EPA-650/2-74-088
OCTOBER 1974
Environmental Protection Technology Series
;:;:::::;:::;x;ii;;:::i:;:i:i:;^
-------
EPA-650/2-74-088
ASSESSMENT OF PARTICLE
CONTROL TECHNOLOGY
FOR ENCLOSED ASBESTOS SOURCES
by
C. F. Harwood, P. Siebert, and T. P. Blaszak
IIT Research Institute
10 West 35th Street
Chicago, Illinois 60616
Contract No. 68-02-1353
ROAP No. 21AFA-006
Program Element No. 1AB015
EPA Project Officer: D. K. Oestreich
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S . ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
October 1974
-------
This report has been reviewed by the Environmental Protection Agency
and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
ii
-------
ABSTRACT
The report gives results of a study to provide informa-
tion, from both the literature and user contact, on the con-
trol of asbestos emissions from enclosed sources. It assesses
the state-of-the-art in asbestos emission control in terms
of the devices or methods used and their efficiency. In
addition, it gives results of a preliminary study to actually
measure the effectiveness of baghouse control devices in con-
trolling emissions from five asbestos plants, Baghouses are
the predominant control device used in the asbestos industry.
Cotton bags are used most frequently. Automatic shaking is
used in most baghouses, with shake cycles of 1% to 4 hours
most common. Most baghouses operate at two pressure drop
ranges, 2.5-5 and 7.5-10 cm H^O. Air-to-cloth ratios range
from 2 to 10:1. Published data on the removal efficiencies
of the control devices was either non-existent, or quoted in
general terms. Five baghouses were tested for removal
efficiency in terms of mass and fiber number: although
mass efficiency was very high, fiber concentrations exceeding
100 million fibers/cu meter, greater than about 0.05 ym long,
are emitted. Using computer modeling, it was found that,
even considering one source, asbestos concentrations of over
500 fibers/cu meter can be anticipated 5 km from the source.
The exposure level at which asbestos in ambient air becomes
a health hazard is not known.
This report was submitted in fulfillment of IITRI Project
Number C6291, Contract Number 68-02-1353, by the IIT Research
Institute, under the sponsorship of the Environmental
Protection Agency. Work was completed as of May 1974.
iii
-------
CONTENTS
Page
Abstract iii
List of Figures v
List of Tables vi
Acknowledgements viii
Sections
1 Conclusions 1
2 Recommendations 3
3 Introduction 5
4 Literature Survey 6
5 Compilation of Control Equipment User's Data 26
6 Emission Data Collection and Analysis 43
7 Estimate of Asbestos Dispersion 67
8 References 79
9 Appendices 82
IV
-------
FIGURES
Sampling Arrangement 45
Coordinate System Showing Gaussian Distributions
in the Horizontal and Vertical 68
The Concentration of Asbestos Fibers with Distance
from Source at Four Stability Conditions for
Johns-Manvilie, Waukegan, Illinois 74
The Concentration of Asbestos Fibers with Distance
from Source at Four Stability Conditions for
Johns-Manvilie, Denison, Texas 75
The Concentration of Asbestos Fibers with Distance
from Source at Four Stability Conditions for
Raybestos, Marshville, North Carolina 76
The Concentration of Asbestos Fibers with Distance
from Source at Four Stability Conditions for
Johns-Manville, Asbestos, Canada 77
The Concentration of Asbestos Fibers with Distance
from Source at Four Stability Conditions for
GAF, Eden Mills, Vermont 78
v
-------
TABLES
No.
1 Filter Fabric Properties 13
2 Fabric Filter Applications -- Asbestos Mining
and Manufacturing 19
3 Rule-of-Thumb Costs of Typical Collectors,
Standard Mild Steel Construction 22
4 Typical Costs for the Canadian Asbestos Industry 23
5 Product Manufactured 28
6 Size of Asbestos Manufacturing Plants 29
7 Types of Asbestos Processed in Plants 30
8 Dust Control Devices 31
9 Method of Waste Disposal 32
10 Baghouse Manufacturers 35
11 Capacity of Dust Collection System 36
12 Air-to-Cloth Ratio 37
13 Bag Fabric 39
14 Bag Cleaning Mechanism 40
15 Bag Cleaning Cycle 41
16 Pressure Drop Across Bags 42
17 Samples and Sampling Conditions 60
18 Sample Weights and Mass Efficiency Data 61
19 Total Fiber Counts and Fiber Removal Efficiencies 62
20 Optical Microscope (500X) Size Distributions and
Fractional Removal Efficiencies 63
21 Electron Microscope (16,364X) Size Distributions and
Fractional Removal Efficiencies 64
VI
-------
TABLES (cont.)
No. Page
22 Key to Stability Categories 71
23 Dispersion Equation Source Terms 73
vii
-------
ACKNOWLEDGEMENTS
The help and cooperation of the asbestos industry is
acknowledged. In particular, Johns-Manvilie, Raybestos, and
the GAF Company, who gave the permission for their baghouses
to be sampled, and assisted in the setting up of the
sampling platforms.
The help and guidance of the original Project Officer,
Mr. Dennis Drehmel, and his successor, Mr. David Oestreich,
is acknowledged.
IITRI personnel who contributed to this program were
David Becker, who produced the bibliography, Scott Preece,
who obtained dispersion data through the COM computer model,
Erdmann Luebcke, who undertook field sampling and optical
counting, and Anant Samudra, who obtained electron microscope
data. The Project Leader was Dr. Colin F. Harwood, assisted
by Paul Siebert and Tom Blaszak. John Stockham had fiscal
responsibility for the program.
viii
-------
SECTION 1
CONCLUSIONS
A survey of the literature has revealed that there has
been little reported on the specific problem of reducing as-
bestos emissions to the atmosphere. A state-of-the-art
review of dust collection has been made, and its application
to asbestos has been stressed whenever possible. The litera-
ture cites the baghouse as being the prime collector used
in the industry.
Information obtained from asbestos product manufacturers
confirmed that baghouses are the predominant dust collection
device used. Typically, baghouses in the asbestos industry
use cotton fabric bags. The cleaning cycle is automated with
1% to 4 hours separating shake cycles. The usual operating
capacity is 140 to 570 cubic meters per minute (5,000 to
20,000 cfm), with an air-to-cloth ratio of just under 3:1.
Baghouses are normally free of operating problems. Normal
installation costs range from $88.00 to $106.00 per cubic
meter per minute ($2.50 to $3.10 per cfm) with operating
costs ranging from $1.80 to $35.00 per cubic meter per
minute per year ($0.05 to $1.00 per cfm per year).
It is not common practice for the users of the baghouses
to measure the efficiencies of their baghouses. No hard
data on baghouse efficiency was obtained from users or from
the literature. Preliminary field measurements undertaken
during this study have confirmed the high efficiency of the
baghouse in removing asbestos fiber from the air stream.
-------
Both the mass efficiencies and measured fractional efficien-
cies are 99+%. However, the dust load is high, resulting
in large numbers of fibers being emitted despite high
/ C Q
efficiencies. Emissions of about 10 -10 fibers/m of
78 3
>1.5 urn and 10 -10 fibers/m of <1.5 ym were found to be
usual.
The dispersion of asbestos fibers from a source was
calculated using the Binomial Continuous Plume Dispersion
Model (BCPDM) and the Climatological Dispersion Model (COM).
The CDM model is designed to develop a long-term, quasi-stable
pollutant concentration profile for a given area. Unreliable
results were obtained using this model, which showed that it
was not suited for the particular conditions of this study.
The exact cause of the failure was not established.
Results obtained with the BCPDM model were consistent.
As expected, the estimated concentration values varied with
the size of the emission source, the time of day, and the
distance from the plant. At a distance of 1 kilometer from
37
the plant, peak values of about 10 to 10 fibers per cubic
meter were calculated. A sharp decline was observed to
about 10 kilometers distance, where the concentrations of
about 2.5 x 10 to 5 x 10 fibers per cubic meter were cal-
culated. Beyond 10 kilometers, the rate of decline of the
fiber concentration was slow, at a distance of 30 kilometers,
the values were calculated to be about 10 to 10 fibers
per cubic meter.
It is stressed that these values extend from a single
source. Fiber emissions from other baghouses within the
same plant and from adjacent plants would lead to increased
ambient concnetrations.
-------
SECTION 2
RECOMMENDATIONS
This study has shown that current control devices emit
very large numbers of small fibers. It is estimated that
these fibers remain suspended and travel large distances from
the source. It is recommended that methods to reduce these
emissions should be investigated.
Since baghouses are the accepted best method of reducing
asbestos emissions, the most logical study would be to
optimize the baghouse performance. A statistically designed
experimental study would establish the efficiency controlling
parameters. Baghouses could then be optimized to control
emissions from specific asbestos waste types.
While initial consideration should be given to optimizing
baghouses, other types of devices should not be overlooked.
It is recommended that both established and novel control
devices be considered and tested either singly or in combina-
tion with baghouses. For example, novel systems, such as
foam injected cyclones, and established devices, such as elec-
trostatic precipitators, have not been evaluated for asbestos
emission control.
It is also recommended that studies should be conducted
to establish the fate of emitted asbestos fibers. The small
size of the fibers, and their indestructable nature, implies
that they may remain suspended indefinitely. The limited
particle scavenging studies that have been conducted do not
include fibrous particles. Studies on approximately spherical,
-------
sub-micron particles indicate that scavenging by snow and rain
is of ultra low efficiency. Implicit in the long-term sus-
pension of these fine fibers, their chemical inertness, and
the lack of an effective scavenging mechanism, is the
possibility that the number of asbestos particles in the
atmosphere is increasing. A test program is recommended
to determine if this is true and, if so, its health signi-
ficance.
-------
SECTION 3
INTRODUCTION
The control of hazardous emissions from operations
involving asbestos products is mandatory under the applica-
tion of the Clean Air Act. It is, therefore, necessary for
the Environmental Protection Agency to evaluate the control
technology applicable to enclosed sources of these hazardous
emissions. In this way, it is possible to introduce legisla-
tion which will require the application of operating practices
capable of protecting the public health. The applicability
and effectiveness of these practices will be supported by
sound scientific procedures and experimental evidence.
To develop the information required for this report,
three methods were used:
1. The scientific literature was surveyed and a
bibliography produced. Published literature per-
tinent to the control of asbestos emissions from
enclosed sources was reviewed.
2. Users and manufacturers of emission control equip-
ment were contacted. Information on equipment
applicabilities and the attainable degree of con-
trol with various control approaches was solicited.
3. Sampling and analysis were conducted to obtain
data on the emissions from five different enclosed
sources. These manufacturing sources were selected
because the control technology employed was typical
of the industry.
-------
SECTION 4
LITERATURE SURVEY
INTRODUCTION
Literaturfe Search
The literature on emission control of asbestos has been
surveyed by computer search. Very few references specific
to asbestos have been found; for this reason, the search was
broadened to include industries with related particulate
emission problems.
A bibliography has been produced; because of its large
size, it has been bound under separate cover from the main
report. It is some 231 pages in length and contains over
3,000 citations. References have been arranged by KWIC
(key word in context), by author, and by citation.
Abstracts of pertinent references are included in
Appendix A.
Types of Control Devices
The major types of collection devices available are
cyclones, wet scrubbers, electrostatic precipitators, and
baghouses. Each of these devices has some applicability
in the asbestos industry, although in the United States,
baghouses are generally used as the final control device.
Cyclones are inertial collectors, which collect particles
by imparting a tangential velocity to the gas stream, so
that the particles are moved by centrifugal forces to the
cyclone wall, where they are collected.
-------
Wet spray collectors, which are designed in a wide
variety, operate by atomizing or breaking down liquid drop-
lets to an extremely fine spray. The increased water surface
area allows better contact with the particles and improves
the chances that the contaminants will be captured. The
waste, a wet slurry, is then removed from the gas stream
by either centrifugal or mechanical means.
Electrostatic precipitators are essentially a chamber
with a series of high voltage electrodes between grounded
plates. The corona around the discharge electrodes ionizes
the gas, and, therefore, the dust which then migrates to
the plates. The particles then fall, or are rapped loose or
washed into hoppers. Micron and sub-micron material can
only be collected by high efficiency bag filters, high
efficiency scrubbers, or ESP's.
Baghouses utilize fabric filters in a bag or tubular
shape, which are mounted either in the plant itself or in
separate modules. As particles are collected, they build
up a filter cake which increases collection efficiency
and the pressure drop across the filter. Occasionally,
this filter cake must be removed, as the power required to
overcome the pressure drop becomes too high.
Use in the Asbestos Industry
In asbestos mining, small fabric filters are used for
control during drilling. Cyclones, bag collectors, and
properly designed ducts are then used for dust control in
the crushing operation. Cyclones, sometimes followed by
baghouses, are used as control devices on the dryers.
Asbestos milling involves crushing and separation from
the dust by air aspiration, grading of the fibers by cyclones
connected to the baghouse. Also connected to the baghouse
are the screens, separators, recirculating systems, regrading
-------
areas, pressure packers, and other dust control systems, i.e.,
vacuum systems. Generally, all conveyors are covered, and
low velocity hoods are used for control of dust in other
areas. (In many asbestos processing operations in which
dust occurs, i.e., textiles and friction materials, cyclones
and baghouses are also used.) Mill ventilation systems gen-
erally receive 5070 of their load from the screens, 25% from
dust control systems, and the remainder from various machines
which open the fiber, separate dust from fibers, or segregate
fiber lengths1. The milling process generally requires
9-10 tons air/ton ore processed, and approximately 10 ton air/
ton finished product2'3' * .
The properties of asbestos which complicate its cleaning
from ventilation air are5: 1) its fibrous nature, i.e., it
tends to interlace and mat, thus creating pneumatic handling
difficulties; 2) its friability, or ability to break down
to smaller and smaller fibers so that a high efficiency is
needed for sizes less than 10 ym; 3) as the size of the
fibers decreases, they become increasingly affected by
moisture so that an impenetrable cake is formed; 4) its low
apparent specific gravity, which is one-fourth to one-fifth
of its real specific gravity of 2.54-2.59, so that it is less
easily collected by gravitational or inertial techniques.
CYCLONES
Cyclones are generally efficient collectors,, for
particles which have diameters greater than 10-20 ym. Low
efficiency cyclones can be used for 10-20 years in a high
temperature, non-corrosive environment; however, their
efficiencies are only 8070 for particles greater than 44 um6.
High efficiency cyclones utilize a much smaller diameter
and various other design refinements to achieve much higher
efficiencies at the cost of a greater pressure drop. Due
to their small diameters and correspondingly small flow
8
-------
capacities, high efficiency cyclones are usually used in
multiple units. These multiple cyclones are capable of col-
lection efficiencies of 100% for particles larger than
10 ym, and greater than 90% for particles larger than 2 ym6.
Cyclones have the advantages of7: 1) simple design;
2) easy protection against wear; 3) high efficiency if scien-
tifically designed; and 4) automatic locks to prevent leakage,
Its major disadvantage is that for high efficiencies for
micron-sized particles, very small diameters susceptible to
clogging and wear are needed. For the large capacities
needed for asbestos applications, small diameter, high
efficiency cyclones are generally not practicable. In one
asbestos mill in Quebec, twin cyclones of 2 m diameter were
used from 1960-67 as the primary control device. The collec-
tion efficiency achieved was only 70%, so that they had to
be replaced when stricter emission regulations were
effected8.
Generally, low efficiency cyclones are used in asbestos
milling to collect most of the fiber and a minimum of rock
dust in the separation process1'1* . Cyclones are also used
for the grading of asbestos into specific size ranges9.
Also, they are frequently used as pre-cleaners before the
final control device, which is usually a baghouse2.
WET SPRAY COLLECTORS
Wet spray collectors are available in a variety -of de-
signs, including the following6'7 .
1. Water injection into fans modified with special
fittings for ultrafine atomization of water.
A single fan can clean up to 100,000 mj/hr
(59,000 cfm) with a water flow of 0.1-0.3 1pm
(0.026-0.079 gpm).
-------
2. Water sprayed filter beds containing several layers
of specially shaped elements. The gas velocity is
less than 2 m/sec previous to the injection of drop-
lets from the spray wash at a flow of approximately
0.14 m , depending on the type and size of the dust.
3. Wet centrifugal scrubbers are more efficient than
dry centrifugal devices such as cyclones; however,
they have a greater corrosive action, tend to plug,
and are more expensive to operate.
4. Water s pr ay s scrubber s are designed so that the air
stream decelerates when the spray contacts it.
5. Baffle box scrubbers pull the dirty gas through
several inches of turbulent water, sometimes using
centrifugal action.
6. Venturi scrubbers atomize the water droplets by
injection at high pressure into the high air
velocity at the throat of the venturi section. As
the venturi area increases, the larger droplets are
still accelerating, while the gas and particles
are decelerating, thus creating a second area of
collection of particles on drops. Venturis operate
at a liquid-to-gas ratio of approximately
0.2-0.9 &/m3 and are capable of achieving efficien-
cies of 90-997o for particles less than 1 vim.
All wet collectors have the disadvantages of requiring some
water treatment for the wet slurry produced, and often for
its removal from the gas stream. They can also require
large amounts of water if the water in the slurry is not
easily recycleable.
The experience with wet collectors as the primary con-
trol device in two mills showed the following difficulties:
1) blocking of the device; 2) corrosion; 3) difficulties in
disposing of slurry products; and 4) overall efficiencies
of 85-95%8. In wet processes used in some asbestos opera-
tions, wet collectors are required, due to the nature of the
operation. Wet processes are not generally used; they
generate production difficulties because of the time required
to dry the product. They also require additional handling
after drying5.
10
-------
ELECTROSTATIC PRECIPITATORS
Electrostatic precipitators are capable of cleaning
a large volume of gas at high flow rates, temperatures, and
humidities, A dry process gas requires either a very large
precipitator, or a large humidity tower before cleaning10 .
The advantages of electrostatic precipitators are7'5'8 :
1) no limits on theoretical efficiency achievable by design;
2) low pressure drop across the collector and, therefore,
low fan power required; 3) exceptional reliability; 4) low
operating cost for total power required of approximately
0.23 kW/100 m3/hr; and 5) simple construction. Their
disadvantages are5: 1) a high installation cost, which in-
creases exponentially with efficiency; 2) the design must
be for a specific dust concentration; and 3) small particles
may create a visible effluent, even though they are 98-99%
efficient on a mass basis.
Electrostatic precipitators are very rarely used for
asbestos processes in the United States; however, they are
more widely used in the United Kingdom. They have very
high theoretical efficiencies, but for these efficiencies to
be achieved, the process must be rigidly controlled with
respect to particle velocity, moisture content, temperature,
and dust concentration8. As asbestos milling produces a
highly variable load, the design must be for a median operar
tion, so that it will not achieve maximum design efficiency
during normal operation5.
BAGHOUSES
Fabric Selection
Baghouses (or fabric filters) are very efficient
(95-99.9%) for smaller gas flows, if the temperature and
humidity are not excessive. The choice of fabric used
depends on: 1) temperatures of gas stream; 2) physical and
11
-------
chemical characteristics of the particles collected; 3) the
chemical composition of the gas; and 4) the moisture content
of the gas11 . A wide range of fabrics are available with
varying characteristics and prices as shown in Table 1. In
many applications, the temperature of the gas stream is the
limiting factor; however, this is not a major problem in
the case of asbestos. The determining fabric characteris-
tics are12 the fiber used, whether it is woven or felted,
its weight, permeability, tensile strength, abrasion resis-
tance, collection efficiency, dimensional stability, whether
or not it is napped, and its static charge. A woven fabric
is suitable for lower air-to-cloth ratios of 0.46 to
1.24:1 m/min (m3/min of air/m2 of cloth, 1.5-4.0:1 cfm/ft2).
With napping and blending, this can be increased to
3.1:1 m/min (10:1 ft/min). Felted cloths are usable at
much higher air-to-cloth ratios of 1.24-3.72 m/min
(4-12:1 ft/min); however, they are more expensive. Not all
fabrics can be felted, and extremely fine particles can become
embedded, making cleaning difficult. The weight of the
2 2
fabric generally ranges from 14-56 g/m (4-16 oz/yd ). The
heavier fabrics have lower thread count of heavy, bulky yarns,
include felted fabrics, and are less flexible. The weaves
used for dust control range from one over one to four over
one, and two or three over two. The higher the sum of the
over and under threads, the higher the weight of the fabric,
the collection efficiency, and the permeability. The permea-
2
bility is measured as cfm of air/ft of fabric at a pressure
drop of 12.7 mm H«0 (0.5 in). The general practice is to
use the most open fabric for the required collection
efficiency. The tensile strength (or fiber tenacity in
g/denier (fiber)) is recommended to be a minimum of
3.52-7.04 kg/cm2 (50-100 lb/in.2), while some fabrics, i.e.,
2
nylon, have tensile strengths greater than 28.1 kg/cm
2
(400 lb/in. ). If all other factors are constant, increased
12
-------
Table 1. FILTER FABRIC PROPERTIES
Fabric
Cotton
Wool
Nylon
Polypropylene
Orion
Acrylic
Polyester
Nomex
Teflon
Fiberglass
Max. Temp.
