United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S4-87/004 Apr. 1987
vvEPA Project Summary
The PM10 Sampler Evaluation
Program: January 1985 to
July 1986
Mark Woods, Fu-Lin Chen, and M. B. (Arun) Ranade
Test inlets designed to measure the
atmospheric concentration of particu-
late matter smaller than a nominal 10
micrometers (|im) aerodynamic diame-
ter (PM10) were tested at the EPA wind
tunnel test facility in Research Triangle
Park, North Carolina. The Andersen
Samplers Model 321A and the Wedding
IP10 size selective inlets (SSI) were eval-
uated following the procedures pro-
posed in 40 CFR Part 53 (Ambient Air
Monitoring Reference and Equivalent
Methods). The tests consisted of meas-
uring the inlet effectiveness over a
range of particle sizes (3 to 20 |im nom-
inal aerodynamic diameter) using both
liquid and solid test particles at two
windspeeds (2 and 8 km/h). Addition-
ally two field-tested Wedding IP10 SSI's
(EPA field study Phoenix, Arizona, May
1986) were compared with a clean
"reference" Wedding IP10 SSI.
Before conducting the above inlet
tests, the procedures and requirements
of 40 CFR Part 53 were revised to make
the test procedures more practical.
Several shortcomings in the sampling
and analysis procedures as previously
practiced were eliminated to ensure
compliance with requirements of 40
CFR Part 53. At the time the tests were
conducted, the wind tunnel and the
wind tunnel test procedures fully met
the requirements of 40 CFR Part 53.
The Andersen Samplers Model 321A
and the Wedding IP10 SSI's were both
found to meet the 50-percent cutpoint
requirement at 2 and 8 km/h for both
liquid and solid particles. The "used"
Wedding SSI's did not meet the 50-
percent cutpoint criterion. However, all
samplers met the expected mass ratio
requirement.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing Systems Laboratory, Research Tri-
angle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
On March 20, 1984, the U.S. Environ-
mental Protection Agency (EPA) pro-
posed revisions to the National Ambi-
ent Air-Quality Standards (NAAQS) for
paniculate matter. New primary stand-
ards were proposed for particulate mat-
ter measured as PM10 (particles with
aerodynamic equivalent diameters less
than a nominal 10 (im). A new Federal
Reference Method (FRM) for the deter-
mination of PM-ig in the atmosphere and
provisions for the designation of refer-
ence and equivalent methods for PM10
determination also were proposed.
Under the provisions of these proposed
regulations, candidate reference and
equivalent methods for PM10 determi-
nation would have to be tested in ac-
cordance with the explicit procedures
contained in 40 CFR Part 53 (Ambient
Air Monitoring Reference and Equiva-
lent Methods). Following satisfactory
completion of all test requirements,
candidate methods would be desig-
nated formally as reference or equiva-
lent methods. The proposed testing re-
quirements of Part 53 include wind
tunnel tests for sampling effectiveness
and a 50-percent cutpoint. Sampling ef-
fectiveness is the ratio of the mass col-
lected by a test inlet compared to the
mass collected by an isokinetic high-
volume sampler. The 50-percent cut-
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point is the particle size that is collected
by the test inlet with 50 percent effi-
ciency.
Sampling effectiveness is determined
in the following manner. A mono-
disperse aerosol of known size is gener-
ated using a Berglund-Liu vibrating ori-
fice aerosol generator. The aerosol is
introduced into the wind tunnel so that
a uniform distribution of particles is
achieved in the test section. The unifor-
mity is evaluated by using an array of
isokinetic samplers (referred to as an
isokinetic rake) to measure the aerosol
concentration profile in the sampling
zone of the test section. To be accept-
able, the concentration at each sample
point on the rake must be within 10 per-
cent of the mean concentration of all
sample points on the rake. After sam-
pling the concentration profile, a test
inlet is placed in the wind tunnel and
operated at a nominal flow rate of 40
cubic feet per minute (ft3/min) for 20
min. A high-volume isokinetic sampler
(40 ft3/min) is then run for 20 min to
determine the true wind tunnel aerosol
concentration. The aerosol mass con-
centration collected by both the test
inlet and the isokinetic sampler is deter-
mined using fluorometry. Liquid aero-
sol particles contain uranine and solid
particles are ammonium fluorescein,
both of which are fluorescent materials.
