A 11 ID a 7 2 A A 2 M NBS

PUBLICATIONS

NBSIR 87-3666

A Method for Measuring the

Effectiveness of Gaseous

Contaminant Removal Devices

Progress Report

Bal M. Mahajan

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Building Technology

Buiilding Environment Division

Gaithersburg, MD 20899

September 1987

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS — QC

100

• U56

87-3666

1987

C . 2

Research Information Center

National Bureau of Standards

Gaithersburg, Maryland 2089Q

NBSIR 87-3666

t S A METHOD FOR MEASURING THE ~ EFFECTIVENESS OF GASEOUS

CONTAMINANT REMOVAL DEVICES ^ PROGRESS REPORT

Bal M. Mahajan

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Building Technology

Buiilding Environment Division

Gaithersburg, MD 20899

September 1987

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Acting Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

ABSTRACT

A research effort to develop test methods for measuring the effectiveness of

gaseous contaminant removal devices is underway. The objectives of the

initial phase of the research effort were to devise or select a practical

test method, design a test apparatus suitable for this purpose, develop

techniques that would permit automation of all aspects of the testing

scheme, and conduct preliminary experiments to demonstrate the feasiblity of

the testing scheme. Various aspects of the testing scheme include : supply

of conditioned air at constant flow rate with a constant value of relative

humidity for duration of the tests; safe means of contaminating the conditioned air with known gaseous contaminants at desired concentrations; and

means for measuring the contaminant concentration both upstream and downstream of the filter media.

This progress report briefly describes the test apparatus designed for

measuring the effectiveness of filter media, various components of the test

loop, instrumentation, and contaminant concentration measuring techniques.

The report also describes various aspects of the planned testing scheme that

will be followed to accomplish the goals of this research project.

1
TABLE OF CONTENTS

ABSTRACT . ii

1. INTRODUCTION ....... .............. 1

2. CONSIDERATION FOR A PRACTICAL TEST METHOD ............ 1

3 „ TEST APPARATUS .......................... 3

3.1 AIR SUPPLY SECTION . ...... ..... 4

3.2 Test Section 5

3.3 Contaminant Generation Section . . . ........ 6

3.4 Analysis Section 6

4. CURRENT STATUS . . .................. 7

5. PLANNED ACTIVITIES 7

6. ACKNOWLEDGMENT 8

7. REFERENCES 8

ii
1 . INTRODUCTION

Filtering devices using granular materials called filter media (or sorbers)

,

such as activated carbons and chemically treated alumina and other organic

substances, are being used to remove or chemically change gaseous pollutants

which are found in buildings. These devices can be incorporated into the

heating, ventilation and air conditioning (HVAC) systems of building, in a manner similar to filters used for the removal of particulate. Particulate

filters can be evaluated by using the American Society of Heating,

Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 52-76 [1].

Over the years, attempts have been made to evaluate gaseous removal filters

for some specific applications; however, no general procedures are available

for evaluating the effectiveness of these devices. Methods are needed to

provide acceptable means to evaluate these devices so that an effective and

economical control method can be promoted for improved indoor air quality.

A research effort to develop the needed methods was initiated at the

National Bureau of Standards (NBS) . The objectives of the initial phase of

the research effort were to devise or select a practical test method, design

a test apparatus suitable for this purpose, develop techniques that would

permit automation of all aspects of the testing scheme, and conduct preliminary experiments to demonstrate the feasiblity of the testing scheme.

Various aspects of the testing scheme include : supply of conditioned air at

constant flow rate with a constant value of relative humidity (Rh) for long

periods of times (from several hours to several months); safe means of

contaminating the conditioned air with known gaseous contaminants at desired

concentrations; and means for measuring the contaminant concentration, both

upstream and downstream of the filter media. The testing apparatus should

be designed to permit simulation of operating conditions, particularly the

filter medium face and/or bed velocities, without exuberant cost of running

the tests.

