EPA-650/3-75-001
JANUARY 1975
Ecological Research Series
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EPA-650/3-75-001
ENVIRONMENTAL EXPOSURE SYSTEM
FOR STUDYING AIR POLLUTION
DAMAGE TO MATERIALS
by
John W. Spence, Fred D. Stump,
Fred H. Haynie, and James B. Upham
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
National Environmental Research Center
Research Triangle Park, North Carolina 27711
January 1975
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application
of environmental technology. Elimination of traditional grouping wan
consciously planned to foster technology transfer and a maximum interface
in related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH series This
series describes research on the effects of pollution on humans, plant and
animal species, and materials. Problems are assessed for their lony- and
short-term influences. Investigations include formation, transport, and
pathway studies to determine the fate of pollutants and their eifccls. This
work provides the technical basis for setting standards to minimize unduti-
able changes in living organisms in the aquatic, terrestrial, and atmospheric
environments.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and Development,
Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and policies
of the Environmental Protection Agency . nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
DISTRIBUTION STATEMENT
This report is issued by the Environmental Protection Agency to report techni-
cal data of interest to a limited number of readers. Copies are available free
of charge to Federal employees, current contractors and grantees, and non--
profit organizations—as supplies permit—from the Air Pollution Technical
Information Center, Environmental Protection Agency, Research Triangle
Park, North Carolina 27711. Document is available to the public, for a fee,
through the National Technical Information Service, Springfield, Virginia
22161.
Publication No. EPA-650/3-75-001
11
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ABSTRACT
Design features of a controiled-environment exposure system consisting
of five chambers are described. The purpose of the environmental system is
to provide simulated environments for conducting statistical experiments for
determining pollutant damage to materials. Design features include independ-
ent controls for regulating temperature, relative humidity, and concentration
of gaseous sulfur dioxide, nitrogen dioxide, and ozone. To achieve acceler-
ated "weathering," the system also includes a variable dew/light cycle that
incorporates chill racks to produce dew and xenon lamps to simulate sunlight.
Before initiating exposure studies, differences in lighting and pollutant
distribution among the chambers were minimized to below 10 percent variation
for 95 percent of the measurements.
111
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CONTENTS
Section
LIST OF FIGURES v
LIST OF TABLES V
ACKNOWLEDGMENTS vi
ABBREVIATIONS AND SYMBOLS vi
INTRODUCTION 1
DESIGN FEATURES OF ENVIRONMENTAL SYSTEM 2
Airflow Details 2
Exposure Chambers 4
Pollutant Control System 6
CHAMBER EVALUATION AND OPERATION 11
Chamber Lighting 11
Pollutant Distribution 13
Control of Environmental Variables 14
SUMMARY 16
REFERENCES 16
APPENDIX A: ENVIRONMENTAL COMPONENTS 17
APPENDIX B: POWER DISTRIBUTION OF ENVIRONMENTAL SYSTEM 17
APPENDIX C: ELECTRICAL AND GAS LINE SCHEMATICS FOR NITROGEN
DIOXIDE DILUTION SYSTEM 29
APPENDIX D: ELECTRICAL AND GAS LINE SCHEMATICS FOR SULFUR
DIOXIDE DILUTION SYSTEM 33
APPENDIX E: SIMPLIFIED CIRCUITRY OF POLLUTANT CONTROLLER 37
IV
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LIST OF FIGURES
Figure Page
1. Environmental System Flow Diagram 3
2. Environmental Exposure Chambers 5
3. Exposure Chill Racks 5
k. Dilution System 7
5. Pollutant Controller 8
LIST OF TABLES
Table
1. Analysis of Variance for Initial Lamp Energy Data 1]
2. Analysis of Variance for Lamp Energy Data 12
3. Analysis of Variance for Pollutant (NCO Distribution
within the Chambers 14
U. Control Capability of Environmental Variables within
the Chambers 15
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ACKNOWLEDGMENT
The authors wish to acknowledge Dennis Body, John Bobrowski, and
Ralph Baudendistel for assisting with the design and construction of the
environmental system and Sarah Meeks for assisting with the balancing of
chamber lighting and pollutant distribution.
The pollutant controllers were designed and built by Adgo, Inc.,
under contract to the Environmental Protection Agency.
ABBREVIATIONS AND SYMBOLS
ac alternating current
°C degrees Celsius (centigrade)
cm centimeters
°F degrees Fahrenheit
min minute
mm millimeters
m cubic meters
N0p nitrogen dioxide
NpO, nitrogen tetroxide
NO oxides of nitrogen
Jt.
0, ozone
ppm parts per million
psig pounds per square inch gauge
SCR silicone controlled rectifier
SO sulfur dioxide
pg micrograms
ym micrometers (microns)
VI
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ENVIRONMENTAL EXPOSURE SYSTEM
FOR STUDYING AIR POLLUTION
DAMAGE TO MATERIALS
INTRODUCTION
This report describes the design, hardware, operation, and safety
features of a controiled-environment exposure system consisting of five
chambers. The system is equipped with automatic controls for regulating
temperature, humidity, dew/light cycle, and concentrations of sulfur
dioxide, nitrogen dioxide, and ozone pollutants within each chamber. The
description of the operational capabilities of the environmental system
should be beneficial to those laboratories within the Environmental Pro-
tection Agency that are conducting controlled environmental effects
research, as well as industrial and educational organizations conducting
similar research.
