United States Industrial Environmental Research EPA-600/2-79-114
Environmental Protection Laboratory June 1979
Agency Research Triangle Park NC 27711
Research and Development
Particulate Sampling
and Support:
Final Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-114
June 1979
Particulate Sampling and Support:
Final Report
by
Kenneth M. Gushing and Wallace B. Smith
Southern Research Institute
2000 Ninth Avenue, South
Birmingham, Alabama 35205
Contract No. 68-02-2131
Program Element No. INE623
EPA Project Officer: D. Bruce Harris
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
This report summarizes the results from the research,
development and support tasks performed during the three year
period of this contract (11/75 - 11/78). These tasks encom-
passed many aspects of particulate sampling and measurement in
industrial gaseous process and effluent streams. Under this
contract Southern Research Institute calibrated and evaluated
cascade impactors, designed and evaluated novel particle sampl-
ing cyclones, wrote technical and procedures manuals for control
device evaluation and particle sampling methods, designed an
electrostatic precipitator backup for high flowrate systems, and
evaluated advanced concepts in monitoring particle mass and size
by optical systems. A number of smaller tasks involving lower
levels of effort are also discussed.
The appendix contains a list of technical documents pub-
lished under this contract.
11
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CONTENTS
Abstract ii
Figures v
Tables ix
Acknowledgment x
1. Introduction 1
2. Technical Summary 3
Develop a computer based cascade impactor data
reduction program 3
Pocket programmable calculators to facilitate
source sampling calculations 6
Non-ideal cascade impactor behavior 9
Sampling charged monodisperse and polydisperse
aerosols with cascade impactors 26
Evaluation of cascade impactor substrate media . . 29
Development of five-stage series cyclone system. . 35
Electrostatic precipitator back up for
sampling systems 41
Guidelines for particulate sampling in
industrial process streams 46
Technical manual for particulate sampling equip-
ment and methods 48
Evaluation of the PILLS IV 51
Cyclone and precollector for Fugitive Ambient
Sampling Train (FAST) 52
Design, construct and evaluate optimized
cascade impactor 60
Design a high temperature test facility 66
A massive volume sampler for health effects
studies 71
Calibration of source test cascade impactors ... 75
Calibration of Soviet particle sizing
instruments 88
Calibration of the Source Assessment Sampling
System cyclones (SASS) 96
Procedures Manual for Electrostatic Precipitation
Evaluation 114
Review of documents and reports furnished by EPA . 116
USA-USSR scientific information exchange program . 117
EPA/IERL/PMB exhibit booth at the 1977
APCA annual meeting 118
Calibration of a SASS middle cyclone for the
health effects research laboratory/RTP 121
Procedures manual for fabric filter
evaluation 126
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Advances in particle sampling and measurement
symposium 128
Presentation to Federal Republic of Germany. . . . 130
Particulate sizing instrument evaluation 131
References 132
Appendix 134
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FIGURES
Number Page
1 HP-65 and HP-25 programmable calculator source
measurement booklets 8
2 Composite of calibration data for the Andersen
impactor stages 2 through 7 12
3 An illustration of the four modeled stage collection
efficiency curves of a typical stage of the
Andersen impactor. Model 1 is the ideal behavior
model, Model 2 is the normal bounce model, Model
3 is the no bounce model, and Model 4 is the
extreme bounce model 14
4 Recovered size distributions on a cumulative per-
centage basis from the Brink impactor models for
ag = 2.0 and MMD's of 1.5, 4.5, 13.5, and 27 ym. . 15
5 Recovered size distributions on a cumulative per-
centage basis from the Brink impactor models as
shown in Figure 4 with the backup filter catches
omitted from the analysis 16
6 Recovered size distributions on a cumulative per-
centage basis from the Brink impactor models for
ag = 3.0 and MMD's of 1.5, 4.5, 13.5, and 27 ym.. 17
7 Recovered size distributions on a cumulative per-
centage basis for the Andersen impactor for ag =
2.0 and MMD's of 1.5, 4.5, and 13.5 ym. The back-
up filter was excluded from analysis in the results
shown 18
8 Recovered size distributions on a differential basis
from the Brink impactor models for MMD's of 4.5
and 27 ym and ag's of 2 and 3. 20
9 Recovered size distributions on a differential basis
from the Andersen impactor models for MMD's of
1.5 and 13.5 ym and ag's of 2 and 3 21
10 Flow chart for acid wash treatment of glass fiber
filter material 34
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11 EPA-SoRI five stage cyclone 36
12 Collection efficiency of the EPA-SoRI cyclones at a
flowrate of 28.3 £/min, a temperature of 25°C,
and for a particle density of 1.00 gm/cm3 .... 39
13 Collection efficiency of the EPA-SoRI cyclones at a
flowrate of 14.2 £/min, a temperature of 25°C,
and for a particle density of 1.00 gm/cm3 .... 40
14 Schematic of the electrostatic collector with the
disc discharge electrode installed 42
15 ESP collector assembly drawing 44
16 Electrostatic precipitator backup filter 45
17 Schematic diagram of Fugitive Ambient Sampling
Train 53
18 Berglund-Liu type vibrating orifice aerosol
generator system 54
19 Ammonium fluorescein aerosol particles generated
using the vibrating orifice aerosol generator . . 56
20 Collection efficiency versus particle diameter for
the FAST pre-separator impactor and cyclone ... 59
21 Assembly drawing of 0.5 ACFM optimized cascade
impactor 65
22 Preliminary layout for high temperature, low pres-
sure wind tunnel test facility 67
23 Schematic diagram of massive volume sampler for
Health Effects Studies 72
i
24 Theoretical impactor efficiency curves for rectangular
and round impactors showing the effect of jet-to-
plate distance S, Reynolds number Re, and throat
length T. 77
25 Collection efficiency vs. Sty. Andersen Mark III
stack sampler with glass fiber collection sub-
strates 79
26 Collection efficiency vs. Sty. Brink Model BMS-11
cascade impactor with glass fiber collection sub-
strates QQ
27 Collection efficiency vs. Sty. Brink Model BMS-11
cascade impactor with greased collection plates . 81
VI
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28 Collection efficiency vs. /$. MRI Model 1502 in-
ertial cascade impactor with greased collection
plates
29 Collection efficiency vs. /if. Sierra Model 226 source
cascade impactor with glass fiber collection sub-
strates. Sampling flow rate is 14 LPM ....... 83
30 Collection efficiency vs. /^. Sierra Model 226 source
cascade impactor with glass fiber collection sub-
strates. Sampling flow rate is 7 LPM ....... 84
31 Collection efficiency vs. ifty . University of Washing-
ton Mark III source test cascade impactor with
greased collection plates ............. 85
32 Cascade impactor wall loss vs. particle diameter . . 86
33 Soviet 14-stage cascade impactor .......... 89
34 Soviet 3-stage impac tor/cyclone ........... 89
35 Collection efficiency vs. particle diameter.
Soviet 12-stage impactor/cyclone. ,.,.,.„.. 90
36 Collection efficiency vs. particle diameter.
Soviet 12-stage cascade impactor ......... 91
37 Collection efficiency vs. particle diameter.
Soviet 3-stage cascade impactor .......... 92
38 Collection efficiency vs. particle diameter.
Soviet 14-stage cascade impactor (small cutpoints) . 94
39 Collection efficiency vs. particle diameter. Soviet
14-stage cascade impactor (large cutpoints) .... 95
40 Schematic of the Source Assessment Sampling System . 97
4*1 Collection efficiency vs. particle diameter.
Large SASS cyclone ................ 98
42 Collection efficiency vs. particle diameter.
Middle SASS cyclone ................ 99
43 Collection efficiency vs. particle diameter.
Small SASS cyclone ................ 100
44 SASS cyclone cutpoints ............... 101
45 Collection efficiency vs. particle diameter.
Large SASS cyclone ................ 103
vii
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46 Collection efficiency vs. particle diameter.
Unmodified middle SASS cyclone 104
47 Collection efficiency vs. particle diameter.
Modified middle SASS cyclone 105
48 Collection efficiency - temperature relationship
SASS middle cyclone 109
49 D50 - viscosity relationship SASS middle cyclone . . HO
50 Collection efficiency - particle density relationship
SASS middle cyclone
51 Collection efficiency at 400°F, 4 SCFM SASS middle
cyclone 113
52 Exxon SASS cyclones 123
Vlll
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TABLES
Number
1
2
3
4
5
Program flow for the cascade impactor data
Simulation conditions of the modeled impactor
Percent errors in AM/AlogD, Andersen impactor. . . .
Percentage of trial cases in which recovered value
Page
4
11
23
24
of (AM/AlogD) is within the indicated factor of
the true value 25
6 Laboratory calibration of the five-stage cyclones. . 38
7 FAST impactor and cyclone calibration data 58
8 Criteria for impactor design 61
9 Optimized impactor design specifications 62
10 Optimized impactor design specifications 63
11 Optimized impactor design specifications 64
12 SASS middle cyclone calibration data 108
IX
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ACKNOWLEDGMENT
The encouragement and support of our Project Officer,
D. Bruce Harris, during the entire contract period is grate-
fully acknowledged.
Over the three year period of this contract, many
individuals in the Southern Research Institute's Physics Divi-
sion contributed to the success of this program. Although
their names are too numerous to mention, their dedication and
efforts are acknowledged.
x
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SECTION 1
INTRODUCTION
The scope of the research, development, and support per-
formed for the Environmental Protection Agency under Contract
68-02-2131 (November 20, 1975-November 19, 1978) by Southern
Research Institute covered many aspects of particulate sampling
in gaseous process and effluent streams. Specific objectives
which were identified and given priority during this contract
were to:
1. Identify current and future requirements for particu-
late sampling - the nature of the particles (shape, volatility,
concentration, size distribution, charge, etc.), the sampling
conditions (temperature, pressure, entrained fluids, etc.),
and the goals of the sampling programs (control device evalua-
tion, health effects, etc.).
2. Continue research on the non-ideal or unmodelled be-
havior of cascade impactors. Investigate problems in using
impactors on nonroutine process streams (wet, high temperature,
high pressure). Design cascade impactors which incorporate
all that we have learned about their fundamental behavior and
operational problems.
3. Design, fabricate, and test cyclone systems for par-
ticle sizing. Evaluate existing cyclone systems for particle
sizing effectiveness. Consider alternatives to back up filters
in high flow rate applications.
4. Study alternatives to impactors and cyclones for par-
ticle sizing such as optical, electrical, or hybrid systems.
Concentrate on devices which offer the possibility of real
time, automatic, sampling and analysis.
5. Study methods of Quality Assurance in sampling and
calibration programs.
6. Generate and review documents on particulate sampling
and continually update our bibliography and literature survey.
7. Continue to study and evaluate new techniques, ideas,
and instruments for particulate sampling.
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8. Attend and organize meetings and symposia on particu-
late sampling.
9. Provide consulting and research and development support
to EPA programs.
There are two sections in the remainder of this report.
The Technical Summary contains a description of the results
from each task undertaken during the contract period. The
Appendix presents a complete list of technical documents printed
or to be printed under this contract.
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SECTION 2
TECHNICAL SUMMARY
DEVELOP A COMPUTER BASED CASCADE IMPACTOR DATA REDUCTION PROGRAM
Cascade impactors have gained wide acceptance as a practi-
cal means of making particle size distribution measurements.
These devices are regularly used in a wide variety of environ-
ments, ranging from ambient conditions to flue gas streams
of 500°C (950°F). Specially fabricated impactors can be used
for more extreme conditions.
Because of the usefulness of cascade impactors, research has
been funded to explore the theoretical and practical aspects of
impactor operation. As part of this research, an effort has been
made to design a comprehensive data reduction system which will
made full use of cascade impactor measurements.
The cascade impactor data reduction system (CIDRS) is
designed to automatically reduce data taken with any one of
four commercially available round jet cascade impactors: the
Andersen Mark III Stack Sampler, the Brink Model BMS-11 (as
supplied and with extra stages), the University of Washington
Mark III Source Test Cascade Impactor, and the Meteorology
Research Incorporated Model 1502 Inertial Cascade Impactor.
Provision is not made in this system for reducing data taken
with slotted jet impactors.
The computer programs which comprise this data reduction
system are written in the FORTRAN IV language. The plotting sub-
routines used were written specifically for the Digital Equipment
Corporation (DEC) PDP-15/76 computer, and these programs are
not compatible with other plotting systems. However, these
programs can be used as a guide when revision is made for use
with another operating system. The overall system incorporates
six programs: MPPROG, SPLINl, GRAPH, STATIS, PENTRA, and PENLOG.
These six programs are described briefly in Table 1. Impactor
design, particulate catch information and sampling conditions from
single impactor runs are used to calculate particle size distribu-
tions. MPPROG and SPLINl perform data analyses and make curve
fits, while GRAPH is totally devoted to various forms of graphical
presentation of the calculated distributions. The particle size
distributions can be output in several forms. STATIS averages
data from multiple impactor runs under a common condition and
PENTRA or PENLOG calculates the control device penetration and/or
efficiency.
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TABLE I
PROGRAM FLOW FOR THE CASCADE IMPACTOR
DATA REDUCTION SYSTEM
BLOCK 1. SINGLE RUN ANALYSIS
I. Impactor Program (MPPROG)
Takes testing conditions and stage weights to produce stage
Dso's, cumulative and cumulative % mass concentrations
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The system utilizes impactor specific calibration infor-
mation together with operating conditions and other pertinent
information such as stage weights, sampling duration, etc.,
to determine particle size distributions in several forms for
individual runs. A spline technique is applied to fit a curve
to the cumulative size distribution obtained from each individual
impactor run. These fitted curves have forced continuity in
coordinates and slopes. Averages of size distributions for
multiple runs are made using the fitted curves to provide inter-
polation values at a consistent set of particle diameters,
irrespective of the diameters at which the data points fall
in the original individual run data sets. Statistical analy-
ses are performed to locate and remove outliers from the data
being averaged, following which averages, variances, standard
deviations and confidence intervals are calculated. The averages
and statistical information are available in tabular and graph-
ical form in several size distribution formats (cumulative
mass loading, cumulative percentage by mass, differential mass, and
differential number). The averaged data are stored in disk
files for subsequent manipulation. Additional programs permit
data sets from control device inlet and outlet measurements
to be combined to determine fractional collection efficiencies
and confidence limits of the calculated efficiencies.
These results are available in graphical form with a choice
of log-probability or log-log presentations. As mentioned
above, the program is set up to handle all commercially avail-
able round jet cascade impactors, including common modifica-
tions, which are in current use in stack sampling. Other
round jet impactors can be easily substituted and slot type
impactors could be accommodated with slight program revision.
Two reports have been written which describe this data
reduction system. An executive summary of the program includ-
ing several examples is given in "A Data Reduction System for
Cascade Impactors", EPA-600/7-78-132a, July 1978. The detailed
program description with program listings can be found in "A
Computer-Based Cascade Impactor Data Reduction System," EPA-
600/7-78-042, March 1978.
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POCKET PROGRAMMABLE CALCULATORS TO FACILITATE SOURCE SAMPLING
CALCULATIONS
A library of twenty-two programs to facilitate calculations
associated with source sampling and air pollution measurement
studies was compiled for the Hewlett-Packard HP-65 and HP-
25 Pocket Programmable Calculators. This library contains
EPA Reference Methods 1-8, cascade impactor programs, and sev-
eral others. Each program includes a general description,
formulas used in the problem solution, a numerical example,
user instructions, and a program listing.
A list of the calculator programs follows.
APol-01 Method 1 - Sample and Velocity Traverses for Stationary
Sources
APol-02 Method 2 - Determination of Stack Gas Velocity and
Volumetric Flow Rate (Type S Pitot Tube)
APol-03 Method 3 - Gas Analysis for Carbon Dioxide, Excess
Air, and Dry Molecular Weight
APol-04 Method 4 - Determination of Moisture in Stack Gases
APol-05 Method 5 - Determination of Particulate Emissions from
Stationary Sources
APol-06 Method 6 - Determination of Sulfur Dioxide Emissions
from Stationary Sources
APol-07 Method 7 - Determination of Nitrogen Oxide Emissions
from Stationary Sources
APol-08 Method 8 - Determination of Sulfuric Acid Mist and
Sulfur Dioxide Emissions from Stationary Sources
APol-09 Cascade Impactor Operation
APol-10 Impactor F'low Rate Given Orifice AH
APol-11 Impactor Flow Rate, Given Gas Velocity and Nozzle
Diameter
APol-12 Impactor Sampling Time to Collect 50 Milligrams
APol-13 Impactor Flow Rate, Sample Volume, Mass Loading
APol-14 Impactor Stage Dso
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APol-15 /¥ Calculation - Round Jets
APol-16 /¥ Calculation - Rectangular Slots
APol-17 Cumulative Concentration vs Dso and AM/AlogD vs
Geometric Mean Diameter
APol-18 Mean, Standard Deviation, 90/95% Confidence Interval,
Mean ± CI
APol-19 Resistivity and Electric Field Strength
APol-20 Channel Concentrations for the KLD Droplet Measuring
Device (1-600 urn) DC-1
APol-21 Aerotherm High Volume Stack Sampler; Stack Velocity,
Nozzle Diameter, Isokinetic AH
APol-22 Flame Photometric Detector Calibration by Permeation
Tube Technique
Both of the program documents were published in two formats.
The first of these was the normal SVxll" bound version; the
second was a special, 5"x7" spiral bound version with plastic
laminated covers. The HP-65 document was published under the
title "HP-65 Programmable Pocket Calculator Applied to Air
Pollution Measurement Studies: Stationary Sources," EPA-600/8-
76-002, October 1976 (NTIS-PB 264 284/1BE). The HP-25 document
was published under the title "HP-25 Programmable Pocket Calculator
Applied to Air Pollution Measurement Studies: Stationary Sources,"
EPA-600/7-77-058, June 1977 (NTIS-PB 269 666/4BE). A photograph
of the two spiral bound booklets is shown in Figure 1.
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00
Figure 1. HP-65 and HP-25 programmable calculator source measurement booklets,
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NOW-IDEAL CASCADE IMPACTOR BEHAVIOR
Cascade impactors have become commonly used measurement
devices for the determination of size distributions of particu-
late matter emissions from industrial sources. Data obtained
with impactors are used to characterize emissions from sources,
to determine the performance of particulate control devices,
and in the selection and design of control devices for specific
sources.
Data provided by impactors are of relatively low resolu-
tion and do not permit the exact reconstruction of the size
distribution of the aerosol being sampled, even over the limited
range of sizes normally covered by most impactors (approxi-
mately 0.5 to 10 ym). However, little has been done to esti-
mate the magnitude of the uncertainties, or errors, which are
inherent in the method insofar as they relate to industrial
source emission measurements and determinations of fractional
collection efficiencies of control devices. The study described
here was one with the specific goals of estimating the effects
of two non-ideal operating characteristics of impactors on
the data obtained with them. These two non-idealities are
(1) the lack of step function stage collection characteristics
and (2) particle bounce. Several authors1'2'3 have proposed
various deconvolution procedures which, when applied to impac-
tor data, would to a large degree, correct for the effect of
the finite slopes of the stage collection efficiency curves.
However, little use has been made of these procedures, pri-
marily because noise in the data frequently results in oscilla-
tory solutions with large negative values. In any case, little
quantitative information regarding the magnitude of the errors
introduced by the lack of sharp size cuts in impactors commonly
used for stack sampling has been published. The magnitude
of errors introduced by particle bounce has not previously
been quantified although the existence of such errors has been
described in the literature.*'5'6'7
Technical Procedures
The approach used in this study was the development of
a computer model of cascade impactor performance. The model
was based on actual impactor performance as measured in a cali-
bration study of commercially available cascade impactors for
stack sampling. A total of four simulation models were used
for both a Brink impactor in a commonly used modified configu-
ration for stack sampling and an Andersen Mark III stack sam-
pler. The use of glass fiber collection substrates was assumed
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for both impactors. Both grease and glass fiber substrates
are commonly used for sampling at temperatures below 150°C
(300°F) but no satisfactory greases have been found for use
at temperatures over 150°C. Therefore, glass fiber substrates
must usually be used for collection substrates at elevated
temperatures.