This progress report briefly describes the selected test method and test

apparatus designed for measuring the effectiveness of filter media, various

components of the test loop, instrumentation, and contaminant concentration

measuring techniques. The report also describes various aspects of the

planned testing scheme that will be followed to accomplish the goals of this

research project.

2 „ CONSIDERATION FOR A PRACTICAL TEST METHOD

Effective design of gaseous contaminant removal equipment for HVAC systems

is a challenging undertaking. Designers need to know gaseous contaminants

that are to be removed from the conditioned space, the probable contaminants

concentration or source of internal generation, and allowable or safe

concentration of these contaminants. Designers also need the following

information on gaseous contaminant removal devices: removal efficiency or

contaminant penetration at operating levels; useful life of the device and

maintenance requirements; sensitivity to humidity and temperature; and the

nature of any effluent products created by the device. The selected test

1
method must, therefore, facilitate the acquisition of performance as well

asuseful life expectancy data for gaseous contaminant removal devices.

Adsorption of vapors or gaseous adsorbates by granular adsorbents has been

studied by many researchers for gas-mask canisters and respirator cartridges

[2-10] . There also exist some performance test methods and standards for

filter media used in respiratory protective devices and other specialized

applications [11-16]. Various methods that have been used for studying the

performance of gaseous contaminant sorbers are summarized by Rivers [17].

These methods include : (1) complete Isotherm; (2) one-point isotherm; (3)

breakthrough or time to set penetration; (4) integrated penetration or

penetration at set inlet concentration (load); (5) odor breakthrough or

perceived breakthrough; and (6) penetration versus load or penetration as a function of elapsed time and inlet concentration.

The first method, the complete isotherm, could be used to estimate the field

performance of such devices for a set of assumed contaminants and operating

conditions. The translation of the isotherm into filter penetration and

life is, however, a laborious undertaking, and far beyond the interest and

scope of HVAC system designers and this research effort. Methods 2 through

5 provide only order-of -magnitude performance data, and are essentially

quality-control procedures [17]. Method 6, namely penetration versus load,

appears to be best suited for our purpose.

In the penetration versus load method, a filter medium is challenged with a known gaseous contaminant introduced into the intake air at a known

concentration (C-j_ or load) and the concentration downstream of the filter

medium (C Q or exit concentration-) is measured for various elapsed times. A

dimensionless quantity called penetration (C 0/C^) is computed from the

measured value of quantities Cj_ and CQ

. It is important to point out that

penetration is equal to one minus efficiency. This method can provide

needed data, namely contaminant removal efficiency and useful life of

sorbers, for at least one contaminant at the operating conditions of the

test. This method, we believe, can also be used to measure the performance

of filter media for contaminant mixtures.

Gaseous contaminant removal performance of a filter medium is dependent on

many factors, which include the following:

1. Filter parameters:

a. Type of sorber (that is, whether the filter material is a physical

adsorber, an absorber, a cheraisorber, or a catalyst).

b. Surface properties of sorber material.

c. Granule size.

d. Packing density.

e. Filter bed depth.

2. Gaseous contaminant parameters:

a. Number of contaminants (that is, one gas or a mixture of gases).

b. Physical and chemical properties of the contaminant.

c. Contaminant concentration (or load).

2
3 . Carrier air parameters:

a. Temperature.

b. Relative humidity.

c. Flow rate and/or bed velocity.

d. Presence of trace amounts of other gaseous contaminants.

4. Other factors:

a. Previous history of the filter medium, particularly its adsorbed

load of contaminants and water vapor.

b. Generation of contaminants by the sorption device.

Evaluating every filter medium for ranges of all the listed factors is

impractical. Therefore, it is important to narrow down the number and

ranges of parameters as much as possible. Initially, we will examine the

influence of some of the filter media parameters, gaseous contaminant

parameters, and carrier air parameters. The effects of the remaining

factors on gaseous contaminant removal performance of filter media will be

examined during the subsequent phases of the project.