The purpose of the environmental system is to provide simulated envi-
ronments for conducting statistical experiments for determining pollutant
damage to materials. Resulting information, such as predictive equations
of dose-response relationships, will be used in setting secondary ambient
air quality standards and in assessing economic damage to real property as
specified in the Clean Air Amendments of 1970.
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DESIGN FEATURES OF THE ENVIRONMENTAL SYSTEM
The controiled-environment exposure system consists of five chambers
and necessary hardware to control the flow, concentration of pollutants
(SO , NO , 0 ), temperature, and relative humidity of the incoming air to
each chamber. In addition, each chamber features a controlled dew/light
cycle that simulates diurnal conditions. This allows the surfaces of
exposed test specimens to absorb and concentrate gaseous pollutants as
material surfaces do in the real world. The system was designed so that
a continuous single-pass movement of air flows through each chamber, there-
by preventing possible accumulation of material decomposition products.
Hardware essential in assembling the environmental system is shown in
Appendix A.
AIRFLOW DETAILS
Figure 1 shows a flow diagram of the environmental system, and Appen-
dix B shows the interfacing of components. Ambient air is drawn into a
galvanized steel duct (6l by 6l cm) and is filtered by a system that removes
99 percent of the 5-ym or greater particulate matter. The air next passes
through a charcoal filter to remove gaseous contaminates, then to a dehu-
midifying/cooling system consisting of a chiller with glycol/water coolant
and aluminum cooling coils. The cooling system has been equipped with a
low-level cutoff switch that automatically shuts off the chiller if a loss
of coolant occurs. The dehumidifying/cooling system conditions the clean
air to about 1°C and 100 percent relative humidity.
The conditioned clean air now passes into an insulated manifold duct
(1*0.6 by U0.6 cm, galvanized steel). The manifold distributes up to 3-U
m3/min of clean air to each chamber through individual air supply ducts.
Each air supply duct contains a heater and steam injection port to recon-
dition the clean air to a specified temperature and humidity and a high-
temperature sensor and cutoff to prevent overheating. From the air supply
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AIR INLET
i
ROUGHING
FILTER
PARTICULATE
FILTER
CHARCOAL
FILTER
DEHUMIDIFYING/
COOL ING SYSTEMS
CENTRIFUGAL
BLOWER
r
i
HEAT AND STEAM
(HUMIDITY)
J.
MIXING BOX
HEAT/HUMIDITY CONTROLS
GASES: S02, N02, 03
INJECTION PORT
MANIFOLD INTO 4
OTHER
ENVIRONMENTAL
UNITS
1
CHAMBER
1
MAN I FOLD FROM 4
' OTHER CHAMBERS
CHARCOAL
FILTER
PURAFIL
FILTER
EXHAUST TO
ATMOSPHERE
Figure 1. Environmental system flow diagram.
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duct, the heated and humidified air flows through an insulated, flexible,
vinyl tubing (10.2-cm diameter) to a mixing box that houses temperature
and humidity control/recording sensors and separate injection ports for
gaseous sulfur dioxide, nitrogen dioxide, and ozone pollutants. Injection
of the pollutants is upstream of the humidity sensors. This feature pre-
vents contamination of the sensor. The mixing box (galvanized steel coated
with epoxy sealant) has fins on the inside walls to promote better disper-
sion of pollutants with the incoming air stream. The reconditioned, pol-
luted air then flows into the base of a stainless steel chamber, across a
plenum to promote mixing of the air, over a chill rack containing the test
specimens, and out through a flexible, vinyl exhaust line (10.2-cm diam-
eter). This airflow pattern is the same for all five chambers.
The exhausted air from each chamber passes into a central air exhaust
duct and then to an outlet containing charcoal and Purafil filters. The
Purafil filter is a chemical system that combines with contaminates that
the charcoal filter does not absorb. The decontaminated air exhausts
directly to the outside environment.
If an interruption in the flow of air in the environmental system
should occur, an airflow sensor, mounted in the duct between the filtering
and cooling sections, automatically deenergizes the entire system and
closes off the pollutant supply lines. This feature prevents buildup
within the exposure chambers of pollutant concentrations that could result
in personnel injury and damage to on-going exposure experiments.
EXPOSURE CHAMBERS
Each of the exposure chambers (Figure 2) has an inside volume of 1.10
m and is covered externally with 10.2- to 12.7-cm-thick polyureathane foam
insulation (a. self-extinguishing material). Each chamber contains a xenon
arc lamp (6000 watts) to simulate sunlight. A cap on top of the chamber
houses the lamp, and clear FEP Teflon film (l mm thick) separates the light
from the environmental conditions within the chamber. This kind of film
was selected because it transmits practically all of the ultraviolet, vis-
ible, and infrared radiation emitted by xenon lamps. Each chamber also
contains a chill rack (Figure 3) upon which the test specimens are mounted.