The first model for each impactor was one having ideal
collection characteristics, i.e., step functions from 0% to
100% collection at the stage D50's. (The stage D5p is that
particle diameter at which the stage has a collection effi-
ciency of 50%. The D50 is generally used as the characteristic
cut off diameter for particles collected by the stage.) This
model was used as a performance standard against which the
remaining three models could be compared and also provided
a basis for checking the program.
The assumed operating conditions and resulting cut sizes
(Dso's) of the two impactors modelled in the study are given
in Table II. The models of the Brink impactor included a cyclone
precollector which was assumed to have the same performance
characteristics in all three of the simulations other than
that of the "Ideal Brink." The cyclone performance was based
on calibration data for a cyclone in common use with the Brink
impactor modified for stack sampling. This cyclone has a col-
lection efficiency of 100% for particles larger than about
20 ym.
The second model for each impactor used the actual cali-
bration data for each stage. In this model the stage collec-
tion efficiencies increased monotonically with increasing
Stokes numbers (increasing particle size) to a maximum value
of about 90% to 95%. The efficiencies then decreased for
larger Stokes numbers to a value of 35% to 40% and remained
constant thereafter. A composite of the calibration data for
stages two (2) through seven (7) of the Andersen impactor,
which illustrates the behavior described above, is shown in
Figure 2. Data for Stages 1 and 8 were offset from the tight
grouping of the data for the remaining stages and hence were
omitted in Figure 2 for purposes of clarity in illustrating
the behavior trends of the stage efficiency curves. The data
for the Brink impactor exhibited similar trends. This model,
Model 2, is called the "Normal Bounce" model.
The third model was identical to the second except that
the rollover and decline in efficiency for larger Stokes numbers
was ignored. Instead, the efficiencies were assumed to smoothly
increase to 100% and remain at that value for increasingly
larger Stokes numbers. This is called the "No Bounce" model.
The fourth model was also identical to Model 2 with the excep-
tion that the collection efficiencies were assumed to drop
10
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Table II.
Simulation Conditions of the Modeled
Impactor Performance
Brink
Andersen
Temperature, °C (°P)
Gas composition
Particle density, gm/cm3
Flowrate, alpm (acfm)
Barometric Pressure,
mm Hg
177 (350)
Std. air
2.27
1.13 (0.040)
749
177 (350)
Std. air
2.27
17.0 (0.600)
749
Stage/Ds o
1
2
3
4
5
6
7
8
601
182
39
85
1.23
0.905
0.589
0.1982
9
6
3
1
7.84
7.40
4.44
2.87
1.58
0.855
0.449
0.200
1. Stage 1 is a cyclone precollector.
2. Stages 2 and 8 are part of the modifications to the impactor
11
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98
90
s?
> 70
u
HI
u 50
E
u.
ui 30
O
U
3 10
8
UJ
O 2
co
0.5
0.1
0.01
I
0.04 0.1 1.0
SQUARE ROOT OF STOKES NUMBER (DIMENSIONLESS)
10.0
3630-027
Figure 2. Composite of calibration data for the Andersen impactor stages
2 through 7.
12
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rapidly to a value of 2% for Stokes numbers larger than that
at which the collection efficiency reached a peak in the cali-
bration data. This model was termed the "Extreme Bounce" model.
The use of the same basic collection efficiency curves
for the "No Bounce," "Normal Bounce," and "Extreme Bounce"
models for particle sizes smaller than those for which the
collection efficiencies were maximal in the calibration data
is probably a realistic representation of the actual perfor-
mance of the impactors in collecting various types of particles.
Rao5 found that impactor collection characteristics for dry
solid particles and oil particles were virtually identical
when glass fiber substrates were used for Stokes numbers smaller
than those at which the peak efficiency was reached for the
dry solid particles. Beyond this point he found that oil par-
ticles were collected with efficiencies which increased to
100% with increasing Stokes number while the efficiencies
declined for the dry particles as a result of bounce. Figure
3 shows an example of the four modelled collection efficiency
characteristics of one stage of the Andersen impactor.
Results and Discussion
The performance of each model of the two impactors was
evaluated for aerosols having log-normal size distributions
with mass median diameters (MMD) of 1.5, 2.6, 4.5, 7.8, 13.5,
and 27 micrometers and geometric standard deviations, a , of
2, 3 and 4. 9
Figures 4 through 7 show typical results for the two im-
pactors in a cumulative percentage presentation. It is evident
from all four of these figures that particle bounce severely
distorts the size distributions, especially for aerosols hav-
ing large mass median diameters. Figures 4 and 5 show the
results of the simulations for the same impactor and size dis-
tributions, the difference between the two being the omission
of the back-up filter catch in presenting the results in Figure
5. Comparison of Figures 4 and 5 indicate that omitting the
back-up filter in calculating the cumulative percentages greatly
reduces the distortion resulting from bounce. Comparison of
Figures 4 and 5 shows that increasing the width of the input
size distribution (increasing a ) reduces the distortion caused
by bounce although the distortion remains appreciable for the
extreme bounce models at large HMD's.
Figure 7 shows the results from the Andersen models cor-
responding to three of the four cases for the Brink Model shown
in Figure 5. Note that the deviations from the input distri-
bution resulting from bounce are more severe in the Andersen
results than in the Brink. This difference in the severity
13
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100 —
5 10 20
PARTICLE DIAMETER, jum
100
3630-028
Figure 3. An illustration of the four modeled stage collection efficiency
curves of a typical stage of the Andersen impactor. Model 1 is
the ideal behavior model, Model 2 is the normal bounce model,
Model 3 is the no bounce model, and Model 4 is the extreme
bounce model.
14
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99.8
N
CC
111
-I
V)
111
IU
U
EC
LU
Q.
Ill
U
NO BOUNCE
NORMAL BOUNCE
EXTREME BOUNCE
0.01
1.0
PARTICLE DIAMETER, jum
10.0
3630-029
Figure 4. Recovered size distributions on a cumulative percentage basis from
the Brink impactor models for 0g = 2.0 and HMD's of 1.5, 4.5, 13.5,
and 27 ym. The bold lines represent the input distributions.
15
-------
99.8
til
N
cc
UJ
(/>
HI
98
90
70
50
30
o
cc
UJ
a.
w 10
U
0.5
0.1
0.01
0.1
• NO BOUNCE
A NORMAL BOUNCE
• EXTREME BOUNCE
1.0
PARTICLE DIAMETER,
10.0
3630-030
Figure 5. Recovered size distributions on a cumulative percentage basis from
the Brink impactor models as shown in Figure 4 with the backup
filter catches omitted from the analysis. The bold lines represent
the input distributions.
16
-------
99.8
• NO BOUNCE
A NORMAL BOUNCE
• EXTREME BOUNCE
0.01
1.0
PARTICLE DIAMETER,
10.0
3630-031
Figure 6. Recovered size distributions on a cumulative percentage basis from
the Brink impactor models for Og = 3.0 and MMD's of 1.5, 4.5, 13.5,
and 27 ym (backup filter included in the analysis). The bold lines
represent the input distributions.
17
-------
99.8
HI
N
CO
o
K
UJ
OL
98
90
70
50|—
< 30
10
2
D
2
D 9
O 2
0.5
0.1
0.01
• NO BOUNCE
A NORMAL BOUNCE
• EXTREME BOUNCE
0.1
PARTICLE DIAMETER, jum
10.0
3630-032
Figure 7. Recovered size distributions on a cumulative percentage basis for
the Andersen impactor for ag = 2.0 and MMD's of 1.5, 4.5, and 13.5 ym.
The backup filter was excluded from analysis in the results shown.
The bold lines represent the input distributions.
18
-------
of the distortions apparently results from the cyclone pre-
collector on the Brink which removes most of the larger parti-
cles that are responsible for raising the apparent percentages
of fines in the recovered size distributions.
It should also be noted that the relative errors in mass
median diameters become increasingly large as the MMD of the
input aerosol decreases. The recovered HMD's were found to
be systematically large for test aerosol HMD's below 10 urn. The
recovered values of CTg were also systematically high with larger
relative errors at the lower values of a , as would be expec-
ted because of the low resolution affordid by impactors.
In many cases (e.g., control device fractional collection
efficiency studies) the slope of the size distribution curve,
expressed in mass concentration units, is the quantity of
greatest interest. The most common manner of presentation
of this slope is the form dM/dlogD (units of mass concentra-
tion) . The quantity dM/dlogD is often approximated directly
from the impactor data, stage by stage, as Am./AlogD., where
f" H
m. = mass concentration of particles retained by the i
stage
and AlogD. = log
(D5o)i
The particle diameter is then taken to be the geometric mean
of (Ds o) • and (Ds o) • -, /
D = /(D5o)i x (DsoJj^-L
Figures 8 and 9 illustrate recovered size distributions
presented in such a manner, together with the input distribu-
tions, for representative sets of Brink and Andersen results.
The results for the "extreme bounce" case are not shown in
Figures 8 and 9 but the values in those cases generally fall
between the "no bounce" and "normal bounce" cases except for
the back-up filters, for which the values were much higher
in the "extreme bounce" case than in the other two cases.
Except for the finest size fractions, represented by the back-
up filter catches, and the fine fraction tails of the low a
distributions, the agreement between the recovered values
of (AM/ AlogD). generally lie reasonably close to the input
distributions. However, errors of up to +35% are not infre-
quent.
19
-------
.O
m
*
Q
O
O
10
10
GEOMETRIC MEAN DIAMETER (MICROMETERS)
3630-033
Figure 8. Recovered size distributions on a differential basis from the Brink
impactor models for MMD's of 4.5 and 27 ym and ag's of 2 and 3.
The bold curves represent the input distributions.
20
-------
10°
I
s
+rf
!S
S
cf
O
O
10-1
10-2
10-3
10-4
MMD = 13.5 jum
ag = 3
I I
10-1
10'° 101 10-1 10'°
GEOMETRIC MEAN DIAMETER (micrometers)
3630-034
Figure 9. Recovered s:Lze distributions on a differential basis from the Andersen
impactor models for HMD's of 1.5 and 13.5 pm and erg's of 2 and 3. The
bold curves represent the input distributions.
21
-------
Tables III and IV show the errors, expressed as percentages,
in the recovered values of (AM/AlogD)i for several cases for
each of the two impactors. (For the purpose of calculating
log D and D for the filter catches, it was assumed that the
diameter range covered by the filter was (DSo)e down to ^(DsoJa-
Although no results for a = 4 have been shown, the agree-
ment between the recovered sizl distributions and the input
distributions was progressively better as a increased and
was quite good in all cases for a = 4 withgthe exception of
back-up filter catches when bounce was present.
Table V shows the percentages of cases in which the re-
covered values (Am/AlogD). lay within factors of 1.2, 1.5,
and 2 of the true value. From these results it appears that
the concentrations of fine particles as measured with impactors
can seldom be taken to be known better than to within a factor
much smaller than 1.5 unless the particles are known to be
adhesive or an effective adhesive coating can be applied to
the substrates.
There is some evidence,8'9 although it is not conclusive,
that the use of adhesive coatings (greases) on the substrates
may become ineffective as the particulate deposits build up
under the impactor jets. This would result in the same type
of errors due to particle bounce resulting in back-up filter
contamination by oversize particles with greased substrates
as has been shown to occur with glass fiber substrates.
Conclusions and Recommendations
From the evidence presented here, it is suggested that
back-up filter catches generally should be omitted from data
presentation when dry, non-sticky particulates are sampled.
Exceptions should be made only if the HMD is smaller than
about 2.5 ym. In addition it is suggested that cyclone pre-
collectors having D5u's somewhat larger than the first impac-
tion stage D50 be used whenever a non-sticky particulate is
sampled. The use of such cyclones tends to greatly reduce
errors due to particle bounce.
The results of this study were reported at the 1977 Air
Pollution Control Association Annual Meeting in Toronto,
Ontario, as Paper No. 77-35.3, entitled "Non-Ideal Behavior
in Cascade Impactors."
22
-------
Table III. Percent Errors in AM/AlogD, Andersen Impactor
No Bounce
MMD: 1.5 4.5 13.5 1.5 4.5 13.5
Stage/Error
F 144 22 38
8 9 -14 -5
7 -8 56 -11 -4
6 -18 13 -10 -8 4
5 -14 -19 18 -12 -17 -24
4 6 -26 -20 -7 -21 -25
3 -19 -30 10 -15 0
2 -23 -28 9 -22 -24
Normal Bounce
F 568 121000 44 173 1720
8 22 920 -12 8 103
7 -6 111 -11 1 37
6 -20 9 293 -12 -11 4
5 -16 -18 39 -12 -16 -11
4 5 -27 -17 -7 -21 -24
3 -20 -30 9 -16 -25
NOTE: Values are omitted for stages for which the collected
mass would be too small to be detected in field sampling
programs.
23
-------
Table IV. Percent Errors in AM/AlogD, Brink Impactor
No Bounce
MMD:
Stage/Error
F
6
5
4
3
2
1
F
6
5
4
3
2
1
1.5 4.5
220
-6
-43
-19
-15
-1
88
13.5
27
550
-10
-40
-20
-16
-1
86
220
-35
3
-3
-10
-14
238
-8
10
-4
-28
-15
84
-8
-15
Bounce
107
7
-18
33
7
1.5
24
-37
-32
-9
-4
4
34
4.5
53
-21
-39
-12
-9
-20
-3
13.5
13
-40
-5
-3
-23
-14
27
-37
4
8
-22
-14
100
3
41
-39
-29
-10
-4
4
33
123
-24
-33
-12
-10
-18
-4
12
-26
0
-3
-20
-16
-10
17
10
-16
-17
NOTE: Values are omitted for stages for which the collected mass
would be too small to be detected in field sampling pro-
grams .
24
-------
Table V. Percentage of Trial Cases in which Recovered
Value of (AM/AlogD) is Within the Indicated
Factor of the True Value
Andersen
Brink
Factor:
Stage/Percent
of cases
F
8
7
6
5
4
3
2
1.2 1.5
2.0
0
57
65
65
75
30
40
(30)
31
71
76
80
100
100
90
(90)
38
79
82
90
100
100
90
(90)
Factor:
Stage/Percent
of cases
F
6
5
4
3
2
1
1.2 1.5
0
35
11
80
74
42
71
33
59
47
95
91
96
72
2.0
56
82
100
100
91
100
100
Andersen table covers all cases
with
MMD = 1.5, 2.6, 4.5, 7.8, 13.5 and
°g = 2, 3
for both normal bounce and no
bounce
Brink table covers all cases with
with
MMD = 1.5, 2.6, 4.5, 7.8, 13.5,
27, and
ag = 2, 3
for both normal bounce and no
bounce
25
-------
SAMPLING CHARGED MONODISPERSE AND POLYDISPERSE AEROSOLS WITH
CASCADE IMPACTORS
In performing particle size distribution measurements
at control devices operating on industrial process streams,
investigators are usually aware that in some cases charged
particles will be present in the gas stream. In order to
assess the influence of particle charge, three different ex-
periments were performed to determine whether or not cascade
impactors sampling charged aerosols can yield erroneous par-
ticle size distribution measurements. The commercially avail-
able cascade impactors utilized in this study were the Ander-
sen Mark III Stack Sampler, the Brink Model BMS-11 Cascade Im-
pactor, the Meteorology Research, Inc. Model 1502 Cascade Impac-
tor, and the University of Washington Mark III Source Test Cascade
Impactor. In general, the measured distributions indicated more
large particles and fewer small particles than actually existed.
The deviations from the true size distribution were found to be
a function of the magnitude of charge. The deviations were
smaller if glass fiber substrates were used as impactor collec-
tion surfaces instead of the metal collection plates alone. For
charge levels representative of electrostatic precipitators oper-
ating at normal charging conditions (an electric field strength
of 400,000 V/m and a current density of 3 x 10=l* A/m2), the dif-
ferences between the true and measured polydisperse size distribu-
tions sampled with glass fiber substrates were small.
The three experiments are briefly described below. In the
first experiment monodisperse aerosols were sampled by the
University of Washington Mark III, Andersen Mark III, and MRI
Model 1502 cascade impactors. The second test involved the sampl-
ing of polydisperse aerosols with a Brink cascade impactor. The
third experiment involved the sampling of polydisperse aerosols
with the Andersen Mark III cascade impactors. A review of the
important parameters and conclusions for each experiment are
described below.
1st Test - Monodisperse Aerosol
1. Tests were done with the impactors operated at the
recommended flow rate and with particle charges equivalent
to those expected at precipitator outlets. However, only two
particle sizes were used.
2. Wall losses were measured along with the stage collec-
tion efficiency.
3. For charge levels approximately five times higher
than those expected at a precipitator outlet, very large effects
were noted.
26
-------
4. For samples taken using glass-fiber substrates at
representative particle charge levels, the effect of particle
charge on impactor performance was found to be minimal.
5. Grounding the impactors generally increased stage
collection efficiencies.
6. The data from this experiment were not taken with
particle concentrations high enough to be representative of
those to be found at the outlet of industrial precipitators.
2nd Test - Polydisperse Aerosol Sampled with a Brink Impactor
1. Tests were done with the impactors operated at the
recommended flow rate with a polydisperse aerosol and particle
charges equivalent to those expected at precipitator outlets.
Only two stages of a Brink impactor were used.
2. The particle concentration was less than would be
expected at a precipitator outlet.
3. A test on wall losses showed that they play a sig-
nificant part in impactor performance when a charged aerosol
is sampled.
4. Tests using glass-fiber substrates did not show an
appreciable difference in the collection of charged and un-
charged particles. Tests using bare metal substrates, however,
showed quite a difference between the collection of charged
particles and the collection of uncharged particles.
•
3rd Test - Polydisperse Aerosol Sampled with Andersen Impactors
1. Tests were performed with entire Andersen impactors
operated at the recommended flow rate and with glass-fiber
substrates only.
2. The particle concentration was similar to that ex-
pected at the outlet of an industrial electrostatic precipi-
tator. The aerosol contained polydisperse ammonium fluores-
cein particles.
3. Wall losses were not considered separately, however,
no visible wall loss was observed for tests with particles
having moderate charge. The wall losses were visibly evident
in the high charge tests.
4. Moderate particle charge levels had little effect
on impactor performance for the middle and lower stages. For
stages with D5o's above 3 micrometers, up to about twice as
much mass was caught in the charged particle impactor than
in the neutral one.
27
-------
5. For charging conditions higher than those considered
moderate here, the effects of particle charge were more sig-
nificant both for the lower impactor stages and the upper impac-
tor stages, with the middle stages giving approximately true
mass measurements.
The details of the experimental work performed under these
tasks is presented in a report entitled "Sampling Charged Particles
with Cascade Impactors," EPA-600/7-79-027, January 1979.
28
-------
EVALUATION OF CASCADE IMPACTOR SUBSTRATE MEDIA
Cascade impactors are widely used to determine particle
size distributions in air pollution control device research
programs. In these research programs a large variety of flue
streams are encountered with temperatures ranging from ambient
to around 370°C (700°F). Gas analyses show that many of these
sources contain some SO components, particularly those asso-
ciated with fossil fuel fired boilers.
Most impactors have collection stages which are too heavy
to allow accurate measurements of the mass of the particles
collected in each size fraction. Weighing accuracy can be
improved by covering the stage with a lightweight collection
substrate made of aluminum foil, teflon, glass fiber filter
material, or other suitable lightweight material , depending
upon the particular application. Some manufacturers now fur-
nish lightweight inserts to be placed over the collection stages.
With such arrangements it is possible to collect enough material
on each stage to make an accurate determination of the mass
collected and avoid overloading the stage. If the stage is
overloaded, some deposited particulate matter can be reentrain-
ed and deposited on another stage or the back-up filter and
lead to erroneous results.
Substrate materials may also serve the purpose of changing
the surface characteristics from those of a bare metal or plastic
to something better suited to holding particles which impact.