The test method will employ an open test loop system in which sample filter

media will be challenged with known gaseous contaminants introduced into the

intake air. Compressed laboratory air will be conditioned to desired levels

of humidity and temperature; the conditioned air will be contaminated with a known gaseous contaminant at desired concentrations; and the contaminated

air will pass through the filter where the contaminant will be removed. The

contaminant concentration upstream of the filter media (C-j_) and downstream

of the filter media (C Q ) will be measured using gas chromatography. Data on

filter media penetration (i.e., C 0/C^) as a function of elapsed time and

other relevant factors will be collected. These data will be utilized to

determine breakthrough conditions and life and or capacity of the filter

media. These data will also make it possible to compare the performance of

different filter media and to estimate system effectiveness and cost.

3. TEST APPARATUS

The apparatus for measuring the performance of filter media will utilize the

test canister described in the ASTM Standard D3803 [13] with some design

modifications. The ASTM test canister is of practical size for small-scale

tests of granular adsorbers, chemisorbers and catalysts. The canister is

small enough to allow convenient control of all the desired test conditions,

and yet large enough to average out the filter media variations and avoid

significant edge effects [17]. The canister is intended for a face velocity

of 0.2 m/s (40 fpm) ; however, tests can be conducted at face velocities as high as 0.4 m/s (80 fpm). Scrubbers, and other gaseous contaminant removal

devices may require a larger test apparatus, but the cost of running the

tests encourages use of the smallest representative of the prototypes.

The schematic of the basic test apparatus is shown in Figure 1. It is an

open loop system consisting of four principal components: an air supply

section, a test section, a contaminant generation section, and an analysis

3
section. A brief description of the four components is given below.

3.1 AIR SUPPLY SECTION

In this section humidity, temperature, and flow rate of air for experiments

are adjusted to desired values and monitored. Compressed laboratory air at

room temperature is conveyed through a 6.4 mm inside diameter (ID) nylon

tube via a manually operated pressure regulator (PR1) followed by a computer

controlled flow regulator (FR1). The flow regulator FR1 will regulate and

monitor the flow rate of air flowing to the system. From this point the air

can be sent directly to the humidification section or, if desired, it can be

routed to the humidification section through a pre-filter section. The prefilter, depending on the need, may consist of: silica gel as a drying and

general absorbing medium; activated carbon as a general control medium; and

any other filter medium needed to remove specific trace contaminants.

The humidification section is shown schematically in Figure 2. It consists

of a controller, a chilled water circulator bath, a constant temperature

water vessel, and a water reservoir. The circulating bath can also be

heated if desired. Only distilled water is used in this system. Water from

the chilled water circulator bath circulates through the constant temperature water vessel containing a platinum resistance temperature detector

(RTD) for monitoring the temperature of the water. The flow rate of the

circulating water and the temperature of water in the vessel are adjustable.

The constant temperature water vessel consists of a heavily insulated

polyethylene bottle; the bottle is placed in a rectangular container

fabricated with polyvinyl chloride (PVC) panels and the space between the

bottle and container is packed with insulating material. The water

reservoir is connected to the water circulator bath to replenish the water

used in humidifying the air.

Air at room temperature (22-24°C) enters the constant temperature water

vessel via a finely perforated nylon tube, bubbles through the water chilled

to any desired temperature, passes through a restrainer, and leaves the

vessel nearly saturated at the vessel temperature from the top in a 10.5 mm

ID 3 m long nylon tube. The air is then routed through a 10.5 mm ID 1.5 m

long stainless steel tube to a measurement section. During its passage

through these tubes air is heated back to room temperature.