(°F)
180
190
225
225
260
260
275
450
475
500
(°C)
82.2
87.8
107.2
107.2
126.7
126.7
135.0
232.2
246.1
260
Abrasion
Resistance
Acid Alkali
Resistance j Resistance
i [
G | P , E
G C i P
E
E
G
G
E
E
F
P
F E
E
G
P
G
G
E
F
E
F
F
F
VG
E
G
Tensile
Strength
G
F
E
E
G
F
G
E
G
Moist
Heat
p
'P
G
f^
G
G
G
E
G
E E
Oxidizing
Agents
P
P
F
G
G
G
G
G
E
G
Cost
Most Economical
Economical
Low-Moderate
Moderate
Moderate
Moderate
Moderate
Expensive
Very Expensive
Expensive
E
VG
G
F
P
Excellent
Very Good
Good
Fair
Poor
(Table abstracted from Reference 12)
-------
tensile strength implies increased bag life. The abrasion
resistance of filament fibers is usually greater than the
staple form. The abrasion resistance is one of the critical
factors in determining bag life, as it is decreased by
either yarn failure by surface abrasion or intrayarn abrasion.
The collection efficiency is determined along with the
pressure drop by the filter cake, which builds up on a par-
ticular fabric. Therefore, the fabric must be strong
enough to support the increasing cake, and tight enough to
"heal" quickly after cleaning. Dimensional stability is a
problem, especially with synthetics, which have a tendency
to stretch under high loads, or shrink at high temperature.
Either type of change can change the porosity and permeability,
i.e., make the fabric too loose or too tight. The most
dimensionally stable fabrics are glass fibers and dacron.
Napping of a fabric exposes more surface area for collection,
and thus increases efficiency; however, it makes the fabric
more difficult to clean. Napping is useful in light dust
loads, low pressure drop, and high air-to-cloth ratio.
Static electricity can be a factor in that particles can
charge the fabric under certain conditions. This can
improve efficiency and/or interfere with cleaning; however,
it is generally considered that the detriments outweigh the
advantage12 .
The bag can be arranged in several ways12'13. Flat
bags have the advantage of a high surface area-to-volume
ratio, made possible by bag spacing. Collection is on the
outside of the bag, so that if they are too close, the
dust will bridge between two bags. Cleaning is usually by
mechanical shaking or reverse air. Multiple pocket tube
type bags collect dust on the inside, with the disadvantages
that there are limitations on the average gas velocity at
the seam, and dimensional instability. Single tubular bags
are used for either top or bottom entry for inside collection.
-------
Supported tube type bags are needed for collection on the
outside of the bag. The bags are usually felt, capable of
handling a high air-to-cloth ratio, and are cleaned by some
sort of air pulse.
Cleaning Mechanisms
There are several major types of cleaning mechanisms:
1) mechanical shaking, 2) reverse air, 3) pulse air cleaning,
or 4) sonic cleaning12'13. Mechanical shaking can either be
by hand, which requires that section of the unit to be
off-stream, or continuous or automatic shaking. This method
uses a mechanical device and several preset, usually adjustable,
timers to shut down one section of the baghouse at a time for
cleaning. Reverse air methods are either of the atmospheric
pressure, off-stream variety, which can be combined with
mechanical shaking, or the high pressure type, which need
2
not be off-stream. Pulse air cleaning uses a 4.22-7.04 kg/cm
(60-100 psig) pulse in supported tubular bags to create a
shock wave, which moves the cloth off the supports and dis-
lodges the filter cake. Its major advantage is that, like
high pressure reverse cleaning, it can be done while the
system is on-line. Sonic cleaning uses a low frequency air
power horn or sonic generator operating at 250 cps. This
creates a sympathetic vibration in the bags, which shakes
loose the cake for cleaning by reverse air flow. Sonic
cleaning and other methods, such as bubble cleaning, are
very rarely used in practice.
Design Characteristics
The design of a baghouse5'12'13>llt is decided by the
following characteristics of the dust to be collected and
the gas stream. The type, size, acidity or alkalinity, and
abrasiveness of the dust, along with the moisture and
temperature of the air determine the filter fabric to be
used. The size of the baghouse is determined by: 1) the
15
-------
dust loading, 2) the estimated air flow, 3) the pressure drop
across the fabric, and 4) the gas velocity needed for the
filtering characteristics for the particular dust. Bag
sizing is determined by the type of cleaning method used with
the limitation of a maximum length-to-diameter ratio of 30:1
for a uniform filtration profile from the botton to the top
of the tube, and an acceptable entrance velocity at the inlet.
Maintenance and inspection considerations require compartment
walkways at cell plate and bag suspension level, and that
bag grouping and suspension is suitable for effective
accessibility.
The critical characteristics1*'12 >13 of a baghouse are
air-to-cloth ratio (theoretically the same as the linear
velocity through the cloth, which actually varies with loca-
tion), capacity, and pressure drop. The air-to-cloth ratio
is generally expressed as the total gas flow in cfm
(0.028 m3/min) divided by the square feet (0.9 m ) of cloth.
It generally ranges between 1.5:1 and 4.0:1 for woven fabrics
and ranges between 4.0:1 and 12:1 for felted fabrics for
efficient collection. The capacity is determined by the
amount of dust-laden air to be cleaned. In combination with
the air-to-cloth ratio found to be necessary for the efficient
removal of a specific dust, the capacity determines the total
fabric area needed for the particular application. The
pressure drop across the baghouse determines the fans required
to push, or, as is more common to prevent erosion of fan
blades from particulates, pull the air through the baghouse,
The fan capacity will then require a certain level of power
for operation of the baghouse.
The need for preventive maintenance measures is deter-
mined by consideration of the following15 : 1) pressure drop
measured by manometer, 2) velocity pressure measured by
16
-------
manometer and pilot tube, with the;
Dust Velocity = 4.005 x 10 x /Velocity Pressure
where Dust Velocity is in ft/min (0.3 m/min)
Velocity Pressure is in in. H20 (2.54 cm H20)
3) ammeter readings to measure the current to each fan motor,
which is proportional to the air volume through that section
of the baghouse, 4) the temperature of the gas, which will
endanger the fabric life if it is too high. These measure-
ments should be taken in conjunction with weekly visual
inspections of the bags for leakage or breakages. The
measurements should be compared with previous ones to
determine any trends, such as an increase, decrease, increasing
change, or stabilization. These trends can be interpreted
as to the necessity or effectiveness of various maintenance
procedures.
Advantages and Disadvantages of Baghouses
The advantages of baghouses for general dust cleaning
operations include the following5'13 .
1. They are efficient down to sub-micron sizes.
2. They create a positive barrier to the dust laden
air not dependent on supplementary devices or
materials, changing direction, or electrical
charging.
3. They present no secondary pollution problem.,
as does a wet collector.
4. Baghouses are extremely reliable.
5. Efficiency is fairly uniform over a wide range of
particle sizes.
The disadvantages of baghouses and their operation
are either limitations on their application or maintenance
difficulties produced by poor design. The temperature of the
gas stream must be above dewpoint and less than 93.3° C
17
-------
(200° F) for most natural fabrics, while some synthetic fab-
rics, especially Dupont "Nomex" and fiberglass can be used
at temperatures up to 232.2-260° C (450-500° F). Baghouses
also have the problem of fairly high pressure drops,
depending on the fabric used and the design of the baghouse,
thus necessitating considerable power consumption and operating
expense. High moisture content of the gas is also a
problem, as natural fabrics will rot at high humidities, and
all fabrics tend to plug if the gas stream is very wet.
Location of a broken bag can cause maintenance problems in
some baghouse designs. Large space requirements can also
be a limiting factor in some applications.
Baghouses are the control device most commonly used in
the asbestos industry. They are used so predominantly for
asbestos control because of; "their extreme efficiency for
asbestos and asbestos cement dust"1, "the toxicity of the
dust, and the value of the product"13 . Collected raw
asbestos is generally recycled directly to regrading screens;
however, its resale value is $13.60-16.33/metric ton
($15-18/ton)3. The application of different types of bag-
houses to various phases of the asbestos industry are
shown in Table 2.
Baghouses for asbestos mills are frequently purchased
separately, and installed in the mill building. Therefore,
they have the advantage of being able to recirculate warn,
heated air in the winter, and to cool by the draft created
in the summer. Recirculation of baghouse air can create
an OSHA problem in that plant air can contain no more than
3
2 fibers greater than 5 ym in length per cm . There is a
trend at present toward modular construction of baghouses,
which decreases the cost and time involved in field instal-
lation, but lose the advantages that a custom designed
unit would have1*'12'17
18
-------
Table 2. FABRIC FILTER APPLICATIONS --ASBESTOS MINING AND MANUFACTURING
Application
Asbestos milling
Asbestos ore dryers
Asbestos cement raw
material handling
Asbestos cement
finishing
machines
Textile carding
Type of
Collector
Continuous
Continuous
Continuous
Intermittent
Intermittent
Type of Cloth
Cotton sateen
Orion
Cotton sateen
Cotton sateen
Cotton sateen
Length of Bags
cm ( in . )
427 (168)
427 (1*8)
320 (126)
427 (168)
320-427(126-168)
Diameter of Bags
cm (in.)
12.7 (5)
12.7 (5)
12.7 (5)
12.7 (5)
20.4 (8)
Air: Cloth Ratio
m/min (ft/min)
0.75-0.91 (2.5-3.0)
0.75 (2.5)
0.75 (2.5)
0.62 (2.0)
1.55 (5.0)
Expected Ap
cm H70 (in. H20)
6.35-10.16 (2.5-4.0)
3.82-5.08 (1.5-2.0)
7.62 (3.0)
3.82-5.08 (1.5-2.0)
3.82-5.08 (1.5-2.0)
Data based on several plants of Johns-Manvilie Corporation. Abstracted from Reference 2.
-------
The only disadvantage of baghouses peculiar to asbestos
is that the filter material and weave must be such that it
is least possible for the fibers to interlace and interlock
with the fabric5. The limitations on gas temperature and
moisture content may also present problems in certain situa-
tions; however, they can usually be overcome by the proper
selection of fabric and the design of the baghouse. As an
example, insulated baghouses using Nomex are used on ore
dryers.
An air-to-cloth ratio of 0.62-0.75:1 m/min
(2.0-2.5:1 ft/min) is preferred for asbestos removal; however,
a ratio of 0.91:1 m/min (3.0:1 ft/min) is more generally
used, as it is more economical due to reduced space, blower,
and filter bag requirements *. Other operating characteristics
are determined by the size of the plant, the design of the
particular baghouse, and the filter fabric used.
COSTS OF OPERATING AND INSTALLING CONTROL DEVICES
The economic and technical factors which determine the
selection of a control device for a particular gas cleaning
application are: 1) particle size, 2) pressure drop,
3) wet or dry state of gas and pollutant, 4) efficiency re-
quired, 5) temperature of gas, 6) wet or dry effluent,
7) presence of dewpoint collectors, 8) cyclic variations of
volume, temperature, and concentration, 9) availability of
services, i.e., water, electricity, compressed air, etc.,
10) pre-filtration conditioning requirements, 11) cost of
initial dust and fume containment and effluent discharge sec-
tions of the total installation, 12) corrosive conditions,
13) relative importance of capital and operating costs,
14) consequential costs from plant failure, 15) commodity
values of the effluent, 16) disposal values of the effluent,
17) intermittent of continuous operation, 18) available
supervisory and maintenance staff, 19) site restrictions,
and 20) total gas volumetric flow19 .
20
-------
Graphs and tables of capital and operating costs ver-
sus gas volume for various types of collectors are given in
numerous publications19'20'21'22'23. The rule-of-thumb costs for
typical collectors are given in Table 3. For asbestos opera-
tions in particular, they are given in Table 4. In general,
in the United Kingdom, ventilation aids add 20-37% to the
cost of a new plant, the total dust extraction bill is 7%
of the wages bill, and 2.7% of the total cost of production
of asbestos fiber3. Fabric bags are responsible for 20-40%
of the total equipment cost and the average bag life is
18-36 months, so that an installation operating for 10 years
must be rebagged 3 to 7 times18 . For a baghouse, the
installation-to-purchase cost ratio is typically 1.8 with
an average low of 1.5, high of 2.0, and an extremely high
value of 5.022 .
The maintenance costs of baghouses are dependent on
1. type of bag suspension
2. internal walkways which determine bag accessibility
3. floor plan, i.e., number of rows between walkways,
which determines the reach to the furthest bag
4. external access to upper and lower levels
5. dampers and operators
6. compartment isolation, i.e., whether or not each
compartment's damper has separate controls
7. the type of cleaning mechanism (In this article11* ,
separate reverse air fans and capacities per com-
partment of 0.12 for mechanical shaking, 0.39 for
simple collapse, and 0.62 nr/min of reverse air per
m2 of cloth (0.4, 1.25, and 2.0 cfm/ft2, respec-
tively) in the compartment are recommended.)
8. bag cleaning controls, i.e., whether there are ad-
justable program timers for the frequency and
duration of bag cleaning and dust settling periods,
pressure activated switches, or intermittent
cleaning.
21
-------
Table 3. RULE-OF-THUMB COSTS OF TYPICAL COLLECTORS, STANDARD MILD STEEL CONSTRUCTION
Type of
Collector
Equipment Cost
$/lpm ($/cfm)
Erection Cost
$/lpm ($/cfm)
Yearly Maintenance
and Repair Cost
$/lpm' ($/cfm)
Mechanical
collector
Electrostatic
precipitator
Fabric filter
Wet scrubber
$0.002-0.009 ($0.07-0.25)
$0.009-0.035 ($0.25-1.00)
$0.012-0.044 ($0.35-1.25)
$0.004-0.014 ($0.10-0.40)
$0.001-0.004 ($0.02-0.12)
$0.004-0.018 ($0.12-0.50)
$0.009-0.018 ($0.25-0.50)
$0.014-0.056 ($0.04-0.16)
$0.0002-0.001 ($0.005-0.02)
$0.0004-0.002 ($0.01-0.025)
$0.001 -0.003 ($0.02 -0.08)
$0.001 -0.002 ($0.02 -0.05)
Data abstracted from Reference 18.
-------
Table 4. TYPICAL COSTS FOR THE CANADIAN ASBESTOS INDUSTRY
to
Type
Cyclone
collector
Multiple
cyclone
Wet collector
Bag filter
Electrostatic
precipitator
Typical Emission Rate
kg/hr
(lb/hr)
(IT
135.0 (300)
45.0 (100)
3.2 (7)
0.5 (1)
2.7 (6)
Cost per Process Rate
cost/metric ton/hr
(cost/ton/hr)
$ 33 ($ 30)
$ 66 ($ 60)
$440 ($400)
$880 ($800)
$440 ($400)
(1) Per ton per hour processed
Data abstracted from Reference 8.
Cost per Flow Rate
cost/lpm
(cost/cfm)
$0.003 ($0.09)
$0.006 ($0.18)
$0.042 ($1.20)
$0.085 ($2.40)
$0.035 ($1.00)
-------
9. protection of bags by arrangement, suspension, and
whether or not internal supports are required for
the cleaning mechanism
10. hopper discharge valves
11. materials handling requirements11*
Several examples of dust collection costs in the asbes-
tos industry are cited in the literature. Johns-Manville
Corporation is probably the largest asbestos manufacturer in
the world. It has hundreds of fabric filters in over a
hundred air and dust handling systems at a total cost of
$18 million9. Their largest single unit at Asbestos, Canada
processes 700-800 tons of ore per hour and handles approximate
127,000 m3/min (4.5 x 106 cfm) at a cost of $8 million.
Johns-Manville has stated that total installation costs range
from $70.50-$176.00/m3 ($2.00-5.00/ft3) at room temperature,
though they are higher at higher temperatures2. Another
o
Quebec asbestos mill cost $1.9 million for a 19,800 m /min
(700,000 cfm) installation8. An amosite mill in the United
Kingdom, producing 21,768 metric ton/yr (24,000 ton/yr), has
O
a dust control system handling 2,550 m /min (90,000 cfm)
operating at 99.5% efficiency for particles greater than
5 ym size which cost 27.5% of the total capital cost of the
plant and operates for $195,000/yr3. Examples of other
baghouse applications and their costs in other industries
can also be found in the literature; however, their appli-
cability to asbestos operations is only general, as the
fibrous nature of asbestos creates special cleaning diffi-
culties because of the ultra small particle size and the
need for extremely high efficiencies.
SUMMARY
Baghouses are the most common control device in the
asbestos industry. They are used both with and without
cyclones as pre-cleaners. Baghouses are extremely efficient
24
-------
for the control of asbestos dust, achieving efficiencies over
99%, and have the additional advantage of recycling valuable
material. An air-to-cloth ratio of 0.62-0.75:1 m/min
(2.0-2.5:1 ft/min) is preferred, but a 0.91:1 m/min
(3.0:1 ft/min) ratio is more common in the asbestos industry
because of the saving in equipment costs. Baghouses may
either be installed within the mill building with the advan-
tage of recirculating heated air in the winter and cooling
in the summer, or of separate construction. Temperature
restrictions are not critical in most applications, so
the fabric used is generally decided by the type of cleaning
mechanism and the cost related to the bag life. Bag shape
is also generally determined by baghouse design and cleaning
mechanism.
The costs of a baghouse installation in the asbestos
industry are widely variant, depending on the size type of
plant, baghouse capacity, type of cleaning mechanism, and
filter bag used. Johns-Manvilie, the largest asbestos manu-
facturer in the United States, suggests a cost of
o 3
$70.50-$176.00/m ($2.00-5.00/ft ) at room temperature. Other
sources suggest capital costs of $0.02-0.06/lpm ($0.60-1.75/cfm)18,
and $0.08/lpm ($2.40/cfm)8. Annual operating costs are
estimated as $0.07-0.28/lpm ($0.02-0.08/cfm) for maintenance
and repair18 . Annual operating costs for blower operation
are highly dependent on fan efficiency and local power costs.
25
-------
SECTION 5
COMPILATION OF CONTROL EQUIPMENT USER'S DATA
INTRODUCTION
'Based on our user's inquiries, baghouses are the
predominate method of controlling asbestos emissions.
Typically, these baghouses use cotton fabric and automatic
3
shakers. The usual capacity is 140-570 m /min
(5,000-20,000 cfm) with an air-to-cloth ratio of less than
0.91 m3/min/m2 of cloth (3.0:1 cfm/ft2). The time between
bag cleanings is less than 4 hr. Baghouses are relatively
free of operating problems. Normal installation costs ranged
from $0.088-0.106 per 1pm ($2.50-3.00/cfm) with operating
costs ranging from $0.0018 to $0.035 per 1pm per year
($0.05-1.00/cfm/yr).
SIZE AND PRODUCTS OF THE PLANTS
The listing of asbestos users from all available
sources totaled 249 locations. Of these, 56 could not be
contacted, 36 refused or were unable to give any information,
31 no longer use asbestos, 35 use asbestos, but have no dust
collectors, 12 did not reply to written inquiries, and
79 plants gave some information about their operations and
dust collection. The companies or locations which use
asbestos but have no control equipment were either involved
in manufacturing finished products from pre-processed as-
bestos of some form (88.6%), or in the sale of asbestos or
processed asbestos (11.470). The companies which no longer
26
-------
use asbestos had generally used very little asbestos
previously and had found substitute materials due to regula-
tory pressures on the use or control of asbestos.
The plants which did give information did not always
reply to all the questions or did not have the information
that was requested. Therefore, the total number of plants
reported for any given inquiry may differ by a large degree
from the total number which gave some information on all
inquiries.
The products manufactured by the 79 respondents are
listed in Table 5. The largest number of plants manufactured
either friction materials (19.0%), textiles (14.4%), floor
tile (12.2%), or roof shingles (10.6%).
The size of the respondent companies, both by total
employees and those in handling asbestos are shown in Table 6.
On a total employee basis, 54.1% have 200 or less, while on
a basis of employees handling asbestos, 65.5% have 100 or
less.
The types and amounts of asbestos consumed are listed
in Table 7. Chrysotile is used by 81.3% of the plants
responding to this question; 50% use 907 metric tons/year
(1,000 tons/yr) or less, and 31.3% use more than 4,535 metric
tons/yr (5,000 tons/yr) of chrysotile.
TYPES OF CONTROL DEVICES USED
The number of plants using any type of control device
and the total number of each device being used are presented
in Table 8. Baghouses are used in the overwhelming majority
of plants (80.07o), and also are the most popular in number
of devices used (90.1%). Wet scrubbers are the second
commonest used by plants and third by number; however, these
devices comprise only 6.8% and 2.1%. of these groups, respec-
tively. It was also found that the scrubbers used are wet
27
-------
Table 5. PRODUCT MANUFACTURED
Asbestos-Containing Product
Friction materials
Textiles
Floor tile
Roofing shingles
Cement pipe
Gaskets
Paper
Wall board, siding, and/or plaster
Insulation
Raw asbestos
Asbestos cement
Paint, asphalt
Liquid filter medium
Industrial rubber
Steel mills and foundary
additives and insulation
Chemical corrosive
resistant materials
Total Number of Plants
No. of Plants
Manufacturing
Product
17
13
11
10
7
7
7
6
3
2
2
1
1
1
1
1
90
Percent
19.0
14.4
12.2
10.6
7.8
7.8
7.8
6.7
3.3
2.2
2.2
1.1
1.1
1.1
1.1
1.1
100.0
28
-------
Table 6. SIZE OF ASBESTOS MANUFACTURING PLANTS
Size Category
No. of Employees
<100
101- 200
201- 300
301- 400
401- 500
501- 800
801-1,000
1,000-1,500
1,501-2,500
Total
Plants with Total Employment
in Indicated Size Category
No. of Plants
14
19
11
4
3
4
2
1
3
61
7o of Plants
22.9
31.2
18.0
6.6
4.9
6.6
3.3
1.6
4.9
100.0
Plants with the Indicated Number
of Asbestos Process Employees
No. of1 Plants
36
12
4
1
1
1
55
r 70 of Plants
65.5
21.8
7.3
1.8
1.8
1.8
100.0
to
VO
-------
Table 7. TYPES OF ASBESTOS PROCESSED IN PLANTS
Type of
Asbestos
Chrysotile
Amosite
Crocodolite
Processed (2)
Total
Plants
Usi
No.