Thus, various greases are often used, either on bare impactor
plates, or, more frequently, on metal foil substrates.
Presented in the published final report (see page 32) are
the results of investigations concerning the use of two classes
of impactor substrates—greased metal foils, and glass fiber filter
materials. Tests were made under both laboratory and field condi-
tions to evaluate each of several greases and filter materials.
The general purpose of this study was to identify specific
materials and handling techniques which may be used to improve
the accuracy of weight measurements in impactors by reducing
uncertainties arising from changes in substrate weights.
Although normal glass fiber substrate preparation includes bak-
ing and desiccation before the initial weighing, it is frequently
found that weight losses can occur when sampling clean air.
Previous tests were conducted to investigate this phenomenon
in detail.10 It was found that with careful handling, weight
loss per glass fiber substrate for Andersen impactors can be
kept below 0.1 mg. This loss is attributed to loss of fibers
which stick to seals within the impactor and to "superdrying"
when sampling hot, dry air. Weight losses of 0.1 mg are small
29
-------
compared to most stage catches when sampling particulate matter,
and they are within an acceptable range for sampling errors.
A more significant problem is excessive weight gain of
the glass fiber material itself due to gas phase reactions.
These reactions appear to be caused by the SOx component in
flue gases. A series of studies was thus directed toward de-
veloping procedures to passivate glass fiber materials against
the effect of SO components in flue gas.
X
Although greases offer good impedance to particle bounce
on substrates, they are subject to temperature limitations.
Sampling clean, hot air while using greased substrates may
result in severe weight losses. These losses appear to re-
sult from one or more of several mechanisms which may include
continued loss of volatile components, erosion of grease by
the action of the gas jet in the impactor, and occasional flow
of grease from the substrate to other surfaces within the impac-
tor. In addition, chemical reactions may play a role in some
cases. Occasionally, some of the weight lost on upper impactor
stages has been found to reappear as a weight gain on a back-up
filter, which is an indication that the grease has been blown
off the collection surface or has chemically reacted to form a
fine "smoke" which was then collected by the back-up filter.
Summary of Results of Evaluation of Greases
Upon preliminary screening by static heating tests in
the laboratory, six of the nineteen greases tested were found
to have acceptable characteristics at elevated temperatures.
Among those greases eliminated by these tests, large changes
in mass or in consistency had occurred.
In the field tests these six greases were applied to metal
foil impactor substrates and were subjected to a flue gas sampl-
ing procedure. Particulate matter was removed by a prefilter so
that the effects of the flue gas alone on the greased substrates
could be observed.
As a result of the field studies it was concluded that
Apiezon H grease performed best of the greases tested. Other
greases studied displayed changes in consistency or a tendency
to flow under the influence of the gas stream.
%
Further tests on Apiezon H have demonstrated that this
grease is a suitable substrate material for applications where
the temperature does not exceed approximately 177°C (350°F).
30
-------
Summary of Results of Evaluation of Filter Media
Untreated glass fiber filter materials used as impactor
substrates will almost invariably increase in mass when sub-
jected to the hot flue gases normally encountered in field
applications. Conversion of SOa to various sulfates appears
to be the cause of mass gains. The various filter materials
tested vary widely in the amount of mass change which occurs
under a particular set of flue gas conditions.
Preconditioning techniques can be used to force the produc-
tion of sulfates in a filter medium, leaving a minimal number
of sites available for chemical reaction in the flue gas, and
hence, providing substrate material for which minimum mass
gains occur during use in an impactor. The best results were
achieved when substrates were washed in sulfuric acid, baked,
and conditioned in situ.
Of the filter materials studied, Reeve Angel 934AH was
found to be most suitable in all respects for use as cascade
impactor substrates.
Conclusions and Recommendations
Collection stages of most types of cascade impactors are
very heavy in comparison with the amounts of particulate material
normally collected. It is therefore the usual practice to
augment each collection stage with a lightweight substrate
to improve weighing accuracy. Generally, two classes of sub-
strates are used—greased metal foils, and glass fiber filter
material.
Greased foils provide resistance to particle bounce and
scouring effects, but greases tend to be unstable at elevated
temperatures. Some tend to harden, and in others the viscosity
may become reduced so that they may flow or be blown off the
surface by the high velocity gas flowing through the impactor
jets. Of the greases tested, Apiezon H was found to perform
most satisfactorily. This grease may be used at temperatures
up to approximately 177°C (350°F). No greases were found to
be usable at higher temperatures.
Mass gains exhibited by glass fiber filter materials when
they are exposed to the SO components in flue gas streams
pose a complicated problem. Experiments show that these mass
gains are caused by formation of sulfates due to a gas phase
reaction with SO . Laboratory and field experiments indicate
that the only glass fiber filter material suitable for use
as a cascade impactor substrate is Reeve Angel 934AH. When
this material is acid treated, according to a procedure given
below, mass gains caused by flue gas reactions can be kept quite
small.
31
-------
It is recommended that acid washing, baking and in situ
conditioning be used whenever large blank mass gains with large
standard deviations are expected. In this context, "large"
refers to glass fiber substrate mass gains greater than several
tenths of a milligram.
Further research may provide a technique for passivating
glass fiber materials to all mass gains. It has been suggested
that a high temperature polymer or silicon compound might be
developed to coat the glass fibers in much the same way that
the Gelman Spectro-Grade material is prepared for use at low
temperatures.
The Final Report for this task was published in a document
entitled "Inertial Cascade Impactor Substrate Media for Flue Gas
Sampling," EPA-600/7-77-060, June 1977 (NTIS-PB 276 583/2BE).
Procedure for Acid Washing Substrates
1. Submerge the glass fiber substrates to be conditioned
in a 50-50 mixture (by volume) of distilled water and reagent
grade concentrated sulfuric acid at 100°-115°C (230-239°F)
for 2 hours. This operation should be carried out in a hood
with clean glassware. Any controllable laboratory hotplate
is suitable.
The substrates may need to be weighted down to keep them
from floating. For this purpose, place a teflon disc on the
top and bottom of the substrate stack. The top disc can be
held down with a suitable glass or teflon weight*
2. When the substrates are removed from the acid bath
they should be allowed to cool to room temperature. They are
next placed in a distilled water bath and rinsed continuously
with a water flow of 10-20/cm3/min. The substrates should
be rinsed until the pH of the rinse water, on standing with
the substrates, is nearly the same as that of the distilled
water. The importance of thorough washing cannot be over-em-
phasized.
3. After rinsing in distilled water the substrates are
rinsed in reagent grade isopropanol (isopropyl alcohol). They
should be submerged and allowed to stand for several minutes.
This step should be repeated four to five times, each time
using fresh isopropanol.
4. Allow the substrates to drain and dry. They can be
spread out in a clean dry place after they have partially dried
(dry enough to handle).
32
-------
5. When the filters are quite dry to the touch they should
be baked in a laboratory oven to drive off any residual moisture
or isopropanol. Bake the substrates at 50°C (122°F) for about
two hours, at 200°C (392°F) for about two hours, and finally
at 370°C (700°F) for about three hours. The substrates are
now ready for in situ conditioning.
As a final check, place two substrates in about 50 ml
of distilled water, and check the pH. The substrates to be
checked for pH should be torn into small pieces, placed in
the water, and stirred for about 10 minutes before the pH is
measured. If the pH is significantly lower than that of the
distilled water, then the filters should be baked out at 370°C
(700°F) for several hours more to remove any residual sulfuric
acid. The boiling point of sulfuric acid is 338°C (640°F),
so high temperatures must be used.
Figure 10 is a flow chart representing the acid wash pro-
cedure described in the foregoing paragraphs.
33
-------
WASH SUBSTRATES IN
50% H2SO4 SOLUTION
RINSE IN WATER
(ROOM TEMPERATURE)
RINSE IN ISOPROPANOL
(ROOM TEMPERATURE)
DRY SUBSTRATES
IN AMBIENT AIR
BAKE OUT
RESIDUAL MOISTURE
pH TOO LOW
TEST pH OF
SUBSTRATES
STORE IN
DESSICATOR FOR
ULTIMATE USE
.Figure 10. Flow chart for acid wash treatment of glass fiber filter material.
34
-------
DEVELOPMENT OF FIVE STAGE SERIES CYCLONE SYSTEM
The majority of measurements to determine the particle-
size distribution in process streams are made with cascade
impactors. Impactors, however, have several limitations:
• There is not enough mass collected for chemical anal-
ysis of the particles in each size fraction.
• Frequently there is not enough mass collected on some
stages to be weighed accurately.
• Particle bounce and reentrainment cause an unpredic-
table, but significant, error in the stage and backup
filter catches.11
• When the mass concentration is high, the sampling time
may be undesirably short.
• Impactors are used with lightweight collection substrates
which are often unstable in mass when exposed to the
process stream.12
A series of cyclones with progressively decreasing cut
points will perform similarly to impactors, but without many
of the associated problems.
Cyclones, however, also have limitations to their applica-
bility:
• There is no general theory to describe the performance
of small cyclones under field test conditions.
• Sampling times may be undesirably long at sources where
the mass concentration is low.
An experimental study was undertaken to develop and eval-
uate a system containing five cyclones and a backup filter
in series.
The EPA-SoRI cyclone system as shown in Figure 11, is an
inertial particle sizing device that is designed for in-situ sampl-
ing of industrial process streams. It will fit through a 10 cm
diameter port and is equipped with nozzles of different diameters
to allow isokinetic sampling at a nominal sample flow rate of
28.3
In this study, the individual cyclones of the system were
tested and calibrated in the laboratory under conditions simi-
lar to those frequently encountered in field tests: gas tem-
peratures of 25, 93, and 204°C, flow rates of 7.1, 14.2, and
28.3 5,/min, and particle densities of 1.05, 1.35, and 2.04
gm/cm3 .
35
-------
-
Figure 11. EPA-SoRI Five Stage Cyclone.
-------
The DSO cut points for the cyclone system at various
operating conditions are given in Table VI. For laboratory
test conditions (25°C, 28.3 2,/min, particle density 1.0 gm/cm3)
the cut points for cyclones I-V are 5.4, 2.1, 1.4, 0.65, and
0.32 urn, respectively. Figures 12 and 13 show some of the
calibration curves that were obtained. Figure 12 shows effi-
ciency vs. aerodynamic (particle density =1.0 gm/cm3) par-
ticle diameter plots for a sampling rate of 28.3 8,/min and Figure
13 shows similar data where the flow rate is 14 &/min • These
two figures illustrate that the small cyclones have "sharp"
efficiency curves and indicate that the system should function
adequately as a particle sizing device. At the test condi-
tions for Figure 12, the pressure drop across the cyclone system
was 170 mm Hg.
Data from this study wherein different_particle densities
(p) were used tend to support the DSO vs. p relationship
suggested by several theories.13'11* On the other hand,
the experimental results indicated that the cut points were
directly proportional to the gas viscosity which is in oppo-
sition to most theories. i 3'1 **'i 5'1 & Also, it was found in this
study and by Chan and Lippmann17 that the Db0's of small
cyclones are not inversely proportional to the square root
of the flow rate as some theories predict.
A detailed description of this cyclone system development
and calibration program can be found in "Development And Labora-
tory Evaluation Of A Five-Stage Cyclone System," EPA-600/7-
78-008, January 1978 CNTIS-PB 279 084/8BE).
37
-------
Table. VI
LABORATORY CALIBRATION OF THE FIVE-STAGE CYCLONES
Dso Cut Points
oo
Cyclone
Particle Density (gm/cm3)
Flow
7.1
14.2
28.3
28.3
28.3
Temperature
°C
25
25
25
93
204
2.04
5.9
3.8
4.4
6.4
I
1.00
(8.4)
(5.4)
(6.3)
(9.1)
2.04
2.4
1.5
2.3
2.9
II
1.00
(3.5)
(2.1)
(3.3)
(4.1)
2.04
Cyclon
(1.7)
.95
1.2
1.9
III
1.35
1.00
so cut points
micrometers
2.1
(2.4)
(1.4)
(1.8)
(2.8)
IV
1.05
2.5
1.5
.64
1.00
(2.5)
(1.5)
(.65)
1.05
1.5
.85
.32
V
1.00
(1.5)
(.87)
(.32)
cut points enclosed in parentheses are derived from the experimental data using Stoke's law.
-------
100
§
£
o
UJ
O
O
U
u
O
O
• CYCLONE I
A CYCLONE II
• CYCLONE III
CYCLONE IV
CYCLONE V
PARTICLE DIAMETER, micrometer?
Figure 12. Collection efficiency of the EPA-S.R.I. Cyclones at a flowrate
of 28.3 H/m±n, a temperature of 25°C, and for a particle density
of 1.00 gm/cm3.
39
-------
100
u
z
UJ
u
u.
U.
O
ui
O
U
CYCLONE I
A CYCLONE II
• CYCLONE III
T CYCLONE IV
CYCLONE V
20 —
PARTICLE DIAMETER, micrometers
Figure 13. Collection efficiency of the EPA-SRI Cyclones at a flowrate
of 14.2 £/min, a temperature of 25°C, and for a particle
density of 1.00 gm/cm3.
40
-------
ELECTROSTATIC PRECIPITATOR BACK UP FOR SAMPLING SYSTEMS
Filters used to collect fine particles in source sampling
trains are troublesome in several ways. A large pump is usually
required to pull the sample gas through a high efficiency filter,
and many tests are terminated prematurely because of the large
pressure drop that results as a dust cake builds up on the
filter as a result of the filter cake being less for small
particles. This problem is especially severe when the test
objective is to collect a large sample of submicron particles.
Contamination of a sample with filter material or physical
removal of the dust from the filter can also be problems.
This program's goal was to design and evaluate the per-
formance of an electrostatic collector to be used as an alter-
native to filters as a fine particle collector. Potential
advantages of an ESP would be low pressure drop and high capacity.
Potential problems would be unreliability and poor collection due
to back corona or lack of particle adhesivity.
The electrostatic precipitator back up filter was designed
to be operated at a nominal sample flow rate of 6.5 ft3/min.,
(184 £pm) at a temperature of 205°C, arid to achieve near 100% col-
lection of submicron particles. Since it is possible that there
would be a need to operate the collector in situ, a secondary require-
ment was that the collector pass through a 4 inch diameter
port. Furthermore, the system was designed to be convenient
to operate and clean, and to require a minimum of operator
training or attention.
Figure 14 is a schematic diagram illustrating the main features
of the system that was designed and fabricated. The collector is
of a cylindrical geometry with the collection electrodes
arranged concentrically to allow a large surface area to be
contained within a relatively short outer cylinder. Disc and
needle discharge electrodes were designed and fabricated, but
only the disc-cylinder geometry was evaluated during this pro-
gram. The system shown in Figure 14 is mechanically rugged
and the collection electrode geometry is such that the flow
is laminar at the design flow rate; thus, it is a simple matter
to calculate particle trajectories and the electrode length
required for 100% collection efficiency.
The ESP back up is a highly efficient collector of sub-
micron particles. When set to 200 yA on the corona disc elec-
trode and 2 kV on the collector (both well below breakdown
values), no further adjustments are necessary for proper opera-
tion. The power supply developed for the ESP collector facili-
tates correct operation. Since there is a potential for de-
graded performance due to back corona if the collected par-
ticles are of high resistivity, the collector can be routinely
used with a back up filter following it in the sampling train.
41
-------
SAMPLE IN
0.32cm
COLLECTION
ELECTRODES
CORONA DISC
ELECTRODE
HIGH VOLTAGE
ELECTRODES
2kV
Figure 14. Schematic of the electrostatic collector with the disc discharge
electrode installed.
42
-------
If experience shows the system to operate reliably at a particular
source, the filter can be eliminated.
After the sample is collected, the ESP is disassembled,
immersed in a suitable liquid, and agitated ultrasonically.
The wash can be filtered or evaporated to dryness, depending
on the nature of the dust and the objectives of the test.
The electrostatic collector prototype developed and tested
in this research effort fulfills the design criteria: near
100% collection of submicron particles when operated at a nomi-
nal sample flow rate of 6.5 ftVrnin and .a temperature of 200°C,
sized to fit through a 4 inch diameter port for in situ opera-
tion, convenient to operate and clean.
Figure 15 shows a detailed assembly drawing of the elec-
trostatic precipitator back up. A photograph of the complete
system is shown in Figure 16. The report describing the develop-
ment of this device is entitled "An Electrostatic Precipitator
Back Up For Sampling Systems," EPA-600/7-78-114, June 1978.
We acknowledge that the disc-cylinder electrode geometry
and method described in this report for ionization and particle
charging are developments of Air Pollution Systems, Inc., Kent,
Washington and the Electric Power Research Institute, Palo Alto,
California, and that we have been advised by Air Pollution Sys-
tems, Inc. that United States and Foreign patents have been ob-
tained and others applied for.* :
We are not aware of the details of said patents or any
pending applications and provide no assurance that practice
of any of the systems or methods disclosed in this report do
not infringe either said patents or any other private rights.
*U.S. Patent No. 4093430
43
-------
Xf-~ A»T fCis ffocfa^m
SOUTHEM KSEAKH MSIITUTE
tl«MINGHAM. AlAIAM* SS205
Figure 15. ESP Collector Assembly Drawing.
-------
Figure 16. Electrostatic Precipitator Backup Filter.
-------
GUIDELINES FOR PARTICULATE SAMPLING IN INDUSTRIAL PROCESS STREAMS
The guideline document written under this technical direc-
tive lists and describes briefly many of the instruments and
techniques that are available for measuring the concentration
and/or size distribution of particles suspended in process
streams. The standard, or well established, methods are de-
scribed as well as some experimental methods and prototype
instruments.
Descriptions of instruments and procedures for measuring
mass concentration, opacity, and particle size distribution
are given. Procedures for planning and implementing tests
for control device evaluation are also included.
A bibliography at the end of the report contains 141
citations to articles pertaining to the topics discussed in
the text. These topics are listed below:
Mass Concentration
Filtration
EPA Test Method 5
EPA Test Method 17
ASTM - Test Method 17
ASME Performance Test Code 27
Advantages and Disadvantages
Filter Materials
Process Monitors
Beta Particle Attenuation Monitors
Piezoelectric Mass Monitors
Charge Transfer
Optical Methods
Conventional Transmissometers
Other Optical Methods
Multiple-wavelength transmissometers
Light scattering
Opacity
Particle Size Distributions
Established Techniques
Field Measurements
Aerodynamic Methods
Cascade impactors
Cyclones
Optical Particle Counters
Diffusion Batteries with Condensation Nuclei Counters
Electrical Mobility
Laboratory Measurements
Sedimentation and Elutriation
Centrifuges
Microscopy
Sieves
Coulter Counter
46
-------
New Techniques
Low Pressure Impactors
Impactors with Beta Radiation Attenuation Sensors
Cascade Impactors with Piezoelectric Crystal Sensors
Virtual Impactors
Optical Measurement Techniques
Hot Wire Anemometry
Large Volume Samplers
Control Device Evaluation
Bibliography
This document has been published as an EPA report entitled
"Guidelines for Particulate Sampling in Gaseous Effluents from
Industrial Process Streams," EPA-600/7-79-028, January 1979.
47
-------
TECHNICAL MANUAL FOR PARTICULATE SAMPLING EQUIPMENT AND METHODS
This technical manual lists and describes the instruments
and techniques that are available for measuring the concentra-
tion or size distribution of particles suspended in gaseous
process streams. The standard, or well established methods
are described as are some experimental methods and pro-
totype instruments. To the extent that the information could
be found, an evaluation of the performance of each instrument
is included.
The manual describes instruments and procedures for mea-
suring mass concentrations, opacity, and particle size distri-
butions. It also includes procedures for planning and imple-
menting tests for control device evaluation, a glossary, and
an extensive bibliography containing 422 citations.
In order to briefly convey the scope of this document
a list of the topics discussed is presented below.