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Figure 2. Environmental exposure chambers.
FigureS. Exposure chill racks.
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With the lamp off, coolant circulates through the rack; this cools the test
specimens and results in the formation of dew. When coolant stops circu-
lating, the lamp comes on and the dew evaporates from the test specimens.
Appendix B shows the interfacing of the lamp power units and chamber chill
racks. Two of the lamp power units are shared by four chambers; the remain-
ing chamber has an individual unit. A safety device protects each power
supply and xenon lamp against coolant overheating or loss of coolant
pressure.
An interlock switch on each chamber door cuts off the lamp if personnel
open the door during the light cycle, thus protecting their eyes against
ultraviolet radiation.
POLLUTANT CONTROL SYSTEM
The pollutant control system consists of a source and controller for
each of the three gaseous pollutants. The purpose of the system is to con-
tinuously dispense, monitor, and control the desired level of sulfur diox-
ide, nitrogen dioxide, and ozone concentrations within each of the environ-
mental exposure chambers. In this report, no attempt is made to determine
concentrations of the reaction products of these gaseous pollutants. How-
ever, product concentrations can be determined since the reaction rates for
these pollutants are known.2
Pollutant Sources
Cylinders of liquid nitrogen tetroxide (N^) and sulfur dioxide (SO )
serve as sources for gaseous nitrogen dioxide and sulfur dioxide, respec-
tively. The cylinders, along with dilution tanks (Figure U), are housed in
a cabinet with an exhaust system to remove fumes in the event of line leak-
age. Both cylinders are maintained at constant temperatures. Schematics
of the electrical wiring and gas lines, with a description of nitrogen
dioxide and sulfur dioxide pollutant source components, are shown in
Appendixes C and D, respectively. The two schemes are basically similar
except for several minor differences in gas line connections. They oper-
ate by diluting regulated flows of concentrated polluted gas with compressed
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Figure 4. Dilution system.
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air in a dilution tank representing a low-pressure sink. The pressure with-
in the dilution tank, which has three compartments to facilitate mixing, is
automatically maintained between set limits. The diluted gas, which is
about 20 percent pollutant, then flows at a reduced pressure (^3 psig) to
the respective pollutant controller, which distributes the gas (at differ-
ent rates depending en desired concentration) to the mixing box of each
chamber. The interfacing of the dilution source with the controllers is
shown in Appendix B.
A modified ozone generator produces ozone by exposing dry air to a
high-voltage discharge (commonly referred to as a silent arc discharge
generator). Concentrations of ozone up to 5 ppm per chamber are readily
available with this unit. No dilution system is necessary. The generator
is operated with dry air and a voltage setting that minimizes the forma-
tion of oxides of nitrogen (NO ). A chemiluminescence analyzer was unable
j£
to detect NO formation within the environmental chambers.
The pollutant source design contains several safety features to pro-
tect personnel and the environmental exposure system. The cylinders of
SO and N_0, have thermal and pressure cutout devices to prevent exceeding
predetermined conditions. In the event of momentary loss of power to the
environmental system, a sensor automatically cuts off the flow of the three
pollutant gases to the controller. This feature prevents the accumulation
of high concentrations of pollutants in the chambers.
Pollutant Controllers
The pollutant controllers (Figure 5) are identical except for the
pollutant analyzers, which are specific for each of the three pollutant
gases. Chamber concentrations of nitrogen dioxide and ozone are monitored
by cherailuminescence analyzers and sulfur dioxide is monitored by flame
photometric detection. Each analyzer samples the chambers one at a time; a
synchronized stepping switch operating solenoid valves automatically main-
tains the sequence of chamber sampling.
The controllers are equipped with adjustable sample and control timers
(sample and control modes of operation). The sampler timer allows the
analyzer to stabilize at the level of pollutant concentration in the chamber
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FigureS. Pollutant controller.
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being sampled. At the end of the stabilization time, the control timer
begins the control function. The amount of pollutant, as determined from a
signal transmitted by the analyzer, is balanced against a preset potentio-
meter that has been calibrated for pollutant concentration. The difference
or imbalance is transmitted by a silicone controlled rectifier (SCR) system
to a servo valve that opens or closes depending on the direction required.
The simplified circuit of the controller is shown in Appendix E. The inter-
facing of the controllers with the pollutant sources and environmental
chambers is shown in Appendix B.
During the initial start-up of a chamber, the imbalance is great since
the concentration of pollutant is low in the chamber. The pollutant servo
valve opens on a time basis that is adjustable and preset by the control
timer. Once the pollutant concentration is near the desired level (the
difference or imbalance has narrowed), the proportional band that is adjust-
able in the SCR system limits the travel of the servo valve until the adjust-
able "dead band" (no control action taken) is reached. Therefore, in the
control mode of operation, the controller functions as both a step system -
opening the pollutant servo valve a set interval of time - and as a propor-
tional system - opening the pollutant servo valve a proportional amount as
determined by the imbalance.
