EFFICIENC Y AN D WAL L LOSSE S O F ER C DICHOTOMOU S FRACTIONATOR .



### 1 9

# I Th e ER C system ha s twi ninlet s whic heac hsampl e 1 4 i/min—on e inle t fo r th e dichotomou s fractionato r andth e secondfo r a tota l filter . Th e characteristi c dimensio no f thes e inlet s i s smal l (a nopenin g norma l t o th e win dand3. 5 m

m i nsize) . Th e result s o f test s fo r thes e tw o inlet s givin g effectivenes s a s a functio no f particl e siz e an dwin dvelocit y

ar e give ni nFigur e 9 . A s ma y b e expected , considerin g th e smal l openin g fo r bot hinle t systems , th e effectivenes s i s strongl y dependen t upo nwin d speed . Th e particl e siz e associate dwit h5 0 percen t effectivenes s fo r th e tota l inle t system

i s reduce dfro

m 1 6 t o approximatel y

6 y m fo r anincreas e i nwin dspee dfro

m 2 t o 8 km/hr . I t ma y b e note dfro

m Figur e 9 tha t ther e i s a larg e differenc e i n effectivenes s fo r th e tota l an dth e fractionato r systems . Collectio no f 1 6 y m particle s decrease s fro m 5 0 percen t t o 2 4 percen t whe nsamplin g wit h th e fractionatio nhead . Th e differenc e i nresult s i s du e t o th e interna l wal l losse s o f th e fractionatio nhead .

Beckma nDichotomou s Sample r Th e Beckma ndichotomou s sample r i s anautomate dsyste m whic hi s designe d t o collec t materia l o na s man y a s 3 6 sequentia l filte r pair s a t pre-pro gramme dtime periods . Th e uni t sample s ambien t ai r a t 16. 7 n/mi nandha s a nomina l cutpoin t o f 2. 5 y m fo r th e interna l fractionator . Th e inle t i s simila r t o a uni t designe db y McFarlan det_ al_ . (14 ) andi t ha s a nomina l cutpoin t o f approximatel y 1 5 ym . Th e result s o f laborator y testin g o f th e interna l fractionato r ar e show ni nFigur e 1 0 , wherei ni t ma y b e note dtha t th e cutpoin t siz e i s 2 . 5 y m andtha t th e wal l losse s associate dwit hth e cutpoin t ar e 6 percent . Losse s



### 20

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### AERODYNAMI C PARTICL E DIAMETER,Ji m
FIGUR E 9 . SAMPLINGEFFECTIVENES S O F ER C DICHOTOMOU S SAMPLE Rr o 

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COLLECTIO N EFFICIENC Y

WAL L LOSSE S

FIGUR E 10 . 

### 2 3 5 7 1 0 AERODYNAMI C PARTICL E DIAMETER , /t m
EFFICIENC Y AN

D WAL L LOSSE S O

F BECKMA

N DICHOTOMOU

S FRACTIONATOR

. FLO W RAT E = 16. 7 JL/MIN . 

### H8 0
U J 

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## a. U J 

### 16 0 Qco " U J c o c o o 

### 4 0

< 

### 2 0

-J o 3 0fo r particle s a s larg e a s 7 5 y m ar e les s than1 0 percent . Wit hrespec t t o win dtunne l evaluatio no f th e system , th e effectivenes s
a s a functio no f particl e siz e fo r a win dspee do f 2 km/h r i s show ni n Figur e 11 . Th e cutpoin t fo r th e inle t i s 15. 5 ym . Test s a t win dspeed s o f 8 an d2 4 km/h r showe dth e cutpoin t t o b e shifte dt o 1 3 an d10. 5 ym , respec tively .