52
2
2
8'
64
ng Type
Percent
81.3
3.1
3.1
12.5
100.0
Amount of Asbestos Used(l)
<. 91
£. 100
1
(6.2)
___
«__
92-453
101-500
4
(25.0)
1
(100.0)
454- 907
501-1,000
3
(18.0)
1
(100.0)
•MM
908-1,361
1,001-1,500
1
(6.2)
____
-T_t_ -
1,362-4,513
1,501-5,000
2
(12.5)
^.^__
> 4,513
> 5,000
5
(31.3)
metric tons/yr
tons/yr
u>
o
(1) For those 18 plants which, reported Quantity Consumed
(2) Processed asbestos includes those industries which do not use raw asbestos, but rather
some pre-processed form, such as insulation, cement, or cement pipe for fabrication
of end products.
-------
Table 8. DUST CONTROL DEVICES
Control Device
Baghouse
Scrubber
Cyclone-baghouse
combination
Cyclone
Filter systems
Scrubber-baghouse
combination
Total
Plants
Using Device
Mo.
72
6
4
4
3
1
90
Percent
80.0
6.8
4.4
4.4
3.3
1.1
100.0
Total
Devices Used
No.
335
8
12
7
6
4
372
Percent
90.1
2.1
3.2
1.9
1.6
1.1
100.0
31
-------
centrifugal scrubbers designed and utilized for the control
of wet processes in plants which also have baghouses for the
control of dry processes. This type of wet centrifugal
scrubber has an efficiency of 98% plus and is EPA approved
for wet processes.
Cyclone and cyclone-baghouse combinations are the
third and fourth most common control systems. Both are
used by 4.47o of the plants; however, the cyclone-baghouse
combination comprises 3.2% of the total control devices,
while cyclones alone comprise only 1.9%. Cyclones as
the sole method of dust control in asbestos applications
are rapidly declining in number. They are being replaced
by baghouses, because their collection efficiencies cannot
meet EPA regulations. Cyclone-baghouse or scrubber-baghouse
combinations have the advantage of increased filter bag
life, as the gas stream is precleaned of the larger, abrasive
particles before it reaches the bags.
Central vacuum filter systems are generally used in
fabricating operations on asbestos products such as brake
linings, asbestos cement pipe, or asbestos insulation. In
design, these systems are often similar to a small-scale
baghouse.
WASTE DISPOSAL AND EFFICIENCY TESTING
The methods of waste disposal and their relative usages
are given in Table 9. The most prevalent methods of waste
disposal are reuse (39.2%) and dumping (37.0%,). Reuse is
most common in those industries which use raw asbestos as
the raw material and use separate dust collection systems
for it, e.g., cement pipe and insulation manufacturing.
Of the plants which responded to whether or not
they had conducted efficiency tests, 62.8% replied positively,
i.e., that some kind of testing, including OSHA testing, had
32
-------
Table 9. METHOD OF WASTE DISPOSAL
Method
Reuse
Dump
Landfill
Sell
Store
Wet slurry*
Total
No. of Plants
Using Method
38
36
13
5
3
2
97
Percent
of Total
39.2
37.0
13.4
5.2
3.1
2.1
100.0
* Form of Waste Ultimate Disposal
not specified.
33
-------
been done, while 37.270 replied negatively. However, of those
37.27,, 7.77° of the total stated that they accepted the
manufacturer's values. Very few (19) companies were willing
and able to give numerical values for efficiency. Of those
reporting, 73.7?0 had mass collection efficiencies greater
than 99.0%.
DETAILS OF BAGHOUSE USE
As baghouses are the predominant means of asbestos con-
trol, a more detailed inquiry was made as to the sizes and
characteristics of those used. The major manufacturers of
baghouses used in the asbestos industry are Wheelabrator-Frye
the Pangborn Division of Carborundum Corporation, and
W.W. Sly. Their products are used in 21.3, 13.9, and 10.67=
of the plants reporting, and amount to 27.2, 13.8, and
14.27o of the total number of baghouses reported, respectively
The complete listing of manufacturers is presented in
Table 10.
The gas flow capacities of both the plants and the
baghouses can be found in Table 11. Of the plants replying,
61.9% had total flows of 2,830 m3/min (100,000 cfm) or
greater; however, 87.670 of the baghouses in the plants are
577 m3/min (20,000 cfm) or less and 98.57o of the plants
have baghouses within this range. The air-to-cloth ratios
3
in m /min of gas flow:square meter of cloth area (cfm of
gas:ft of cloth) of 0.75:1 (2.5:1) or less and from
0.75:1 to 0.91:1 (2.5-3.0:1) are used by 28.670 of the plants.
While 40.07o of the baghouses have ratios of 0.75:1 (2.5:1)
or less, 20.97o have 0.75-0.91:1 (2.5-3.0:1) and 30.970 have
1.24-3.10:1 (4.0-10.0:1). Generally, the ratios of
0.91:1 (3.0:1) or less are on mechanically shaken units,
while those with ratios of 1.24:1 (4.0:1) or greater are on
reverse jet units. The air-to-cloth ratios used are given
in Table 12.
34
-------
Table 10. BAGHOUSE MANUFACTURERS
Manufacturer
Wheelabrator-Frye
Pangborn Div. , Carborundum
Corp.
W.W. Sly
Industrial Clean Air (Rees
Blowpipe)
MikroPul
Torit
Flex Kleen, Sub. Research
Cottrell
American Air Filter
Home /Custom Made
J.A. Kleissler
Dravo
Amerjet
Parsons
Air Purification Methods
Due on
Johnson-March Corp,
Western Precipitation, Sub.
Joy Mfg.
Cincinnati
Mine Safety Appliance
Buffalo Forge
Northern Blower
Tenner & Hans
Aget
Trybourns
Walch
Dynavane
Farr
Wm. J. Schmitt
Porter
Kurt & Bloom Mfg. Co.
Hoffman Air & Filtration
Ruemelin
Carter Day Div. , Hart -Carter
Co.
Lorbrow
John Wood
Tek Air
Wiedenmann
Tongeren
Fuller
Total
Plants Using
Product
No.
26
17
13
9
6
4
3
3
3
3
3
3
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
124
Percent
21.2
13.9
10.6
7.4
4.9
3.3
2.3
2.3
2.3
2.3
2.3
2.3
1.6
1.6
1.6
1.6
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
99.9
Baghouses
in Operation
No.
95
48
50
17
17
12
10
8
6
6
5
5
8
4
4
3
5
5
4
4
4
5
3
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
349
^Percent
27.2
13.8
14.2
4.9
4.9
3.4
2.9
2.3
1.7
1.7
1.4
1.4
2.3
1.1
1.1
0.9
1.4
1.4
1.1
1.1
1.1
1.4
0.9
0.6
0.6
0.6
0.6
0.6
. 0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
99.9
35
-------
Table 11. CAPACITY OF DUST COLLECTION SYSTEM
Capacity
m /min
< 142
-T-
143- 283
284- 566
567- 849
850-1,416
1,417-2,832
2,833-5,663
> 5,663
cfm
< 5,000
5,001-
10,001-
20,001-
30,001-
10,000
20,000
30,000
50,000
50,001-100,000
100,001-200,000
>200,000
Total
Plants Having
Stated Total
Capacity
No.
1
1
4
2
8
5
21
Percent
4.8
4.8
19.0
9.5
38.2
23.7
100.0
Baghouses in
Plants Having
Stated Total
Capacity
No.
19
27
31
4
2
4
1
88
Percent
21.6
30.7
35.3
4.5
2.3
4.5
1.1
100.0
Plants Having
Baghouses Within
Stated Range
of Capacity
No.
5
9
8
3
1
1
1
28
Percent
17.8
32.2
28.5
10.7
3.6
3.6
3.6
100.0
-------
Table 12. AIR-TO-CLOTH RATIO
Air-to-Cloth Ratio
m/min
<. 0,62:1
0.63-0.75:1
0.76-0.91:1
0.92-1.24:1
1.25-3.10:1
ft/min
< 2.0:1
2.1- 2.5:1
2.6- 3.0:1
3.1- 4.0:1
4.1-10.0:1
Total
Plants Having
Ratio
No.
3
3
6
2
7
21
Percent
14,3
14.3
28.6
9.5
33.3
100.0
Baghouses
Having Ratio
Kfd.
22
22
23
9
34
110
Percent
20.0
20.0
20.9
8.2
30.9
100.0
37
-------
The fabric used (see Table 13) in the majority (72.2%)
of baghouses in the asbestos industry is cotton. The auto-
matic shaker type of cleaning mechanism is used by 59-0% of
the plants and in 63.3% of the baghouses. The other less
popular cleaning mechanisms used are listed in Table 14.
The cleaning cycle used (see Table 15) is less than 15 min.,
from % to 1% hr, and from 1% to 4 hr in 25.0, 29.5, and
25% of the plants and 19.8, 31.2, and 30.2% of the baghouses,
respectively. The pressure drop across the baghouses is
7.6 cm (3 in.) of water or less in 50% of the plants and
57.8% of the baghouses. The breakdown of pressure drop
is given in Table 16.
Seventy-two plants responded to the question on baghouse
operating problems, and 63 said they had none. Shaker
mechanisms and breaking bags were the major problem, each
being reported by 4.2%, of the plants responding. Overloading,
freezing bags, and steam were each reported by one plant
(1.4%).
COST OF EQUIPMENT
The cost of installing or operating a baghouse is
difficult to ascertain, as most companies do not give out
such information or do not have it readily available.
Manufacturers usually bid on a contract to supply control
equipment. They claim that each unit is different with
few standard parts. Therefore, they fabricate individual
units to suit the particular plant. This explains to some
extent their reluctance to quote a figure. In general, from
user's data, the cost of purchasing a baghouse is in the range
of 7c-10.5
-------
Table 13. BAG FABRIC
10
Fabric
Cotton
Dacron
Polyester
Canvas
Wool
Nylon
Orion
Polyprolene
felt
Polyphrone
felt
Burlap
Total
Plant
Using Fabric
No.
36
8
5
2
2
1
1
1
1
1
58
Percent
62.3
13.8
8.6
3.4
3.4
1.7
1.7
1.7
1.7
1.7
100.0
Baghouses
Using Fabric
No.
164
31
15
4
2
4
3
3
1
227
Percent
72.2
13.7
6.6
1.8
0.9
1.8
1.3
1.3
0.4
100.0
Bag Cleaning Mechanism Used With
Type of Fabric, No. (%) of Baghouses
Hand
Shaker
27
(16.4)
Automatic
Shaker
125
(76.8)
23
(74.2)
_ __
4
(100.0)
2
(100.0)
4
(100.0)
3
(100.0)
__ —
Reverse
Jet
10
(6.7)
3
(9.7)
5
(33.3)
• ~ _
___
•_• —
_-._
1
(100.0)
Pulse
Jet
2
(1.2)
5
(16.1)
10
(66.7)
_ _ _
___
_ __
3
(100.0)
-------
Table 14. BAG CLEANING MECHANISM
Cleaning
Mechanism
Automatic shaker
Pulse jet
Reverse jet
Hand shaker
Total
Plants Using
Mechanism
No.
39
10
9
8
66
Percent
59.0
15.2
13.6
12.2
100.0
Baghouses Using
Mechanism
No.
160
28
33
32
253
Percent
63.3
11.0
13.1
12.6
100.0
40
-------
Table 15. BAG CLEANING CYCLE
Cleaning Cycle
At <_ 5 min
5 min < At £ 15 min
15 min < At <_ 45 min
45 min < At <_ 1 hr
1 hr < At 5 1% hr
1% hr < At <_ 4 hr
4 hr < At 5 1 day
Intermit tent
Total
Plants
Using Cycle
No.
3
3
2
3
2
6
3
2
24
Percent
12.50
12.50
8.25
12.50
8.25
25.00
12.50
8.25
100.00
Baghouses
Using Cycle
No.
10
9
8
12
10
29
16
2
96
Percent
10.4
9.4
8.3
12.5
10.4
30.2
16.7
2.1
100.0
Bag Cleaning Mechanism Used
No. (%)
kand
Shaker
8
(80.0)
--
--
--
--
--
12
(75.0)
2
(100.0)
Automatic
Shaker
2
(20.0)
2
(22.2)
6
(75.0)
12
(100.0)
10
(100.0)
29
(100.0)
4
(25.0)
—
Reverse
Jet
— — —
Pulse
Jet
7
(77.8)
2
(25.0)
— —
At = time between cleaning cycles
-------
Table 16. PRESSURE DROP ACROSS BAGS
Pressure Drop
cm (in.) H20
Ap <_ 2.
2.54 (1) < Ap £ 5.
5.08 (2) < Ap £ 7.
54 (1)
08 (2)
62 (3)
7.62 (3) < Ap £ 10.2 (4)
Total
Plants
Having Ap
No.
2
3
5
10
20
Percent
10.0
15.0
25.0
50.0
100.0
Baghouses
With Ap
No.
2
40
17
43
102
Percent
2.0
39.2
16.6
42.2
100.0
Bag Cleaning Mechanism Used
No. (%)
Hand
Shaker
—
7
(17.5)
—
7
(16.3)
Automatic
Shaker
2
(100.0)
16
(40.0)
11
(64.7)
26
(60.4)
Reverse
Jet
10
(25.0)
4
(23.5)
4
(9.3)
Pulse
Jet
7
(17.5)
2
(11.8)
6
(14.0)
-------
SECTION 6
EMISSION DATA COLLECTION AND ANALYSIS
INTRODUCTION
Emissions data was collected from baghouses at five
locations. They were chosen because of the nature of the
asbestos processing undertaken. They include: two asbestos
refining mills dealing with natural asbestos, two asbestos
cement product plants where the asbestos was bound into the
product, and an asbestos textile plant where the product
is loosely bound. In all of the locations, chrysotile
asbestos was used exclusively.
Membrane filter samples were taken both upstream and
downstream of the baghouse. Two types of samples were taken.
Samples were taken over a four hour period to obtain .mass
efficiency data. To obtain size efficiency data, samples were
taken for short time periods of approximately 5 minutes on
the inlet side, and 30 minutes on the outlet side. These
filter samples were then examined by optical and electron
microscope, and the number and size distribution of the
fibers was noted.
The purpose of the emission testing was to provide
preliminary factual data on the extent of the emissions from
baghouses. It was to provide a quick answer on the question
of whether a study on improving the efficiency of baghouses
was warranted, and to provide base data from which the
ambient air exposure levels in the vicinity of the plant
could be calculated.
43
-------
GENERAL SAMPLING PROCEDURES
The sampling scheme used for this study followed the
EPA method as detailed in the Federal Register 3£-247. The
general outline is given here, specific details of the
procedures at each site will be given separately in the
follwoing text.
Sampling points in the ductwork were selected in re-
gions where the most stable flow patterns existed. The ports
were located, where possible, eight to ten diameters down-
stream and three to five diameters upstream from any bends,
elbows, junctions, or other constrictions in the stack
or duct .
The velocity profile in the stack or duct was measured
by means of an S-type pitot tube. The pitot tube was tra-
versed across the stack or duct, the gas velocity was deter-
mined at the center of each equal area zone. The average
velocity was then determined by averaging the velocities
in all of the zones from:
(V )
_
v_ =
s N
where V = Average velocity
S
V. = Velocity at one point
N = Number of points
Two standard EPA Method 5 isokinetic sampling systems
(as shown in Figure 1) were used to collect the air samples
from the upstream and downstream ductworks of the baghouse.
The sampling probes and nozzles were fabricated from stain-
less steel. The probes were 1.27 cm (0.5 in.) I.D. and 107 cm
(42 in.) long, and the nozzles were 0.63 cm (0.25 in.) I.D.
44
-------
Filter Holder
Probe
Reverse - Type
Pitot Tube
Figure 1. Sampling arrangement
A5
-------
On the upstream side of the baghouse, samples were
drawn through a cyclone followed by a 10.2 cm (4 in.) mem-
brane filter (Millipore) of 0.8 ym pore size. On the down-
stream side, no cyclone was used; the air stream was lead
directly to the membrane filter. After sampling, the
filters were placed into marked plastic folders. Material
adhering to the inside of the probe and tube was washed into
the cyclone sample collector using acetone. The collector
was then marked and sealed.
In some instances, it was not possible to collect
samples by the isokinetic stack sampling method. This was
because there was no suitable length of ducting or stack
from which valid samples could be collected. Here, a high
volume sampler was used with a 20.3 x 25.4 cm (8 x 10 in.)
membrane filter. Some error would be introduced by using
this method. However, because of the small size of the par-
ticles passing through the baghouse, the error would be
small. When this method was used, the sampler was located
inside the baghouse, close to the exiting point.
SPECIFIC SITE INFORMATION
Johns-Manvilie, Asbestos Cement Pipe Plant, Waukegan, Illinois
Plant Details -
Dust Source: Lathes for cutting and trimming asbestos
cement pipes containing asbestos, cement,
and sand.
Baghouse: Parsons unit, installed December, 1972
Four compartments
200 bags per compartment, total 800 bags
Capacity: 283 nH/min (10,000 cfm) per compartment
1,132 m3/min (40,000 cfm) total
Operating temperature: 20.5 C (69 F)
Pressure drop: 15.2 cm (6 in.) H20
Air-to-cloth ratio; 2:1
46
-------
Bags : Cotton sateen
12.7 cm (5 in.) diameter
3.05 in. (10 ft) length ~ «
Total area per bag: 1.22 m (13.1 ft )
Permeability: 4.57 + 1.52 m/min at 1.27 cm HoO
(15 +~5 cfm/min at 0.5 in. H-OJ
Bag life: 2-3 years'
Baghouse Cleaning: Mechanical shake
Each compartment is shaken for
2 minutes every 30 minutes
A compartment is shut off while
shaken; there are always 3 com-
partments on stream.
Collected waste is taken to dump.
Baghouse Effluent: vented to the exterior through a
short stack about 3 m (10 ft)
tall and a total of 10 m (30 ft)
above the ground
Procedure -
Upstream samples were collected from a 86 cm (34 in.)
circular duct approximately 5.5 m (18 ft) from the floor.
A Platform was erected to reach the duct at a point more than
eight diameters from any obstruction or bend in the ductwork.
•^0 sampling ports, one entering the duct vertically, the
°ther horizontally, were cut into the duct; each was
aPproximately 5 by 7 cm (2 by 3 in.).
Linear gas velocities in the duct were measured using
^ S-type pitot tube. The duct was traversed both vertically
atld horizontally. The pressure drop across the- manometer
and the stack temperature were measured at distances of 10,
25, 41, 56, 71, and 87 cm (4, 10, 16, 22, 28, and 34 in.)
inside the duct. The average duct velocity calculated from
the vertical traverse was found to be 1,021 m/min
(3,354 fpm) and from the horizontal traverse 1,032 m/min
(3,386 fpm).
Dust samples were collected isokinetically on Millipore
Membrane filters of 0.8 ym pore size. To obtain fiber size
47
-------
distribution data, samples were collected with particle
loadings such that the determination could be made by direct
observation of the filter by either optical or electron
microscopy. The time required to obtain ideal loading, that
is, with the particles on the filter evenly distributed
without touching, was not known. For this reason, samples
were collected for times of 0.25, 15, and 30 minutes. The
samples were removed isokinetically from a single sampling
point 76 cm (30 in.) vertically inside the duct. At this
point, the linear velocity was almost identical to the
average velocity. Samples for mass efficiency measurement
were collected at each of the traverse points for a period
of 5 minutes. The entire sampling sequence was distributed
over a 3% hour time period.
Downstream samples were collected from a 81 by 107 cm
(32 by 42 in.) rectangular stack. A platform was constructed
inside the building about 8 m (25 ft) from the floor and 1.7 m
(5 ft) from the roof. Three equally spaced sampling ports
were cut into the 81 cm (32 in.) face of the duct at a dis-
tance of 2.5 m (8 ft) from the baghouse fan, which was located
in the stack between the baghouse and the louvred exit on the
roof. This sampling point was unsatisfactory because of its
close proximity to the fan, but it was the only practical
point to erect a platform within the constraints of the plant
layout.
Linear gas velocities were measured by traversing the
duct through each of the ports at depths of 10, 25, 41, 56,
71, 87, and 102 cm (4, 10, 16, 22, 28, 34, and 40 in.).
The three ports gave average velocities of 1,083 m/min
(3,555 fpm) , 1,113 m/min (3,654 fpm) and 1,175 m/min (3,856 fpm),
respectively.
48
-------
Samples for microscopic examination of the fiber size dis-
tribution were taken from the central port at a depth of 33 cm
(3-3 in.). The samples were collected for time periods of
5> 15, and 30 minutes.
To obtain mass efficiency data, samples were collected
from each port at each traverse point for a period of
10 minutes. The upstream and downstream sampling was
Performed within the same 3% hour total sampling time
Period.
E^ybestos. Asbestos Textile Plant. Marshville, North Carolina
Slant Details -
Dust Source: Carding machine which combs raw asbestos
fiber into a roughly parallel array prior
to spinning.