Following the initial sample and control time, the pollutant controller
switches automatically to the next chamber and begins the sample and con-
trol modes of operation. The sequence is repeated continuously for the five
chambers. As the controller approaches the set point (desired level of
pollutant concentration) for each chamber, proportional control is estab-
lished and maintained for the exposure period. The controller maintains
the desired pollutant concentration by operating in the proportional band.
Each of the pollutant controllers has means to override any of the
automatic operations, including by-passing individual chambers during
sequencing.
10
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CHAMBER EVALUATION AND OPERATION
The experimental results of a chamber exposure study will only "be as
good as the control system. Before proceeding with exposure experiments
to determine pollutant damage to materials, the control capability of the
environmental variables as well as the chamber distribution of light energy
and pollution concentration were minimized below 10 percent for 95 percent
of the measurements. This level of variability was considered acceptable
for conducting material-effects research. Statistical techniques were
used to determine what parts of the environmental control system needed
adjustment.
CHAMBER LIGHTING
The energy distribution from the xenon lamp within the chambers was
measured and recorded as millivolts by a Talley Industries SOL-A-Meter.
The distribution of energy on the specimen racks within the five chambers
was initially balanced by: (l) varying the lamp wattage, (2) placing
reflectors in the light cap, and (3) varying the angle of the specimen
rack. Analysis of variance (Table l) was conducted on the energy data to
determine chamber and position effects.
Table 1. ANALYSIS OF VARIANCE FOR INITIAL LAMP ENERGY DATA
Source
Position
Chamber
Residual
Total
Sum of
squares
311-9379
1*9- ^9
206.2371
567.61*99
Degrees of
freedom
17
It
68
89
Mean
squares
18.31*93
12.3687
3-0229
6.3781
F
calc .
6.05
It. 08
F
table
1.76a
2.05a
0.05 probability level.
Residual is confounded with a possible chamber times position interaction
effect because the experiment was not replicated. It is taken as the
error term in calculating F values.
11
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The calculated F statistics determined for the positions on the specimen
racks and the chambers exceed the Table F value (0.05 probability level).
Therefore, the observed differences for the positions and chambers are
statistically significant and caused by something other than random error.
The best estimate of the overall mean (x) energy was 63-28 millivolts. Based
on 89 degrees of freedom, the standard deviation (2S) is 5-05- The coeffi-
cient of variation is 1* percent. With these tolerance limits, we can be 95
percent certain that less than 10 percent variation from the mean energy may
be expected from 95 percent of the measurements.
High energy readings at particular positions were lowered by selec-
tively reducing the reflectivity of the walls with a light spray of flat,
black paint. Individual lamp wattages were adjusted to reduce differences
among chambers. Analysis of variance (Table 2) was performed on the new
data for the five chambers.
Table 2. ANALYSIS OF VARIANCE FOR LAMP ENERGY DATA
Source
Position
Chamber
Residual
Total
Sum of
squares
55-5960
5-7005
89.0596
150.3560
Degrees of
freedom
IT
4
68
89
Mean
squares
3-270U
1.1*251
1-3097
1.6891*
F
calc.
2.05
1.09
F
table
1.76a
2.50a
0.05 probability leve].
Residual is confounded with a possible chamber times position interaction
effect because the experiment vas not replicated. It is taken as the
error term in calculating the F values.
The calculated F statistics (Table 2) now reveal that the chamber
differences are statistically insignificant. The position effect, however,
is still significant at the 0.05 probability level. The best estimate of
the overall mean (x) energy was 61.51 millivolts with a standard deviation
(2S) of 3.38 for 89 degrees of freedom. The coefficient of variation is 3
percent. With these tolerance limits, we can be 95 percent certain that
less than a 6.8 percent variation from the mean energy exists for 95 percent
12
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of the measurements. This relatively small amount of variability does not
warrant the stratification of position as a variable. Placing the material
test specimens randomly within each of the five chambers minimizes any bias
that could be caused by the position effect.
POLLUTANT DISTRIBUTION
It is essential that the movement of polluted air be uniformly dis-
tributed across the test specimens. The airflow from each chamber was
measured in the exhaust ducts with a pitot tube and was balanced by adjust-
ing a vane installed in the chamber air supply duct.
To establish the distribution pattern of polluted air within the
chambers, blue colored test fabrics were placed at various locations
within the chambers about 15 -2h en above the base and parallel to the
airflow. The test fabric was developed by the American Association of
Textile Chemists and Colorists and changes color on exposure to nitrogen
dioxide. All five chambers were operated with no dew/light at the follow-
ing constant conditions:
Temperature 35°C
Relative humidity 5 percent
•3
Nitrogen dioxide 9^0
Airflow 1.13 m /min per change
After U8 hours of exposure, color changes of the fabric samples were mea-
sured photoelectrically with a Hunter Model D 25A Color Difference Meter.
Statistical computation of mean fade and standard deviation indicated that
pollutant distribution was not balanced within the five chambers.