Mass Concentration
Filtration
Introduction
EPA Test Method 5
Nozzle
Probe
Pitot Tube
Particulate Sample Collector
Gaseous Sample Collector
Sampling Box
Meter Box
Performance
ASTM - Test Method
ASME Performance Test Code 27
Isokinetic Sampling
High Volume Samplers
Filter Materials
Summary
Process Monitors
Introduction
Beta Particle Attenuation Monitors
Instrument Development
Performance
Summary
Piezoelectric Mass Monitors
Performance
,Temperature
Humidity
Particle collection characteristics
Linear response limit
Considerations for stack application
Summary
48
-------
Charge Transfer
Instrument Development
Performance
Summary
Optical Methods
Conventional Transmissometers
Summary
Other Optical Methods
Multiple-wavelength transmissometers
Light scattering
Other Methods
Opacity
Particle Size Distributions
Established Techniques
Field Measurements
Aerodynamic Methods
Cascade impactors
Cyclones
Optical Particle Counters
Diffusion Batteries with Condensation Nuclei Counters
Electrical Mobility
Laboratory Measurements
Sedimentation and Elutriation
Centrifuges
Microscopy
Sieves
Coulter Counter
New Techniques
Low Pressure Impactors
Impactors with Beta Radiation Attenuation Sensors
Cascade Impactors with Piezoelectric Crystal Sensors
Virtual Impactors
Optical Measurement Techniques
Hot Wire Anemometry
Large Volume Samplers
Control Device Evaluation
Objectives of Control Device Tests
Type and Number of Tests Required
General Problems and Considerations
Plant Location
Laboratory Space
Sampling Location and Accessibility
Power Requirements
Type of Ports
Flue Gas Velocity and Nozzle Sizes
Duct Size
Gas Temperature and Dew Point
Water Droplets and Corrosive Gases
Volatile Components
Process Cycles and Feedstock Variations
Long and Short Sampling Times
Planning a Field Test
49
-------
This report has been published as: "Technical Manual:
A Survey of Equipment and Methods For Particulate Sampling
In Industrial Process Streams," EPA-600/7-78-043, March 1978
50
-------
EVALUATION OF THE PILLS IV
The operating characteristics of the PILLS IV in situ
particle sizing instrument have been investigated theoretically
and experimentally. The results of both types of work show
large errors in this instrument's ability to size particles.
Attempts to correlate the experimental findings with qualita-
tive theoretical explanations have been successful.
This prototype device is an extension of the PILLS (Particu-
late Instrumentation by Laser Light Scattering) technology to
fine particles designed by Environmental Systems Corporation,
Knoxville, Tennessee. It measures particle size using the ratio
of intensities of light scattered from a particle at two small
angles (14° and 7°) with respect to an incident laser beam. The
intensity ratio was chosen as the sizing parameter because of
its relative independence of particle refractive index. However,
the magnitude of the scattered intensity at 14° is also used for
several important decisions in the electronic processing logic,
which, for this particular optical system, render it especially
sensitive to refractive index and detector variations for the
determination of particle size distributions. This investigation
established a sensitivity to particle refractive index and detec-
tor response that seems to account for the observed characteristics
of the instrument. Further measurements would be required to test
this explanation quantitatively. Possible solutions to these
problems with only minor hardware changes are offered in the pub-
lished final report entitled "Evaluation of the PILLS IV," EPA-
600/7-78-130, July 1978.
51
-------
CYCLONE AND PRE-IMPACTOR FOR FUGITIVE AMBIENT SAMPLING TRAIN
Under this task Southern Research Institute designed and
calibrated the impaction preseparator stage and cyclone collector
of the Fugitive Ambient Sampling Train (FAST) developed by The
Research Corporation of New England (Project Manager: Mr.
Roland Severance).
The FAST system, shown in Figure 17, was designed to operate
at a flow rate of approximately 184 ACFM with the impaction stage
designed to have a 95% collection efficiency for aerodynamic 15 ym
diameter particles and thy cyclone collector designed to have a 501
collection efficiency for 2.5 ym diameter particles.
In order to verify the 95% collection efficiency of the
impaction stage, ammonium fluorescein particles with Stokes
diameters of 15 ym and 10 ym were sampled. To verify the
50% collection efficiency of the cyclone collector, ammonium
fluorescein particles with Stokes diameters of 2 ym and 3 ym
were sampled. The impaction stage was initially evaluated
with pre-cut glass fiber collection substrates. After this
system proved unsuccessful, two tests were performed using a
thin grease coating on the bare metal impaction plates.
Figure 18 is a schematic diagram showing the operating
principle of the Vibrating Orifice Aerosol Generator (VOAGl used in
this study. A solution of known concentration [in our case,
a solution of fluorescein (C^oE12Os) in O.IN^NH OH is forcod
through a small orifice (5, 10, 15, or 20 ym diameter)J, The
orifice is attached to piezoelectric ceramic which, under
electrical stimulation, will vibrate at a known frequency.
This vibration imposes periodic perturbations on the liquid
jet causing it to break up into uniformly-sized droplets.
Knowing the liquid flow rate and the perturbation frequency,
the droplet size can be readily calculated. The solvent
evaporates from the droplets leaving the non-volatile solute
as a spherical residue. The final dry particle size can be
calculated from the droplet size through the known concentra-
tion of the liquid solution.
To calculate the dry particle size, the expression
/nr vV3
is used,
10 TTF
where GV is the solution concentration or volume of solute/
volume of solution,
Q is the solution flow rate (cm3/min), and
F is the perturbation frequency (Hz).
52
-------
INLET
CYCLONE
VACUUM
PUMP
EXHAUST
Figure 17. Schematic diagram of Fugitive Ambient Sampling Train.
53
-------
COMPRESSED AIR LINE
Ui
REGULATOR
& TRAP
^ | REGULATOR
DRYER
y
[REGULA
g VALV
[ROTOME
| DISF
ABSOLUTE
FILTER
TOR]
E (V) VIBRATING
y ORIFICE
1 GENERATOR
] IT
1 DILUTION AIR u
— H h—
'"*!""
sV-'
^t^^
1
•ERSION AIR
DUMP •*
SYRINGE
GENERATOf
1
VALVE
FLOW DIVIDER
MASS
FLOWMETER
UNDER
TEST
COLD
TRAP
EXHAUST
Figure 18. Berglund-Liu type vibrating orifice aerosol generator system.
-------
By the use of smaller orifices, one can obtain much higher
operating frequencies. This in turn yields higher particle
number concentrations and allows a shorter running time to
collect the same mass per stage. The running time must be
sufficiently long, however, to allow accurate determination
of the collection efficiencies. It was our experience that
the 20 urn orifice was consistently easier to use in particle
generation, primarily because of fewer clogging problems.
Prior to particle generation the orifices were washed
in detergent with ultrasonic agitation and then rinsed several
times in distilled water, also with ultrasonic agitation. The
aerosol solution is fed from a syringe under pressure provided
by a syringe pump. As a final precaution for cleanliness, the
syringe is fitted with a filter so that the aerosol solution is
filtered before it is transported to the orifice. After the filter
and liquid handling system were flushed several times with the
aerosol solution to be used, an orifice was placed, still wet with
distilled water, or blown dry, into the crystal holder, and the
syringe pump was turned on. A jet of air was played over the
orifice to keep the surface clean until enough pressure was built
up behind the orifice to form a jet.
After a stream of particles was generated, a determina-
tion of monodispersity had to be made. Two methods were used
to accomplish this. By using a small, well-defined air jet
to deflect the stream of particles, it was possible to tell
when the aerosol was mono- or polydisperse. Depending on
particle size, the stream was deflected by the air at differ-
ent angles, and if the aerosol was polydisperse, several
streams could be seen at one time. By varying the crystal
oscillation frequency, the system could be fine-tuned to give
only a single deflected particle stream, thus indicating mono-
dispersity. On several occasions, the aerosol tended to drift
from monodispersity. To protect against this occurrence, peri-
odic filter samples were taken and checked by optical micro-
scopy. This also provided a good check on the sphericity of
the aerosol because the final particles were observed
instead of the primary liquid droplets. The microscopy thus
served as a check on proper drying, satellites, correct size,
and multiplets. Polonium 210 alpha particle sources were placed
near the air'stream as charge neutralizers to reduce agglomera-
tion and loss of particles due to electrostatic forces. A
three-foot-high plexiglass cylinder was placed on the generator
and dispersion and dilution air turned on to disperse, dilute
and loft the particles. During each test, filter samples were
drawn at intervals to insure continued monodispersity. Because
of its nonhygroscopicity and physical properties, ammonium
fluorescein was used throughout these studies as the test aero-
sol, although in theory, any material that will dissolve readily
in an evaporable solvent could be used. Figure 19 shows one
of the test aerosols generated with the VOAG. In general,
it was found that about 4% to 8% by mass of the particles were
of twice the volume (1.26 x diameter) of the primary particles.
55
-------
€5
* ,
Figure 19. Ammonium fluorescein aerosol particles generated using the
vibrating orifice aerosol generator. The particle diameters
are 5.4 pm.
56
-------
When it had been determined that particles of the correct
size were being generated, the FAST was allowed to sample from
the VOAG outlet for the required length of time to collect
a suitable sample. Point sampling was utilized across the
face of the louvered FAST inlet. On the majority of the tests the
VOAG outlet tube was situated at eighteen different points. Sampl-
ing duration at each point ranged from one minute to 60 minutes
depending on the particle size being sampled.
At the conclusion of the sampling period, the FAST was
carefully disassembled and all surfaces cleaned with a solution
of 0.1N NIUOH. Using a known amount of the solution, each
surface was washed to dissolve and rinse off the ammonium
fluorescein particles. Where petroleum jelly was used, a small
amount of benzene was poured over the greased collection plate
in a small dish which was then placed in an ultrasonic cleaner.
A small amount of agitation caused the grease to dissolve and
the ammonium fluorescein particles to become well mixed. Adding
a known abount of O.lN NH^OH to the mixture with stirring caused
the ammonium fluorescein to dissolve. After the benzene mixture
floated to the top of the NHi,OH, the ammonium fluorescein solu-
tion was pipetted off.
The quantity of material on each surface was determined
by absorption spectroscopy. A Bausch and Lomb Spectronic 88
Spectrophotometer, calibrated with solutions of known concentra-
tion of ammonium fluorescein, was used to measure the concen-
tration of ammonium fluorescein in each wash. From knowledge
of the amount of wash solution, the dilution factor, if any,
and the absolute concentration, the mass of particles on each
surface could be calculated. All particles from the Louvers
to the Substrates were combined with the Impactor Catch. All
particles from the Substrate Support Plate to the Cyclone Cup
were combined as the Cyclone Catch. The remaining material
was associated with the Filter Catch. This scheme of combin-
ing the dust from various parts of the system is based on the
manner in which the system will be cleaned after each field
test. With the mass on each surface known, the collection
efficiencies could be calculated.
During each run the pressure drops across the cyclone,
filter, and blower were monitored as were the ambient tempera-
ture and pressure. All data from the individual tests and
the calculated collection efficiencies are given in Table VII.
The efficiency data are plotted in Figure 20. The D50 for
the cyclone is approximately 2.8 vim aerodynamic diameter.
The impactor was not able to achieve the 95% collection effi-
ciency' even with a grease layer on the impactor collection
plate. Further study will be required to satisfactorily
achieve the desired pre-separator performance.
57
-------
Table VII
FAST IMPACTOR AND CYCLONE CALIBRATION DATA
15.0 Urn
Concentration (C) » 3.949 x 10"
Ul
00
3
o
s
iH
s
Date
Measured Particle Size
turn) (p - 1.35 gm/cms)
Impactor Substrate Type*
Temperature (°C)
Duration/point (min)
Total Duration (min)
Louvres
Screen
Inlet Transform
Impactor Top Plate
Jet Plate
Substrates
Substrate Support Plate
Cyclone Inlet Transform
Cyclone (Top)
Cyclone (Body)
Catch Cup
Cyclone Outlet Tube
Filter Transform
Filter
Total Mass
•^
Impactor % Collection 50.1
Efficiency
Cyclone % Collection
Efficiency
6/20-21/78
)
*
1st
Sample
0.177
0.113
0.026
0.003
0.043
0.459
0.012
0.032
0.133
0.239
0.337
0.012
0.008
0.046
1.640
50.1
91.9
15.75
GF
3.1
22.0
2.3
21.0
1.0
45.0
2nd
Sample
0.183
0.116
0.035
0.000
0.054
0.469
0.012
0.023
0.144
0.265
0.342
0.011
0.004
0.040
1.698
50.5
93.5
6/22/78
14.07
GF
3.0
22.0
2.3
21.0
4.0
72.0
0.081
0.417
0.119
0.016
0.083
2.192
0.188
0.345
0.684
0.862
3.915
0.023
0.009
0.033
8.967
32.4
98.9
7/28/78
15.41
GF
2.65
22.0
2.3
21.0
4.0
72.0
0.077
0.365
0.267
0.015
0.060
1.800
0.077
0.237
0.390
3.511
0.713
0.627
0.022
0.499
8.660
29.8
81.1
8/1/78
14.72
Gr
2.7
22.0
2.2
21.0
4.0
72.0
0.167
0.446
0.042
0.005
0.022
6.766
0.066
0.125
0.419
1.190
1.884
0.045
0.019
0.043
11.239
66.3
97.2
10 Vim
1.171 x
8/10/78
10.72
Gr
3.0
20.0
2.2
21.0
3.0
54.0
0.089
0.368
0.071
0.009
0.015
5.709
0.026
0.041
0.108
0.226
0.159
0.016
0.006
0.016
6.859
91.3
93.6
9
10"2 C = 8.
6/12/78
10.05
GF
3.0
20.0
2.1
20.80
3.0
54.0
1st 2nd
Sample Sample
0.121 0.116
1.274 0.821
0.035 0.025
0.010 0.010
0.034 0.034
0.565 0.525
0.038 0.038
0.055 0.049
0.077 0.069
0.252 0.245
0.121 0.120
0.044 0.033
0.018 0.011
0.153 0.130
2.797 2,226
72.9 68.8
71.6 75.0
lira
531 x 10
1st
Sample
0.143
0.589
0.010
0.005
0.021
5.640
0.030
0.048
0.284
0.889
0.958
0.049
0.028
0.124
8.818
72.7
91.7
J C
6/15/78
10.72
GF
3.1
22.5
2.3
20.26
3.0
150.0
2nd
Sample
0.143
0.610
0.007
0.005
0.017
5.925
0.039
0.042
0.280
0.880
0.958
0.055
0.034
0.118
9.113
73.6
91.4
3 urn
= 3.161 x 10
6/26-30/78
3.0
GF
3.15
23.4
2.4
21.0
20.0
360.0
0.035
0.332
0.043
0.003
0.062
0.100
0.187
0.137
0.494
3.695
3.353
3.059
0.132
1.488
13.120
4.4
62.7
2 urn
- 9.3662 x 10~
7/20-26/78
2.0
Gf
3.0
22.8
2.3
21.0
60.0
18 his.
0.019
0.038
0.025
0.003
0.025
0.017
0.034
0.043
0.072
0.425
0.756
0.536
0.202
2.280
4.475
2.8
30.6
*GF » Glass Fiber; Gr - Greased (Vaseline and Toluene)
-------
Ul
vo
o
LU
O
EL
LU
LU
z
o
u
Ul
o
u
100
90
80
70
60
50
40
30
20
10
0
.3
1 I 1 I I I I
Impactor —
1 I I I I I I I
greased plates O
glass fiber substrates
Cyclone — A
1 J I I I I I
I I I I I 1 I
.5 .6 .7 .8 .9 1.0 2 3 456789 10
PARTICLE DIAMETER, MICROMETERS
20
Figure 20. Collection efficiency versus particle diameter for the Fugitive Assessment
Sampling Train pre-separator impactor and cyclone.
-------
DESIGN, CONSTRUCT, AND EVALUATE OPTIMIZED CASCADE IMPACTORS
Based on the current knowledge of impactor operation theory
and the results of field and laboratory testing of currently
available commercial and prototype cascade impactors by Southern
Research Institute, high and low flow rate impactors are being
designed which will attempt to meet the criteria for optimized
cascade impactors. An optimized cascade impactor can be defined
as one which is designed to operate both in a laboratory and
field environment in such a way that the effects of particle
bounce, reentrainment, wall loss, non step function collection
efficiency curves, etc., are minimized. Mechanical reliability
and ease of operation are also to be considered in the design
of these impactors. Our criteria for optimized cascade impactors
are listed in Table VIII.
Design parameters for the 0.1, 0.5, and 2.0 ACFM, optimized,
cascade impactors have been generated by a special computer
program written at Southern Research Institute. Six impaction
stages with cut points of 9.6, 4.8, 2.4, 1.2, 0.6, and 0.3
micrometers aerodynamic diameter were chosed as a design goal
for these cascade impactors. The actual theoretical stage Dso's
as calculated by the computer program were very close to the
desired stage cut points. Identical stage cut points were not
realized because there was neither an unlimited number of holes
per stage available, nor an infinite range of drill sizes. The
final design parameters are presented in Tables IX, X, and XI.
An assembly drawing of the 0.5 ACFM impactor is shown in Figure 21
A prototype of the 0.5 ACFM optimized cascade impactor is
to be fabricated by Southern Research Institute for calibration
and testing purposes.
60
-------
TABLE VIII- CRITERIA FOR IMPACTOR DESIGN
1. The jet Reynolds number should be between 100 and 3000.
2. The jet velocity should be 10 times greater than the settl-
ing velocity of particles having the stage Dso.
3. The jet velocity should be less than 110 m/sec.
4. The jet diameter should not be smaller than can be attained
by conventional machining technology.
5. The ratio of the jet-plate spacing and the jet diameter or
width (S/W) should lie between 1 and 3.
6. The ratio of the jet throat length to the jet diameter (T/W)
should be approximately equal to unity.
7. The jet entries should be streamlined or countersunk.
61
-------
Impactor Sampling Rate = 0.1 ACFM
Initial Guess of Stage D$o
Jet Inlet Pressure (atm)
Best Jet Drill Diameter (cm)
Number of Jets on this Stage
Actual Jet Reynolds Number
Jet Velocity (m/sec)
Actual Square Root of Stokes f
Cunningham Slip Correction Factor
Theoretical Stage DSo (Mm)
Table IX
OPTIMIZED IMPACTOR DESIGN SPECIFICATIONS
Gas Temperature = 204.0°C
Initial Cut Point Guess (ym)
9,6 4.8
Particle Density = 1.0 gm/cc
0.6
0.3
0.987
0.47
1
362.6
2.72
0.478
1.017
9.474
0.986
0.30
1
568.0
6.68
0.476
1.034
4.776
0.985
0.19
1
895.3
16.65
0.475
1.070
2.359
0.975
0.098
2
859.2
31.29
0.475
1.145
1.195
0.953
0.0254
31
209.0
30.05
0.480
1.297
0.589
0.921
0.0254
19
396.9
71.05
0.477
1.777
0.297
-------
Table X
OPTIMIZED IMPACTOR DESIGN SPECIFICATIONS
Impactor Sampling Rate = 0.5 ACFM Gas Temperature = 204.0°C Particle Density = 1.0 gm/cc
Initial Cut Point Guess (ym)
Initial Guess of Stage Dso
Jet Inlet Pressure (atm.)
Best Jet Drill Diameter (cm)
Number of Jets on this Stage
Actual Jet Reynolds Number
CT>
co Jet Velocity (ra/sec)
Actual Square Root of Stokes #
Cunningham Slip Correction Factor
Theoretical Stage DSO
9.6
0.987
0.794
1
1073.6
4.77
0.474
1.017
9.221
4.8
0.986
0.518
1
1643.4
11.19
0.471
1.035
4.797
2.4
0.981
0.206
4
1030.1
17.75
0.474
1.070
2.372
1.2
0.970
0.107
8
981.5
32.99
0.474
1.146
1.212
0.6
0.931
0.025
155
204.4
30.05
0.480
1.304
0,588
0.3
0.901
0.016
235
206.9
49.95
0.480
1.707
0.316
-------
Table XI
OPTIMIZED IMPACTOR DESIGN SPECIFICATIONS
Impactor Sampling Rate = 2.0 ACBM Gas Temperature = 204.0°C. Particle Density = 1.0 gra/cc
Initial Cut Point Guess (urn)
Initial Guess of Stage DSO
Jet Inlet Pressure (atm.)