Baghouse; Wheelabrator model 112, installed in 1953
Single compartment, 304 bags
Capacity: 473 m3/min (16,700 cfm)
Operating temperature: 26.7° C (80° F)
Pressure drop: 5.59 cm (2.2 in.) 1^0
Air-to-cloth ratio: 3:1
Bags: Cotton sateen
20.3 cm (8 in.) diameter
2.82 m (9.25 ft) length 2 2
Total area per bag: 1.80 nT (19.4 ft )
Permeability: 4.57 + 1.52 m/min at 1.27 cm H£0
(15.0 + 5.0 cfm/min at 0.5 in. H20)
Bag life: 5 years
Baghouse Cleaning; Mechanical shake
At the finish of each shift, the
cake from the bags is shaken into
an empty hopper - this material
is put in polythene bags and
dumped at a city site.
Three times during each shift the
material collecting in the bag-
house hopper (without shaking)
is collected and recycled.
49
-------
Baghouse Effluent: Effluent is either recirculated to
conserve heat, or vented to the
outside air, depending on ambient
temperature conditions. A very
short (1 m) stack is used to vent
the effluent to the outside air.
Sampling Procedures -
Upstream samples were collected from a 76 cm (30 in.)
diameter duct. The only convenient sampling point was about
3 duct diameters from the baghouse and 5 duct diameters from
a bend. Because of the very thick duct walls and the
inaccessibility of the duct, only one sampling port, which
allowed a horizontal traverse to be made, was used. Linear
gas velocities were measured at distances into the duct of:
2.5, 5.1, 7.6, 11.0, 15.0, 20.0, 29.0, 48.0, 56.0, 61.0,
69, 71, and 74 cm (1, 2, 3, 4,4, 6, 8, 11, 19, 22, 24, 25,
27, 28, and 29 in.). The average gas velocity was found to
be 956 m/min (2,915 fpm).
Dust samples were collected isokinetically on Millipore
membrane filters of 0.8 ym pore size. Samples for the deter-
mination of fiber size distribution were taken from a point
30.5 cm (12 in.) into the duct. Three sampling periods of
0.25, 1, and 5 minutes were utilized to obtain three filters
with different loading levels. The filter with the most
even loading was to be used for the fiber count. To deter-
mine the mass loading, samples were removed isokinetically
for five minutes at each traverse point. Two traverses
were made over a total time period of about 6 hours.
Downstream samples were taken from a 99 by 46 cm
(39 by 18 in.) rectangular duct. A sampling port was cut into
the 46 cm face of the duct well clear of any obstruction or
bend. Only one port was cut because of the thick walls of
the duct, which made it a difficult task. Linear gas
velocities were measured at distances into the duct of 7.6,
50
-------
T-5, 23, 30, 38, 46, 53, 61, 69, 76, 84, and 91 cm (3, 6, 9,
12, 15, 18, 21, 24, 27, 30, 33, 36, and 39 in.). The
average velocity was found to be 676 m/min (2,062 f pm) .
Dust samples were collected isokinetically from the
duct on 0.8 ym pore size Millipore membrane filters. Sam-
Pies for fiber size distribution determination were collected
at a point 61 cm (24 in.) into the duct for time periods of
5> 15, and 30 minutes. Samples for mass loading determination
collected by traversing the duct and collecting a sample
10 minutes at each traverse point. The entire sampling
Sequence was spread over a 6 hour time period. Both
uPstream and downstream samples were collected over the
same 6 hour time period.
Johns -Manvi lie, Asbestos Cement Pipe Plant, Denison. Texas
Details -
Dust Source: Lathes for cutting and trimming asbestos
cement pipes containing asbestos, cement,
and sand.
Baghouse: Wheelabrator Model 2b
Single compartment, 640 bags
Capacity: 736 m3/min (26,000 cfm)
Operating temperature: 20.5° C (69° F)
Pressure drop: 14.5 cm (5.7 in.) H90
Air-to-cloth ratio: 3:1 z
Bags ; Cotton sateen
12.7 cm (5 in.) diameter
3.18 m (10.4 ft) long 2 9
Total area per bag: 1.27 m (13.6 ft )
Permeability: 4.57 + 1.52 m/min at 1.27 cm H90
(15.0 + 5.0 cfm/min at 0.5 in/H^O)
Bag life: 1 year
Baghouse Cleaning: Mechanical shake, manually started
at shift breaks and changes.
Waste is taken to plant dump.
51
-------
Sampling Procedure -
Upstream samples were collected from a 80 cm (32 in.)
diameter duct. A sampling location greater than eight
diameters from any bend or flow disturbance was selected.
A platform approximately 5 m (15 ft) high was erected to
reach the two sampling ports which were cut into the duct
to allow both vertical and horizontal duct traverses.
Linear gas velocities were measured at distances into the
duct of 1.7, 5.3, 9.7, 14.5, 20, 29, 43, 53, 67, 72, 76,
and 80 cm (0.67, 2.1, 3.8, 5.7, 8.0, 11.4, 16.9, 20.8, 26.3,
28.2, 29.9, and 31.3 in.) in both a vertical and horizontal
direction. The average gas velocities were found to be
1,510 m/min (4,605 fpm) from the vertical traverse and
1,539 m/min (4,694 fpm) from the horizontal traverse.
Dust samples were collected isokinetically on Millipore
membrane filters of 0.8 ym pore size. Samples for the
determination of fiber size distribution were taken from
a point 46 cm (18 in.) inside the duct vertically from the
lower port. Samples were collected for 0.5, 1, and 5 minutes
to obtain samples with different loading levels. To obtain
information for the determination of the mass loading,
samples were taken at each traverse point in both the verti-
cal and horizontal ducts for a period of 5 minutes. Samples
were collected over a total time period of 5 hr 7 min.
Downstream samples were collected using a high volume
sampler with an 0.8 ym pore size Millipore membrane filter,
located within the baghouse close to the exit. The sampler
was mounted on clamps such that the membrane face was
presented face-on to the direction of the air flow. A high
volume sampler was used because the very short stack between
the fan and the louvred roof exhaust exit (about 1 m)
presented no acceptable sampling point. Samples were collect6
for fiber size distribution determination for periods of
52
-------
5, 15, and 30 minutes to obtain samples with different
loading levels. Samples for mass loading determination were
collected for 5 hr 7 min. Both the upstream and downstream
samples were collected over the same 5 hr 7 min time period.
Johns-Manville, Asbestos Ore Mill. Asbestos. Canada
Plant Details -
Dust Source; Fiber screening and air aspiration system.
Baghouse: Wheelabrator, special design
One compartment, 79,200 bags
Capacity: 127,000 m3/min (4,500,000 cfm)
Operating temperature? 21.1° C (70° F)
Pressure drop: 7.62 cm (3 in.) 1^0
Air-to-cloth ratio: 3:1
Bags; Cotton sateen
12,7 cm (5.in.) diameter
4.27 m (14 ft) length 2 2
Total area per bag: 1.70 m (18.3 ft )
Permeability: 7.62 m/min at 1.27 cm H20
(25 cfm/min at 0.5 in. H20)
Bag life: 6-10 years
Baghouse Cleaning; Mechanical shake
2 minute shake cycle every 30 minutes
Bags are shaken in groups of 7,200 bags
Collected dust is recycled
Cyclone: Cyclone is used as a pre-cleaner
Unit is 2.44 m (8 ft) in diameter
Capacity: 424 m^/min (15,000 cfm)
Inlet velocity: 1,219 m/min (4,000 fpm)
Exit velocity: 914 m/min (3,000 fpm)
Claimed mass efficiency is 98.5% for 30-500 ym
dust at 251 m3/min (9,100 cfm)
Baghouse Effluent; recirculated to plant for most of
the year, vented outside during warm
weather.
Sampling Procedure -
Upatream samples were collected from a 38 cm (15 in.)
duct leading to the cyclone* It would have been preferable
to sample in the duct separating the cyclone and baghouse,
53
-------
but it was inaccessible and had a very short (less than 1 m)
connecting duct. Two identical ducts lead to the cyclone
from the plant. The ducts brought air from identical opera-
tions in the plant and should have identical dust loadings.
Therefore, only one duct was sampled.
The dust loading within the duct was very high and
quickly blocked the sampling probe and pitot tube. The
average duct velocity was estimated to be about 665 m/min
(2,618 ft/min). Single point samples were taken from a
point 30 cm (12 in.) into the duct. Samples were collected
under isokinetic conditions until signs of blocking
occurred (as observed by sudden fluctuations on the manometer)
Four samples of 1.4, 1.7, 2.8, and 3.5 liters were collected.
Downstream samples were collected on a high volume
sampler located within the baghouse between the sets of bags.
The baghouse forms the complete top floor of the 14 story
building and air is generally recirculated from the baghouse
area to the plant by means of blowers. In exceptionally warm
weather, the air is vented directly out through louvres in
the side of the baghouse. There was no stack.
Samples for fiber size distribution determination were
collected for 5 and 30 minutes to obtain a loading range.
Samples for mass loading determination were collected for
5 hr.
GAF, Asbestos Ore Mill, Eden Mills, Vermont
Plant Details -
Dust Source: Fiber screening and air aspiration system.
Baghouse; Wheelabrator, Model B-607, Series VIII
-8 compartments
336 bags per compartment, 2,688 bags total
Capacity: 8,490 m3/min (300,000 cfm)
Operating temperature: 21.1° C (70° F)
Pressure drop: 10.2 cm (4 in.)
Air-to-cloth ratio: 3.2:1
54
-------
Bags: Cotton sateen
20.3 cm (8 in.) diameter
5.3 m (17.5 ft) length 2 2
Total area per bag: 3.22 m (35 ft )
Permeability: 4.88-6.10 m/min at 1.27 cm HoO
(16-20 cfm/min at 0.5 in. H2&)
Bag life: 5 years
Baghouse Cleaning: Mechanical shake
2 minute shake cycle every 30 minutes ,
one compartment at a time
Dust is recycled.
Baghouse Effluent: Baghouse is not enclosed; therefore,
air always diffuses back into the
plant.
Cyclone; Cyclone is used as a pre-cleaner.
Unit is 3m (9.8 ft) in diameter.
Procedure -
Upstream samples were collected from a 76 cm (30 in.)
duct leading from the cyclone to the baghouse. The duct
Was short (about 3 m overall) and the only accessible section
was about 1 m from the cyclone. Two sampling ports, at
right angles to each other, were cut into the angled duct.
Linear gas velocities were measured at distances into the
duct of 2.5, 5.0, 10, 15, 20, 25, 30, 36, 41, 46, 51, 56,
51, 66, 71, and 76 cm (1, 2, 4, 6, 8, 10, 12, 14, 16, 18,
20, 22, 24, 26, 28, and 30 in.) from both sampling ports.
The average gas velocity was found to be 1,330 m/min
(4,364 fpm).
Dust samples were collected isokinetically on Millipore
filters of 0.8 urn pore size. Samples for the deter -
of fiber size distribution were collected from a
Point 30 cm (12 in.) into the duct for time periods of
^•» 5 and 30 seconds to obtain samples at different loading
Bevels. A sample for the determination of mass loading was
°btained by sampling at each traverse point for 5 minutes over
a total time period of 6 hr.
55
-------
Downstream samples were collected using a high volume
sampler located within the central part of the baghouse. The
baghouse had no stack air being allowed to diffuse into the
plant from the open baghouse.
Samples for the determination of fiber size distribution
were: collected for time periods of 10, 30, and 60 minutes
to obtain samples with differing loading characteristics.
The mass loading was determined by collecting a single sam-
ple for a time period of 6 hr. Both upstream and downstream
samples were collected over the same time period.
SAMPLE ANALYSIS
Introduction
The mass efficiency and the efficiency in terms of fiber
size removal were measured at each of the five sites which
were sampled. The mass efficiency was found by weighing
the quantity of material collected for a given volume of
air, before and after the baghouse. Fractional efficiency
was determined by comparing the size frequency of fibers be-
fore and after the baghouse.
In determining the mass efficiency of the baghouse, it
should be noted that the measured efficiency includes non-
asbestos as well as asbestos material. No attempt was made
to analyze the filters to determine the asbestos content
before and after the filter to see if there is a change in
the composition.
The fiber counts were made with the criteria that all
particles having a greater than 3:1 aspect ratio were
fibers. The assumption was made that all fibrous particles
coming from an asbestos plant were asbestos. Spot checks
on fibers were made, and the selected area diffraction
pattern was found to be characteristic of chrysotile asbestos.
Thus, the assumption was deemed valid.
56
-------
Mass Efficiency
The mass efficiency was found by accurately weighing the
samples collected from before and after the baghouse. The
filters were weighed on electronic balances at a sensitivity
°f + 0.1 mg. On the upstream side, the dust deposited in
the probe, the sampling train, and the cyclone was washed
with water into a weighed sampling bottle. It was then
dried in vacuum oven at 110° C, cooled, and reweighed.
From these weights, the mass efficiency was calculated.
Fiber Counting
Optical microscope analysis was performed using the
Method described in the NIOSH criteria document on asbestos
(HSM 72-10267). A portion of the membrane filter was mounted
°n a slide. Using a 1:1 solution of dimethyl phthalate
and diethyl oxalate, the filter was allowed to clear. A
°lean cover slip was placed on top of the sample and the
fiber concentration determined. The light microscope used
was equipped with phase-contrast and polarized light. The
objective lens of 4mm resulted in a total magnification
°f 500X. From randomly chosen fields, the number of fields
f°r a total count of 100 fibers was noted (with a minimum
°f 20 fields observed), or, 100 fields were observed when
the distribution was sparse.
For the electron microscope analysis, a circle of the
sample filter 3.5 mm in diameter was cut. This piece of
filter was placed on top of a carbon-coated 100 mesh elec-
tron microscope grid. The grid with the filter on it was
Placed in a condensation washer using acetone as a solvent.
The filter medium was dissolved away by the acetone,
Depositing the fibers of the sample undisturbed on the car-
bon substrate of the grid. The specimen was then counted on
a Hitachi HU-11 transmission electron microscope at the
Magnification of 16,364X.
57
-------
The optical microscope analysis enumerated the fibers
greater than 5 ym in length and a minimum diameter of 0.5 ym.
The electron microscope analysis counted fibers down to
0.06 ym in length and 0.020 ym in diameter.
The NIOSH document on asbestos cited the above states
that the fiber counts follow a Poisson distribution. The
standard deviation for a count of 100 fields is /YOU, or
10 fibers or + 10%. To keep the statistical error at the
957o confidence level, approximately two standard deviations
must be considered. The uncertainty in the counts is then
+ 207=.
Calculation of Fiber Numbers
To relate the number of fibers counted to the asbestos
concentration in the air, the following equation was used:
no. of fibers _
3
m
of air
no. of fibers counted
no. of fields
effective filter area,
area of microscope's field of view, cm
2
volume of air sampled, m"
Effective filter area = 81.7 cm^ for 4 in. filter
Effective filter area =63.2 cm2 for 4 in. hi-vol filter
Effective filter area
-1
Area of field of view =
Area of field of view =
426.4 cm for 8 in. x 10 in. hi-vol
filter
/ O
6.514 x 10~ cm for optical micro-
scope (500X)
-7 2
1.344 x 10 cm for electron micro-
scope (16.364X)
58
-------
Efficiency Calculation
To calculate the efficiencies, both by mass and by
number, the following relationships were used:
Hass Efficiency (%) =
100
, mass in a given volume of air after the baghouse
mass in the same volume of air before the baghouse
Number Efficiency (%) =
no. of fibers per cubic meter after the baghouse
100
1 -
no. of fibers per cubic meter berore the baghouse
RESULTS OF THE ASBESTOS SAMPLING STUDIES
The results of the sampling study are summarized in the
following tables. Table 17 gives the details of the samples
and the sampling conditions at each of the five locations.
Ift Table 18, the mass efficiencies at each of the five
kaghouses are given. The total number of fibers, in both
the optical and electron microscope size ranges, for the
uPstream and downstream sides of the baghouses are given in
^able 19. The distribution of the fibers in the optical
Microscope size range (1.5-30.0 ym) is presented in Table 20.
Ir* Table 21, the size distribution of the fibers in the
electron microscope size range (0.06-1.50 ym) is given.
DISCUSSION OF THE RESULTS
The mass efficiency of the baghouses tested was shown
to be extremely high and in all instances was greater than
. A high mass efficiency had been anticipated, and
figures are in agreement with the very limited data
is available in the literature as reported earlier in
text.
The information gained from this study on the number of
asbestos fibers emitted from a baghouse exhibiting a high mass
59
-------
Table 17. SAMPLES AND SAMPLING CONDITIONS
Sampling
Site
Waukegan,
Illinois
Marshville,
North Carolina
Denison,
Texas
Asbestos,
Canada
Eden Hills,
Vermont
Sampling
Location
Upstream
Upstream
Upstream
Downstream
Downstream
Downstream
Upstream
Downstream
Upstream
Upstream
Upstream
Downstream
Downstream
Downstream
Upstream
Downstream
Upstream Hor.
Upstream Vert.
Downstream
Downstream
Downstream
Downstream
Ups tream
Upstream
Ups tream
Upstream
Downstream
Downstream
Downstream
Upstream
Ups tream
Upstream
Upstream
Downstream
Downstream
Downstream
Downstream
Average Linear
Velocity, m/min
1,026
1,026
1,026
1,098
1,098
1,098
1,026
1,098
3,410
3,410
3,410
3,400
3,400
3,400
3,410
3,400
4,560
4,560
665
665
665
665
1,330
1,330
1,330
1,330
i
Sampling Time
4 min 25 sec
1 minute
15 seconds
5 minutes
15 minutes
27 minutes
1 hr (over 3^ hr)
3*5 hours
5 minutes
1 minute
15 seconds
5 minutes
15 minutes
30 minutes
2 hr 10 min f over the 1
4 hr 20 min ^arae 6 hr period]
60 minutes
60 minutes
16 minutes
5 minutes
30 minutes
5 hr 7 min
= 1 sec (1.7 i)
Z 1 sec (3.54 JO
: 1 sec (1.4 fc)
x I sec (2.83 i)
10 minutes
30 minutes
5 hours
1 second
5 seconds
30 seconds
1 hr 10 min
10 minutes
30 minutes
1 hour
6 hours
Volume ,
Sampled (m )
1.75
12.98
•I
2.83 x 10,
5.94 x 10,
4.42 x 10
2.76
6.404
4.18
4.18
4.30
1.40
8.49
195.00
1.7 x 10":?
3.54 x 10~,
1.4 x 10":;
2.83 x 10
0.57
1.70
101.8
4.25 x 10~4
3.08
4.10
11.90
23.80
143.00
Filter Size and
Collection Method
(all filters 0.8 urn
membrane)
,
All 10 cm
diameter.
Isokinetic
All 10 cm
diameter.
Isokinetic
10 cm-Isokinetic
20 cm x 25 cm
Ki-Vol
10 cm-Isokinetic
10 cm~Hi-Vol
10 cm-Isokinetic
10 cm— Hi Vol
Sampling
Purpose
Size
Size
Size
Size
Size
Size
Mass
Mass
Size
Size
Size
Size
Size
Size
Mass
Mass
Size & Mass
Size & Mass
Size
Size
Size
Mass
Size
Size
Size
Mass
Size
Size
Mass
Size
Size
Size
Mass
Size
Size
Size
Mass
Filter
No.
10
9
2
5
7
3
11
12
15
16
17
18
19
20
22
21
23
23
5
7
18
11
27
34
25
28
42
43
41
31
32
33
26
37
38
36
40
-------
Table 18. SAMPLE WEIGHTS AND MASS EFFICIENCY DATA
Plant
Location
Waukegan ,
Illinois
Marshville,
North Carolina
Denison,
Texas
Asbestos,
Quebec
Eden Mills.
Vermont
Sampling
Location
Upstream
Downstream
Upstream
Downstream
Upstream
Downstream
Upstream
Downs treara
Upstream
Downstream
Volume
Sampled
m3 (ft3)
1.755
(62)
12.984
(458.8)
.2,765
(97.7)
6.404
(226.3)
4.163
(147.8)
196.0
(6,907.5)
1.40 (2)
(0.05)
101.80
(3,600.)
3.085
(109)
143
(5,040)
Filter
Code
Number (1)
11
12 .
22
21
23
11 (A)
28
41 (B)
26
40 (B)
Sample
Weight on
Filter, R
0.2270
0.0000
0.0383
0.0002
0.8895
0.0000
0.0003
0.0103
1.6733
0.0084
Sample Weight
in Cyclone
and Probe, g
7.3822
0.0000
1.5511
0.0000
53.0758
0.1645
16.7.487
Total
Sample
Weight, £
7.6092
0.0000
1.5894
0.0002
-
53.9653
0.0000
0 . 1648
0.0103
17.9220
0.0084
Dust
Concentration
R/m
4.336
0.000
0.580
0.000031
12.901
0.000
117.0
0.0001
5.804
0.000059
Mass Removal
Efficiency
7.
100
with
experimental
limits
>99.99
100
with
experimental
limits
>99.99
>99.99
(1) All samples taken except: A) 25 x 20 cm Hi-Vol, B) 10 cm diameter Hi-Vol.
(2) Heavy dust loading prevented sampling for more than a few seconds.