All inlet tests covered in this project
summary included two inlets run se-
quentially during a single test. The pro-
cedure was to first run the isokinetic
rake and then three replicates of the
series consisting of test inlet one, the
isokinetic high-volume inlet, and test
inlet two.
During most of calendar year 1984,13
tests were performed on various inlets
at the EPA test facility. During most of
calendar year 1985, shortcomings in the
sampling and analysis procedures were
identified and eliminated, and in 1986
inlet tests were resumed.
The aerosol distribution system used
during 1984 worked well at windspeeds
of 2 and 8 kilometers per hour (km/h).
However, at a windspeed of 24 km/h,
the aerosol concentration was high at
the center of the wind tunnel and low
near the sides. The aerosol distribution
system was modified (largely by trial
and error) until acceptable performance
was achieved at each of the three re-
quired windspeeds.
After the aerosol distribution system
was redesigned, it was necessary to
measure again the velocity and turbu-
lence profiles in the test section. The ve-
locity and turbulence profiles were
measured using a TSI Model 1050-1
Anemometer and a ruggedized probe
along with a TSI Model 1056 RMS,
mean-square, direct current (dc) volt-
meter. The probe was calibrated on a
TSI Model 1125 calibrator, and the cali-
bration curve was linearized using a
fourth order least squares polynominal
fit to the original data. The reproducibil-
ity of the velocity profiles also was de-
termined over the period of several
weeks.
The isokinetic high-volume sampler
was used as the aerosol concentration
reference for all sampling effectiveness
calculations. Because a single isokinetic
high-volume measurement was used as
a reference for two test inlets (one run
before the isokinetic reference and one
run after the isokinetic reference), it was
necessary to determine the repeatabil-
ity of duplicate isokinetic concentration
measurements. This was accomplished
by making a series of four or five con-
secutive isokinetic high-volume sam-
pler concentration measurements. Ad-
ditionally, it was necessary to stop the
wind tunnel fan to replace inlets in the
wind tunnel. Therefore, the effect on
concentration of stopping the wind tun-
nel fan between isokinetic sampler runs
also was investigated.
The rake was used to measure aero-
sol uniformity, and the high-volume
sampler was used to measure the wind
tunnel aerosol concentration. Both are
isokinetic sampling devices, and there-
fore the two methods should yield iden-
tical concentration values. In reality, a
discrepancy exists, and a record has
been kept on the quality of agreement
obtained when both measurements are
made.
Fluorometry is the analytical tech-
nique used to determine the mass con-
centration of aerosol particles collected
by a test inlet. An SLM Aminco Fluoro-
Colorimeter II is used at the EPA wind
tunnel. A calibration curve was devel-
oped by preparing serial dilutions of a
uranine solution (liquid particles) or of
an ammonium fluorescein solution
(solid particles). The precision of the in-
strument was determined by measuring
the fluorescence of five samples of the
same solution concentration.
After the test protocol was modified,
the inlet tests were resumed. First, the
Wedding IP10 SSI was run at a wind-
speed of 8 km/h using liquid and solid
aerosol particles. This was a prelimi-
nary test designed chiefly to evalual
the new test protocol. Following thi
preliminary test, the Wedding IP10 SJ
and the Andersen Samplers Mode
321A SSI were tested using both soli
and liquid aerosol particles at wine
speeds of 2 and 8 km/h. A "dirty" fiek
tested Wedding IP10 SSI (Phoenix, Ar
zona, May 1986) then was tested wit
the "clean" Wedding SSI used in prev
ous wind tunnel tests at a windspeed c
2 km/h with liquid particles. Liquid part
cle tests then were conducted at 2 km/
on a cleaned, field-tested Wedding IP-
SSI and the "clean" Wedding referenc
inlet.