Best Jet Drill Diameter (cm)
Numberof Jets on this Stage
cr\ Actual Jet Reynolds Number
*>
Jet Velocity (m/sec)
Actual Square Root of Stokes I
Cunningham Slip Correction Factor
Theoretical Stage DSO
9.6
0.987
0.794
4
1073.6
4.77
0.474
1.017
9.221
4.8
0.986
0.404
8
1054.1
9.21
0.474
1.035
4.694
2.4
0.983
0.206
17
971.0
16.71
0.474
1.070
2.448
1.2
0.973
0.107
32
984.3
32.99
0.474
1.145
1.212
0.6
0.934
0.045
119
602.5
49.88
0.476
1.324
0.598
0.3
0.849
0.022
355
375.6
69.95
0.478
1.844
0.300
-------
U1
y/f^, &e>i jv^.^. . jj
J -*/ ~?&fl-
Z/f~i 9aff. JW«» s/
SOUTHEBN DESiMCH INSIITim
MUMINOHAM, AUIAMA 33205
• • S ~Z> //
Figure 21. Assembly drawing of 0.5 ACFM optimized cascade impactor
-------
DESIGN A HIGH TEMPERATURE TEST FACILITY
A particle sampling test facility has been designed.
An engineering drawing of the proposed test facility is shown
in Figure 22.
The facility will be used to simulate the behavior of
various process streams. Gas temperatures will be variable
between ambient and 500°C (932°F). Duct pressure will be
variable from 0.7 atm to 1.0 atm, and gas velocity will be
adjustable from 1.5 m/sec (5 ft/sec) to 15 m/sec (50 ft/sec).
This range of velocities is adequate to simulate most process
streams. A velocity range was chosen which is representative
of many process streams, and a duct size was chosen which would
keep the size and cost of piping/ within reason, but not lead
to any objectionable blockage of the duct by any of the devices
to be tested. A diameter of 30 cm (12 inches) was chosen.
This gives a resulting gas volume flow from 0.11 m3/sec
(232 cfm) to 1.1 m3/sec (2320 cfm).
In order to have a low pressure system without excessive
pumping capacity, a closed loop system was selected. However,
with a closed circuit, the dust must be removed after each
circuit so that control can be maintained over the test aero-
sol. Since a bag collector will be used, the temperature must
be reduced from the 540°C maximum test temperature to a fea-
sible operation temperature for the collector, about 260°C
(500°F). A cooler to cool down to 260°C plus a heater to heat
up to 540°C would be expensive to operate. Therefore, an air-
to-air shell-and-tube heat exchanger was chosen to cool the
air down to 260°C and then to heat it back up again to 455°C.
A temperature difference of about 85°C is needed to establish
good heat flow. If too much insulation were used on the fan
and filter piping, there would be too low a temperature dif-
ference, and the gas would not be cooled enough for the sur-
vival of the filter bags. Thus, it will be necessary to in-
stall the insulation on a trial basis, gradually increasing
the insulation to minimize the required reheat while making
sure that the bag temperature does not exceed 260°C.
The size of the wind tunnel has been dictated by the size
of the apparatus to be tested. The largest presently used
probe is about 10.2 cm (four inches) in diameter; and if in-
serted into a 30.5 cm diameter pipe to 5 cm beyond the center-
line, the probe will obscure 27% of the open area. It is
expected that impactors and cyclones would obscure a much
smaller area. The required velocity times the area of the
test section gives the total volume of gas for determining
the size and cost of piping and ancillary equipment.
66
-------
Figure 22. Preliminary layout for high temperature, low pressure wind tunnel test facility.
-------
It will be necessary to provide sufficient strength in
all components to withstand 0.35 kilogram per square centi-
meter of negative pressure. Therefore, a cylindrical heat
exchanger and cylindrical bag collector with reinforced top
cover will be required. The circulating fan housing must be
stiffened, and the fan provided with a shaft seal good for 260°C
and 0.35 kg/cm2.
Thermal expansion of the materials of construction must
be accommodated by either motion or stress. Flexible expan-
sion joints would have to be anchored solidly against the
0.35 kg/cm2 suction forces, or solidly joined members would
have to be anchored against extremely high expansion forces.
To reduce the magnitude of such forces, the design provides
for a symmetrically overhung, high temperature test section
in which the expansions either tend to compensate, or merely
expand out into unrestrained space as a cantilever beam. The
overhung, cantilevered weight is restrained by two guy wires
with turnbuckles. These guys are supported by struts to bring
the angle of the wires perpendicular to the direction of expan-
sion so that negligible changes in alignment will occur.
The thermal expansion of the connecting piping is accommo-
dated by using hinge type expansion joints which permit a hinge
action in one plane without any axial change due to pressure
or vacuum. Three such joints in a run of pipe are the equiva-
lent of a three hinged arch, which is statically determinate
and has zero built-in stress.
The circulating fan will be solidly joined to the piping
from the dust collector, and the base will be mounted on sliding
pads of oil impregnated sintered bronze positioned to slide
parallel to the piping between the dust collector and fan.
Because the volumetric efficiency of a vacuum pump is
reduced by high temperature, low density gas, a water jacketed
cooler will be used between the hot circulating loop and the
vacuum pump. Simple coolers for air compressors are commer-
cially available. The vacuum pump itself should be protected
against high temperatures resulting from cooling water failure,
and from dust carryover from torn bags, or from bag changing
operations. Therefore, a fluid piston Nash vacuum pump was
selected to meet the above fail-safe conditions. Because the
vapor pressure of water is a half an atmosphere at 82°C, water
cannot be used as a compressant fluid. Therefore, a recircu-
lated and cooled oil will be used as a compressant fluid.
68
-------
The heat exchanger, fan, dust collector, and vacuum pump
are bulky pieces of equipment and do not need to be inside
the building. We therefore chose to pierce the building wall
in a third floor laboratory and to locate everything except the
test section on a structural steel platform outside. We selec-
ted a spiral access stairway because a ladder is less safe
and a zig zag stairway requires more space- A manual full
circle winch crane of 455 kg (1000 Ib) capacity is included
for lifting the covers off the dust collector and for raising
miscellaneous material to the platform.
The test section is furnished with 15 cm (6 inch) pipe
flanged access ports about 4, 6, and 8 diameters downstream
from the dust injection point. Ports are arranged on all four
sides so that equipment may be mounted either horizontally,
vertically, or through, (as for obscurometers or for Schlieren
photography).
The SoRI POP 11/34A Minicomputer Based Data Acquisition
System will be used for digital display of the operating con-
ditions of the components of the facility as well as control
of the system.
The conditions to be monitored are:
1. test section gas temperature;
2. test section pressure;
3. test section gas flow rate (using a venturi meter);
4. temperature of the device under test;
5. pressure drop across the device under test;
6. gas flow through the device under test;
7. gas temperature at the inlet to the bag house;
8. pressure drop across the bag house;
9. gas temperature at the outlet of the heater; and,
10. gas temperature at the inlet of the vacuum pump.
Provisions will be made for multipoint injection of a
test aerosol generated by dispersion of dry powder, nebuliza-
tion, and high output generators of monodisperse aerosols.
Care will be taken in design of the injection system to insure
an even distribution of the test aerosol through the test sec-
tion of the facility. Included in the available equipment are:
69
-------
1. Climet Model 208 Particle Size Analyser modified
for operation to 0.3 pm;
/
2. Royco Model 225 Particle Size Analyser;
3. a large particle dilution system;
4. a small particle dilution system;
5. Nuclear Data Model ND60 Multichannel Analyser for
use with the above particle counters;
6. Lear Siegler Model RM41P Transmissometer;
7. Thermo Systems Model 3030 Fine Particle Electrical
Aerosol Analyser; and,
8. Environment One Model Rich 100 Condensation Nuclei
Counter with diffusion batteries.
All control and monitoring equipment will be designed for
interfacing with a laboratory computer system.
70
-------
A MASSIVE VOLUME SAMPLER FOR HEALTH EFFECTS STUDIES
Today, there is a critical need for information pertaining
to the health effects of the particulate pollution emitted
from emerging alternative energy sources. These data are obtained
from bioassay and animal inhalation studies conducted with
samples of these particulate emissions. The extended time
periods needed to perform these studies requires large particu-
late samples. The purpose of this task was to design, fabricate,
and test a sampling system which would collect large particulate
samples in relatively short time periods. In order to meet
this objective a sampling rate of 340 Nm3/hr (200 SCFM) was
chosen. Task requirements also demanded that the sampler also
separate the sample into two size fractions, a coarse fraction
and a fine fraction. This necessitated a two stage
sampler design. Minimization of wall loss deposition at other
locations within the system was also an important considera-
tion.
The ultimate goal of this task was that the particle size
distribution and biological impact of the collected sample
should be an accurate representation of the particulate emis-
sions produced by the energy source. Fulfilling the particle
size distribution aspect necessitated building a traversing
sampler capable of near isokinetic sampling. Accomplishing
the biological impact goal required a sampler that would pre-
vent or minimize contamination of the sample. This was accom-
plished by maintaining flue gas temperatures in the sampler thus
eliminating condensation of organic and inorganic vapors in
the gas stream. Also special materials for construction were
used to minimize sample contamination on the walls of the sam-
pler. Since the device would be used at various sites, the
sampler had to be built to make it readily movable from site
to site and conveniently adaptable to different site conditions.
The prototype system (see Figure 23) consists of a probe,
a cyclone dust collector, fabric filter, flowmeter, blower,
and sampling/interconnecting line.
The probe is 2.1 m (7 ft.) long and possesses an adjust-
able opening at its insertion end to establish isokinetic sam-
pling. The probe is capable of traversing and although it
is designed for a 9 cm (4") nominal port, it can be easily
adapted to larger ports.
A Fisher-Klosterman XQ-5 cyclone with a calibrated cut
point at 50% efficiency of 2.5 micrometers aerodynamic dia-
meter at 340 Nm3/hr (200 SCFM) is the initial particle collec-
tor. The cyclone with its heated enclosure measures approxi-
mately 2.1 m H x 0.6 m W x 0.6 m L (61 H x 2' W x 2' L) and
weighs 91 kg (200 Ibs).
71
-------
-J
to
PROBE
DOTTED LINE: INSULATION, 2" THICK
I" : PRESSUR6 TAP
ALL SAMPLING LINE (EXCEPT PROBE]
IS 4.5" O.D. + 4" OF INSULATION
Figure 23.
Schematic diagram of massive volume sampler for Health
Effects Studies.
-------
Immediately following the cyclone is a single chamber
fabric filter. Its dimensions are approximately 2.1 m H x
0.9 m W x 0.9 m L (71 H x 3' W x 3' L) and its mass is 113 kg
(250 Ibs) . It can accommodate from 1 to 20 envelope bags.
The filtration surface of the bags is composed of Gore-Tex
porous teflon laminate; the filtration surface is backed by
Nomex. Each bag contributes 0.5 m2 (5.0 ft2) of collection
surface. The fabric filter is equipped with a manual shaker
and can be easily modified to become a double chambered,
automatic shaker design.
The flowmeter is an orifice plate type meter which is
used to monitor the 340 Nm3/hr (200 SCFM) flow rate selected
for the sampler. This 340 Nm3/hr (200 SCFM) flow rate must
be stable in order to maintain the 2.5 ym D50 of the cyclone.
A hand operated damper attached to the outlet of the blower
is used to adjust the flow rate. At this flow rate the sam-
pler requires about 2% days of continuous sampling in order
to collect 1 kilogram of particulate matter from the outlet
of an efficient control device with a particulate mass concen-
tration of 0.05 grams/Mm3 (0.2 gr/Nft3).
The blower is a centrifugal pressure blower powered by
a 3
-------
Provisions exist to monitor both the temperature and
pressure at the probe and at the inlet and outlet of the
cyclone, fabric filter and blower.
Design operating temperature of the sampler is 204°C
(400°F). Use of the sampler between the temperatures of
204°C (400°F) and 316°C (600°F) may be possible. This would
depend on the effects of such temperatures on the sealing
integrity of the teflon gaskets, and the degree of degrada-
tion experienced by the fabric filter bag material. Other
factors subject to the temperature of the gas stream are the
magnitude of the pressure drop presented to the blower (the
static pressure available from the blower decreases with in-
creasing temperature), and the heating load placed on the
heaters.
The construction of this sampler has been completed and
initial field tests will take place early in 1979.
74
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CALIBRATION OF SOURCE TEST CASCADE IMPACTORS
To the user of an inertial cascade impactor the most
important consideration is the degree to which the data
obtained will duplicate the actual particle size distribu-
tion sampled. In order to transform the mass collected by
several impaction stages into a size distribution, an
accurate knowledge of the relationship between collection effi-
ciency and particle size for each stage is essential.
The impaction efficiency of a jet-plate system is defined
as the fraction of particles of a certain size in the jet that
impact on the collection plate. The collection efficiency
of an impactor stage, however, is the ratio of the mass (or
number) of particles of a certain size collected on an impac-
tion surface to the total mass (or number) of particles of
the same size in a jet impinging on that surface- The col-
lection efficiency is the product of the impaction efficiency
and the adhesion efficiency.5 The adhesion efficiency is the
fraction of the number of particles that adhere to the surface
after touching it by the impaction process, depending mainly
on the surface characteristics of the particle and the collec-
tion surface. Thus, there is disagreement between the theo-
retical impaction efficiency and the experimentally determined
collection efficiency in the cases where particle bounce, reen-
trainment, electrostatic effects, wall losses, and non-ideal
geometry have an effect. For this reason, the theory of impac-
tion may not be sufficiently accurate in predicting impactor
performance.
The theory of the impaction process has been developed
by several researchers18'19 to a state where the efficiency,
E, of impaction can be estimated as a function of the parti-
cle size (Dp) , Reynolds Number (Re) , the jet diameter or width
(Dj,W), the jet to plate distance (S) , and the jet throat
length (T) . (Marple19 specifically uses the dimensionless
reduced quantities (D/Dj , S/W) and (T/D-j, T/W) when considering
the jet to plate distance and the jet throat length, respec-
tively. )
E = E (D , Re, S/Dj. T/Dj) (1)
It is common practice to relate the particle diameter
D to the square root of the inertial impaction parameter
(ftp) , which is the ratio of the particle stopping distance
(I) to the jet diameter or width (D^ or W) . Thus,
\|> =
75
-------
or ^n n
\p = D 2 1QP ° (2)
y p 18 y D.
where C = Slip Correction Factor,
V = Jet Velocity (cm/sec),
y = Gas Viscosity (poise),
pp = Particle Density (gm/cm3), and
D. = Jet Diameter (cm).
The square root of the inertial impaction parameter,
is used in impaction theories as a dimensionless quantity pro-
portional to particle diameter,
h
(3)
The inertial impaction parameter is useful in graphing
impactor calibration data because information from all stages
of an impactor can be placed on a single graph, and under many
circumstances would, in theory, lie along a common curve.
The value of /\|j at 50% collection efficiency, /^so, defines
the impaction stage D$o, which is the particle diameter for
which half of the particles are collected and half are passed
to the next stage. In data reduction the Dg0 is used as the
effective stage cut diameter.
Recently Marple19 has been able to calculate theoretical
impaction efficiency curves for several values of the jet to
plate distance, jet Reynolds Number, and jet throat length.
Figure 24 shows the results of these calculations for both
round and rectangular jet impactors. It can be seen from
Figure 24 that for certain ranges of jet to plate spacing,
Reynolds Number, or jet throat lengths, the magnitude of
o is sensitive to these parameters.
In this study five source-test cascade impactors, all
of which are commercially available in the United States,
have been calibrated using monodisperse aerosols in order to
determine both their inertial sizing parameters and wall
losses as a function of particle size.
A Vibrating Orifice Aerosol Generator was used to produce
monodisperse ammonium fluorescein aerosol particles 18 micro-
meters to one micrometer in diameter. A Pressurized Cdllison
Nebulizer System was used to disperse Polystyrene Latex (PSL)
and Polyvinyltoluene Latex (PVTL) Spheres 2.02 micrometers to
0.46 micrometer in diameter.
76
-------
100
o
ui
LL
U.
Ill
± L-JLJ III! I I J 1 I I i I I I
1.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
fmmmiimm.
(a) EFFECT OF JET TO PLATE DISTANCE (Re=3,000)
100
5 40
20
Re(S/Dj=1/2)
10
3,000-
25,000 •
^sjrsrs'~s'~ —
/"#/ V / Re(S/W-1) -
//// / - 10
if - J. - 100
,'ff—f - 500
' t - - 3,000 -i
- 25,000
— — — Rectangular
lll
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
VSTTK
(b) EFFECT OF JET REYNOLDS NUMBER IT/WMI
100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
V STK
(c) EFFECT OF THROAT LENGTH (Re-3,000)
Figure 24. Theoretical impactor efficiency curves for rectangular and round
impactors showing the effect of jet-to-plate distance S, Reynolds
number Re, and throat length T. Note that /STK = D (Cp V0/9 yD.) /2,
whereas v^ = D (Cp V0/18 yD )1/z . After Marple.19
77
-------
The impactors tested and their manufacturers are:
1. Andersen Mark III Stack Sampler (Andersen)
Andersen Sampler, Inc.
Atlanta, Georgia 30336
2. Brink Model BMS-11 Cascade Impactor (Brink)
Zoltek, Inc.
St. Louis, Missouri 63166
3. MRI Model 1502 Inertial Cascade Impactor (MRI)
Meteorology Research, Inc.
Altadena, California 91001
4. Sierra Model 226 Source Cascade Impactor (Sierra)
Sierra Instruments, Inc.
Carmel Valley, California 93924
5. University of Washington Mark III Source Test
Cascade Impactor (U. of W.)
Pollution Control Systems, Inc.
Renton, Washington 98055
The 5-stage Brink Impactor was modified to include an in-
line cyclone pre-collector, a "0" stage, and a "6" stage.
The Andersen impactor was used with glass fiber collection
substrates supplied by the manufacturer. For the Brink impac-
tor a small disc of glass fiber material was used as a sub-
strate as well as a thin grease layer (petroleum jelly). The
MRI and U. of W. impactors were tested with thin films of grease
(Petroleum jelly) on the collection plates. The Sierra was
operated with pre-cut glass fiber mats, supplied by the manu-
facturer.
Results were reported showing stage collection efficien-
cies versus the square root of the inertial impaction parameter,
\|>, (see Figures 25 through 31) and impactor wall losses versus
particle size (see Figure 32).
Based on this work, several conclusions can be drawn.
1. The value of /4>5o for each stage of a multiple stage
impactor may be different. (It has been the practice of many
cascade impactor manufacturers and users to assume that the
value of /^so for every stage was identical. In many cases
the experimental value determined by Ranz and Wonglf was used.)
78
-------
99.8
o
z
UJ
o
01
UJ
_J
8 20 —
0.03
0.05 0.08 0.1
0.6 0.8 1.0
2.0
Figure 25. Collection efficiency vs. /t(J. Andersen Mark III
stack sampler with glass fiber collection substrates,
79
-------
99.8
as
o
u
LU
z
o
o
LU
_J
8
0.2
0.03
0.05 0.08 0.1
Figure 26. Collection efficiency vs. v^J. Brink Model BMS-11
cascade impactor with glass fiber collection substrates.
80
-------
99.8
o
z
UJ
o
u.
LL
LU
O
O
UJ
O
O
0.03
0.05 0.080.1
Figure 27. Collection efficiency vs. ^ . Brink Model BMS-11
cascade impactor with greased collection plates.
81
-------
99.8
0.2
0.03
Figure 28. Collection efficiency vs. v^J . MRI Model 1502 Inertial
cascade impactor with greased collection plates.