A plenum (sheet of aluminum with 0.7^-cm-diameter holes spaced 2.5
cm apart) was next installed about 12.7 cm above the base of the chamber.
The plenum creates a pressure drop in the movement of air across it,
thereby facilitating the mixine of pollutants within the chambers. The
pressure drop across the plenum was measured and balanced for the five
chambers. The exposure of the test fabric was repeated. An analysis of
variance (Table 3) was conducted on the new data to determine the signi-
ficance of chamber and position effects.
13
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Table 3. ANALYSIS OF VARIANCE FOR POLLUTANT
DISTRIBUTION WITHIN THE CHAMBERS
Source
Position
Chamber
Residual
Total
Sum of
squares
0.023UU
o.ooteU
0.02U1
0.05209
Degrees of
freedom
8
U
32
kk
Mean
square
0.00293
0.00106
O.OOOT6
0.00118
F
calc.
3.ei*
1.1+0
F
table
2.25a
2.67a
0.05 probability level.
^Residual is confounded with a possible chamber times position interaction
effect because the experiment was not replicated. It is taken as the
error term in calculating F values.
The calculated F statistic (Table 3) for the pollutant distribution
within the chambers indicates that the chamber effect is statistically
insignificant; however, position effects exist at the 0.05 probability
level. The best estimate of the overall mean (x) for the Ae values was 3-50
with a standard deviation (2S) of 0.069 for 8 degrees of freedom. The
coefficient of variation is 1 percent. With these tolerance limits, we can
be 95 percent certain that less than a 2.25 percent variation from the mean
fade is expected for 95 percent of the measurements. Again, randomly placing
the test specimens within the chambers minimizes bias that this variable may
cause.
CONTROL OF ENVIRONMENTAL VARIABLES
Tested control points and the resulting control capabilities of the
environmental variables are shown in Table U.
Air temperature and humidity are controlled in the air stream (mixing
box) entering each environmental chamber. During the cycle of dew and
light, the air temperature and humidity within the chambers are allowed tc
fluctuate, thereby simulating diurnal conditions; but the desired
concentration of each gaseous pollutant is monitored and controlled within
the chambers during the dew/light cycle by the controller system.
The control capability was computed from data obtained from a strip
chart during 2k hours cf continuous dew/light (?0 minutes) exposure. The
14
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variability (2S) for the control capability of the environmental variables
appears to increase with the mean level (x). This is frequently encountered
in automatic controlled experimentation and should pose no problem in the
computation of exposure data. The variation of the five variables is within
the acceptable limit of 10 percent.
Table U. CONTROL CAPABILITY OF ENVIRONMENTAL VARIABLES*1
Env ir onmen t al
variable
Temperature, C°
b
Humidity, percent
Ozone, yg/m
Sulfur dioxide, ug/m
0
Nitrogen dioxide, pg/m
Control
point
35
90
50
980
196
1310
262
9^0
Control capability
X
3U.8
88.8
50.1*
991.8
199-9
1372.9
275-1
930.6
2S
+2
+2.2
+1.1
+31. U
+11.8
+131.0
+23.6
+26.3
of the five chambers was operated with a 20-minute dew/light cycle,
Controlled in mixing box.
15
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SUMMARY
An environmental system for controlling the temperature, humidity,
and concentration of gaseous pollutants within five chambers has been
designed and assembled. The environmental system was basically designed
to assess the effects of gaseous air pollutants on materials; the opera-
tional capabilities, however, could benefit other laboratories conducting
controlled environmental experimentalion. In addition, statistical tech-
niques were utilized to reduce chamber differences in lighting and pol-
lutant distribution to below 10 percent variation for 95 percent of the
measurements. This feature was necessary before planned exposure studies
could be initiated and should be of interest to those researchers collecting
effects data from chamber exposure studies.
REFERENCES
1. Clean Air Amendments of 1970. Public Law 91 6Qk. December 31, 1970.
2. Leighton, P.A. Photochemistry of Air Pollution. New York, Academic
Press, 1961.
16
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APPENDIX A:
ENVIRONMENTAL COMPONENTS
17
-------
AIR CONDITIONING SYSTEM
Farr, Type J-12 Prefliter and Type 200 Particulate Filter
Barneby-Cheney, Type FMA Charcoal Filter Cell
Dunham-Bush, Package Chiller, 5 tons
Westinghouse Electric, WAF-l82l+-6D Aluminum Water Coil
ILG Industries, Type BCF Blower, Size 2000
AIR RECONDITIONING SYSTEM
Edwin L. Weigend, Model CAB-62 Duct Type Heater
Barber-Coleman, CP 5^09-208 Solid State Proportional Temperature Con-
troller, ESP 6111 Solid State Receiver Controller, ESP 686l Solid
State Transmitter, ASAP 301 Power Supply, and Ts 5229 Temperature
Sensor
Fluid Flow Products, Model 2331FUB Motorized Steam Valve Hydrodynamics,
Model 15-3226 Humistat and Narrow Range Humidity Sensors
Edwin L. Weigend, Model CES 72 Boiler, Chromalox Electric
Honeywell, Model Y153836-(2lt)-(i*8)-0-000-002-10-002-l8l-062 Recorder,
Temperature Sensor, and Relative Humidity Gold Grid Sensor
Adgo, Gaseous Pollutant Controllers
Bendix Process Instrumentations, Model 8300 Total Sulfur Analyzer,
Model 8101-B Oxides of Nitrogen Analyzer, and Model 8002 Ozone
Analyzer
Welbach Ozone Generator, W-10 Unit
Atlas Electric Devices, Model RM-60 Xenon Arc System (6000 watts)
AIR EXHAUST SYSTEM
Barneby-Cheney, Type FMA Charcoal Filter
Burrough and Associates, PC-22A Purafil Chemical Filter
18
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APPENDIX B:
POWER DISTRIBUTION OF
ENVIRONMENTAL SYSTEM
19
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NJ
O
L.