# I SUMMAR

YAN D DISCUSSIO N Ambien t aeroso l sampler s wer e evaluate dunde r simulate dfield,condition s a s a functio no f aerodynami c particl e siz e an dwin dspeed . Th e followin g conclusion s ma y

prov e t o b e helpfu l t o gai ninsigh t int o th e validit y o f usag e o f presen t aeroso l sampler s andt o encourag e modification s t o th e standar dmetho dfo r samplin g particulat e matter : 1 . Win dvelocit y

i s a majo r caus e o f dat a bia s i naeroso l sampling . Fo r particle s >1 0 ym , samplin g effectivenes s fo r al l th e sampler s teste ddecrease dwit hincreasin g win dvelocities . 2 . Fo r Hi-Vo l sampler s th e effectivenes s fo r 3 0 y m particle s ca nvary fro m 7 0 t o 4 0 percen t a s win dspee di s increase dfro m 2 t o 2 4 km/hr . Othe r biase s i nth e inle t system o f th e Hi-Vo l ar e th e win ddirec tiona l effect s andstandb y mod e collection . Th e sample r i s mos t effectiv e whe nth e roo f ridg e i s oriente da t anangl e o f 4 5 degree s t o th e win dflow . Winddrive nparticles , suc ha s woul dexis t i n highconcentration s i nth e cas e o f a sandstorm , canb e deposite d whe nth e sample r i s no t i noperation . Th e inle t system o f th e Hi-Vo l sample r coul db e modifie dt o provid e a bette r define dcut poin t size , on e whic hi s les s dependen t uponwin dspee dand



### 2 3

### 10 0

U J CJ C C U J C L C O C O U J 

# z U J > r O U J 

## u . u . U J



### AERODYNAMI C PARTICL E DIAMETER , /i m

FIGUR E 11 . EFFECTIVENES S O F BECKMA N DICHOTOMOU S SAMPLER . FLOW RAT E = 16. 7 Jl/min . WIN D SPEE D = 2 km/hr . 

# JP.3 0

i directio n( a symmetrica l inlet ) andwhic hpreclude s depositio no f

win ddrive nparticles . 3 . Aeroso l collectio nwit hth e rainshiel dinle t o f th e membran e and cascad e impacto r sampler s i s somewha t variabl e wit hwin dspeed . Hig hinterna l wal l losse s o f th e cascad e impacto r rais e question s o f th e validit y

o f result s derive dfro m it s us e inth e past . Qualit y dat a coul db e obtaine dwit hth e impacto r i f eithe r th e flow rat e i s reduce dt o 28. 3 «,/mi no r th e stage s ar e designe dt o accommodat e highe r flow rates . A

nadequat e flo

w contro l system an dth e reshapin g o f th e rainshiel dinle t woul dals o improv e th e samplin g capabilitie s o f th e systems . 4 . A nearl y versio no f th e ER C dichotomou s sampler , becaus e o f th e smal l inle t opening s (3. 5 mm) , prove dt o b e th e leas t desirabl e inle t system

sinc e particle s a s smal l a s 3. 0 y m see m t o b e im pacte donth e inle t wall s b y win deffects . Th e sample r i s a valuabl e too l fo r fractionatin g respirabl e fro m non-respirabl e particles , bu t shoul dno t b e use da s anambien t sample r wit hth e small-size dinlet . I t shoul db e note dtha t th e manufacture r ha s change dth e inle t desig nsinc e th e time a t whic hthes e test s wer e performed . Th e Beckma ndichotomou s sample r provide s a ninterna l fractionatio no f 3. 5 y m andha s lo

w wal l losse s fo r particle s a s larg e a s 1 5 ym . Th e inle t i s no t highl y sensitiv e t o win dspeed , bu t shoul dprobabl y

b e improved . Base donth e result s o f thi s study , furthe r researc ho f ambien t aeroso l sampler s shoul dconside r th e desig nan devaluatio no f inle t system s wit h collectio ncharacteristic s whic har e les s sensitiv e t o win deffects .


### 2 5P.3 1



# L LITERATUR E CITE D

1 . Wedding , J.B. , McFarland , A.R. , Cermak , O.E. , "Larg e Particl e Collec tio nCharacteristic s o f Ambien t Aeroso l Samplers" , Environ. Sci. .Technol.. 11 , 4 , 38 7 (1977) . 2 . Spirtas , R. , Levin , H.J. , "Characteristic s o f Particulat e Patterns" , Nationa l Ai r Poll . Contro l Adm. , Raleigh , N.C. , Marc h1970 . 3 . Davies , C.N. , "Th e Samplin g o f Aerosols" , Staub 28 , 1 (1968) . 4 . Davies , C.N. , "Th e Entry o f Aerosol s int o SamDling Tube s an d Heads" , Brit. J. Appl. Phys., 2 , 1 , 92 1 (1968) . 5 . Agarwal , J.K. , "Aeroso l Sampling and Transport" , Particl e Technolog y Lab. , Mechanica l Technology Lab. , Publicatio nNo . 265 , Universit y o f Minnesota , Ma y