82
-------
se
99.8
99
98
95
90
80
\
H 70
O
E 60
u.
w 50
z
O
111
8
40
30
20
10
2
1
0.5
0.2
0.03
TT
STAGE SYMBOL
I IT
1
2
3
4
5
6
I III
0.05 0.08 0.1
0.2
0.4 0.6 0.8 1.0
2.0
Figure 29. Collection efficiency vs. i^TT Sierra Model 226 source
cascade impactor with glass fiber collection substrates,
Sampling flow rate is 14 LPM.
83
-------
99.8
a?
u
UJ
o
ul
u.
UJ
O
5
Ul
8 20 —
0.03
Figure 30. Collection efficiency vs. v^j7 . Sierra Model 226 source
cascade impactor with glass fiber collection substrates.
Sampling flow rate is 7 LPM.
84
-------
99.8
o
o
111
_J
o
CJ
Figure 31. Collection efficiency vs. v^ . Universtiy of Washington
Mark III source test cascade impactor with greased collection
plate.
85
-------
70 i
60
50
II III
1 1 1
V
o
1 1
o
A
0
A
C7 MMM
^9
A —
o
A
20
10
O
V
A
O
_i
<
a
A
*
o
6
8
a
*fi
a
A
D
1.5 2 3 4 5 6 7 8 9 10
PARTICLE DIAMETER, micrometers
15
20
O
D
A
V
O
ANDERSEN MARK III STACK SAMPLER. NONISOKINETIC SAMPLING.
MODIFIED BRINK MODEL BMS-II CASCADE IMP ACTOR. GLASS FIBER SUBSTRATES. NONISOKINETIC SAMPLING.
MODIFIED BRINK MODEL BMS-II CASCADE IMPACTOR. GREASED COLLECTION PLATES. NONISOKINETIC SAMPLING.
MRI MODEL 1502 INERTIAL CASCADE IMPACTOR. NONISOKINETIC SAMPLING.
SIERRA MODEL 226 SOURCE CASCADE IMPACTOR. 14LPM. NONISOKINETIC SAMPLING.
SIERRA MODEL 226 SOURCE CASCADE IMPACTOR. 7LPM. ISOKINETIC SAMPLING
U. of W. MARK III SOURCE TEST CASCADE IMPACTOR. NONISOKINETIC SAMPLING.
Figure 32. Cascade impactor wall loss vs. particle diameter.
86
-------
2. The theories of cascade impactor operation at this
time do not describe the behavior of cascade impactors accu-
rately enough to obviate empirical calibration of each device.
3. The stage collection efficiencies are sensitive to
the type of impactor collection substrate that is used. This
dependence is evident in the comparison of the Brink Cascade
Impactor data using glass fiber collection substrates and
greased collection plates. The strong dependence of collec-
tion efficiency on stage collection substrate material has
also been illustrated and discussed by Willeke20 and Rao.5
4. In the majority of cases the stage collection effi-
ciency never reaches 100% for any particle size but reaches
a maximum value that usually falls between 80% and 95%.
Hence, some greatly oversized particles will reach every
stage beyond the first stage. Unless suitable compensation
can be made for the presence of these oversized particles,
their presence will tend to bias the apparent particle size
distribution toward higher than actual concentrations of fine
particles and reduced concentrations of large particles. The
errors probably tend to be more significant for the fine particle
end of the distribution.
5. The use of grease on the collection plates as well
as a reduction in the impactor flow rate tends to decrease
the magnitude of this problem. The Sierra impactor data illu-
strate the increase in collection efficiency which resulted
from a decrease in sampling flow rate and concomitant reduc-
tion in bounce and cascading of large particles to lower
stages. This study shows that in some cases the maximum
efficiency was almost doubled by lowering the flow rate. A
discussion of this phenomenon has also been presented by Rao.
6. All of these cascade impactors are roughly equivalent
in performance, except for the Sierra operated at 14 LPM. It
must be remembered, however, that the type of substrate and the
sampling flow rate which are employed will cause some differences
in impactor operation as well as other possible factors asso-
ciated with sampling at industrial sites (temperature and pres-
sure extremes, particle density, particle adhesiveness, mois-
ture content, etc.).
This work has been reported in "Particulate Sizing Tech-
niques For Control Device Evaluation: Cascade Impactor Cali-
brations," EPA-600/2-76-280, October 1976 CNTIS-PB 262 849/3BE).
87
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CALIBRATION OF SOVIET PARTICLE SIZING INSTRUMENTS
Under this task three Soviet cascade impactors and one
Soviet impactor/cyclone were calibrated. The three cascade
impactors included one twelve stage device and two fourteen
stage impactors. The three stage impactor/cyclone had a
single impaction stage followed by two cyclonic stages. All
four devices had an integral back-up filter holder which used
a plug of glass wool fibers.
A photograph of one of the fourteen stage Soviet impactors
is shown in Figure 33. Figure 34 shows the Soviet impactor/
cyclone. The upper stages of these sizing devices were cali-
brated using ammonium fluorescein aerosols (20 ym to 2 ym)
dispersed by a Vibrating Orifice Aerosol Generator. The lower
stages were calibrated using monodisperse polystyrene latex or
Polyvinyltoluene latex spheres (2.02 ym to 0.46 ym) dispersed by
a Pressurized Collison Nebulizer System.
Soviet Three Stage Impactor/Cyclone
As mentioned above, this instrument consisted of a single
impaction stage followed by two cyclonic stages. A back-up
filter collected all particles passing the last stage. This
device was constructed from a titanium alloy. A set of nozzles was
supplied with the impactor/cyclone. All three stages were
calibrated using monodisperse ammonium fluorescein particles
with sizes ranging from 18 micrometers diameter to 2.3 micro-
meters diameter. The ambient pressure was 29.5" Hg, the tem-
perature was 22°C, the particle density was 1.35 gm/cm3, and
the sampling flow rate was 10 liters per minute. At these con-
ditions the cut points of the three stages were determined
to be 13.5, 6.4, and 2.6 micrometers. The results are presented
graphically in Figure 35.
Soviet 12-Stage Cascade Impactor
This impactor was unique in that several stages were de-
signed to have identical cut points. Because of this feature,
the impactor had seven effective stages. The twelve stages
were paired as follows: 1 and 2, 3 and 4, 5, 6 and 7, 8, 9
and 10, 11 and 12. In field use the mass collected by single
stages 1 and 2 was combined as the catch for effective stage
1. In a similar manner the mass collected by single stages
11 and 12 became the combined catch for effective stage 7.
The calibration conditions were an ambient pressure of
29.5" Hg, a temperature of 22°C; the particle density was 1.35
gm/cm3 and the sampling rate was ten liters per minute. Be-
cause of the type of construction of this impactor, it was
only possible to calibrate it using ammonium fluorescein aero-
sols between 2 and 20 micrometers diameter. The calibration data
are shown by stage both on an individual basis (Figure 36)
and on an effective stage basis (Figure 37).
88
-------
Figure 33. Soviet lA-stage cascade impactor.
Figure 34. Soviet 3-stage impactor/cyclone,
89
-------
100
90
10
.5 .6.7.8.91.0 2 3 4 5 6 7 89 10
Particle Diameter, Micrometers
20
-Figure 35. Collection efficiency vs. particle diameter. Soviet 124-.stage
impactor/cyclone.
1 - impaction stage 2 - 1st cyclone 3 - 2nd cyclone
(29.5 in. Hg, 22°C, 1.35 gm/cm3, 10 LPM)
90
-------
100
90
.5 .6.7.8.91.0 2 3 4 5 6 7 89 10
Particle Diameter, Micrometers
20
Figure 36. Collection efficiency vs. particle diameter. Soviet 12-stage
cascade impactor. Data shown for the first nine stages from
2 to 20 microns. (29.5 in. Hg, 22°C, 1.35 gm/cm3, 10 LPM).
91
-------
100
90
80
<*>
o 70
£
0)
•H
•H 60
§ 50
•H
•P
o
-------
Soviet 14-Stage Cascade Impactor (Small D50's)
Soviet 14-Stage Cascade Impactor (Large DSo's)
These cascade impactors were similar in design to the
Soviet 12-Stage impactor in that their 14 single stages were
divided into seven effective stages with a pair of single
stages per effective stage; each member of a pair is theoreti-
cally designed to have the same cut point. These seven effec-
tive stages were numbered 1.1/1.2, 2.1/2.2, 3.1/3.2, 4.1/4.2,
5.1/5.2, 6.1/6.2, and 7.1/7.2. In practice the mass collected
by individual stages 1.1 and 1.2, for example, was combined
to give a total mass collected by the first effective stage.
This procedure was repeated for the rest of the impaction
stages. These two impactors had different cut points but
shared identical stages on five of the seven effective stages
as illustrated in the following chart.
14-Stage Cascade Impactor
Small Dsos Large DsoS
7.1/7.2
Effective stages 1, 2, 3, 4, and 5 of the small Dso impac-
tors were identical with stages 1, 4, 5, 6, and 7 of the large
Dso impactor, respectively. It was possible to calibrate both
impactors with ammonium fluorescein and polystyrene latex par-
ticles; however, it was not possible to complete the calibra-
tion on stages 7.1/7.2 of the small Dbo impactor since the
pressure drop across these stages was greater than our calibra-
tion apparatus could maintain. The results of the calibration
are depicted graphically in Figures 38 and 39.
93
-------
100
90
80
u 70
c
0)
-H
•H 60
4-1
IH
W
§ 50
-H
•P
O
-------
.5 .6.7.8.91.0 2 3 4 5 6 7 89 10
Particle Diameter, Micrometers
20
Figure 39. Collection efficiency vs. particle diameter. Soviet 14-stage
cascade impactor. (Large cutpoints)
(29.5 in. Hg, 22°C, 1.35 fm/cm3, 10 LPM)
95
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CALIBRATION OF THE SOURCE ASSESSMENT SAMPLING SYSTEM CYCLONES
Three separate Technical Directives were issued under
this contract covering various aspects of calibrating the SASS
cyclones. A schematic of the SASS instrument is shown in
Figure 40. The first technical directive called for the cali-
bration of the three cyclones at ambient temperatures and pres-
sures.
The calibrations of the Large (10 ym) and Middle (3 ym)
Cyclones were performed using ammonium fluorescein aerosols
generated with Southern Research Institute's Vibrating Orifice
Aerosol Generator (VOAG). Monodisperse ammonium fluorescein
aerosols with diameters of 2, 3, 4, 5, 7.5, 10.5, and 14.5
micrometers were sampled at flow rates of 4 ACFM and 3 ACFM.
These particles have a density of 1.35 gm/cm3. After sampling
for a sufficient length of time, each cyclone was washed with
a known amount of NHitOH to dissolve the ammonium fluorescein
aerosol. The total mass of the collected aerosol was deter-
mined using absorption spectroscopy. The collection efficiency
of each cyclone was calculated and plotted versus particle
diameter. Figures 41 and 42 present these Collection Effi-
ciency Versus Particle Diameter data for the Large and Middle
Cyclones, respectively.
The Small Cyclone was calibrated using Dow Corning
polystyrene latex (PSL) and polyvinyltoluene latex (PVTL) spheres
dispersed with the Institute's Pressurized Collison Nebulizer
System. Using an auxiliary pump, aerosols were pulled through
the Small Cyclone at two flowrates, 3.1 ACFM and 1.8 ACFM. A
Climet Instruments Model 208A Particle Analyzer was used to
measure the number concentration of unit density 0.82 ym and
1.1 ym diameter PSL spheres and 2.02 ym diameter PVTL spheres up-
stream and downstream of the Small Cyclone. The collection effic-
iencies were calculated and plotted versus the particle diameter
as shown in Figure 43.
Based on the results of this limited calibration study,
it appeared that the cyclone D5 o cut point varied approximately
inversely with the square root of the particle density as pre-
dicted by theory.
The specific data obtained in this study were extrapolated
to obtain cyclone Dbo's for four combinations of flow rate
and particle density (4 ACFM and 3 ACFM flow rates and 1.00
gm/cm3 and 2.3 gm/cm3 particle densities). The resulting
graphs shown in Figure 44 indicate the approximate range of
D5o cut points which can be expected of the SASS cyclones
at temperatures near ambient.
After the above ambient calibration work was completed,
a recalibration of the three cyclones of the Source Assessment
96
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HEATER
CONTROLLER
CONVECTION OVEN
FILTER
MMHBBH1
1n
•M
w
•••••••
A
<
1
•^^^••^•^p^v^^
DRY GAS METER
ORIFICE METER
CENTRALIZED TEMPERATURE
AND PRESSURE READOUT
CONTROL MODULE
OVEN
T.C.
XAD-2
CARTRIDGE
CONDENSATE
COLLECTOR
^"
/
GAS COOLER
GAS
TEMPERATURE
T.C.
IMP/COOLER
TRACE ELEMENT
COLLECTOR
1MPINGER
T.C.
10 CFM VACUUM PUMP
Figure 40. Schematic of the Source Assessment Sampling System.
-------
00
100
90
O
ui
a
u.
IU
O
ai
O
U
70
60
50
40
30
20
10
1 I TT
FT
1 1 1 I I I 1
1
.3 .4 .5 .6 .7 .8 .9 1.0 2 3 456789 10
PARTICLE DIAMETER, MICROMETERS
20
Figure 41. Collection efficiency vs. particle diameter. Large SASS cyclone.
Particle density - 1.35 gm/cm3.
-------
VO
3*
O
UJ
u.
u.
U4
O
5
UJ
_J
_l
O
u
100
90
80
70
60
50
40
30
20
10
1 I Mill
1 1 I I l 1 i
ILIUM
I I I I I I
.5 .6 .7 .8 .9 1.0
6789 10
20
PARTICLE DIAMETER, MICROMETERS
Figure 42. Collection efficiency vs. particle diameter. Middle SASS cyclone.
Particle density - 135 gm/cm3.
-------
o
o
o
114
O
uZ
u.
ui
u
Ul
100
90
80
70
60
50
40
O 30
20
10
1 I I I 1 I I
3.1 ACFM
I I I
17~1 | Mill
1.8 ACFM
I I I I I I I
.5 .6 .7 .8 .9 1.0 2 3 456789 10
PARTICLE DIAMETER, MICROMETERS
20
Figure 43. Collection efficiency vs. particle diameter. Small SASS cyclone.
Particle density - 1.35 gm/cm3.
-------
I
•H
CO
Q)
Q
0)
H
U
•H
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m
At
345
Micrometers
10
20
30 40
Figure 44. SASS cyclone cut points. (At 23°C)
-------
Sampling System (SASS) at 400°F and 4 SCFM was performed.
The previous calibration at 75°F and 4 ACFM gave approximately
0.86 yin, 3.5 ym, and 11.0 urn D50's for the Small, Middle, and
Large Cyclones, respectively.
The calibration of the Large and Middle Cyclones was per-
formed using ammonium fluorescein aerosols generated with
Southern Research Institute's Vibrating Orifice Aerosol Genera-
tor (VOAG). With the cyclones placed in a heated oven and
using a heated inlet line, the temperature of the gas stream
at the inlet to the Large Cyclone was maintained at 400°F.
Particle integrity of the ammonium fluorescein at high tem-
perature was a major problem. It appeared that rapid heating
of aerosol particles which had not dried sufficiently after
generation caused these particles to rupture creating a large
concentration of contaminating small particulate matter. This
problem was alleviated by allowing the aerosol to come up to
temperature more slowly. A color change in the ammonium fluores-
cein before and after heating was observed. Microscopic obser-
vation also indicated a possible crystalline change, causing
the integrity of the dry ammonium fluorescein particles to
be questioned.
The Large Cyclone was modified to try to obtain a D5u
closer to the desired 10 micrometers. This modification in-
volved the removal of the vortex buster from the Large Cyclone
outlet. Unfortunately, there was no apparent effect on the
performance of this cyclone. The data for the Large Cyclone
is shown in Figure 45.
The Middle Cyclone was also modified in an attempt to
obtain a Dso closer to the desired 3 micrometers. This was
done by reducing the Middle Cyclone inlet diameter from 0.62
inches to 0.53 inches. The effect of this change was minimal
as can be seen in Figure 46 and Figure 47 for the Unmodified
and Modified Middle Cyclone, respectively.
As a result of this laboratory calibration, the approximate
DSO'S for the Large and Middle Cyclones at 400°F and 4 SCFM
are 15 micrometers and 4.4 micrometers, respectively.
After considering the data obtained during this recalibra-
tion, it was felt that the desired Dou's might possibly be
obtained by removal of the vortex busters in the collection
cups of the Large and Middle Cyclones. The resulting large
tangential velocities near the walls of these cups would re-
move a sufficient number of particles to cause a significant
and measurable change in the cut points.
102
-------
o
U)
U
Ut
U
Z
u.
Ui
u
100
90
80
70
60
50
40
30
20
10
1 I I I I I I
1 I I I I I I I
1 I I I I 1 I
I
I I I I I
.4 .5 .6 .7 .8 .9 1.0 2 3 456789 10
PARTICLE DIAMETER, MICROMETERS
20
Figure 45. Collection efficiency vs. particle diameter. Large SASS cyclone.
(4 SCFM, 400°F, 1.00 gm/cm3)
-------
U
UJ
O
LL
u.
UJ
U
ui
8
100
90
80
70
60
50
40
30
20
10
I I I I I I I
I I I I I I I
I
1
I i 1 1 I 1 1
.5 .6 .7 .8 .9 1.0 2 3 456789 10
PARTICLE DIAMETER, MICROMETERS
Figure 46. Collection efficiency vs. particle diameter. Unmodified middle
SASS cyclone. (4 SCFM, 400°F, 1.00 gm/cm3)
20
-------
O
HI
UJ
o
Ul
100
90
80
70
60
SO
40
30
20
10
1 I Mill
1 I \ \ I l i
1
1 I 1 (MIL
i I I 1 I I I I
.5 .6 .7 .8 .9 1.0 2 3 456789 10
PARTICLE DIAMETER, MICROMETERS
20
Figure 47. Collection efficiency vs. particle diameter. Modified middle
SASS cyclone. (4 SCFM, 400°F, 1.00 gm/cm3)
-------
On September 14, 1976, a meeting was held at Research
Triangle Park to discuss the results of the recalibration
of the SASS train cyclones at 4 SCFM and 400°F. It was de-
cided that the results of this study were not sufficiently
conclusive to recommend changes in the cyclone construction
to obtain the desired cut points of 10, 3, and 1 micrometer
at operating conditions of 400°F and 4 SCFM. Data were pre-
sented indicating possible physical changes in the ammonium
fluorescein aerosol at high temperature. Also the shift in
the cyclone calibration curves at these conditions was not
expected based on current cyclone operation theories.
It was concluded that calibration with aerosols which
could withstand these high temperatures should take place.
As a result of this meeting a decision was made to cali-
brate the Source Assessment Sampling System Middle Cyclone
at 400°F and 4 SCFM. Because previous tests have indicated
ammonium fluorescein was unstable at 400°F, a search was ini-
tiated for an aerosol with some or all of the following char-
acteristics:
Non-toxic
Stable at temperatures up to 500"F or above
Soluble in water or other non-toxic, non-residue forming
solvent
Amorphous - dries to form solid, homogeneous spheres when
dispersed in solution from a VOAG
Known or easily measured density
Has a definite, distinct absorption spectrum peak for
absorption spectroscopy measurement between 400 NM
and 900 NM.
The initial search for such an aerosol was unsuccessful,
so, ammonium fluorescein was used to determine the D3U cut
points of the Middle Cyclone at 70°F, 200°F, and 350°F and
5.45 ACFM and the data obtained from these tests was used to
extrapolate to determine the Dg0 cut point at 400"F. This
method proved to be difficult when it was found that ammonium
fluorescein particles smaller than 4 \im in diameter were un-
stable at 350°F. Attempts to alleviate this problem were
largely unsuccessful. Meanwhile the search for an acceptable
aerosol was continued using commercially available dyes.
Of several samples from three chemical companies, du Font's
"Pontamine" Fast Turquoise 8 GLP dye was the first found to
satisfactorily meet the requirements listed above. A spectral
106
-------
analysis performed on a dilute water solution of this dye in-
dicated a distinct absorption peak at 622 nanometers. Measure-
ments with a Helium-Air pycnometer gave a density of 2.04 gm/cm3.