BOILER
FUSES
CHAMBER
BLUE M
HUM TEMP
AND
VACUUM
MAIN
CIRCUIT
BREAKER
PANEL
F BREAKER PANEL
3
O
ae
o
i
t-
co
CHAMBER POWER OISTR
LOW WATER RESERVOURl ^. RRF'SSU
LEVEL CUTOFF SW | CUTOUT
1
CM BREAKER
*23
*25
CKT BREAKER
*27
PKT RRPAKFR
*29
;KT BREAKER
*31
1 7T^ '
r1
HIGH TEMP
SENSOR
AND CUTOUT
7
1
IHIGH TEMP
SENSOR
AND CUTOUT
RESET
— j ..
HEATER RELAY -
-3
HIGH TEMP
ccfjcnp
AND CUTOUT
-3
HIGH TEMP
• SENSOR
AND CUTOUT
3
N
HIGH TEMP
• ^FKKOR
AND CUTOUT
RESET
• 1
RESET
W ' '
HEATER RELAY
RESET J
i i
HtAltn NtUY
RESET 1
— J ,
r?>
HEATER RELAY
RE GENERATOR -~ BOILER HATER |_^ WATER ! PWP
SW (BOILER) LEVEL SWITCH | MOTOR
CONTROLLER *1
HEATFRf.2 ^ HEATER
CONTROLLER »Z
CONTROLLER *3
HEATERS ^ HEATER
"" CONTROLLER *«
HEATER* 5 -^ HEATER
CONTROLLER »5
(Al
-------
\Ci/ /-
CKT BREAKERS;
10
CKT BREAKER
#3
^ )
i^
ZEROSWITCHE
— —| RESET I*-
X*
^ nun FT?
. , — 1
=£ ± RECORDER ?- °3 ANALYZER^
n
Iv ZERO SWITCHES
\^
f~' r''|HL
jAS CONTROLLER
SHUTDOWN TIMER
1 '
CONTROLLED
OUTLETS SHUT '
DOWN RELAY
LOW WATER
PRESSURE
N02
CORDE
*
1 ZERO
i SWITCHES
"n r
~l
n ^ K i NO? ANAI Y7FR -^ -• *
y^-, RECORDER |— ^ [*°2 ANALYZER)-. Jft-
-€ ^
IT ^
r
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Ul
^
7
y
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1
L
J
-*•
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-••
i I
s k
pp
03 - 3 03 L L L
CONTROLLER • T~f T
J i U
f T r
N02 =- N°2 _L
b CONTROLLER - ^ f r
- * r— ' '
S02 I U S02
CONTROLLER - -»
JLj
OTHER
CONTROLLED
OUTLETS M,
03 MANIFOLD t — ^ 03
AND » — ^ SAMPLES
VACUUM PUMP 4 — ,
_} 1
N02 MANIFOLD t = ^ N02
AND » — ^ SAMPLES
VACUUM PUMP •• — i
_*
S02 MANIFOLD* - ^ iU2
AND S - 3 SAMPLES
UAnillM PUMP —
-1 ! 1
— »•
CHANCE R
)_ ». (ONE OF FIVE)
i
_ OZONE
SWITCH1 GENERATOR
, N02
1
r J
II
II
-------
ts>
I-J
o.
CE
CC
m
z
o
o
a.
a:
WALL
OUTLET
DILUTION SYSTEM
VENT AIR
—»- TO OUTDOORS
-------
<
Q-
o
t—
3
m
Q_
cr
UJ
to
0
,
S
HUMIDITY SENSOR
&un rnwrpni i FR
#1
HUMIDITY SENSOR
AND CONTROLLER
#?
HUMIDITY SENSOR
&un rnuTDni i FR
#1
HUMIDITY SENSOR
#4
HUMIDITY SENSOR
Awn rnwTorii i PR
#5
STEAM VALVE
MOTOR #1
STEAM VALVE
MOTOR*?