Results
The final aerosol distribution configi
ration consisted of a six-point injectio
system, a 4 ft x 4 ft baffle located jus
upstream of the injection points, a 16-i
diameter mixing fan located just dowr
stream of the injection points (and d
reeled into the bulk air flow), and flov
straighteners located just upstream c
the 4 ft x 4 ft baffle. Using this configu
ration, the aerosol concentration a
each rake nozzle was found to be withii
±10 percent of the mean concentratioi
at 2, 8 and 24 km/h.
The velocity and turbulence profile
again were measured. Atypical velocit
and turbulence profile obtained at
windspeed of 8 km/h is shown in Fie
ure 1. The air velocity is within 10 pei
cent of the mean velocity, and the turbi
lence intensity is less than 5 percent a
all points measured in the test sectior
The maximum deviation in day-to-da
widespeed measurements at a give
point was 1.7 percent, and the max
mum deviation in turbulence intensit
was 1.0 percent.
Concentration stability was detei
mined by making a series of isokineti
high-volume sampler measurements £
each of the three required windspeed
(2, 8, and 24 km/h). The coefficient c
variation (the standard deviation d
vided by the mean) was less than 3 pei
cent at each of the three windspeeds
The isokinetic measurements takei
after stopping the wind tunnel fan be
tween runs all fell within one standan
deviation of their respective means ex
cept in one case where the concentra
tion was within two standard deviation
of the mean.
A record of the agreement betweei
concentration values indicated by th
isokinetic rake and the isokinetic high
volume sampler has been kept for run
-------
10
9
I'
Velocity Profile
fb
* = 6" above centerline
9 = Centerline
O = 6" below centerline
•no
I
j_
18 30 42
Distance from East Wind Tunnel Wall (in)
54
5.0
a
4.0
3.0
Turbulence Intensity
O
+
•
O
I
j_
6 18 30 42 54
Distance from East Wind Tunnel Wall (in)
Figure 1. Velocity and turbulence profiles in the test section at 8 km/h.
in which both measurements were
made. The concentration indicated by
the isokinetic rake has been on average
7 percent higher than the concentration
indicated by the isokinetic high-volume
sampler.
The relative error of the fluorometer is
calculated using the equation
RE = (p x 100%)/(x) (1)
where
p = instrument precision (fxg/mL)
x = measured concentration (n,g/mL).
The precision of the fluorometer was
determined over its range of operation
using uranine solutions of 1, 0.1, 0.01,
and 0.001 p,g/mL. Six samples were pre-
pared at each concentration mimicking
the procedures used to handle filter
samples from an actual inlet test. Fluo-
rometer readings were obtained for
each solution concentration and con-
verted to uranine concentrations using
a current calibration curve. The stand-
ard deviation of replicate uranine con-
centration values was taken to be the
precision of the fluorometer. The rela-
tive error (required to be less than 5 per-
cent in 40 CFR Part 53) then was calcu-
lated using Equation 1. A plot of uranine
concentration versus relative error
shows that a uranine concentration of
0.014 (jig/mL corresponds to a relative
error of 5 percent. Uranine concentra-
tions encountered in the wind tunnel
are typically much greater than 0.014
|j.g/mL except when small particles (3 or
5 n-m) are used at high windspeeds (24
km/h). A new rake flow system is being
installed to provide for the collection of
greater quantities of uranine in the
same amount of sampling time.
The two most important parameters
obtained from the inlet tests are the 50-
percent cutpoint and the expected mass
ratio. The 50-percent cutpoint was de-
fined previously. The expected mass
ratio is the mass collected by the test
inlet (found by integrating the inlet's
sampling effectiveness curve against an
assumed aerosol size distribution) com-
pared to the mass predicted for an
"ideal" sampler. The sampling effec-
tiveness values for the ideal sampler
and the aerosol size distribution are
both found in 49 FR, 10461, Table D-3.