The sample seemed pure and its stability at 400°F was excellent.
The expansion problems encountered with small diameter ammonium
fluorescein particles were absent. Aerosol particles made
from a solution of the dye in distilled water were very nearly,
if not perfectly, spherical..
The calibration of the SASS train cyclones was performed
using the Institute's Vibrating Orifice Aerosol Generator (VOAG).
The VOAG generated monodisperse ammonium fluorescein particles
and turquoise dye particles with diameters from 2 micrometers
to 7 micrometers.
Throughout the testing, close watch was kept on the tem-
perature and flow rate of the aerosol stream. Any discrepancies
were quickly corrected, and readings of all temperatures were
recorded periodically. Therefore repeatability of the tests
and test results was insured.
After each test, the cyclone and filter substrates were
washed to dissolve and rinse off all the aerosol particles.
The wash solutions used were 0.1 N NH.fOH for ammonium fluores-
cein and a sodium bicarbonate solution for turquoise dye.
A Bausch and Lomb Spectronic 88 Spectrophotometer, cali-
brated with solutions of known concentration of the aerosol
solute (turquoise dye or ammonium fluorescein) was used to
measure the absorbance of the wash from the cyclone and the
filter. From knowledge of the amount of wash solution, the
dilution factor, if any, and the absolute concentration, the
mass of particles in the cyclone and on the filter was calcu-
lated. With these two masses known, the collection efficiency
of the cyclone for that particular particle size was calculated.
Results
Table XI lists the D5o cut points of the cyclone at various
conditions. Figure 48 shows the collection efficiency curves
of the cyclone when calibrated with ammonium fluorescein par-
ticles at 70°F, 200°F, and 350°F. The D5o's obtained from
these curves and plotted in Figure 49 indicate that the D50-
gas viscosity relationship is linear. This does not correspond
to Lapple's13 prediction that Dsu would vary directly with
the change in the square root of the gas viscosity.
Figure 50 shows the collection efficiency of the cyclone
for ammonium fluorescein particles and turquoise dye particles
when collected under similar conditions. The relative differ-
ences between the two aerodynamic DSO cut points derived from
the two curves differ from the prediction of Lapple's equation
by only 7%.
107
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Table XII
SASS Middle Cyclone Calibration Data
Material
Vortex
Bus ter Temperature
Flow Rate
ft.3/min
Actual/S tandard
Dso Physical D5o Aerodynamic
Micrometers Micrometers
Ammonium
Fluorescein
o Ammonium
00 Fluorescein
Ammonium
Fluorescein
Turquoise
Dye
Turquoise
Dye
Turquoise
Dye
IN
IN
IN
IN
OUT
IN
Ambient
200
350
OF
°F
Ambient
400
400
OF
op
5
5
5
5
6
6
.31 /
.41/
AC I
.42/
.50/4.00
.50/4.00
2
3
4
2
2
3
.8
.5
.2
.2
.5
.4
3
4
4
3
3
4
.3
.0
.9
.1
.5
.9
-------
1001
75V-
I I T
AMMONIUM FLUORESCEIN
070°F,5.37ACFM
A200°F, 5.41 ACFM
D350°F, 5.46ACFM
35
O
—
o
u.
u.
m
UJ
_l
_t
O
U
50
25
I ! I
I I I I I
2 3 4 56789 10
PARTICLE DIAMETER, micrometers
3630-007
Figure 48. Collection efficiency - temperature relationship SASS middle
cyclone. Ammonium fluorescein particle density = 1.35 gm/cm3
109
-------
180 220
VISCOSITY, poise x KT6
260
3630-011
Figure 49. DSQ - viscosity relationship SASS middle cyclone. Ammonium -
fluorescein particle density =1.35 gm/cm3.
110
-------
100
80
2 60
o
O
U
40
20
DENSITY COMPARISON
O AMMONIUM FLUORESCEIN —
70°F, 5.45 CFM
O TURQUOISE DYE
70°F, 5.42 CFM
1 I I ( i I I
2 3 4 56789 10
PARTICLE DIAMETER, micrometers
3630-008
Figure 50. Collection efficiency - particle density relationship SASS
middle cyclone. Ammonium fluorescein particle density =1.35 gm/cm3,
Turquoise dye particle density = 2.04 gm/cm3.
HI
-------
Figure 51 shows the collection efficiency curves of the
cyclone when calibrated with turquoise dye particles with and
without the vortex buster in place. It was determined using
Lapple's equation that the Dso cut point of the cylcone with
the vortex buster removed is 3.5 vim for 1.00 gm/cm3 particles,
which is within the acceptable range.
112
-------
100
TURQUOISE DYE
400°F, 4 SCFM
O WITHOUT VORTEX BUSTER
A WITH VORTEX BUSTER
I I I I I I I
5 6 7 8 910
PARTICLE DIAMETER, micrometers
3630-009
Figure 51. Collection efficiency at 400°F, 4 SCFM SASS middle cyclone.
dye particle density =2.04 gm/em3.
Turquoise
113
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PROCEDURES MANUAL FOR ELECTROSTATIC PRECIPITATOR EVALUATION
A manual entitled "Procedures Manual for Electrostatic
Precipitator Evaluation," EPA-600/7-77-059, June 1977 (NTIS
PB 209 698/7BE) has been written. The purpose of this pro-
cedures manual is to describe methods to be used in character-
izing the performance of electrostatic precipitators for air
pollution control. A detailed description of the mechanical
and electrical characteristics of precipitators is given.
Procedures are described for measuring the particle size dis-
tribution, the mass concentration of particulate matter, and
the concentrations of major gaseous components of the flue gas-
aerosol mixture. Procedures are also given for measuring the
electrical resistivity of the dust. A concise discussion and
outline is presented which describes the development of a test
plan for the evaluation of an industrial precipitator. Several
appendixes contain detailed information on testing methods as
well as a listing of the Federal Stationary Source Performance
Standards and Federal Source Testing Reference Methods.
To give a better idea of the scope of this document
the contents listing is reproduced below.
INTRODUCTION
ELECTROSTATIC PRECIPITATOR INSTALLATIONS
Types of Electrostatic Precipitators
Characteristics of Typical Precipitator Installations
Parameters Which Govern Electrostatic Precipitator Operation
PARTICULATE SAMPLING FOR ELECTROSTATIC PRECIPITATOR EVALUATION
General Problems
Particulate Mass Measurements
Particle Sizing Techniques
Particulate Resistivity Measurements
TECHNICAL DISCUSSION
ELECTRICAL AND MECHANICAL CHARACTERIZATION OF AN ELECTROSTATIC
PRECIPITATOR
Electrical and Mechanical Design Data
Collecting Electrode System
Discharge Electrode System
Electrical Power Supplies
Rapping Systems
Dust Removal Systems
MASS EMISSION MEASUREMENTS
General Discussion
EPA-Type Particulate Sampling Train
ASTM-Type Particulate Sampling Train
ASME-Type Particulate Sampling Train
General Sampling Procedures
114
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PARTICLE SIZE MEASUREMENT TECHNIQUES
General Discussion
Inertial Particle Sizing Devices
Optical Measurement Techniques
Ultrafine Particle Sizing Techniques
PARTICULATE RESISTIVITY MEASUREMENTS
General Discussion
Laboratory Determination of Particulate Resistivity
In Situ Particulate Resistivity Measurement
PROCESS EFFLUENT GAS ANALYSIS
General Discussion
Qualitative Gas Analysis
Quantitative Gas Analysis
DEVELOPMENT OF TEST PLANS FOR ELECTROSTATIC PRECIPITATOR EVALUATION
General Discussion
Level A Evaluation
Level B Evaluation
Level C Evaluation
Appendix A - AEROSOL FUNDAMENTALS, NOMENCLATURE, AND DEFINITIONS
Appendix B - PARTICULATE MASS CONCENTRATION MEASUREMENTS
Appendix C - CASCADE IMPACTOR SAMPLING TECHNIQUES
Appendix D - SIZE DISTRIBUTIONS OF SUBMICRON AEROSOL PARTICLES
Appendix E - LABORATORY DETERMINATION OF PARTICULATE RESISTIVITY
Appendix F - IN SITU PARTICULATE RESISTIVITY MEASUREMENTS
Appendix G - FEDERAL STATIONARY SOURCE PERFORMANCE REFERENCE METHODS
Appendix H - FEDERAL STATIONARY SOURCE PERFORMANCE STANDARDS
115
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REVIEW OF DOCUMENTS AND REPORTS FURNISHED BY EPA
During the course of this contract two documents furnished
by our Project Officer were critically reviewed. Criticisms,
comments, and suggestions for improvement were returned to
the Task Officer in charge. These documents were:
IERL-RTP Procedures Manual: Level 1 Environmental Assessment
by J. W. Hamersma, S. L. Reynolds, and R. F. Maddalone, EPA-
600/2-76-160a, June 1976.
Procedures For Cascade Impactor Calibration and Operation in
Process Streams by D. Bruce Harris, EPA-600/2-77-004, January
1977.
116
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U.S.A.-U.S.S.R. SCIENTIFIC INFORMATION EXCHANGE PROGRAM
Under this task Southern Research Institute personnel
participated as consultants on particle sizing in a program
of technical information exchange with scientists in the
Soviet Union. During July, 1976 particle sizing equipment
was prepared and shipped to the Soviet Union for a field test-
ing program at a scrubber installed on a metallurgical plant.
Mr. J.DJ. McCain of the Southern Res'earch Institute staff accompanied
several EPA staff scientists to the test site. The actual
field test took place during August, 1976. No results have
been published as of this date.
117
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EPA/IERL/PMB EXHIBIT BOOTH AT THE 1977 APCA ANNUAL MEETING
On June 21, 22, 23, 1977, the Process Measurements Branch
of IERL/RTP supported an exhibit booth at the 70th Annual Air
Pollution Control Association Meeting in Toronto, Ontario,
Canada. This 10" x 20' booth used a color scheme of dark
blue booth back wall and side walls, light blue carpet, and
green draped tables. Three tables along the back wall were
used for document display. Two tables, one on each side,
were used to display hardware. On the white I1 x 20' header
board in black letters was printed the following title:
United States Environmental Protection Agency
Industrial Environmental Research Laboratory - RTF
Process Measurements Branch
On either side of the title was an EPA LOGO in color.
On the back wall were hung six 31 diameter discs which
briefly described the research and development efforts of the
six 1977 Task Level of Effort contractors for the PMB. . These
six contractors were Acurex/Aerotherm, Arthur D. Little, Inc.,
Research Triangle Institute, Southern Research Institute, The
Research Corporation of New England, and TRW, Inc. Representa-
tives from each of the contractors were at the booth on a rotat-
ing basis to answer technical questions.
The hardware on display included a complete Source Assess-
ment Sampling System, a KLD Droplet Analyser, and a Five Stage
Series Cyclone and IERL/PMB Advanced Sampling System.
Approximately 200 copies each of twenty-one EPA Research
and Development Reports were distributed on a first-come, first
served basis to the 4200 registrants at the meeting.
The following is a list of the documents which were dis-
tributed:
HP-25 Programmable Pocket Calculator Applied to Air Pollu-
tion Measurement Studies: Stationary Sources. EPA-600/7-
77-058, June 1977
Procedures Manual for Electrostatic Precipitator Evalua-
tion, EPA-600/7-77-059, June 1977
Industrial Environmental Research Laboratory - RTF Annual
Report 1976
Flow and Gas Sampling Manual. EPA-600/2-76-203, July
1976
IERL-RTP Procedures Manual: Level 1 Environmental Assess-
ment. EPA-600/2-76-106a, June 1976
118
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Selection and Evaluation of Sorbent Resins for the Collec-
tion of Organic Compounds. EPA-600/7-77-044, April 1977
Technical Manual for Measurement of Fugitive Emissions:
Upwind/Downwind Sampling Method for Industrial Emissions.
EPA-600/2-76-089ar April 1976
Technical Manual for the Measurement of Fugitive Emissions:
Roof Monitor Sampling Method for Industrial Fugitive Emis-
sions. EPA-600/2-76-089b, May 1976
Technical Manual for Measurement of Fugitive Emissions:
Quasi-Stack Sampling Method for Industrial Fugitive Emis-
sions. EPA-600/2-76-089c, May 1976
Technical Manual for Process Sampling Strategies for Organic
Materials. EPA-600/2-76-122, April 1976
Technical Manual for Analysis of Organic Materials in
Process Streams. EPA-600/2-76-072, March 1976
Particulate Sizing Techniques for Control Device Evalua-
tion: Cascade Impactor Calibrations. EPA-600/2-76-280.
October 1976
Inertial Cascade Impactor Substrate Media for Flue Gas
Sampling. EPA-600/7-77-060, June 1977
Operating and Service Manual: Source Assessment Sampling
System. Acurex/Aerotherm Report UM-77-81, March 1977
Environmental Assessment Sampling and Analysis: Phased
Approach and Techniques for Level 1. EPA-600/2-77-115,
June 1977
Procedures for Cascade Impactor Calibration and Operating
in Process Streams. EPA-600/2-77-004, January 1977
Technical Manual for Inorganic Sampling and Analysis.
EPA/2-77-024, January 1977
Development and Trial Field Application of a Quality Assur-
ance Program for Demonstration Projects. EPA-600/2-76-
083, March 1976
HP-65 Programmable Pocket Calculator Applied to Air Pollu-
tion Measurement Studies: Stationary Sources. EPA-600/8-
76-002, October 1976.
Process Measurements- Branch: Report Listing, June 1,
1977
119
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Pollution Control Technology and Environmental Assessment;
Brochure Describing the Research and Development Efforts
of the Six PMB Contractors
At the conclusion of the exhibit all of the reports had
been given out, except for a few HP-65 booklets. Reaction
to the exhibit by the attendees at the meeting was quite favor-
able.
120
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CALIBRATION OF A SASS MIDDLE CYCLONE FOR THE HEALTH EFFECTS
RESEARCH LABORATORY/RTF
Exxon Research and Engineering Corporation used a Source
Assessment Sampling System at a coal-fired power plant in
Paducah, Kentucky early in 1977. This work was performed
for the Health Effects Research Laboratory of the National
Environmental Research Center/RTF. The SASS was used to size
and sample the particulate effluent. In order to determine
the actual Middle Cyclone D5o as run Southern Research Insti-
tute was requested to calibrate the actual SASS Middle Cyclone
used by Exxon at the actual sampling conditions.
Exxon used the following sampling conditions.
600°F inlet gas temperature to the oven
Oven temperature 375°F
No filter element in the filter housing in the heated
oven
Pump flow wide open with filter on pump inlet and muf-
fler on pump outlet
Vacuum measured ahead of pump filter - 14 inches EzO
vacuum under sampling conditions
Stack moisture 8%
Gas temperature in middle cyclone unknown
Vortex busters in the collection cups of the Large and
Middle cyclones
These conditions and those of the calibration system were not
completely compatible. The inlet gas temperature was 450°F,
the constraint being the temperature limit of the calibration
aerosol. The oven temperature was 375°F. The humidity of
the air was not measured.
No probe was supplied with the cyclones; however, a tele-
phone conversation revealed that Exxon used an Aerotherm probe
which was twelve feet long. The sampling line of this probe
is one-half inch O.D. Stainless Steel tube. The heat loss
through this probe in our lab was unacceptable, and the par-
ticle loss would probably be quite high. Also a filter had
to be used in the filter holder so that all the mass would
be caught for collection efficiency determinations. Therefore,
the flow rate at the inlet of the large cyclone had to be de-
termined. The field set-up was duplicated as closely as possi-
ble and the flow was measured to be 13 ACFM at an oven inlet
temperature of 399°F. Then the probe was removed and a glass
fiber filter was added to the filter holder. The flow was
adjusted so that the inlet flow to the cyclones was 13 ACFM.
There was a definite but unknown amount of water in the air.
A note should be made as to the conditions of the cyclones
when they arrived. There were a few dents in the cup and the
121
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inlet of the Middle cyclone was bent such that the air stream
did not enter the cyclone strictly tangentially. The only
modification made to the cyclones by SoRI was replacement
of some teflon gaskets which were badly deformed.
The calibration system used was a Vibrating Orifice Aerosol
Generator with du Pont "Pontamine" Fast Turquoise 8 GLP dye
as an aerosol. The collected particles were washed off the
cyclones and filter with a sodium bicarbonate solution, and
their mass was determined with a spectrophotometer .
For a temperature of 450°F, a flow of 13 cfm, and a parti-
cle density of 2.04 gm/cm3, the Dso cut points of the large
and middle cyclones were 7.6 urn and 2.13 ym, respectively (see
Figure 52). For a particle density of 1.00 gm/cm3 and the
same conditions, the Dso cut point of the large and middle
cyclones would be 11 urn and 3.0 ym, respectively.
Estimation of D50 of Middle Cyclone at 600°F
The
cut point for the Middle cyclone is 3.0 urn for
a temperature of 450°F, a flow rate of 13 CFM, and a particle
density Of 1.00 gm/cm3, with the vortex buster in place. Ex-
perimental work with the middle cyclone has indicated the
following may be obtained by extrapolating the DSO vs. vis-
cosity curve.
Flow Rate
5.4 CFM
5.4 CFM
5-4 CFM
Dso
5.0 ym
5.8 ym
6.2 ym
Temperature
375"F
450°F
600°F
Particle Density
1.00 gm/cm3
1.00 gm/cm3
1.00 gm/cm3
Assuming that the D5o cut point will increase at the same rate
with increasing temperature at flow rates of 5.4 and 13.0 CFM,
the following relationships are obtained.
Dso (600°F; 13 CFM)
Dso (450°F; 13 CFM)
and
P-JUL
DSO
(375°F; 13 CFM)
(450°F; 13 CFM)
D50 (600°F; 5.4 CFM)
DSO (450°F; 5.4 CFM)
Dso (375°F; 5.4 CFM)
DSQ (450°F; 5.4 CFM)
Thus,
122
-------
100
0)
a
Ik
u
z
LU
o
u.
y.
LU
2
O
t~
U
LU
O
O
1
O NOZZLE
A LARGE CYCLONE
Q MIDDLE CYCLONE
80
60
50
40
20
Temperature = 450°F
Particle Density = 2.04 gm/cm^
Flow = 13 ACFM
1.0
5.0 10.0
PARTICAL DIAMETER, micrometers
20.0
Figure 52. Exxon SASS cyclones.
123
-------
Dso (600°F, 13 CFM) = 3.0 X |^ = 3.2 ym.
and
D50 (375°F; 13 CFM) = 3.0 x |^-| = 2.6 ym.
Therefore, the D50 cut points of the middle cyclone for a flow
rate of 13 ACFM were estimated to be 2.6 ym for a temperature
of 375°F, and 3.2 ym for a temperature of 600°F.
Estimation of Dso of Small Cyclone at 600°F
The small cyclone has previously been calibrated at two
flows:
Flow Dso Temperature Particle Density
1.8 ACFM 1.88 77°F 1.00 gm/cm3
3.1 ACFM 1.11 77°F 1.00 gm/cm3
Using this relationship Dso = KQ from Chan and Lippmann17
Dh0 (1.88) K (1.8)N
D50 (1.11) K (3-1)N
N = -0.97
So
1.88 = K (1.8)~°'97
K = 3.32
Assuming the Dsu vs. Q relationship above holds at Q = 13 ACFM,
—n QT
D = 3.32Q U'y/
= 3.32(13)~°*97
= 0.277 ym.