STEAM VALVE
MOTOR #3
STEAM VALVE
MOTOR#4
STEAM VALVE
MOTORtfS
STEAM
• SOLENOID
SWITCH
lON PANEL i
•-*• -a STEAM
S SOLENOID
•-*- -S VALVE
z
K
=3
»—
UJ
o:
fT)
T
to
(A)
-------
ro
POWER OFF SWITCH
(BEHIND MAIN PANEL)
MAIN AC
POWER
CONTRACTOR
(SIMPLIFIED)
TO OUTLETS
BY CONTROL
PANEL
-------
XENON LAMPS AND SPECIMEN
CHILLER CYCLE CONTROLLER
MAIN
I SWITCH
L»I>;
TIMER
SWITCH
\
COLO WATER
SOLENOID*!
SELECT LAMP#4 OR#5
SELECT LAMP #2 OKtH
IGNITE*40R#5
COLD WATER
SOLENOID*?
INTERLOCK PWR SUPPLY* 1
ERLOCKPWR SUPPLY*.2
LAMP COOLANT
LAMP COOLANT
XENON PWR
SUPP#3
XENON LAMP#3
CONTROL CIRCUIT
NJ
in
-------
tsi
XENON PWR
SUPP«2
CKT
BREAKER
* 35
RESET
LAMP COOLANT
PRESSURE
INTERLOCK
SNITCH
LAMP COOLANT
TEMPERATURE
SWITCH
-------
<
UJ
K
m
^~
3
o
o
z
o
o
OL
LAMP COOLANT
PRESSURE
INTERLOCK SWITCH
LAMP COOLANT
TEMPERATURE
SWITCH
-------
N>
00
CKT BREAKER
13 AND#14
AUX CHILLER
MAIN CHILLER
CKT BREAKER
#5
CKT BREAKER
BLUE M VACUUM
CKT BREAKER
433
BLUEM
HUM TEMP
LOW GLYCOL
LEVEL CUTOFF
SWITCH
MAIN
CHILLER
-------
APPENDIX C:
ELECTRICAL AND GAS LINE SCHEMATICS
FOR NITROGEN DIOXIDE DILUTION SYSTEM
29
-------
HEATER
TAPE
& 2li
. ELECTRIC LINE
. GAS LINE
CONTROLLER
TT
^i
m.
-------
ELECTRICAL CIRCUITRY
A. 110-volt ac electrical line.
B. Thermo-overcurrent circuit breaker (0.1 amp) and sensing thermo-
stat with manual reset - cuts off current to heater tape and gas
solenoid valve when nitrogen tetroxide (NpOi ) cylinder tempera-
ture exceeds a predetermined temperature.
C. Toggle switch (located on top of the vented cabinet) - manual
switch that deenergizes dilution system.
D. SCR therrao-controller (208 volts) transformer and heater tape -
maintains nitrogen tetroxide cylinder at 120°F.
E. Overpressure cutout switch with automatic reset - cuts off current
to SCR thermo-controller and heater tape when pressure of the
nitrogen tetroxide cylinder exceeds a predetermined pressure.
F. Dilution pressure control switch - opens and closes both air and
nitrogen dioxide solenoid valves to maintain the dilution tank
pressure in the preselected range.
G. Heating tape and control Variac - keeps dilution tank above
ambient room temperature.
H. Circuit protective 3-amp fuse.
I. Neon bulb - indicates system is energized.
GAS LINE
1. Cylinder of nitrogen tetroxide (NO,).
2. Manual valves on nitrogen tetroxide cylinder.
3. Compressed air line - maintained at 30 psig.
U. Manual valve - permits venting nitrogen dioxide line.
5. Solenoid valves with pressure control switch - supplies air and
nitrogen dioxide gas when dilution tank pressure drops below 20
psig.
6. Manual valve (nitrogen dioxide line) - allows flow adjustment of
nitrogen dioxide gas (100 percent) to dilution tank.
7. Manual valve (air line) - allows flow adjustment of compressed
air to dilution tank.
8. Short length of Teflon tubing - permits observing flow of diluted
gas to tank.
31
-------
9. Dilution tank - supplies nitrogen dioxide gas (^20 percent) in
pressure range of 20 to 29 psig.
10. Manual valve - permits venting of the dilution tank.
11. Solenoid valve - stops flow of diluted nitrogen dioxide gas to
controller if power failure occurs.
12. Manual valve - off/on valve in diluted gas line.
13. Low-pressure regulator - maintains pressure of 3 psig of diluted
nitrogen dioxide gas to controller.
32
-------
APPENDIX D:
ELECTRICAL AND GAS LINE SCHEMATICS
FOR SULFUR DIOXIDE DILUTION SYSTEM
33
-------
OJ
.p..
SET FOR 2
IQO'F
AIR
TO CONTROLLER
~
11
(LOW PRESSURE
REGULATOR IN
CONTROLLER)
12
. ELECTRIC LINE
.GAS LINE
iOl TUBING HEATING TAPE
G
SCR
C
.BOTTLE
( HEAT 13
t TAPE
-------
ELECTRICAL CIRCUITRY
A. 110-volt ac electrical line.
B. Thermo-overcurrent circuit "breaker (0.1 amp) and sensing ther-
mostat with manual reset - cuts off current to heater tape and
gas solenoid valves when sulfur dioxide (S0p) cylinder temperature
rises above a predetermined temperature.