1975 . 6 . Raynor , G.S. , "Variatio ni n Entranc e Efficienc y o f a Filte r Sample r wit hAi r Speed , Flo

w Rate , Angl e an

d Particl e Size" , AIM Journal 31 , 29 4 (1970) . 7 . May , K.R. , Pomeroy , N.P. , Hibbs , S. , "Sampling Technique s fo r Larg e Windborn e Particles" , J. Aerosol Science

7 , 5 3 (1976) . 8 . Watson , H.H. , "Error s Du e t o Anisokineti c Samplin g o f Aerosols" , AIM Journal 15 , 2 1 (1954) . 9 . Vitols , V. , "Theoretica l Limit s o f Error s du e t o Anisokineti c Sampling o f Particulat e Matter" , J. Air Pollution

Contvo. Assoc. 16 , 7 9 (1966) . 10 . Sehmel , G.A. , "Particl e Sampling Bia s Introduce db y Anisokineti c Samplin g and Depositio nwithi nth e Sampling Line" , AIM Journal 31 , 75 8 (1970) . 11 . Selden , M.G. , "Nozzl e Samplin g Bias" , AIHA Journal 36 , 54 9 (1975) . 12 . Parker , G.J. , "Som e Factor s Governin g the Designo f Probe s fo r Sam pling Particl e and Drop-Lade nGa s Streams" , Atm. Env. 2 , 47 7 (1968) . 13 . Breslin , J.A. , Stein , R.L. , "Efficienc y o f Dus t Samplin g Inlet s i n Cal m Air" , AIHA Journal

36 , 57 6 (1975) . 14 . McFarland , A.R. , Wedding , O.B. , Cermak , O.E. , "Win dTunne l Evaluatio n o f a Modifie dAnderse nImpacto r an d a n Al l Weathe r Sample r Inlet" , Atm. Env. 11 , 53 5 (1977) . 15 . Burton , R.M. , Howard , J.N. , Penley , R.L. , Ramsay , P.A. , Clark , T.A. , "Fiel dEvaluatio no f th e High-Volume Particl e Fractionatin g Cascad e Impactor" , J. Air

Pollution

Control

Assoc. 23 , 27 7 (1973) . 

### 2 6•

- 1 i Cascad e Particl e r ,'I f Paci ' f i c Northwes t C. , 1973 . Parameter s o n th e Samplin g i s fo r Measurin g Particl e Con- • is , Chalmer s Institut e o f Efficienc y

o f Tw o Type s o f f Aerosol s in Ambien t Air " i Labs. , B 230 , Gothenburg, '
Measurement s o f Particl e Confoun dStatio nwit hDifferen t Wate r and Ai r Pollutio nLabs. ,

o f Technique s fo r Generatin g Drople t Generator" , I n Fissio n Energ y Comm . (1970) . io no f Monodispers e Aeroso l

. 14 7 (1973) . l a 1 is" , American Medical fc K , 48 1 (1956) . Singl e Particl e Optica l Sci. Technol., 1 , 10 , 80 1
in g wit ha Sid e Por t Probe" , i r Surveillanc e Cascad e Measurement s o f Suspende d Tech. 6 , 12 , 101 9 (1972) . c Metho dfo r Determinin g •ende di nthe Air" , Pape r ociatio nannua l meeting , * Z,4 "Th e Evaluatio no f e s i n Air" , Atm. Env. 6 , Anderse nImpactor" , M.S . ilson , W.E. , Stevens , R.K. , "The Siz e th e Air" , Science

183 , 109 8 (1974) . dea l Collectio nCharacteristics , o f ors" , AIM

Journal 38 , 17 4 (1977) . lertch , R.W. , Jr. , "Particl e Collectio n ig e Dichotomou s Sampler" , Environ. Scv.

ie Environmenta l Monitorin g and Suppor t vironmenta l Protectio nAgenc y (EPA ) unde r suppor t i s gratefull y acknowledged .

.. "



### 28 P.3 2