Recent experimental work with the Five Stage Series Cyclone
II (which has identical dimensions as the SASS small cyclone
except for the width and depth of the cup) has indicated the
following
124
-------
Flow
1 CFM
1 CFM
1 CFM
DSO
2.30 ym
5.21 ym
4.11 ym
Temperature
77°F
600°F
375°F
Particle Density
1.00 gm/cm3
1.00 gm/cm3
1.00 gm/cm3
Assuming that the D5o cut point will increase at the same
rate with increasing temperature at flows of 1 and 13 CFM,
we obtain the following relationships:
DSO (600°F; 13 CFM) _ Dso (600°F, 1 CFM)
DSO (77°F; 13 CFM)
Dso (77°F, 1 CFM)
and
Dso (375°F; 13 CFM)
Dso (77°F; 13 CFM)
Dso (375°F; 1 CFM)
Dso (77°F; 1 CFM)
Thus, the DSO cut points of the small cyclone for a flow
of 13 ACFM were estimated to be 0.49 ym for a temperature of
375°F and 0.63 ym for a temperature of 600°F.
125
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PROCEDURES MANUAL FOR FABRIC FILTER EVALUATION
The procedures manual for the evaluation of fabric filters (bag-
houses) has been published under the title "Procedures Manual for
Fabric Filter Evaluation." EPA-600/7-78-113, June 1978 (NTIS-PB
283 289),
The purpose of this procedures manual was to describe
methods to be used in experimentally characterizing the performance
of fabric filters for pollution control. A detailed description
of the mechanical characteristics of fabric filters is presented.
Procedures are described for measuring the particle size distri-
bution, the mass concentration of particulate matter, and the
concentration of major gaseous components of the flue gas-par-
ticle mixture. A concise discussion and outline is presented
which describes the development of a test plan for the evalua-
tion of a fabric filter installation. By following this outline
useful tests may be performed which range in complexity from
qualitative and relatively inexpensive to rather elaborate
research programs.
In order to detail the scope of this document the Table
of Contents is reproduced below,
INTRODUCTION
FABRIC FILTER INSTALLATIONS
Particle Filtering Mechanisms
Factors Affecting Filter Performance
Filter Fabrics
Types of Fabric Filters
PARTICULATE SAMPLING FOR FABRIC FILTER EVALUATION
General Considerations
Particulate Mass Measurements
Particle Sizing Techniques
TECHNICAL DISCUSSION
MECHANICAL CHARACTERIZATION OF A FABRIC FILTER INSTALLATION
Mechanical Design and Operating Data
The Fabric Filter Bags
Filter Fabrics
Dust Removal Systems
Baghouse Operation-General Maintenance Considerations
MASS EMISSION MEASUREMENTS
General Discussion
EPA-Type Particulate Sampling Train (Method 5)
ASTM-Type Particulate Sampling Train
ASME-Type Particulate Sampling Train
General Sampling Procedures
126
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PARTICLE SIZE MEASUREMENT TECHNIQUES
General Discussion
Inertial Particle Sizing Devices
Optical Measurement Techniques
Ultrafine Particle Sizing Techniques
PROCESS EFFLUENT GAS ANALYSIS
General Discussion
Qualitative Gas Analysis
Quantitative Gas Analysis
DEVELOPMENT OF TEST PLANS FOR FABRIC FILTER EVALUATIONS
OBJECTIVES OF CONTROL DEVICE TESTS
TYPE AND NUMBER OF TESTS REQUIRED
Fabric Filter Level A Evaluation
Plant Operating Data
Baghouse-Fabric Filter Design Data
Flue Gas Characteristics, Baghouse AP, Maintenance Data
Fabric Filter Level B Evaluation
Quantitative Gas Analysis
Inlet and Outlet Mass Concentration Measurements Total
Mass Collection Efficiency
Fabric Filter Level C Evaluation
GENERAL PROBLEMS AND CONSIDERATIONS
APPENDICES
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
AEROSOL FUNDAMENTALS, NOMENCLATURE, AND DEFINITIONS
PARTICULATE MASS CONCENTRATION MEASUREMENTS
CASCADE IMPACTOR SAMPLING TECHNIQUES
SIZE DISTRIBUTIONS OF SUBMICRON AEROSOL PARTICLES
SUMMARY OF SOURCE PERFORMANCE METHODS
FEDERAL STATIONARY SOURCE PERFORMANCE STANDARDS
127
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ADVANCES IN PARTICLE SAMPLING AND MEASUREMENT SYMPOSIUM
Southern Research Institute coordinated a symposium for the
Process Measurements Branch/IERL-RTP on May 15-17, 1978 at the
.Grove Park Inn and Country Club, Asheville, North Carolina. The
number of attendees was 176. There were five sessions with
a total of seventeen speakers. The symposium had morning
and evening sessions with the afternoons free for recreation.
A proceedings from this technical meeting has been published.
The scope of the meeting can be seen in the following reprint
of the technical program.
TECHNICAL PROGRAM
ADVANCES IN PARTICLE SAMPLING AND MEASUREMENT
A Symposium Sponsored by The Process Measurement Branch,
Industrial Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina.
MONDAY MORNING, MAY 15
SESSION I: INSTRUMENTS AND TECHNIQUES FOR
PARTICLE-SIZE ANALYSIS
8:30 am Welcome Address - John K. Burchard (EPA), Director, Industrial Environmental
Research Laboratory - RTP
8:40 Opening Remarks • Symposium Chairman, D. Bruce Harris (EPA/I ERL-RTP)
8:55 Opening of Technical Program - Session Chairman, A. McFarland (Texas A & M)
9:00 First Paper - "Inertia Effects in Sampling Aerosols", C. N. Davies and M. B. Subari
(U. of Essex, England)
9:45 Break
10:05 Second Paper - "Cyclone Sampler Performance", M. Lippmann (NYU) and
T. L. Chan (Gen. Motors Res. Lab.)
10:50 Third Paper - "Research on Dust Sampling and Measurement in Our Laboratory",
K. linoya (Kyoto U., Japan)
11:35 First Session Adjourns
MONDAY EVENING
SESSION II: INSTRUMENTS AND TECHNIQUES FOR
PARTICLE-SIZE ANALYSIS (CONTINUED)
7:30 pm Call to Order - Session Chairman, D. Lundgren (U. of Florida)
7:35 First Paper - "Sizing Submicron Particles with a Cascade Impactor", M. Pilat
(U. of Washington)
8:20 Second Paper - "Experience in Sampling Urban Aerosols with the Sinclair Diffusion
Battery and Nucleus Counter", D. Sinclair and E. Knutson (Dept. of Energy)
9:05 Third Paper - "Selecting Laboratory Instruments forfarticle Sizing", R. Draftz (IITRI)
9:50 Second Session Adjourns
128
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TUESDAY MORNING, MAY 16
SESSION III: REAL-TIME MEASUREMENTS OF PARTICLE
CONCENTRATION AND SIZE
8:30 am Call to Order - Session Chairman, W. Kuykendal (EPA/IERL-RTP)
8:35 First Paper - "Long-Term Field Evaluation of Continuous Particulate Monitors",
A. W. Gnyp, S. J, W. Price, C. C. St. Pierre, and D. S. Smith (U. of Windsor, Canada)
9:20 Second Paper - "An In-Situ Stack Fine Particle Size Spectrometer - A Discussion of
Its Design and Development", R. Knollenberg (Particle Meas. Systems)
10:05 Break
10:25 Third Paper - "Optical Measurements of Particulate Size in Stationary Source Emissions",
A. L. Wertheimer, W. H. Hart, and M. N. Trainer (Leeds & Northrup)
11:10 Fourth Paper - "Studies of Relating Plume Appearance to Emission Rate and Continuous
Particulate Mass Emission Monitoring", K. T. Hood and H. S. Oglesby (NCASI)
11:55 Third Session Adjourns
TUESDAY EVENING
SESSION IV: DATA REDUCTION, ACCURACY
AND QUALITY CONTROL
7:30 pm Call to Order Session Chairman, T. T. Mercer (U. of Rochester)
7:35 First Paper - "A Data Reduction System for Cascade Impactors", J. D. McCain,
G. I. Clinard, L. G. Felix, and J. W. Johnson (Sou. Res. Inst.)
8:20 Second Paper - "Aerosol Generation and Calibration of Instruments", D. Y. H. Pui
and B. Y. H. Liu (U. of Minnesota)
9:05 Third Paper - "Collection Substrates for Cascade Impactors", D. B. Harris (EPA),
G. I. Clinard, L. G. Felix, G. E. Lacey, and J. D. McCain (Sou. Res. Inst.)
9:50 Fourth Session Adjourns
WEDNESDAY MORNING, MAY 17
SESSION V: CONTROL DEVICE EVALUATION
8:30 am Call to Order Session Chairman, G. B. Nichols (Sou. Res. Inst.)
8:35 First Paper - "Particle Size Measurement for Evaluation of Wet Scrubbers",
S. C. Yung, R. Chmielewski, G. Monahan, and S. Calvert (APT, Inc.)
9:20 Second Paper - "Evaluation of Performance and Particle Size Dependent
Efficiency of Baghouses", D. S. Ensor, R. C. Hooper, G. Markowski (MRI),
and R. D. Carr (EPRI)
10:05 Break
10:25 Third Paper - "Evaluation of the Efficiency of Electrostatic Precipitators",
W. B. Smith, J. P. Gooch, J. D. McCain, and J. E. McCormack (Sou. Res. Inst.)
11:10 Fourth Paper "Some Studies of Chemical Species in Fly Ash", L. D. Hulett,
R. R. Turner, J. M. Dale, A. J. Weinberger, H. W. Dunn, C. Feldman, E. Ricci
(Oak Ridge Nat. Lab.) and J. 0. Thompson (Consultant)
12:00 noon Symposium Adjourns
-------
PRESENTATION TO FEDERAL REPUBLIC OF GERMANY
Under this technical directive Mr. J,D. McCain of Southern
Research Institute wrote and presented a paper on manual par-
ticulate mass and size measurements at a workshop held in Ju-
lich, Federal Republic of Germany on March 16 and 17, 1978.
130
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PARTICULATE SIZING INSTRUMENT EVALUATION
Criteria were developed for the evaluation of three real-
time particle sizing instruments. The instruments are:
1. a light scattering instrument—Particle Measuring Systems,
Inc., Boulder, CO
2. a light sensing virtual impactor—Meteorology Research, Inc.,
Altadena, CA
3. an acoustic instrument—KLD Associates, Huntington Station, NY
The suggested evaluation program is based on the operational
principle of each instrument. The evaluation criteria based on
measurable parameters that are of greatest interest to EPA/IERL/
RTP have been developed to allow comparisons of the three instru-
ments .
The test plan is entitled "Particulate Sizing Instrument
Evaluation," Southern Research Institute Report Number SORI-EAS-
78-595, October 6, 1978.
131
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References
1. Cooper, Douglas W. and John W. Davis, "Cascade impactors for
aerosols: Improved data analysis," Amer. Ind. Hyg. Assoc.,
p. 79, 1972.
2. Cooper, Douglas W. and Lloyd A. Spielman, "Data inversion
using nonlinear programming with physical constraints:
Aerosol size distribution measurement by impactors,"
Atmospheric Environment, Vol. 10, pp. 723-729, 1976.
3. Picknett, R. G., "A new method of determining aerosol size
distributions from ministage sampler data," Aerosol Science,
1972.
4. McCain, J. D. , K. M. Gushing, and W. B. Smith, "Methods
for determining particulate mass and size properties:
Laboratory and field measurements," J. APCA 2£(12): 1172-
1176, December 1974.
5. Rao, A. K., "An experimental study of inertial impactors,"
Ph.D. Dissertation, University of Minnesota, Minneapolis,
Minnesota, 1975.
6. Dzubay, T. G., L. E. Hines and R. K. Stevens, "Particulate
bounce errors in cascade impactors," Atmospheric Environment,
Vol. 10, pp. 229-234, 1976.
7. Natusch, D. F. S. and J. R. Wallace, "Determination of air-
borne particle size distributions: Calculation of cross-
sensitivity and discreteness effects in cascade impaction,"
Atmospheric Environment, Vol. 10, pp. 314-324, 1976.
8. Gushing, K. M., J. D. McCain, and W. B. Smith, "Experimental
Determination of sizing parameters and wall losses of five
commercially available cascade impactors," in Proceedings
of the 69th Annual Meeting of the Air Pollution Control
Association, Portland, Oregon, 1976, paper No. 76-374.
9. Lundgren, D. A. (1967). "An aerosol sampler for determina-
tion of particle concentration as a function of size and
time," J. APCA YT_, pp. 225-229.
10. Smith, W. B., K. M. Gushing, and G. E. Lacey, Andersen Filter
Substrate Weight Loss Study. EPA-650/2-75-022, U.S. Environ-
mental Protection Agency, Research Triangle Park, N.C., 1975.
132
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11. McCain, J. D., J. E. McCormack, and D. B. Harris. Non-Ideal
Behavior in Cascade Impactors. 70th Annual Meeting, APCA,
Toronto, Ontario, Canada, 1977. Paper 77-35.3.
12. Felix, L. G., G. I. Clinard, G. E. Lacey, and J. D. McCain.
Inertial Cascade Impactor Substrate Media for Flue Gas
Sampling. EPA-600/7-77-060, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, 1977, 89 pp.
13. Lapple, C. E. Processes Use Many Collector Types. Chemical
Engineering, 58: 144-151, 1951.
14. Sproull, W. T. Air Pollution and Its Control. Exposition
Press, New York, 1970.
15. Muschelknautz, E. Design of Cyclone Separators in the
Engineering Practice. Staub-Reinhalt. Luft, 30(5): 1, 1970,
16. Leith, D. and W. Licht. The Collection Efficiency of Cyclone
Type Particle Collectors-A New Theoretical Approach, A.I.Ch.E,
Symposium Series, New York, New York, 1971, pp. 196-206.
17. Chan, T., and M. Lippmann. Particle Collection Efficiencies
of Air Sampling Cyclones: An Empirical Theory. Environ-
mental Science and Technology, 11(4): 377-382, 1977.
18. Ranz, W. D., and J. B. Wong. Impaction of Dust and Smoke
Particles, Ind. and Eng. Chem., 50, No. 4 (April, 1958).
19. Marple, V. A. A Fundamental Study of Inertial Impactors.
Ph.D. Thesis, Mechanical Engineering Department, University
of Minnesota, Minneapolis, Minnesota 55455, 1970.
20. Willeke, K. Performance of the Slotted Impactor. Am. Ind.
Hygiene Assoc. J., 683-691, September 1975.
133
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APPENDIX
A List of Reports Written under
Contract No. 68-02-2131
134
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Particulate Sizing Techniques For Control Device Evaluation:
Cascade Impactor Calibrations
Kenneth M. Gushing, George E. Lacey, Joseph D. McCain,
Wallace B. Smith
EPA-600/2-76-280, October 1976, NTIS (PB 262 849/3BE)
(Original work supported by EPA Contract No. 68-02-0273.)
HP-65 Progammable Pocket Calculator Applied To Air Pollution
Measurement Studies: Stationary Sources
James W. Ragland, Kenneth M. Gushing, Joseph D. McCain,
Wallace B. Smith
EPA-600/8-76-002, October 1976, NTIS(PB 264 284/1BE)
HP-25 Programmable Pocket Calculator Applied To Air Pollution
Measurement Studies: Stationary Sources
James W. Ragland, Kenneth M. Gushing, Joseph D. McCain,
Wallace B. Smith
EPA-600/7-77-058, June 1977, NTIS(PB 269 666/4BE)
Procedures Manual for Electrostatic Precipitator Evaluation
Wallace B. Smith, Kenneth M. Gushing, Joseph D. McCain
EPA-600/7-77-059, June 1977, NTIS(PB 269 698/7BE)
Inertial Cascade Impactor Substrate Media For Flue Gas Sampling
Larry G. Felix, George I. Clinard, George E. Lacey, Joseph D.
McCain
EPA-600/7-77-060, June 1977, NTIS(PB 276 583/2BE)
Development and Laboratory Evaluation of a Five-Stage Cyclone
System
Wallace B. Smith, Rufus Ray Wilson, Jr.
EPA-600/7-78-008, January 1978, NTIS(PB 279 084/8BE)
Particulate Sampling Support: 1977 Annual Report
Kenneth M. Gushing, William E. Farthing, Larry G. Felix,
Joseph D. McCain, Wallace B. Smith
EPA-600/7-78-009, January 1978, NTIS(PB 279 170/5BE)
A Computer-Based Cascade Impactor Data Reduction System
Jean W. Johnson, George I. Clinard, Larry G. Felix,
Joseph D. McCain
EPA-600/7-78-042, March 1978, NTIS (PB 285 433)
Technical Mannual: A Survey of Equipment and Methods for
Particulate Sampling in Industrial Process Streams
Wallace B. Smith, Paul R. Cavanaugh, Rufus Ray Wilson
EPA-600/7-78-043, March 1978, NTIS (PB 282 501)
135
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Procedures Mannual For Fabric Filter Evaluation
Kenneth M. Gushing, Wallace B. Smith
EPA-600/7-78-113, June 1978, NTIS CPB 283 389)
An Electrostatic Precipitator Backup for Sampling Systems
P. Vann Bush, Wallace B. Smith
EPA-600/7-78-114, June 1978, NTIS (PB 283 660)
Evaluation of the PILLS-IV
William E. Farthing, Wallace B. Smith
EPA-600/7-78-130, July 1978, NTIS CPB 283 173)
A Data Reduction System for Cascade Impactors
Joseph D. McCain, George I. Clinard, Larry G. Felix, Jean W. Johnson
EPA-600/7-78-132a, July 1978
Design a Particle Sampling Test Facility
Norman L. Francis, Kenneth M. Gushing
SORI-EAS-78-560, September 22, 1978
Particulate Sizing Instrument Evaluation
William E. Farthing
SORI-EAS-78-595, October 6, 1978
Sampling Charged Particles With Cascade Impactors
William E. Farthing, David H. Hussey, Wallace B. Smith,
Rufus Ray Wilson, Jr.
EPA-600/7-79-027, January 1979
Guidelines For Particulate Sampling In Gaseous Effluents From
Industrial Processes
Rufus R. Wilson, Jr., Paul R. Cavanaugh, Kenneth Gushing,
William E. Farthing, Wallace B. Smith
EPA-600/7-79-028, January 1979
Proceeding: Advances in Particle Sampling and Measurement
(Asheville, North Carolina, May, 1978)
Wallace B. Smith, Compiler
EPA-600/7-79-065, February 1979
136
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.„ TECHNICAL REPORT DATA
(flease react Instructions on the reverse before completing)
. REPORT NO.
EPA-600/2-79-114
2.
3. RECIPIENT'S ACCESSION-NO.
. TITLE AND SUBTITLE
Particulate Sampling and Support: Final Report
5. REPORT DATE
June 1979
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S) —^— ~
Kenneth M. Gushing and Wallace B. Smith
8. PERFORMING ORGANIZATION REPORT NO.
'ERFORMING ORGANIZATION NAME AND ADDRESS
Southern Research Institute
2000 Ninth Avenue, South
Birmingham, Alabama 35205
10. PROGRAM ELEMENT NO.
INE623
11. CONTRACT/GRANT NO.
68-02-2131
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND.PERIOD COVERED
Final; 11/75 - 11/78
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES JERL-RTP project officer is D. Bruce Harris, Mail Drop 62,
919/541-2557.
16. ABSTRACT The repOrj- summarizes results of research, development, and support
tasks performed during the 3-year period of the contract (11/75-11/78). The tasks
encompassed many aspects of particulate sampling and measurement in industrial
gaseous process and effluent streams. Under this contract: cascade impactors were
calibrated and evaluated; novel particle sampling cyclones were designed and eval-
uated; technical and procedures manuals were prepared for control device evaluation
and particle sampling methods; an electrostatic precipitator backup was designed
for high flow rate systems; and advanced concepts in monitoring particle mass and
size, using optical systems, were evaluated. A number of smaller tasks, involving
lower levels of effort, are also discussed. The appendix lists technical documents
published under the contract.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATl Field/Group
Pollution
Dust
Sampling
Measurement
Optical Measurement
Industrial Processes
Impactors
Cyclone Separators
Electrostatic Pre-
cipitators
Pollution Control
Stationary Sources
Particulate
Cascade Impactors
13B
11G
14B
13H
131
07A
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
147
20 SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
137
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