C. SCR thermo-controller (110 volts) and heater tape - maintains
sulfur dioxide cylinder at 90°F.
D. Toggle switch (located on top of the vented cabinet) - manual
switch that deenergizes dilution system.
E. Overpressure cutout switch with automatic reset - cuts off
current to SCR thermo-controller and heater tape when line
pressure exceeds a predetermined pressure.
F. Dilution pressure control switch - opens/closes both air and
sulfur dioxide solenoid valves to maintain dilution pressure in
the preselected range.
G. Heater tape on sulfur dioxide lines - maintains lines above
ambient room temperature to prevent condensing of the sulfur
dioxide.
H. Circuit protective 3-amp fuse.
I. Neon bulb - indicates system is energized.
GAS LINE
1. Cylinder of liquid sulfur dioxide (S0?).
2. Manual valves on sulfur dioxide cylinder.
3. Compressed air line - maintained at U6 psig.
h. Solenoid valves with pressure control switch - supplies air and
sulfur dioxide gas (100 percent) when dilution tank pressure
drops below 32 psig.
5. Manual valve - permits venting of sulfur dioxide gas (100 percent)
6. Pressure gauge - monitors pressure in the sulfur dioxide cylinder.
T. Manual valve (sulfur dioxide line) - allows flow adjustment of
sulfur dioxide gas (100 percent) to dilution tank.
8. Manual valve (air line) - allows flow adjustment of air to dilu-
tion tank.
35
-------
9. Dilution tank - supplies sulfur dioxide gas (^20 percent) in
pressure range of 32 to 39 psig.
10. Manual valve - allows contents of dilution tank to be vented.
11. Solenoid valve - stops flow of diluted gas to controller if power
failure occurs.
12. Low-pressure regulator - maintains pressure of 3 psig of diluted
sulfur dioxide gas to controller.
36
-------
APPENDIX E:
SIMPLIFIED CIRCUITRY OF
POLLUTANT CONTROLLER
37
-------
00
RETRANSMITTING
SLIDEW1RE ON RECORDER
AC
SAMPLE
TIMER
CONTROL
TIMER
SCR
CONTROL
VALVE
OPEN
REVERSIBLE MOTOR FOR VALVE CONTROL
(1 OF 5)
TO CCW, MOTOR #1
/ \»
SCR
CONTROL
VALVE
CLOSE
I
AC TO DC
RECTIFIER
TOCCW.MOTORj#2
TO CCW, MOTOR #3
TO CCW, MOTOR #4
TO CCW, MOTOR #5
TO CW, MOTOR #1
TO AC NEUTRAL
.TOCW,MOTOR#2
-TOCW,MOTOR#3
-TO CW.MOTOR #4
-TO CW, MOTOR #5
POLLUTANT
METERING TO CHAMBER
VALVE
(1 OF 5)
POLLUTANT
SOURCE
SET POINT POTENTIOMETER
(1 OF 5)
"7
TO SET POINT POT #2
TO SET POINT POT #3
TOSET POINT POT #4
TO SET POINT POT #5
STEPPING SWITCH
NEUTRAL
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO
EPA-650/3-75-001
3 RECIPIENT'S ACCESSIOWNO.
TITLE AND SUBTITLE
Environmental Exposure System for Studying Air
Pollution Damage to Materials
5 REPORT DATE
January 1975
6 PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
John W. Spence, Fred D. Stump, Fred H. Haynie,
and James B. Upham
8 PERFORMING ORGANIZATION REPORT NO
9 PERFORMING OR~ANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Research and Development
National Environmental Research Center
Research Triangle Park, North Carolina 27711
10 PROGRAM ELEMENT NO
11 CONTRACT/GRANT NO
12 SPONSORING AGENCY NAME AND ADDRESS
13 TYPE OF REPORT AND PERIOD COVERED
Final
14 SPONSORING AGENCY CODE
15 SUPPLEMENTARY NOTES
16 ABSTRACT
Design features of a controlled-environment exposure system consisting of five
chambers are described. The purpose of the environmental system is to provide
simulated environments for conducting statistical experiments for determining
pollutant damage to materials. Design features include independent controls for
regulating temperature, relative humidity, and concentration of gaseous sulfur
dioxide, nitrogen dioxide, and ozone. To achieve accelerated weathering, the
system also includes a variable dew/light cycle that incorporates chill racks to
produce dew and xenon lamps to simulate sunlight. Before initiating exposure
studies, differences in lighting and pollutant distribution among the chambers
were minimized to below 10 percent variations for 95 percent of the measurements.
17
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
IDENTIFIERS/OPEN ENDED TERMS
COSATI I icId/Group
air pollution
materials (air pollution effects)
experimental techniques (air pollution
effects)
nitrogen dioxide
ozone
sulfur dioxide
13 DISTRIBUTION STATEMENT
Release unlimited
19 SECURITY CLASS (This Report)
Unclassified
21 NO OF PAGES
50
20 SECURITY CLASS /Thispage)
Unclassified
22 PRICE
EPA Form 2220 1 (9-73)
39
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