-------
Table 19. TOTAL "FIBER COUNTS AND FIBER REMOVAL EFFICIENCIES
Plant
Location
Waukegan,
Illinois
Marshville,
North Carolina
Denison,
Texas
Asbestos,
Quebec
Eden Mills,
Vermont
Sampling
Location
Upstream
Downstream
Upstream
Downstream
Downstream
Upstream
Downstream
Upstream
Downstream
Upstream
Downstream
Volume of
Air Sampled
00
1.75
13.0
2.83 x 10"3
4.42 x 10"1
5.94 x 10~2
4.18
8.49
1.69 x 10"3
1.70
4.25 x 10~4
23.8
Optical Microscope,
500X
Total
Fibers
(No. ofj
Fiber s/m )
> 1010 (1)
6.37 x 103
8.07 x 108
1.42 x 104
1.02 x 105
2.88 x 104
2.19 x 109
8.33 x 105
1.42 x 109
4.52 x 104
Efficiency
CO
> 99.99
> 99.99
97.18
99.96
> 99.99
Electron Microscope,
16,364X
Total
Fibers
(No. ot
Fibers/in )
> 1014 (1)
1.08 x 107
2.45 x 1011
3.28 x 109
5.04 x 109
3.20 x 107
1.38 x 107
1.24 x 1012
1.44 x 109
1.36 x 1013
1.29 x 108
Efficiency
(%)
> 99.99
98.69
97.94
57.90
99.88
> 99.99
Filter
No.
11
12
17
20
18
23
18B
27
43B
31
36B
(1) Samples too dense to count; sample diluted for size distribution.
no' of fibers downstream)
„,.,-. .
Efficiency
inni
100 11
uo. ol xibers upstream.
)
1
J
-------
Table 20. OPTICAL MICROSCOPE (500X) SIZE DISTRIBUTIONS AND FRACTIONAL REMOVAL EFFICIENCIES
Sampling
Site
Waukegan,
Illinois
Marshville,
Jorth Carolina
Denison,
Texas
Asbestos,
Eden Mills,
Sampling
Location
Jp stream
3ownstrean
Upstream
Downstream
Upstream
Downstream
Upstream
Downstream
Upstream
Downstream
Total
Fibers
(No. of
Fibers
per m3)
i> io10**
3.
>. 37x10
J.07xl08
L.42xl04*
L.02xl06
2.88x10
2.19xl09
C
J. 33x10
L.42xl09
4
4.52x10
Size Distributions (by length)
1.5-10
Fiber
Count
(No. of
Fibers
per m3)
>5.06xl09
3
2.70x10
5.46xl08
1.14xl04
7.32xl05
2.19xl04
1.31xl09
C
6.27x10
1.22xl09
4
3.42x10
% of
Sample
50.6
42.4
67.6
80.0
71.8
76.2
59.7
75.3
86.8
75.7
Jm
Efficiency
m
>99.99
>99.99
97.01
99.95
____
>99.99.
10-20 um
Fiber
Count
(No. of
Fibers
I
% of Efficiency
per m3)jSamplej (%)
>2.10xl09
3,
2.31x10
1.78xl08
21.0
36.4
22.0
2.84xl03 20.0
1.92xl05
5.99xl03
6.61xl08
C
1.48x10
1.48xl08
q
8.14x10
18.8
20.8
30.2
17.8
10.4
18.0
>99.99
>99.99
96.88
99.98
>99.99
20-30 urn
Fiber
Count
(No. of
Fibers
per m3)
>1.67xl09
2
5.80x10
4. 84x1 O7
0.0
8.57xl04
5.76xl02
1.77xl08
4.00x10*
2.70xl07
2.03x10'
% of
Sample
16.7
9.1
6.0
0.0
7.4
2.0
8.1
4.8
1.9
4.5
Efficiency
(%)
>99.99
100
99.33
99.98
99.99
> 30 um
Fiber
Count
(No. of
Fibers
per m^)
>1.17xl09
n
7.71x10
3.55xl07
0.0
1.53xl04
2.88xl02
5.26xl07
"5
1.75x10^
1.28xlO?
j
8.13x10
]
i
% of I
Efficiency
Sample^ (%)
11.7 i
1
12.1
4.4
0.0
1.5
1.0
2.4
2.1
0.9
1.8
>99.99
100
98.12
99.67
99.99
Filter
No.
11
12
17
20
23
18B
27
43B
31
36B
* Sample contained five fibers in 100 fields.
** Sample too dense to count; sample diluted for size distribution.
Efficiency (Z) - 100 1 -
no. of fibers downstream)
no. of fibers upstream J
-------
Table 21. ELECTRON MICROSCOPE (16.364X) SIZE DISTRIBUTION AND FRACTIONAL REMOVAL EFFICIENCIES
Sampling
Site
Waukegan ,
Illinois
Marshville,
lorth Carolina
Denison,
Texas
Asbestos f
Quebec
Eden Mills.
Vermont
Sampling
Location
Jpstream
)owns tream
Jpstream
towns tream
>owns trean
Upstream
Downstrean
Jpstream
Downstream
Upstream
Downstream
Total
(No of
Fibers
per m3)
> 1014(1)
l.OSxlO7
2.45X1011
}.04xl09
i.28x!09
J.20xl07
L.38xl07
1.24xl012
1 . 44xl09
1.36xl013
1.29xl08
- <0.06 ym
Fiber
Count
(No of
Fibers
per m^)
>8.7 xlO12
0.0
2.74xl010
1.28xl09
5.25xl08
0.0
0.0
0.0
3.48xl08
2.12xl012
1. 24x10 7
7. of
Sample
8.7
0.0
11.2
25.3
16.0
0.0
0.0
0.0
24.2
15.6
9.6
Efficiency
100
95.33
98.08
(2)
>99.99
0~T55-0.18 urn I
Fiber
Count
(So. of
Fibers
per m^)
>1.06xl013
0.0
l.lOxlO11
2.89xl09
1.88xl09
0.0
l.lOxlO6
2.36xl010
7.53xl08
6.17xl012
4.26xl07
% of
Sample
10.6
0.0
44.9
57.3
57.3
0.0
8.0
1.9
52.3
45.4
33.0
Efficiency
(7.)
0.0
97.37
98.29
(2)
96.81
>99.99
0.18-0.36 ym
Fiber
Count
(No. of
Fibers
per mj)
>1.25xl013
1.88x10
6.05xl010
6.90xl08
6.56x10
4.35xl06
1.66xl06
6. 94x10 10
1.38xl08
2.64xl012
1.86xl07
1 of
Sample
12.5
17.4
24.7
13.7
20.0
13.6
12.0
5.6
9.6
19.4
14.4
Efficiency
>99.99
99.89
98.92
61.80
99.80
>99.9«
0.36-0.54
Fiber
Count
(No. of
Fibers
per m3)
>1.83xl013
1.40x10°
1.37xlOIU
1.06xl08
8.86x10
4.35xl06
3.86xl06
1.39X1011
1.73xl07
1.32xl01''
7. of
Sample
18.3
13.0
5.6
2.1
2.7
13.6
28.0
11.2
1.2
9.7
1.48xl07 11.5
Sfficiency
(7.)
>99.99
99.23
99.35
11.30
99.99
>99.99
[ 0.54-1.50 urn '
Fiber
Count
(No. of
Fibers
per m-*)
>5.0 xlO11
7.52x10
3.31xl010
8.57xl07
7. of
Sample
50.0
69.6
13.5
1.7
1.31xl08
2.33xl07
7.18x10
l.OlxlO13
1.83xl08
1.35xl012
4. 14x10 7
4.0
72.7
52.0
81.3
12.7
9.9
32.1
efficiency
(7.)
>99.99
99.74
99.60
69.20
>99.99
>99.99
Filter
No.
11
12
17
20
18
23
18B
27
43B
31
36B
(1) Samples too dense to count; total fiber count > 10 fibers/m .
(2) Negative efficiency indicated within experimental limits.
_„. . ._, 1nrif, no. of fibers downstream]
Efficiency «) - 100[1 - no. of fibers upstream J
-------
efficiency is of importance. No other comparable data was
found in the literature. In general terms, it can be seen
from Table 19 that the number of fibers emitted which were
greater than 1.5 ym in length was of the order of 10 fibers
Per cubic meter at the five locations. At the same time,
the number of fibers emitted which were in the very small
size group of 0.06 to 1.5 ym in length was of the order
°f 10 fibers per cubic meter.
Two reasons could be given to explain the above result.
Either the collection efficiency for the very small particles
could be very low or there could be very many more fibers
challenging the fabric filter at the same collection
efficiency. From Table 19, it is seen that, in general
terms, the collection efficiency for fibers greater than
1.5 ym was in excess of 99.99%, while the collection
efficiency for the fibers less than 1.5 ym in length was
greater than 98%. (The one low result, 57.9%, for the
collection efficiency at the Denison plant, could be in
error, although it is noted that it also had the lowest
efficiency in the greater than 1.5 ym size group at 97.18%.)
Obviously.then, the reason for the very large number of fibers
emitted in the 0.6 to 1.5 ym size range is the enormously
numbers of fibers present in this range and not from
significant change in the collection efficiency with
Particle size.
The form of the fractional efficiency curves for fabric
filters have been studied by a number of workers21*'25.
Peterson and Whitby26 reported that the fractional efficiency
goes to a minimum at a particle size of about 0.3 ym, and
increases in efficiency for particle sizes above and below
this point. Their conclusions were based on the fractional
efficiency measurements made using a monodisperse aerosol
to challenge the filter. Colley27 has found that while the
efficiency is at a minimum with a particle size of 0.1-0.2 ym,
65
-------
there is no evidence to show that the efficiency actually
increases with decreasing particle size beyond this size.
The explanation for the observed flattening of the curve
is that larger particles have a comparatively high inertia
and the path of the particles is not altered by Brownian
movement. As the particles decrease in size, Brownian
movement becomes more effective and will cause the particles
to alter their path such that they are captured by the
fabric.
The present results show a pronounced flattening of
the fractional efficiency curve, indicating that the
smaller particles, which might be expected to penetrate the
filter, are being captured by Brownian movement. For asbes-
tos, which has a fibrous form, there will be a more compli-
cated aerodynamic approach theory than for simple spheres.
The fibrous form could aid capture efficiency if the par-
ticles approach the fabric length-ways on. Alternatively,
the capture efficiency could be reduced if the fibers line
up in the direction of flow and present a small cross-section
for capture.
A highly significant point resulting from this study is
the fact that, in very many instances, air is recirculated
within an asbestos plant. Plant operators have considered
this to be reasonable if the return air can be shown to
contain asbestos at a level lower than the OSHA standard of
less than 2 fibers per cubic centimeter, where a fiber is
only counted if it is greater than 5 cm in length.
It has been shown here that while the number of fibers
greater than 5ym is low, there are very large numbers of
fibers less than 5 ym. However, plant operators who recircu-
late plant air are inadvertently exposing their workers to very
high levels of very small fibers whose health significance
has not been established.
66
-------
SECTION 7
ESTIMATE OF ASBESTOS DISPERSION
INTRODUCTION
Two methods were used to estimate the dispersion of the
asbestos emissions from the source. Both were based on
the well-known equations of Pasquill28 as restated by Gifford29
The first method involved the manual calculation of the
Dispersion using the Binormal Continuous Plume Dispersion
Model as detailed by Turner30 . This technique enables
Predictions of the ambient pollutant concentration downwind
from a known source under given metoerological conditions.
The second method utilized the Climatological Dispersion
Model (CDM). This model predicts the long-term (seasonal
°r annual) quasi-stable pollutant concentrations in an area
surrounding the source. The long-term wind rose data,
obtainable from the "National Climactic Center, is required
f°r this model, and, because of the very large number of
computations, it is only suitable for use by computer.
using the CDM were found to be inconsistent due to
inherent limitations of the model. For this reason,
those results obtained with the first model are included
wi-th this report.
THE BINORMAL CONTINUOUS PLUME DISPERSION MODEL
The system considered in this model is shown in Figure 2.
*he x-axis extends horizontally in the direction of the mean
^ind. The y-axis is in the horizontal plane perpendicular
t° the x-axis, and the z-axis extends vertically. The plume
67
-------
travels along a parallel to the x-axis from point H, which
represents the sum of the physical stack height, h, and the
plume rise, AH.
Origin
(x,-y,Z)
(x,-y,o)
Figure 2. Coordinate system showing
Gaussian distributions in the
horizontal and vertical
The concentration, X, of the aerosolized particles
(i.e., less than about 20 ym diameter) at x,y,z from a
continuous source with an effective emission height, H,
is given by equation (1).
X(x,y,z;H) =
2TTC U
y z
1
2
(i)
exp
1
I
Z - H
+ •• exp
Z + H
68
-------
Any consistent set of units may be used, for the present
study:
3
X = concentration (fibers/m )
Q = emission rate (fibers/sec)
u = mean wind speed (m/sec)
H,x,y,z = effective stack height and coordinate (m)
a , a = standard deviations of plume coordinate (m)
In establishing this equation, a number of assumptions
are made:
The plume spread has a Gaussian distribution in
both the horizontal and vertical planes.
The wind is constant in speed and direction.
The emission rate is uniform.
Total reflection of the plume takes place at the
earth's surface, i.e., there is no deposition or
reaction at the surface.
There is no diffusion in the direction of the
plume travel.
F°r concentrations calculated at ground level, i.e., z = 0,
and downwind along the centerline of the plume, i.e., y = 0,
equation simplifies to
H 2
X(x,0,0;H) =
(2)
In most real circunstances, a stable layer exists above
the unstable lower layer with the effect of restricting the
vertical diffusion. The model can be modified to account for
this situation by considering the height of the base of the
stable layer from the ground level to be L. At a height
above the plume centerline, the concentration
r
69
-------
is one tenth of the concentration at the centerline at the
same distance along x. When one tenth of the plume center-
line concentration reaches the stable layer, height L, it
is assumed that the distribution is affected by the stable
layer. At this point, which is called x, , 2.15cr = L, or
a = 0.47L.
z
At distance, x,. , the plume is assumed to have a
Gaussian distribution in the vertical. It is further assumed
that when the plume travels twice this distance, to 2x, , the
plume has become uniformly distributed between the earth's
surface and the stable layer at height L. Between these
limits, the concentration does not change with height.
At distances greater than 2x,, the downwind centerline con-
centration is calculated from:
X(x,0,z;H) = Q (3)
/2rra LU
y
for any value of z from 0 to L.
THE METHOD OF CALCULATION USING THE BINORMAL CONTINUOUS
PLUME DISPERSION MODEL
As input for the model, the following basic information
is required.
The mean wind speed, u, (m/sec)
• The source emission rate, Q (fibers/sec)
The effective source height, H (m)
Stable layer height, L, for daytime and nighttime
conditions (m)
The stability class
The values of mean wind speed, u, source emission rate,
Q, and the effective source height, H, are measured values
taken at a given site. The stable layer height, L, for
70
-------
daytime and nighttime conditions were assumed from the average
conditions reported in the literature. Values of 800 m and
150 m were assumed for daytime and nighttime conditions,
respectively. The stability class was taken from observa-
tions of the meteorological conditions and reference to
Table 22.
Table 22. KEY TO STABILITY CATEGORIES
Surface
Wind Speed
at 10 ra
(m/sec)
< 2
2-3
3-5
5-6
> 6
Day
Incoming Solar Radiation
Strong
A
A-B
B
C
C
Moderate
A-B
B
B-C
C-D
D
Slight
B
C
C
D
D
Night
Thinly Overcast
or
> 4/8 Low Cloud
E
D
D
D
>3/8 Cloud
F
E
D
D
Note: The neutral class D should be assumed for overcast
conditions during day or night.
Ambient air concentrations downwind from the source were
calculated using equation (2) for distances of x less than
XT and from equation (3) for distances of x greater than
2x, . The distance x, is found from the assumed stable layer
LI LI
height, L, which gives the value of a (from a = 0.47L).
Z Z*
The distance x, can then be found directly from Figure 3.3
in the Atmospheric Dispersion Estimates Workbook30.
The only remaining unknown is then a , which can be
found for a given distance from the source directly from
pigure 3.2 in Reference 30.
71
-------
RESULTS FROM THE BINORMAL CONTINUOUS PLUME DISPERSION MODEL
Using the service terms for each site as shown in
Table 23, values for the downwind concentration of asbestos
fibers were estimated for both daytime and nighttime con-
ditions using two stability classes in each instance. Detail6
results for distances up to 30 kilometers are tabulated in
Appendix B. In these tables, separate values have been
computed for those fibers observed by optical microscope
(i.e., greater than 1.5 ym) and those observed by electron
microscope (i.e., less than 1.5 ym).
The results for the five locations at Waukegan, Illinois)
Denison, Texas, Marshville, North Carolina, Asbestos,
Canada, and Eden Mills, Vermont, are displayed graphically
in Figures 3, 4, 5, 6, and 7. The fiber concentration, x,
plotted on the graphs, represents the number of fibers
observed by electron microscope, although this may be taken
as the total number of fibers with very little error, since,
in general, the number of fibers observed under the electron
microscope exceeded those observed under the optical microscoP
by about three orders of magnitude.
Fiber concentrations are observed to increase initially
with distance from the source due to the effect of plume
height. However, after a short distance of about 0.1 to 0.3
kilometers, there is a rapid fall in concentration until
about 10 kilometers distance after which the graph asymp-
totically approaches ambient air fiber concentration.
The effect of the stable layer height is pronounced;
much higher values are estimated to occur during nighttime
due to the lowering of the height of the stable layer.
Typically, this difference is about an order of magnitude in
the distance range of 10 to 30 kilometers from the source.
72
-------
Table 23. DISPERSION EQUATION SOURCE TERMS
-4
UJ
Plant
Location
Waukegan, 111.
Marshville, N.C.
Denison, Tex.
Asbestos, Que.
Eden Mills, Vt.
Baghouse Air
Throughput
nr*/min
1.13 x 103
4.73 x 102
7.36 x 102
1.27 x 105
8.49 x 103
Emitted Fiber Concentration
From Optical
Microscope
Analysis
Number/in^
6.4 x 103
1.4 x 104
2.9 x 104
8.3 x 105
4.5 x 104
From Electron
Microscope
Analysis
Number/m^
1.1 x 107
5.0 x 109
1.4 x 107
1.4 x 109
1.3 x 108
Source Term
From Optical
Microscope
Analysis
Fibers/ sec
1.2 x 105
1.1 x 105
3.5 x 105
7.6 x 108
6.4 x 106
From Electron
Microscope
Analysis
Fibers/sec
2.0 x 108
4.0 x 1010
1.7 x 108
3.1 x 1012
1.8 x 1010
-------
JM Waukegan, III.
Stability Classes
o B
a C
D
JDay
JNight
10
4>
5 10 20
Distance From Source
30
Km.
Figure 3. The concentration of asbestos fibers with distance from source
at four stability conditions for Johns-Manvilie, Waukegan, Illinois
74
-------
10
J-M Denison Texas
Stability Classes
Day
Night
10'
IO
-vs
VI
k.
<1>
JD
L
10
5 10 20
Distance From Source
30
Km.
Figure 4. The concentration of asbestos fibers with distance from source
at four stability conditions for Johns-Manville, Denison, Texas
75
-------
IO
Raybestos N.C.
Stability Classes
0 n
Day
Night
5
Distance
10
From Source
Km.
Figure 5. The concentration of asbestos fibers with distance from source
at four stability conditions for Raybestos, Marshville, North Carolina
76
-------
Asbestos Canada
Stability Classes
o B
a C
* D
v E
/Day
JNIght
10
M
l_
tt)
5 10
Distance From Source
20
30
Km.
Figure 6. The concentration of asbestos fibers with distance from source
at four stability conditions for Johns-Manville, Asbestos, Canada
77
-------
GAP Vermont
Stability Classes
o B
a C
JDay
j Night
10
X
in
k-
0)
.o
5 10
Distance From Source
20
30
Km.
Figure 7. The concentration of asbestos fibers with distance from source
at four stability conditions for GAP, Eden Mills, Vermont
78
-------
SECTION 8
REFERENCES
1 Roper, G. W. Asbestos Mill Filters. IIT Research
Institute. (Presented at IIT Research Institute Seminar
on Asbestos, Chicago, Illinois. 1972).
2. Goldfield, Joseph. Fabric Filters in Asbestos Mining
and Manufacturing. (Presented at APCO Fabric Filter
Symposium. Charleston, Virginia. 1971).
3- Hills, D. W. Economics of Dust Control. Annals of the
New York Academy of Science. 132:322-334, 1964.
^- Rozovsky, H. Air in Asbestos Milling. Canadian Mining
Journal. 78:95-103, May 1957.
**• Wieschhaus, L. J. Recovering Asbestos Floats with Dust
Collectors. Rock Products. 50(8):104-105, 1947.
6- Dust Control Methods. Coal Age. 72(8):56-62, 1967.
?- Dust Collection Plants. Cement Technology. Pp. 229-232,
November/December 1972.
D
• Quebec Asbestos Producers Join Forces in Fighting Dust.
Engineering and Mining Journal. 174(10):82-83, 1973.
Q
Control Techniques for Asbestos Emissions. Johns-Manvil]
Research and Development Division internal report.
Precipitators and Filters at 'Cleanest Ever1 Cement
Works. Filtration and Separation. 10(1):40, 1973.
Cross, F. L. Baghouse Filtration of Air Pollutants.
Pollution Engineering. 6(2):25-34, 1974.
b
Dick, G. A. Fabric Filters. Canadian Mining Journal.
91(10):72-80, 1972.
79
-------
13. Jensen, Kenneth E, Concepts of Fabric Filtration for
Air Pollution Control. Filtration and Separation.
6(3):254,257, 1969.