The sampling effectiveness curve must
be such that the test inlet has the 50-
percent cutpoint between 9.0 and 11.0
(jim and an expected mass ratio be-
tween 0.90 and 1.10. The results of the
inlet tests are summarized in Table 1.
Except where the test inlet is designated
as a field test inlet, the same Wedding
IP10 SSI and the same Andersen Model
321A SSI were used.
The two field-tested Wedding IP10
inlets do not meet the 50-percent cut-
point criterion; however, all inlets
tested meet the expected mass ratio re-
quirement. Both the Wedding IP10 SSI
and the Andersen Samplers Model
321A SSI meet the 50-percent cutpoint
requirement at windspeeds of 2 and 8
km/h using both solid and liquid aerosol
particles.
Conclusions and
Recommendations
The changes made in the test protocol
at the EPA wind tunnel test facility have
made it possible to meet all require-
ments set forth in 40 CFR Part 53 regard-
ing wind tunnel tests.
The wind tunnel tests performed on
the Wedding IP10 and Andersen Sam-
plers Model 321A SSI's show that both
inlets meet the proposed specification
for 50-percent cutpoint and sampling ef-
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Table 1. Summary of Inlet Test Results
Test inlet
Wedding IPW
Wedding IPW
Wedding IPW
Wedding IPW
Wedding IPW
Wedding IPW
Wedding IPW
("Dirty" field-
tested inlet)
Wedding IPW
Wedding IPW
("Cleaned" field
tested inlet)
Model 321 A
Model 321 A
Model 321A
Model 321 A
Windspeed
(km/h)
a
8
8
2
2
2
2
2
2
8
8
2
2
Particle
type3
L
L
S
L
S
L
L
L
L
L
S
L
S
50-percent
outpoint
(pm)
9.20
9.20
9.30
9.35
9.35
9.35
6.95
9.35
8.70
10.40
10.60
10.50
10.20
Slope
(Vg)"
1.37
1.32
1.37
1.28
1.28
1.30
1.68
1.28
1.36
1.44
1.48
1.39
1.40
Expected
mass
ratio
0.976
0.985
0.990
0.989
0.987
0.989
0.936
0.989
0.965
1.021
1.025
1.030
1.026
aL = Liquid, S = Solid.
bThe slope of the sampling effectiveness curve is estimated by the parameter cra =
U.S. Environmental Protection Agency
under Contract Number 68-02-3992 to
Research Triangle Institute (RTI). It has
been subjected to the Agency's peer
and administrative review, and it has
been approved for publication as an
EPA document.
fectiveness at windspeeds of 2 and
8 km/h using both solid and liquid aero-
sol particles. The two field-tested Wed-
ding IP10 SSI's met the sampling effec-
tiveness criterion but not the 50-percent
cutpoint criterion.
The new rake flow system should be
completed before tests are run at 24 km/
h, to ensure adequate quantities of ura-
m'ne are collected for fluorescence
measurements.
The sampling effectiveness curves
generated for the test inlets have not
been corrected for the presence of mul-
tiplets. Multiplets occur when two or
three particles aggregate forming a sin-
gle larger particle. At present, no single
algorithm for the correction of multi-
plets has been widely accepted. A single
correction method should be developed
and applied consistently to all sampling
effectiveness measurements involving
the PM10 test inlets.
Th§ information in this document has
beerrfiunded wholly or in part by the
Mark Woods, Fu-Lin Chen, and M. B. (Arun) Ranade are with Research Triangle
Institute (RTI), Research Triangle Park, NC 27709.
Kenneth A. Rehme is the EPA Project Officer (see below).
The complete report, entitled "The PMto Sampler Evaluation Program: January
1985 to July 1986." (OMer No. PB 87-145 801/AS; Cost: $18.95. subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
'"••"-
: :c-^~ 0,22
Official Business
Penalty for Private Use S300
EPA/600/S4-87/OC4
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