14. Pring, R. T. Reducing Baghouse Maintenance by Design.
Minerals Processing. 11(5):8-13, 1970.
15. Jones, A. H. How to Improve Maintenance of Fabric
Dust Collectors. Minerals Processing, 10(5):21-23,35,
1969.
16. Dust and Fume Control Equipment in the Non-Ferrous Metals
Industry. Filtration and Separation. 10(1):48, 1973.
17. Design and Operation of Asphalt Plant Bag Collectors.
Pit and Quarry. 65(11):109, 1973.
18. Reigel, S. A., R. P. Bundy, and C. D. Doyle. Baghouses -'
What to Know Before You Buy. Pollution Engineering.
5(5):32-34, 1973.
19. Cosby, W. T. and G. Punch. Dust Filters and Collectors,
Cost and Performance of Filtration and Separation
Equipment, Filtration and' Separation. 5(3):252-255,270,
1968.
20. Selikoff, I. J. , E. C. Hammond, and E. Heimann. Critical
Evaluation of Disease Hazards Associated with Community
Asbestos Air Pollution. Proceedings of the Second Inter-
national Clean Air Congress. Pp. 165-171, 1970.
21. Minifie, F. G. and A. J. Moyes. Low Cost Electrostatic
Precipitator. Filtration and Separation. 9(l):52-59,
1972.
22. Control Techniques for Asbestos Air Pollution. United
States Environmental Protection Agency Report No. AP-11?*
1973.
23. Hailstone, R. E. Air Pollution in the Cement Industries-
Minerals Processing. 10(5):11-15, 1969.
24. Stairmand, C. J. The Design and Performance of Modern
Gas-Cleaning Equipment. Jnl. Inst. of Fuel. Pp. 58-81,
February 1956.
25. Sommerlad, R. S. Fabric Filtration -- State of the Art.
Livingston, New Jersey, Foster Wheeler Corporation,
March 6, 1967. c
80
-------
26. Petersen, C. M. and K. T. Whitby. Fractional Efficiency
Characteristics of Unit Type Collectors. ASHRAE Journal.
May 1965.
27. Colley, D. G. Stack Sampling Yields Fractional Efficien-
cies for Dust Collectors. (Presented at Air Pollution
Control Conference. Purdue University. October, 1970.)
28. Pasquill, F. The Estimation of the Dispersion of
Windborne Material. Meteorol. Mag. 90(1063):33-49, 1961
29. Gifford, F. A. Uses of Routine Meteorological Observa-
tions for Estimating Atmospheric Dispersion. Nuclear
Safety. 2(4):47-51, 1961.
30. Turner, D. B. Workbook of Atmospheric Dispersion
Estimates. PHS Publication No. 999-AP-26, 1970.
81
-------
SECTION 9
APPENDICES
Page
A. Selected Bibliography and Abstracts 83
B. Binomial Continuous Plume Dispersion Model Results 110
82
-------
Appendix A
SELECTED BIBLIOGRAPHY AND ABSTRACTS
83
-------
SELECTED BIBLIOGRAPHY AND ABSTRACTS
Addingley, C.G., "Dust Measurement and Monitoring in the Asbes-
tos Industry," Annals of the New York Academy of Science,
132, pp 298-305, 1965.'
All methods of dust counting of asbestos air concentra-
tions require examination under a microscope. The Royco
Particle Counter, using light scattering principles, is in-
vestigated as an on-line monitor for asbestos concentrations
in the air. Results show agreement with membrane filter
techniques to within 25%.
Addingley, C.G.. "Asbestos Dust and Its Measurements," Annals
of Occupational Hygiene, 9, pp 73-82, 1966.
The nature of asbestos dust and the testing requirements
are discussed. Existing standard methods are briefly reviewed.
The development of a membrane filter method of dust
counting for asbestos is described in detail. It is thought
to be an improvement on existing methods.
Tyndallometric methods are considered, and a description
of the application of the "Royco" Particle Counter, an instru-
ment based on this principle, to factory testing is described.
It is believed that this instrument represents a big advance
in routine test methods.
Aldred, Robert, "Dust Filtration Apparatus," British Patent
No. 1293592, 1969.
The patent discusses dust filtration in mines, avoiding
the use of water, which gives further problems in cooling
the mine, etc. Two stages are used, the first being a sort
of cyclone, with deflectors, and then a band filter for
retaining the finer dust. A fan is used downstream of the
filter unit to pull the dirty air stream through the unit.
84
-------
Anonymous, "Bag Collects 60,000 Tons of Sinter Dust," Air
Engineering, 10, No. 7, pp 8, 11, 1968.
The dust collection system on the sinter line of the
Bethlehem, Pennsylvania plant of the Bethlehem Steel Corpora-
tion is described. The system operates at 99% efficiency and
has reclaimed over 60,000 tons of dusts over five years.
Anonymous, "Bag Life Extended at Copper Refinery," Air Engin-
eering. 11, No. 1, pp 18-19, 1969.
The baghouse at the Carteret, New Jersey plant of AMAX's
United States Metals Refining Company is described. Adoption
°f a new filter fabric made of Dupont's high temperature
fiber, "Nomex" nylon, has resulted in an effective bag life
^ times greater than that of glass fiber bags.
Anonymous, "Control Techniques for Asbestos Air Pollution,"
United States Environmental Protection Agency report
No. AP-117, 1973.
Asbestos is the generic name for a group of hydrated
Mineral silicates that occur naturally in a fibrous form.
^he technological utility of asbestos derives from its physi-
Cal strength, resistance to thermal degradation, resistance
to chemical attack, and ability to be subdivided into fine
fibers.
The subdivision of asbestos into fine fibers produces
Articulate matter that is readily dispersed into the atmosphere,
Adverse effects of airborne asbestos on'human health have been
Associated primarily with direct and indirect occupational
e*posures, but a level of asbestos exposure below which there
*s no detectable risk of adverse health effects to the gener-
population has not yet been identified. Because of the
of a practical technique of adequate sensitivity for
small concentrations of airborne asbestos, neither
9ccurate emission factors nor emission-effect relationships are
Bailable.
85
-------
Engineering appraisals9 based on limited data, indicate
that the milling and basic processing of asbestos ore (crushing
and screening the ore and aspirating the fiber to cyclones for
grading) and the manufacture of asbestos-containing friction
materials, asbestos-cement products, vinyl-asbestos tile, as-
bestos textiles, and asbestos paper account for over 85 per-
cent of total asbestos emissions. Other sources include:
(1) the manufacture of other products containing asbestos,
such as paints, coatings, adhesives, plastics, rubber materials*
and molded insulating materials; (2) the use of spray on as-
bestos products, such as those used for fireproofing or insula*
ting; (3) the demolition of buildings or structures containing
asbestos fireproofing or insulating materials; and (4) the
sawing, grinding, or machining of materials that contain asbes-
tos, such as brake linings and molded pipe insulation. In
most of the manufacturing operations, the major emissions of
asbestos occur when the dry asbestos is being handled, mixed
with other dry materials, or dumped into the wet product mix,
but the weaving of asbestos fibers into textiles and the
machining or sanding of hard asbestos products also produce
major emissions.
Emissions are controlled in several ways: (1) by care-
ful handling of dry materials to avoid generating dust;
(2) by enclosing dusty operations; (3) by substituting wet
processes for dry processes; (4) by wetting dry materials be-
fore handling, sawing, or grinding; (5) by cleaning the
dust-laden air by drawing it into ducts that lead to fabric
filters; and (6) by reducing the amount of asbestos added to
products the use of which leads to the generation of emission^'
The last technique is particularly applicable to situations
where the control of emissions by other methods is very diffi"
cult, as with spray application of insulation or demolition
of structures. The costs of needed emission control techniqueS
86
-------
can be estimated from those associated with existing practices.
Anonymous, "Control Techniques for Asbestos Emissions," Johns-
Manville Corporation Research and Engineering Division
internal report, 1970,
Johns-Manville is the largest producer of asbestos fiber
and asbestos products in the free world. During the past
14 years, Johns-Manville has installed over 100 air and dust
handling systems in its plants. The costs of these systems
exceeded $18,000,000. The largest single installation was
at the Jeffrey Mill No. 5 in Asbestos, Quebec. This bag-
O £.
house handles 1.27 x 10 lpm (4 x 10 cfm) and the total cost
was $8,000,000.
Anonymous, "Design and Operation of Asphalt Plant Bag Collec-
tors," Pit and Quarry, 65, No. 11, p 109, 1973.
Dust-laden exhaust gases from dryers in asphalt processing
Plants are cleaned using baghouses. Operation and design of
baghouse dust collection systems is described.
Anonymous, "Dust and Fume Control Equipment in the Non-Ferrous
Metals Industry," Filtration and Separation. 10, No. 1,
p. 48, 1973.
Bag filters, electrostatic precipitators and wet scrubbers
are the equipment most used by the British non-ferrous metals
industry to cope with fume, grit and dust arising from smel-
ting and other operations.
Emissions from the non-ferrous metals industry comprise
dust and fine metallic particles, smoke from burning oil
contaminating the raw materials, metallic oxide fumes, and,
in the aluminum industry, chlorides and fluorides. Dust
and metal particles are readily collected in settling cham-
bers, cyclones, etc., but micron and submicron material (the
Worst problem) can only be collected by high efficiency bag
87
-------
filters, high pressure drop scrubbers or electrostatic pre-
cipitators.
Anonymous, "Dust Collection Plants," Cement Technology,
November-December, pp 229-232,
The task imposed on dust collection plants as used in
industry are many and various, resulting in the development
of a range of dust collection plants based on a variety of
working principles and designed to complement each other
efficiently.
On the basis of details supplied by the customer regarding
his specific problem, the most suitable dust collecting sys-
tem for his particular system can be worked out, which may,
in fact, consist of a combination of two different dust
collection methods.
The types of equipment employed for dust collection come
under the following general groups: (1) electrical dust
precipitation; (2) cyclone dust collection; and (3) wet
type dust collection.
Anonymous, "Dust Control Methods," Coal Age. 72, No. 8,
pp 56-62, 1967.
The first step towards effective dust control is choosing
equipment best suited to handle your dust problem. To do
this requires an adequate understanding of dust control methods
and dust collector characteristics.
The different types of dust collectors are categorized
in terms of their characteristics, including size, efficiency,
and their applications.
88
-------
Anonymous, "Precipitators and Filters at 'Cleanest Ever'
Cement Works," Filtration and Separation. 10, No. 1,
p 40, 1973.
The dust collection system at the new four million- tons
Per acre cement factory at Northfleet, Kent is described.
Fabric filters are preferred for smaller gas flows where
temperatures and humidity are not excessive, e.g. at conveyor
transfer points, cement packing and loading plants, and in
some cases cement mill exhausts. But for treating very large
gas volumes and flow rates electrostatic precipitators are
used, particularly where high humidities and temperatures
are encountered, as, for example, in the main kiln exhaust,
the exhaust of excess air from moving grate clinker coolers,
and, in some cases, the ventilating air from large cement
mills.
Anonymous, "Quebec Asbestos Producers Join Forces in Fighting
Dust/' Engineering and Mining Journal, 174, No. 10,
pp 82-83, 1973,
The eastern townships of Quebec have been the center of
the asbestos mining industry for nearly a century. In this
area, approximately 115 miles east of Montreal, six mines
produce approximately 29% of the world's asbestos. Because
of close proximity of the towns to mine and mill operations,
Quebec asbestos mining firms have long recognized the need
to control the environment and have combined resources to do
so. An Environmental Control Committee of the Quebec Asbes-
tos Mining Association (QAMA) unites the competing companies
in commitment of management, engineering, and environmental
inspections to protect workers and communities. Substantial
Deduction of dust emission points throughout the asbestos
Plants has been achieved, often as a result of sharing
hard-won knowledge among the member companies.
89
-------
Aureille, R. and Blanchot, "Experimental Investigation on the
Effect of Different Parameters on the Separation Effic-
iency of an Electrostatic Precipitator," Staub-Reinhalt.
Luft, 31, No. 9, pp 23-28, 1971.
To improve the efficiency of electrostatic precipitators
for waste-gas cleaning of thermal power stations working with
coal dust, Electricite de France, in its research and devel-
opment center in Chatou, has erected a semi-industrial experi-
mental electrostatic precipitator installation. With this
installation, which is designed for horizontal flow of the
waste gases, it is possible, during operation, not only to
check the most important parameters likely to affect pre-
cipitator efficiency, but also to vary each individual para-
meter, while all other magnitudes remain unchanged. The
experimental investigations extended from 1961 through 1969.
Part of the results obtained are reported.
Berlyand, M.E., "Investigations of Atmospheric Diffusion
Providing a Meteorological Basis for Air Pollution Con- .
trol," Atmospheric Environment, 6, No. 6, pp 379-388, 19/*'
A summary of the principal lines of inquiry into the
problem of atmospheric diffusion, including practical appli-
cations, in the U.S.S.R. Topics summarized are Gaussian and
K-theory diffusion models, plume and point-source diffusion
methods, mulitple sources, and abnormal meteorological con-
ditions.
'S, Charles E., and Wilder, John, "Handbook of Fabric
Filter Technology," GCA Corporation internal report
Billings,
Fill
No. GCA-TR-70-17-G, 1970.
This report is the state-of-the-art of fabric filters.
Major topics discussed are: (1) operating principles; (2)
areas of application; (3) technology of fabric filtration
processes; (4) types of fabric filters commercially available;
(5) fabric selection; (6) engineering design of fabric
90
-------
systems; (7) performance of fabric filters; (8) economics;
and (9) operation and maintenance of fabric filters.
British Occupational Hygiene Society Committee on Hygiene
Standards. "Hygiene Standards for Airborne Amosite Asbes-
tos Dust. Annals of Occupational Hygiene. 16. pp 1-5,
1973.
The sub-committee on asbestos has reviewed the informa-
tion on the results of human exposure to airborne amosite
dust and animal experiments. The subcommittee believes it
has insufficient knowledge of the relationship between air-
borne amosite dust exposure and the risk of asbestos to permit
an accurate statement of the degree of protection afforded by
a specified hygiene standard. Nevertheless, on the basis of
comparisons between the effects of amosite and chrysotile
dust on men and animals it is recommended that the standards
for amosite should be no less stringent than those for chryso-
tile.
The sub-committee believes that a proper and reasonable
objective would be to reduce the risk of contracting asbestosis
to 1 percent of those who have a lifetime's exposure to the
dust. By 'asbestosis1 this sub-committee means the earliest
demonstrable effects on the lung due to asbestos. "The
Hygiene Standards for Chrysotile Asbestos Dust" (British
Occupational Hygiene Society, 1968) showed that the risk of
being affected to the extent of having such early clinical
signs will be less than 1 percent for an accumulated exposure
of 100 fiber-year/cm . That is, for example, a concentration
°f 2 fiber/cm for 50 years, 4 fiber/cm for 25 years, or
10 fiber/cm for 10 years. An accumulated exposure of 100
fiber-years per cm is therefore recommended for amosite.
It is further recommended that exposures to amosite asbestos
lie in certain ranges of dustiness be designated by
91
-------
categories according to the scheme recommended in the hygiene
standards for chrysotile asbestos dust.
Busse, Adrian D.; Zimmerman, John R., "User's Guide for the
Climatological Dispersion Model," U. S. Environmental
Protection Agency report No, EPA-R4-73-024, 1973.
The Climatological Dispersion Model (CDM) determines long*
term (seasonal or annual) quasi-stable pollutant concentra-
tions at any ground-level receptor using average emission rates
from point and area sources and a joint frequency distribution
of wind direction, wind speed, and stability for the same
period.
This model differs from the Air Quality Display Model
(AQDM) primarily in the way in which concentrations are
determined from area sources and in the use in the CDM of
Briggs1 plume rise formula and an assumed power law increase
in wind speed with height that depends on stability.
The material presented is directed toward the engineer
familiar with computer techniques and will enable him to
perform calculations with the CDM. Technical details of the
computer programming are discussed; complete descriptions of
input, output, and a test case are given. Flow diagrams and
a source program listing are included. Companion papers by
Calder (1971) on the technical details of the model and by
Turner et al. (1972) on validation are included.
Cheng, Lung, "Collection of Airborne Dust by Water Sprays,"
Industrial Engineering Chemical Process Design and
Development, 12, No. 3. pp 221-225, 1973.
A general theoretical equation was developed for the
collection efficiency of airborne dust particles by spray
drops. The model assumes an inertial impaction collection
mechanism and is based upon mean interdrop length and mean
92
-------
interparticle area. Particular attention was given to the
optimum drop size for collection with open and also confined
sprays from a high-pressure nozzle. This general model was
specifically adapted to the collection of dust particles in
a horizontal tunnel by a solid-cone water spray by including
the effects of duct size and spray configuration. The
theoretical collection efficiencies agreed reasonably well
with experimental data. The present results can be used to
select a specific spray nozzle that will provide optimum col-
lection efficiency for airborne dust based upon the available
water flow rate and the line pressure.
Cosby, W.T.; Punch, G., "Dust Filters and Collectors - Cost
and Performance of Filtration and Separation Equipment,"
Filtration and Separation, 5, No. 3, pp 252-255, 270, 1968.
In arriving at the 'best buy1 in gas cleaning plant, it
is essential to consider the duties to be performed, methods
of containing the dust or fume and its disposal after removal.
In this paper, the authors try to show how the selection
of equipment is influenced by factors other than the character-
istics of particles and collectors. They base their cost
comparison data on two hypothetical duties each demanding
efficiencies of 98-99%. Annual costs are calculated for
fabric filter, dry plate precipitators, and venturi scrubberse
The effect on collector costs of high initial gas temperatures
are considered and the provision of cooling equipment is taken
into account.
Cross, Frank L., Jr., "Baghouse Filtration of Air Pollutants,"
Pollution Engineering, 6, No. 2, pp 25-34, 1974.
Filtration is one of the oldest methods of source control
and is especially desirable for the removal of particulate mat-
ter from a gas stream. Satisfactory efficiencies are obtained
93
-------
with this type of unit with only moderate power consumption
and relatively low maintenance problems if the proper filter
is selected.
Dick, G.A., "Fabric Filters," Canadian Mining Journal. 91,
No. 10, pp 72-80, 1972.
A fabric filter is a device used for freeing process
gases and liquids from suspended impurities, and both wet
and dry filtration is practiced in the mining industry for
ticle separation. This paper deals solely with dry filtra-
tion and gas cleaning techniques for the recovery of parti-
culate matter to meet air quality control standards. The
mining industry has long recognized the need for effective
control of airborne contaminants and has used some form of
"cloth filter" or "baghouse" for dust control work since the
turn of the century. This method of gas cleaning has repre-
sented one of the best means of obtaining the highest con-
sistent recovery of gas-borne particulate matter and fabric
filters have demonstrated that, when properly operated and
maintained, collection efficiencies of airborne particulates
can be exceptionally high.
Edmisten, Norman G.; Bunyard, Francis L., "A Systematic Pro-
cedure for Determining the Cost of Controlling Particular
Emissions from Industrial Sources," Journal of the Air ^n
Pollution Control Association, 20, No. 7, pp 446-452, 19/U'
The increasing concern about the air quality of our na-
tion has created a similar concern in the costs associated
with reducing emissions to desirable levels. The purpose
of this paper is to present a methodology for assessing the
cost of controlling particulate emissions from industrial
sources. Basic equipment costs were collected and evaluated
for dry centrifugal and wet collectors, fabric filters, elec-
trostatic precipitators, and afterburners. Manufacturers,
94
-------
installers, users, and operators of air pollution control
equipment were contacted to obtain the necessary cost data
for the year 1968. A basic premise of the procedure devel-
oped is that the most meaningful approach to the evaluation
and comparison of air pollution control costs is based on the
total cost of control annualized over the expected economic
life of the equipment. Items such as capital charges and
expenditures for operation, maintenance, and collected waste
disposal are generally more significant in cost accounting
than the depreciated value of the initial investment. By
defining the size and efficiency of collection required; the
Degree of difficulty in installing the equipment; and know-
ledge of some of the characteristics of the involved process,
gas stream, and pollutant characteristics, the cost of control
can be estimated with the assistance of cost factors and
guidelines presented.
Gifford, Franklin A., Jr., "Atmospheric Dispersion," Nuclear
Safety, 1, No. 3, pp 56-68, 1960.
One of the chief sources of uncertainty in estimating
the hazard associated with accidental or planned release to
the atmosphere of fission-product activity has been the lack
°f reliable measured values of atmospheric dispersion coef-
ficients. In the absence of any obvious alternative, Button's
^ell-known mathematical dispersion model has been used in
reactor hazards analyses for evaluating effects far beyond
limits for which the model can confidently be expected to
ke reliable, e.g., distances of the order of 1 km and near
adiabatic (neutral) conditions of atmospheric stability.
Consequently, the appearance, in several recent papers, of a
sizable quantity of new atmospheric dispersion observations
^•s of considerable interest in connection with the meteorology
°f nuclear safety problems. Furthermore, the calculation
°f atmospheric dispersion by the method of moving averages,
95
-------
as has been proposed recently, seems to provide an improved
means of calculating dispersion, not only because the tech-
nique has less restrictive boundary conditions but also be-
cause it is well adapted to the interpretation of continuously
monitored atmospheric data.
Gifford, Franklin A., Jr., "Atmospheric Dispersion Calculations
Using the Generalized Gaussian Plume Model," Nuclear
Safety, 2, No. 2, pp 56-59, 67-68, 1960.
A number of formulas for dealing with various practical
dispersion problems that arise in reactor hazard analyses are
based on the widely used dispersion model formulated by
Sutton. However, results of recent dispersion experiments have
more and more often been presented in terms of the simple
Gaussian interpolation formula.
Gifford, Franklin A., Jr., "Use of Routine Meteorological
Observations for Estimating Atmospheric Dispersion,"
Nuclear Safety, 2, No. 4, pp 47-51, 1961.
Estimates of atmospheric dispersion are essential infor-
mation in the selection of a reactor site and in the evaluation
of the hazards of reactor operation. In selecting a site, the
dispersion characteristics of the atmosphere at the various
sites under consideration are important because most reactors,
if not all, generate or induce some atmospheric radioactivity
during routine operation and because there is the possibility
of accidental release of radioactivity to the atmosphere.
Only a few forecasters are familiar with low-level dispersion
problems, and consequently it is desirable that simple, easily
applied methods of estimating atmospheric dispersion, preferable
those employing routine meteorological observations, be dis-
cussed.
96
-------
Gifford, Franklin A., Jr., "The Area Within Ground-Level
Dosage Isopleths," Nuclear Safety, 4, No.2, pp 91-92, 97,
1962.
The total radioactive dosage to a population has frequent-
ly been identified as an important aspect of the potential
hazard associated with reactor accidents.
The total population dosage is equal to the product of
people times radioactive dosage, summed over the population,
with appropriate high- and low-dosage cutoffs taken into
account. To expedite computation of this quantity, it is
evidently necessary to be able to calculate the area inside
ground-level isodose contours, i.e., the intersection between
the surface formed by a given air concentration or dosage
Value and the ground.
Based on ground-level air-concentration isopleths compu-
ted by means of the generalized Gaussian dispersion model
is described.
Goldfield, Joseph, "Fabric Filters in Asbestos Mining and
Asbestos Manufacturing," APCO Fabric Filter Symposium,
Charleston, Virginia, 1971.
Johns-Manvilie Corporation has hundreds of fabric filters
In use in its plants. The advantages of baghouses are their
high efficiency and reliability. The largest single baghouse
is that installed at the Jeffrey Mill No. 5 in Asbestos,
Quebec, Canada. This installation is described in detail.
Its overall mass efficiency is 99.992%.
Hailstone, R.E., "Air Pollution Control in the Cement Industry,"
Minerals Processing, 10, No. 5, pp 11-15, 1969.
There are many technical difficulties to adapt presently
available emission control devices to this complex manufacturing
Process of cement making. Controlling emissions within the
limits of recently enacted or pending air pollution control
97
-------
regulations are great in magnitude and cost. Neglect of any
one of a multitude of design parameters, or inadequate, impro-
per design of control devices can make a continuous high level
operating efficiency essentially impossible to attain.
Increased technology may permit further emission control
improvements but at high cost. Proper emphasis should now
be placed on the "technically feasible, economically reason-
able, practically enforceable" air pollution control regula-
tion, and logical priorities. The portland cement industry
recognizes that only through the cooperative efforts of the
control agency, the public and industry will it be able to
achieve the goals of desirable air quality levels.
Hills, D.W., "Economics of Dust Control," Annals of the New
York Academy of Science, 132, pp 322-334, 1964.
A brief historical introduction is given about conditions
in the U.K. asbestos textile industry in the late 1920's and
early 1930*s; reference is made to the 1931 conference between
employers and the Home Office that resulted in a code of
practice being established for dust suppression in asbestos
textile factories. Details are given of the various methods
used for dust control in the Company's factories together with
the cost of these measures. Some figures are also given for
the cost of dust control at the Cape Asbestos Company, Ltd.'s
new amosite mill at Penge. Current work on improving dust
control is discussed together with the part now played in
this by the Asbestosis Research Council.
Although asbestos textiles form only a part of the as-
bestos industry, their particular significance for this
monograph is that, at least in the United Kingdom, the hazards
associated with the processing of asbestos were recognized
sooner on the textile side than almost anywhere else. This
98
-------
was because most of the processes were dry, and hence dust
was readily formed, and also because the workers in some of
the largest factories formed a close-knit population whose
employment records went back for many years. Thus, when the
hazard was first investigated, an excellent sample of people
with varying periods of exposure to dust was available.
Hussey. A.M.W., "Dust Collection in Industry," Filtration and
Separation, 10, No. 2, pp 181-188, 1973.
The author describes the four basic types of dust col-
lection equipment: cyclone collectors, wet scrubbers, bag
filters, and electrical precipitators, and discusses some of
their major applications. He emphasizes that a successful
installation requires complete understanding between supplier
and user and to assist towards this he summarizes equipment
selection data which should be considered when installations
are being planned.
Jensen, Kenneth, E., "Concepts of Fabric Filtration for Air
Pollution Control," Filtration and Separation. 6, No. 3,
pp 254,257, 1969.
A brief review of other accepted methods of air and gas
cleaning equipment would be in order to relate them to cloth
filtration.
Where conditions permit, the filtration of gases through
a fabric media offers a number of advantages: efficiencies
down to the sub-micron range is inherent; there is a positive
barrier in place that does not depend on supplementary de-
-ices or materials such as water, changes in direction, or
electrical charges; and there is no secondary pollution
Problem. The material collected in a dry state is re-usable
if this is desired and in some cases can be sold to help
offset collection costs.
99
-------
The application of a fabric collector to a dust collection
problem is not, however, completely dependent upon economic
and efficiency factors. The physical conditions that pre-
vail have a great bearing on whether or not cloth collection
is the proper answer.
Jones, Allen H., "How to Improve Maintenance of Fabric Dust
Collectors," Minerals Processing, 10, No. 5, pp 254,257,
1969.
The key to low maintenance of a cloth dust collection
system is early detection of problems. Dust collection sys-
tems are self destructive once they begin to malfunction and
small problems becomes disasters very rapidly. Trouble in one
part of a system can affect another in a short period of time.
Weekly visual inspection of a collection system combined
with proper measurements is mandatory to maintain low cost
maintenance, free from shut-downs and crises.
The only way to accurately evaluate dust filter perfor-
mance and to anticipate maintenance trouble is to take mano-
meter, pilot tube, ammeter, and. tachometer readings. If
these readings are taken on a regular basis and compared with
former readings it will not be necessary to wait for disaster
to hit.
Lundgren, D.A.; Greene, V.W., "Filtration and Dust Control
Equipment in the Production of Controlled Air Environ-
ments," Filtration and Separation, 5, No. 5, pp 405-412,
1968.
After summarizing information which is basic to the de-
sign and operational problems of controlling the contamination
level of air within an enclosure, the authors discuss per-
formance and cost criteria for selecting air cleaning devices.
They deal in turn with the characteristics of seven types of
100
-------
air filters and other dust control devices and conclude by
considering the problems of controlling microbes in air.
Minifie, F.G.; Moyes, A.J., "Low Cost Electrostatic Precipita-
tion," Filtration and Separation, 9, No. 1, pp 52-59, 1972.
Three well-known types of dust collector are compared and
contrasted. The phenomena occurring in an electrostatic
precipitator are described to show why the various components
are needed. The factors which lead to heavy costs in elec-
trostatic precipitator construction are described. Means of
reducing these costs, using unit precipitators of pre-estab-
lished design, are indicated. Costs of installing three
types of dust collector on two different duties are compared,
and the fallacy that electrostatic precipitators are expensive
is dispelled.
Minnick, L. John, "Control of Particulate Emissions from
Lime Plants - A Survey," Journal of the Air Pollution
Control Association, 21, No. 4, pp 195-200, 1971.
This paper describes the achievements of the lime indus-
try in developing methods of handling and controlling the
various finely divided products which they produce. An ex-
tensive survey provides useful data on the availability and
performance of many of the control devices that are currently
In use, and an analysis is made of the operating efficiencies
and costs of this equipment. The environmental control pro-
grams which are currently underway in this industry are des-
cribed, and an evaluation is made of these programs. The
ultimate goals that are believed to be attainable are pre-
sented from the standpoint of emission control from individual
processes as well as from operating plant complexes. While
the paper deals primarily with practical operating and engin-
eering aspects of the subject, some information is also inclu-
ded on methods of tests and the monitoring systems that are in use.
101
-------
Morrison, Joseph N., Jr., "Controlling Dust Emissions at Belt
Conveyor Transfer Points," Transactions of the Society
of Mining Engineers, 250, No. 1, pp 47-53, 1971.
A comprehensive solution is offered to the problem of
dust emissions at belt conveyor transfer points. Details of
enclosure design are discussed and a straightforward procedure
for calculating required dust control exhaust volume is pre-
sented. Many design variables are taken into account which
heretofore have been commonly ignored or inadequately consi-
dered. These include belt widths, belt speeds, enclosure
openings, material flow rate, material bulk densities, material
lump sizes, height of material fall, material temperature, and
ambient air temperature. All of these questions are handled
by means of a "fill-in-the-blanks" type of calculation form,
permitting quick, reliable solutions by relative "non-experts.
Pasquill, F., "The Estimation of the Dispersion of Windborne
Material," The Meteorological Magazine, 90, No. 1063,
33-49,
The theoretical estimation of the concentrations arising
from sources of gaseous or finely divided particulate material
has for long been based on treatments of atmospheric diffusion
developed by Sir Graham Sutton. These formulae are reliable
for specifying the average distribution, over a few hundred
meters downwind of a source operating for a few minutes on
level unobstructed terrain, with a steady wind direction and
neutral conditions of atmospheric stability. Extension to
other circumstances has depended on empirical and often specu-
lative adjustments of the diffusion parameters.
During the last few years, investigations have shown that
a fairly rational allowance can now be made for the effects
of much of the wide variation in atmospheric turbulence which
occurs in reality. This progress includes some extension to
longer distances of travel.
102
-------
The purpose of this article is to review the recent
background of theoretical and experimental results, and to give
details of the proposed system of calculating the distribution
of concentration downwind of a source. These details are
set out in two appendices, the first giving complete instruc-
tions for carrying out the calculations, the second presenting
an example.
Popa, Bazil; Jancau, Vasile, "The Probability of Certain Con-
centrations in the Dispersion of Solid Dust Particles in
Industrial Regions," Staub-Reinhaltung der Luft. 33,
No. 1, pp 20-24, 1973.
The measurement of particulate components in the air is
necessary to the health of a community. The prediction of
concentrations of particulates is necessary for the planning
of controls on present sources and the introduction of new
industry, i.e., new sources in the region.
The influence of the wind is of prime importance; not
only its speed, but its direction, is discussed. Wind is a
random variable and mathematical presentation using statistics
are given. Various distribution curves (exponential, logistic,
Fisher-Tippett type II (Frechent) and type I (Gumbel), Cauchy,
normal Laplace-Gauss) are compared. The town of Chy, Romania
is used as an example.
Pring, R.T., "Reducing Baghouse Maintenance by Design,"
Minerals Processing, 11, No. 5, pp 8-13, 1970.
Structural baghouses comprise one branch of the fabric
collector family and are characterized by:
1. Large volume capacity
2. Normally high-temperature service
3. Custom design to fill specific needs
4. Use of large diameter filter bags
103
-------
5. Absence of internal moving parts
6. Suitability for continuous heavy duty service
Because of design flexibility, baghouses can be furnished
in almost infinite configurations and, within reason, at almost
any price the purchaser is willing to pay - ranging from the
"Model T" to the "Cadillac". Further, the choice of accessories
can affect cost materially.
Because the very substantial investment in air pollution
control equipment returns no profit, the industry-wide ten-
dency is, understandably, to keep capital costs to an absolute
minimum. It is suggested that familiarity with the many
available options in design and accessories and how they
affect maintenance and operation will help prevent problems
after startup.
Rajhans, Cyan S., "Fibrous Dust - Its Measurement and Control,
The Canadian Mining and Metallurgical Bulletin, 63,
No. 8, pp 900-910, 1970.
The strategy of fibrous dust sampling is discussed,
sampling methods are critically reviewed and their application
to coal dust is demonstrated. Fiber counting is described in
detail. An attempt is made to explain the basis of determining
the threshold limit value of asbestos and other dusts.
The paper also discusses such dust control methods as
enclosure of the process, effective local exhaust ventilation,
segregation, substitution, wet processing, and continuous
monitoring of the return air for recirculation.
Reigel, S.A.; Bundy, R.P.: Doyle, C.D., "Baghouses - What to
Know Before You Buy, Pollution Engineering, 5, No. 5,
pp 32-34, 1973.
With the advent of stricter emission standards designed
o
to produce the national quality standard of 75 |jg/m of
104
-------
particulate, only the most efficient removal devices will be
suitable. The baghouse traditionally yields high removal
efficiencies (99.9+%).
Reitze, William B.; Haladay, D.A.; Romer, Harold; Fenner, E.M. ,
"Control of Asbestos Fiber Emissions from Industrial and
Commercial Sources," Proceedings of the Second Interna-
tional Clean Air Congress, pp 100-103, 1970.
There are five major sources from which asbestos fiber
enters the air: (1) raining; (2) milling; (3) manufacturing;
(4) certain segments of the construction industry; and
(5) naturally occurring sources. The first four are created
by modern man's technology and the last by normally occurring
changes in our environment.
The operations of each source with controls that are now
in use are listed.
Roper, G.W., "Asbestos Mill Filters," IIT Research Institute
Seminar on Asbestos, 1972.
The asbestos milling industry is the largest user of cloth
filters of all industries, since the separation of the fibers
from the ore is done pneumatically. Dust collection systems
installed by the Wheelabrator Corporation at various asbestos
mills are described.
Rozovsky. H., "Air in Asbestos Milling," Canadian Mining
Journal, 78, pp 95-103, 1957.
The production of asbestos fiber in modern times depends
almost completely on air movement. Almost every part of the
operation employs air. Whether it is for ventilation and
dust control or for drying, separation or conveying, air is
required.
Nearly 400 tons of air per minute are employed in all
phases of this industry in Canada. It is readily apparent
105
-------
that to move this 10,000,000 cfm a considerable amount of
power and equipment is required. Nearly 90% of this air is
used directly in drying and milling processes.
The purpose of this paper is to discuss the importance
of air and its use in asbestos milling plants.
Rushton, A.; Griffiths, P.V.R., "Role of Cloth in Filtration,"
Filtration and Separation, 9, No. 1, pp 81-89, 106, 1972.
The influence of cloth weave patterns on the permeability
of clean monofilament and multifilament cloths is presented
and a successful correlation of pressure drop-flow data is
reported for several cloth types. The effect of cloth pore
structure on the mechanisms of cake deposition and the con-
ditions required for bridging the pore is discussed,,
Schoek, V.E., "In Mechanical Dust Collectors, It's the Fabric
that Really Counts," Engineering and Mining Journal, 173,
No. 1, pp 98-99, 1972.
Baghouse filters for reducing particulate emissions and
recovering metal values are becoming more efficient, thanks
to better filter fabrics. Here are some tips on fabric selec*
tion and installation.
Selikoff, I.J.; Hammond, E.G.; Heimann, E., "Critical Evalua-
tion of Disease Hazards Associated with Community Asbes- i
tos Air Pollution," Proceedings of the Second Internatio*1
Clean Air Congress, pp 165-171, 1970.
The results of 3,000 consecutive autopsies in New York
City is correlated with asbestos bodies. The results of
sampling the ambient air of New York City show an asbestos
—93
air level of 11-60 x 10 g/m . Types of exposure as well
as sources and control methods are discussed.
106
-------
Sullivan, Ralph J.; Athanassiadis, Yanis C., Air Pollution
Aspects of Asbestos, National Air Pollution Control
Administration, No. PH-22-68-25, Washington, B.C.,
1969.
Inhalation of asbestos may cause asbestosis, pleural or
peritoneal mesothelioma, or lung cancer. Mesothelioma is a
rare form of cancer which occurs frequently in asbestos workers
All three of these diseases are fatal once they become es-
tablished. The dose necessary to produce asbestosis has been
estimated to be 50 to 60 million particles per cubic foot-
years. No information is available on the dose necessary to
induce cancer. Random autopsies of lungs have shown "asbes-
tos bodies" in the lungs of one-fourth to one-half fo samples
from urban populations. Thus, the apparent air pollution by
asbestos reaches a large number of people.
Animals have been shown to develop asbestosis and cancer
after exposure to asbestos.
No information has been found on the effects of asbestos
air pollution on plants or materials.
The likely sources of asbestos air pollution are uses of
the asbestos products in the consturction industry and asbes-
tos mines and factories. Observations in Finland and Russia
indicate that asbestos does pollute air near mines and fac-
tories. However, no measurements were reported of the con-
centration of asbestos near likely sources in the United States,
A concentration in urban air of 600 to 6,000 particles per
cubic meter has been estimated.
Bag filters have been used in factories to control asbes-
tos emissions; the cost of this type of control in a British
factory was approximately 27.5 percent of the total capital
cost and about 7 percent of the operating cost. No informa-
tion has been found on the costs of damage resulting from
Asbestos air pollution.
107
-------
No satisfactory analytical method is available to deter-
mine asbestos in the atmosphere.
Turner, D.Bruce, Wgrkbopk of Atmospheric Dispersion Estimates,
National Air Pollution Control Administration, Cincinnati,
1970.
This workbook presents methods of practical application
of the binormal continuous plume dispersion model to estimate
concentrations of air pollutants. Estimates of dispersion
are those of Pasquill as restated by Gifford0 Emphasis is on
the estimation of concentrations from continuous sources for
sampling times up to 1 hour. Some of the topics discussed are
determination of effective height of emission, extension of
concentration estimates to longer sampling intervals9 inver-
sion break-up fumigation concentrations, and concentrations
from area, line, and multiple sources. Twenty-six example
problems and their solutions are given. Some graphical aids
to computation are included.
Werle, Donald K., "Fabric Filters in Pollution Control/' IIT
Research Institute internal report No. I.ITRI«C8196~T49
1972.
Fibrous filters are commonly used in the cleaning of air
for ventilation purposes and for industrial gas cleaning„
The latter application, of primary interest in this report9
can involve the cleaning of gases with very high dust loadings,
and many filter fabrics are available for use where corrosive
gases or moderate temperatures are involved. The intent of
the report is to cover the operating principles, design
methodology, economics, and application of fabric filters in
air pollution control.
108
-------
Wieschhaus, L.J., "Recovering Asbestos Floats with Dust Col-
lectors," Rock Products, 50, No. 8, pp 104-105, 1947.
Dust clouds created in the milling of asbestos have long
defied efficient and economical collection and it is only
recently that this problem has been successfully solved. Be-
cause of the vast quantities of asbestos lost in the form of
dust and because of the high market value of these "floats"
at the present time, it may be well to consider some of the
factors involved in the collection of asbestos.
109
-------
Appendix B
BINORMAL CONTINUOUS PLUME DISPERSION MODEL RESULTS
110
-------
SYMBOLS USED IN THE FOLLOWING TABLES
x = distance from source downwind in the direction of the
mean wind (kilometers)
a - the standard deviation in the crosswind direction of
y the plume concentration distribution (meters)
a = the standard deviation in the vertical of the plume
concentration distribution (meters)
X = fiber concentration (fibers per cubic meter)
OM = number of fibers observed by optical microscope
EM = number of fibers observed by electron microscope
111
-------
Calculation of Concentrations for Various Distances
JOHNS-MANVILLE CORPORATION ASBESTOS PRODUCTS PLANT
WAUKEGAN, ILLINOIS
Mean Wind Speed: 4.47 m/sec
Source Term -- Based on Optical Microscopy: 1.20 x 10
fibers/sec «
Based on Electron Microscope: 2.03 x 10
fibers/sec
Source Height: 10 m
Daytime Mixing Height: 800 m
Nighttime Mixing Height: 150 m
Stability Class B; DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.1
6.2
7.0
10.0
15.0
20.0
30.0
(m)
19.0
52.0
83.0
130
158
290
420
440
800
880
1,200
1,700
2,150
3,050
a
z
(m)
11.0
31.0
51.0
85.0
109
233
360
370
800
800
800
800
800
800
X 3
(fibers/in )
OM
2.71 x 101
5.03
1.98 T
7.68 x 10"t
4.94 x 10"}
1.26 x 10,
5.65 x 10,
5.25 x 10,
2.37 x 10,
2.15 x 10",
1.58 x 10~,
1.11 x 10";
8.81 x 10"o
6.21 x 10"J
EM
4.58 x 10o
8.51 x 10^
3.35 x 10o
1.30 x 10,
8.36 x 10,
2.13 x 107
9.56 x 10}
8.88 x 107
4.01 x 10}
3.64 x 10}
2.67 x 10}
1.88 x 10}
1.49 x 10}
1.05 x 10L
112
-------
Stability Class C; DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
6.5
7.3
14.6
17.0
20.0
25.0
30.0
a
(m)
12.5
34.0
55.0
86.0
105
200
285
450
570
630
1,150
1,330
1,520
1,850
2,170
a
z
(m)
7.5
20.5
30.2
49.0
61.0
115
170
265
340
380
800
800
800
800
800
X 3
(fibers /in )
OM
3.76 x 10}
1.09 x 101
4.87
1.99
1.32 1
2.70 x 10~t
1.76 x 10";
7.16 x 10"«
4.41 x 10",
3.57 x 10,
1.65 x 10" «
1.42 x 10",
1.25 x 10",
1.02 x 10"o
8.72 x 10~J
EM
6.36 x lo£
1.84 x 10,
8.24 x 10,
3.37 x 10,
2.23 x 10,
6.26 x 10,
2.98 x 10,
1.21 x 107
7.46 x 10t
6.04 x lot
2.79 x 107
2.40 x I0t
2.11 x 107
1.73 x lot
1.48 x 104-
Stability Class D: NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.5
7.0
10.0
15.0
20.0
30.0
(m7)
8.1
22.0
36.0
55.0
67.0
130
188
215
400
550
790
990
1,430
a
z
(m)
4.6
12.0
17.5
26.5
31.5
49.0
64.0
71.0
150
150
150
150
150
X 0
(fibers/m )
OM
2.18 x IQ}
2.29 x I0t
1.15 x 101
5.46
2.85
1.31 .
7.02 x 10~t
5.54 x 10"t
2.52 x 10~t
1.84 x 10"7
1.28 x 10~t
1.02 x 10",
7.06 x 10"z
EM
3.69 x 10?
3.87 x 107
1.95 x 10,
9.24 x 10,
6.51 x 10,
2.22 x 10,
1.19 x 10,
9.37 x 10,
4.26 x 10,
3.11 x 10,
2.17 x 10,
1.73 x 10,
1.19 x 10^
113
-------
Stability Class E: NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
8.0
16.0
20.0
25.0
30.0
(m)
6.0
16.5
26.5
40.0
50.0
95.0
140
220
335
620
750
920
1,070
On)
3.5
8.8
13.0
18.0
21.3
33.5
43.0
55.0
71.0
150
150
150
150
X 3
(fibers/nT)
OM
6.80 .
3,07 x 107
1.85 x 10t
1.02 x 10X
6.97
2.57
1.38 ,
6.95 x 10 "t
3.56 x 10"v
1.63 x 10":
1.35 x 10"J
1.10 x 10"i
9.44 x 10
EM
1.15 x 10?
5.19 x 10?
3.13 x 10?
1.73 x 10?
1.18 x 10o
4.35 x 10o
2.33 x 10n
1.18 x 10«
6.02 x 10-
2.76 x 10^
2.28 x 10,
1.86 x 10,
1.60 x 10
114
-------
Calculation of Concentrations for Various Distances
JOHNS-MANVILLE CORPORATION ASBESTOS CEMENT PIPE PLANT
DENISON, TEXAS
Mean Wind Speed: 4.07 m/sec
Source Term -- Based on Optical Microscopy: 3.53 x 10
fibers/sec
Based on Electron Microscopy: 1.69 x 10
fibers/sec
Source Height: 10 m
Daytime Mixing Height: 800 m
Nighttime Mixing Height: 150 m
Stability Class B; DAYTIME
8
(tan)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.1
6.2
7.0
10.0
15.0
20.0
30.0
a
o5
19.0
52.0
83.0
130
158
290
420
440
800
880
1,200
1,700
2,150
3,050
az
(m)
11.0
31.0
51.0
85.0
109
233
360
370
800
800
800
800
800
800
X 3
(fibers /m )
OM
8.74 x lo}
1.70 x 101
6.40
2.48
1.60 -
4.08 x 10"}
1,83 x 10"}
1.70 x 10,
7.65 x 10",
6.95 x 10",
5.10 x 10",
3.60 x 10",
2.84 x 10",
2.01 x 10"z
EM
4.18 x 10o
8.14 x 10o
3.06 x 10.
1.19 x 10,
7.66 x 10,
1.95 x 107
8.76 x 107
8.14 x ID}
3.66 x 107
3.33 x 10}
2.44 x 10}
1.72 x 107
1.36 x 101
9.62
115
-------
Stability Class C: DAYTIME
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
6.5
7.3
14.6
17.0
20.0
25.0
30.0
ay
(m)
12.5
34.0
55.0
86.0
105
200
285
450
570
630
1,150
1,330
1,520
1,850
2,170
vz
(m)
7.5
20.5
30.2
49.0
61.0
115
170
265
340
380
800
800
800
800
800
X .
(fibers/m )
OM
1.22 x 10?
3.52 x lot
1.57 x 101
6.41
4.25
1.20 -,
5.69 x 10~t
2.31 x 10"!
1.42 x 10 "I
1.15 x 10";
5.32 x 10~«
4.60 x 10~~
4.02 x 10,
3,31 x 10~«
2.82 x 10"z
EM
5.84 x 10 J
1.69 x 10,
7.52 x 10,
3.07 x 10,
2.03 x 10«
5.75 x 10«
2.72 x 10«
1.11 x 107
6.80 x 107
5.51 x lot
2.55 x lOt
2.20 x lot
1.92 x lot
1.58 x lot
1.35 x 101
Stability Class D: NIGHTTIME
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.5
7.0
10.0
15.0
20.0
30.0
a
(m)
8.1
22.0
36.0
55.0
67.0
130
188
215
400
550
790
990
1,430
vz
(m)
4.6
12.0
17.5
26,5
31.5
49.0
64.0
71.0
150
150
150
150
150
X 3
(fibers/in )
OM
6.96 x lot
7.39 x lot
3.72 x I0t
1.76 x 107
1.24 x 101
4.24
2.27
1.79 ,
8.16 x 10"t
5.93 x 10"t
4.13 x 10"t
3.30 x 10 "I
2.28 x 10"1
EM
3.33 x lo£
3.54 x 10?
1.78 x 10,
8.43 x 10,
5.94 x 10,
2.03 x 10,
1.09 x 10«
8.57 x 10«
3.91 x 10«
2.84 x 10«
1.98 x 10,
1.58 x 10«
1.09 x 10Z
116
-------
Stability Class E: NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
8.0
16.0
20.0
25.0
30.0
(m5)
6.0
16.5
26.5
40.0
50.0
95.0
140
220
335
620
750
920
1,070
az
Cm)
3.5
x 3
(fibers/nr)
OM
2.20 x 10}
8.8 9.93 x 10t
13.0
18.0
21.3
33.5
43.0
55.0
71.0
150
150
150
150
5.96 x 10t
3.29 x 10t
2.25 x 101
8.29
4.46
2.25
1.15 ,
5.26 x 10"!
4.35 x 10"!
3.55 x 10"!
3.05 x 10"1
EM
1.05 x 10?
4.75 x 107
2.85 x 107
1.58 x 107
1.08 x 10?
3.97 x 10^
2.14 x 10.
1.08 x 10-
5.51 x 10«
2.52 x 10-
2.08 x 10«
1.70 x 10o
1.46 x 10^
117
-------
Calculation of Concentrations for Various Distances
RAYBESTOS - MANHATTAN ASBESTOS TEXTILE MANUFACTURING PLANT
MARSHVILLE, NORTH CAROLINA
Mean Wind Speed: 3.35 m/sec
Source Term -- Based on Optical Microscopy: 1.12 x 10
fibers/sec
Based on Electron Microscopy: 3.97 x 10
fibers /sec
Source Height: 10 m
Daytime Mixing Height: 800 m
Nighttime Mixing Height: 150 m
Stability Class B; DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.1
6.2
7.0
10.0
15.0
20.0
30.0
(m)
19.0
52.0
83.0
130
158
290
420
440
800
880
1,200
1,700
2,150
3,050
(mZ)
11.0
31.0
51.0
85.0
109
233
360
370
800
800
800
800
800
800
X 3
(fibers/nr)
OM
3.37 x 101
6.27
2.47 n
9.56 x 10 T
6.15 x 10"|
1.57 x 10,
7.04 x 10,
6.54 x 10,
2.95 x 10",
2.68 x 10";
1.96 x 10",
1.39 x 10",
1.10 x 10".
7.73 x 10"J
EM
1.19 x 10?
2,22 x 10?
8.76 x 10?
3.39 x 10?
2.28 x 10?
5.57 x 10?
2.50 x 10?
2.32 x 10?
1.05 x 107
9.50 x 10o
6.95 x 10o
4.92 x 10o
3.90 x 10o
2.74 x 10J
118
-------
Stability Class C: DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
6.5
7.3
14.6
17.0
20.0
25,0
30.0
(/)
12.5
34.0
55.0
86.0
105
200
285
450
570
630
1,150
1,330
1,520
1,850
2,170
az
(m)
7.5
20.5
30.2
49.0
61.0
115
170
265
340
380
800
800
800
800
800
X 3
(fibers/nr)
OM
4.69 x loJ-
1.36 x 101
6.07
2.47
1.64 ,
4.61 x 10"t
2.19 x 10",
8.92 x 10",
5.49 x 10",
4.45 x 10";
2.05 x 10";
1.77 x 10";
1.55 x 10";
1.27 x 10",
1.09 x 10"z
EM
1.66 x 10?
4.82 x 10?
2.15 x 10?
8.76 x 10?
5.81 x 10?
1.63 x 10?
7.76 x 10?
3.16 x 10?
1.95 x 10?
1.58 x 10o
7.27 x 10o
6.27 x 10o
5.49 x 10^
4.50 x 10o
8.86 x 10J
Stability Class D; NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.5
7.0
10.0
15.0
20.0
30.0
CT
(m)
8.1
22.0
36.0
55.0
67.0
130
188
215
400
550
790
990
1,430
az
(m)
4.6
12.0
17.5
26.5
31.5
49.0
64.0
71.0
150
150
150
150
150
X 3
(fibers/m )
OM
2.71 x 10}
2.85 x 107
1.44 x 101
6.80
4.80
1.64 ,
8.74 x 10 ~t
6.90 x 10 ~t
3.14 x 10 ~t
2.29 x 10 ~t
1.59 x 10 ~t
1.27 x 10,
8.79 x 10"z
EM
9.61 x lo5
1.01 x loi
5.10 x 10?
2.41 x 10?
1.70 x 10?
5.81 x 10?
3.10 x 10?
2.45 x 10?
1.11 x 10?
8.12 x 10?
5.64 x 10?
4.50 x 10?
3.12 x 10^
119
-------
Stability Class E; NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
8.0
16.0
20.0
25.0
30.0
a
y
(m)
6.0
16.5
26.5
40.0
50.0
95.0
140
220
335
620
750
920
1,070
a
z
(m)
3.5
8.8
13.0
18.0
21.3
33.5
43.0
55.0
71.0
150
150
150
150
X 3
(fibers/m )
OM
8.46 T
3.83 x I0t
2.30 x lo!
1.27 x 101
8.68
3.20
1.72 -,
8.65 x 10~t
4.43 x 10"|
2.03 x 10"t
1.68 x 10"r
1.37 x 10 i
1.18 x 10"1
EM
3.00 x 10$
1.36 x 10£
8.15 x 10?
4.50 x 10?
3.08 x 10?
1.13 x 10?
6.10 x 10?
3.07 x 10c
1.57 x 10?
7.20 x 107
5.95 x 10?
4.86 x 10?
4.18 x 10^
120
-------
Calculation of Concentrations for Various Distances
JOHNS-MANVILLE CORPORATION MILL NO. 5
ASBESTOS, QUEBEC, CANADA
8
Mean Wind Speed: 3.89 m/sec
Source Term -- Based on Optical Microscopy: 7.63 x 10
fibers/sec
Based on Electron Microscopy: 3.05 x 10
fibers/sec
Source Height: 40 m
Daytime Mixing Height: 800 m
Nighttime Mixing Height: 150 m
12
Stability Class B: DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.1
6.2
7.0
10.0
15.0
20.0
30.0
(m)
19.0
52.0
83.0
130
158
290
420
440
800
880
1,200
1,700
2,150
3,050
°z
(m)
11.0
31.0
51.0
85.0
109
233
360
370
800
800
800
800
800
800
x 3
(fibers/nr)
OM
3.97 x 10?
1.68 x 10?
1.08 x 10.J
5.05 x 10:?
3.39 x 10X
9.10 x 10,
4.10 x 10,
3.82 x 10,
1.73 x 10,
1.57 x 10,
1.15 x lOf
8.14 x 10|
6.44 x 107
4.53 x 101
EM
1.58 x 10?
6.72 x 104
4.32 x 10^
2.02 x 104
1.36 x 10;
3.64 x 10?
1.64 x 10?
1.53 x 10c
6.92 x 10?
6.28 x 10?
4.60 x 10c
3.25 x 10?
2.57 x 10c
1.81 x 10D
121
-------
Stability Class C: DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
6.5
7.3
14.6
17.0
20.0
25.0
30.0
ay
(m)
12.5
34.0
55.0
86.0
105
200
285
450
570
630
1,150
1,330
1,520
1,850
2,170
CTZ
(m)
7.5
20.5
30.2
49.0
61.0
115
170
265
340
380
800
800
800
800
800
X 3
(fibers/in )
OM
4.52 x 1071
1.33 x 107
1.57 x 10?
1.06 x 10o
7.86 x 10.
2.55 x 10-
1.25 x 10,
5.18 x 10,
3.20 x 10,
2.59 x 10,
1.20 x 10,
1.04 x 107
9.10 x lOT
7.48 x lot
6.37 x 101
EM
1.81 x 10?
5.31 x 107
6.28 x 107
4.24 x 107
3.14 x 107
1.02 x 10;
5.00 x 10?
2.07 x 10?
1.28 x 10^
1.04 x 10c
4.80 x 10c
4.16: x 10?
3.64 x 10r
2.99 x 10?
2.55 x 103
Stability Class D: NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.5
7.0
10.0
15.0
20.0
30.0
a
(m)
8.1
22.0
36.0
55.0
67.0
130
188
215
400
550
790
990
1,430
(m2)
4.6
12.0
17.5
26.5
31.5
49.0
64.0
71.0
150
150
150
150
150
X 3
(fibers/in )
OM
6.15 x lo:11
9.25 x 10o
7.20 x 10,
1.37 x 10?
1.32 x 10?
7.03 x 10n
4.27 x 10-
3.49 x 10^
1.84 X 10q
1.34 x 10,
9.34 x 10,
7.45 x 10,
5.16 x 10
EM
2.46 x 10ft7
3.70 x 10?
2.88 x 107
5.48 x 107
5.28 x 107
2.81 x 107
1.71 x 107
1.40 x 10ft
7.36 x 10?
5.36 x 10?
3.73 x 10?
2.98 x 10?
2.06 x 10°
122
-------
Stability Class E: NIGHTTIME
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
8.0
16.0
20.0
25.0
30.0
a
(m)
6.0
16.5
26.5
40.0
50.0
95.0
140
220
335
620
750
920
1,070
a
z
(m)
3.5
X 3
(fibers/in )
OM
1.79 x io;22
8.8 1.38 x 10o
13.0
18.0
21.3
33.5
43.0
55.0
71.0
150
150
150
150
1.58 x 10-
7.38 x lOf
1.00 x 10o
7.67 x 10^
6.73 x 10o
3.96 x 10^
2.24 x 10^
1.19 x 10«
9.8 x 10«
8.02 x 10o
6.89 x 10^
EM
7.16 x 10"i9
5.52 x 10^
6.32 x 10$
2.95 x I0i
4.00 x 10^
3.87 x 10^
2.69 x 104
1.58 x 10^
8.95 x 10?
4.76 x 105
3.93 x 10^
3.21 x 10?
2.75 x 10b
123
-------
Calculations of Concentrations for Various Distances
GAF, INCORPORATED ASBESTOS MILL
EDEN MILLS, VERMONT
Mean Wind Speed: 3.89 m/sec
Source Term -- Based on Optical Microscopy: 6.40 x 10
fibers/sec
Based on Electron Microscopy: 1.83 x 10
fibers/sec
Source Height: 20 m
Daytime Mixing Height: 800 m
Nighttime Mixing Height: 150 m
10
Stability Class B: DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.1
6.8
7.0
10.0
15.0
20.0
30.0
a
y
(m)
19.0
52.0
83.0
130
158
290
420
440
800
880
1,200
1,700
2,150
3,050
a
z
(m)
11.0
31.0
51.0
85.0
109
233
360
370
800
800
800
800
800
800
X 3
(fibers/ni )
OM
4.79 x 10?
2.64 x 10«
1.15 x lOf
4.61 x lOt
2.99 x 101
7.72
3.46
3.21
1.45
1.32 ,
9.67 x 10~r
6.83 x 10"t
5.40 x 10" t
3.80 x 10"1
EM
1.32 x 10?
7.55 x 10c
3.29 x 10c
1.32 x 10?
8.55 x 10?
2.21 x 10.J
9.89 x 10^
9.18 x 10-
4.15 x 10^
3.77 x 10^
2.77 x 10o
1.95 x ID.
1.54 x 10o
1.09 x 10J
124
-------
Stability Class C; DAYTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
6.5
7.3
14.6
17.0
20.0
25.0
30.0
a
(m)
12.5
34.0
55.0
86.0
105
200
285
450
570
630
1,150
1,330
1,520
1,850
2,170
a
z
(m)
7.5
20.5
30.2
49.0
61.0
115
170
265
340
380
800
800
800
800
800
X 3
(fibers/m )
OM
1.58 x 10?
4.67 x 10,
2.53 x 10,
1.14 x 107
7.55 x 107
2.24 x 10J
1.07 x 101
4.38
2.70
2.19
1.01 ,
8.72 x 10~r
7.63 x 10 ~t
6.27 x 10 i
5.35 x 10"1
EM
4.52 x 10?
1.34 x 10c
7.23 x 10c
3.26 x 10c
2.22 x 10?
6.40 x 10?
3.06 x 10?
1.25 x 10?
7.72 x 10-
6.26 x 10o
2.89 x 10-
2.49 x 10.
2.18 x 10o
1.79 x 10o
1.53 x 10J
Stability Class D: NIGHTTIME
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
3.5
7.0
10.0
15.0
20.0
30.0
a
(m)
8.1
22.0
36.0
55.0
67.0
130
188
215
400
550
790
990
1,430
az
(m)
4.6
12.0
17.5
26.5
31.5
49.0
64.0
71.0
150
150
150
150
150
X 3
(fibers/inj)
OM
1.09 ,
4.92 x 10,
4.34 x 10,
2.70 x 10,
2.03 x 107
7.56 x 107
4.14 x lot
3.30 x 10t
1.55 x 107
1.13 x 101
7.83
6.25
4.33
EM
3.12 x 10?
1.41 x 10£
1.26 x 10c
7.72 x 10?
5.80 x 10c
2.16 x 10^
1.18 x 10?
9.49 x 107
4.43 x 10?
3.23 x 10?
2.24 x 107
1.79 x 10?
1.24 x 10^
125
-------
Stability Class E: NIGHTTIME
X
(km)
0.1
0.3
0.5
0.8
1.0
2.0
3.0
5.0
8.0
16.0
20.0
25.0
30.0
a
(m5)
6.0
16.5
26.5
40.0
50.0
95.0
140
220
335
620
750
920
1,070
a
z
(m)
3.5
X 3
(fibers /m )
OM
2.07 x 10:3
8.8 2.74 x 10o
13.0
18.0
21.3
33.5
43.0
55.0
71.0
150
150
150
150
4.65 x 10,
3.93 x 10-
3.16 x 10^
1.38 x lOf
7.81 x 10,1
4.04 x lOt
2.12 x KT
9.98
8.25
6.73
5.78
EM
5.91 c
7.83 x 10?
1.33 x 10?
1.12 x 10?
9.04 x 10c
3.95 x 10^
2.23 x 10c
1.16 x 10?
6.06 x 10?
2.85 x 10?
2.36 x 10?
1.92 x 10?
1.65 x 10^
126
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-65f)./2-74-Q88
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Assessment of Particle Control Technology for
Enclosed Asbestos Sources
6. REPORT DATE
October 1974
6. PERFORMING ORGANIZATION CODE
Colin F
Thomas P. Blaszak
PaulSiebert, and
8. PERFORMING ORGANIZATION REPORT NO
C6291-11
i PERFORMING ORG '\NIZATION NAME AND ADDRESS
IIT Research Institute
10 West 35th Street
Chicago, Illinois 60616
10. PROGRAM ELEMENT NO.
1AB015; ROAP 21AFA-006
11. CONTRACT/GRANT NO.
68-02-1353
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 6/73-5/74
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
B. ABSTRACT -phc report gives results of a study to provide information, from both the
literature and user contact, on the control of asbestos emissions from enclosed sou-
rces. It assesses the state-of-the-art in asbestos emission control in terms of the
devices or methods used and their efficiency. In addition, it gives results of a pre-
liminary study to actually measure the effectiveness of baghouse control devices in
controlling emissions from five asbestos plants. Baghouses are the predominant con-
trol device used in the asbestos industry. Cotton bags are used most frequently.
Automatic shaking is used in most baghouses, with shake cycles of 1-1/2 to 4 hours
most common. Most baghouses operate at two pressure drop ranges, 2. 5-5 and
7. 5-10 cm H2O. Air-to-cloth ratios range from 2 to 10:1. Published data on the re-
moval efficiencies of the control devices was either non-existent, or quoted in gen-
eral terms. Five baghouses were tested for removal efficiency in terms of mass and
fiber number: although mass efficiency was very high, fiber concentrations exceed-
ing 100 million fibers/cu meter, greater than about 0.05 urn long, are emitted. Using
computer modeling, it was found that, even considering one source, asbestos con-
centrations of 500 f/cu meter can be anticipated 5 km from the source. The exposure
level at which asbestos in ambient air becomes a health hazard is not known.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Asbestos
Fibers
Oust
Dust Collectors
Measurement
Cyclone Separators
Scrubbers
Efficiency
Air Pollution Control
Stationary Sources
Enclosed Sources
Particulate
Baghouses
Fabric Filters
13B , 07A
08G
HE
11G
13A
14B
8- DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
135
20. SECURITY CLASS (This page)
[Unclassified
22. PRICE
PA Form 2220-1 (9-73)
127
------- |