The measurement section is a combination of 10.5 mm ID nylon and stainless

steel tubes, where the temperature and relative humidity of the air are

monitored with a thermistor and a dew point hygrometer respectively. At

this point air may either be routed to the test section or it may be sent to

the exhaust hood. By maintaining constant temperature and water level in

the constant temperature vessel the relative humidity of the supply air can

be maintained at nearly a constant value for any length of time. The value

of relative humidity can be changed by changing the temperature of water in

the vessel. When the flow rate and relative humidity of the supply air has

been properly adjusted to the desired value, the conditioned air is then

directed to the test section and the testing is initiated.

4
3 . 2 Test Section

The test section, including important dimensions of its various parts, is

shown schematically in Figure 3. All parts of the test section have been

fabricated with stainless steel materials. The test section consists of

three sub-sections: air contamination section; test canister assembly, and

exhaust. These three sub-sections and their components are listed below,

and the listing follows the direction of the air flow.

The Air Contamination Section consists of the following: A 10.5 mm ID

tube, containing a port 'P0' for adding gaseous contaminant to the air

stream; a 6.4 mm ID tube, which is connected to a 10.5 mm ID tube, about 260

mm long, ending in a 90° elbow; a 10.5 mm ID tube, leading to the top end

cap of the test canister assembly, and containing a port 'PI' for

withdrawing samples of contaminated air for measuring the inlet contaminant

concentration (C-jO or contaminant load. The contaminated air enters the

test canister assembly through the side wall, where the air flow expands as well as changes its direction by 90 degrees.

The Test Canister Assembly consists of the following cylindrical vessels:

a top end cap; two interchangeable test canisters (one 25 mm deep and one 51

mm deep), only one of the two test canisters has the filter media, and. the

canister containing the filter media is followed by the empty canister; and

a bottom end cap. The side wall of the bottom end cap is fitted with a 10.5

mm ID tube, containing a port 'P2' for withdrawing samples of the filtered

air for measuring the contaminant concentration downstream of the filter

(Co).

The details of the test canister are shown schematically in Figure 4. It

essentially is the test canister described in ASTM D3803 with some design

modifications suggested by Rivers [18]. The canister is a 52 mm ID, 25.4 mm

or 50.8 mm long, cylindrical vessel. Both ends of the canister are

specially designed to accommodate a perforated screen, a baffle ring, and a snap ring at each end. One of the ends also accommodate an 0-ring. The

space between the two perforated screens is packed with the filter medium.

The Exhaust system , primarily, consists of the laboratory exhaust hood. The

open end of the tube of the bottom end cap containing port P2 is connected

to a rotameter type flowmeter (FR1) for monitoring the flow rate of air

flowing through the test apparatus. Air leaving the rotameter is routed to

the laboratory exhaust hood via a 10.5 mm ID nylon tube. The location of

the rotameter has been indicated in Figure 1. The tube leading to the

exhaust hood is not shown in any Figure.

Conditioned air will enter the 10.5 mm ID tube of the air contamination

section. The gaseous contaminant will be introduced into the air stream

through port P0 at a constant flow rate. The passage of the contaminated

air through the reduced diameter tube and 90 degree elbow will enhance the

mixing process. The contaminated air will then flow through the test

canister assembly containing the filter medium where a portion of the

gaseous contaminants will be removed. The air will then be exhausted into

the exhaust hood. Samples of contaminated air will be drawn through ports

5
PI and P2 at regular intervals and sent to a gas chromatograph where they

will be analyzed for the purpose of measuring the contaminant concentrations

C-l (load) and C Q (exit concentration).

3 • 3 Contaminant Generation Section

The contaminants, which are gases at room temperature, will be acquired as high purity commercially available compressed bottled gases. The high

purity gaseous contaminant from a compressed cylinder will be routed to port

PO of the test section in a 3.2 mm outside diameter (OD) nylon tubing. A

manually operated pressure regulator (PR2) , a computer controlled flow

regulator (FR2) , and a rotameter type flowmeter (FM2) will be placed in the

gas line for adjusting and monitoring flow rate of the contaminant. The

location of these instruments has been indicated in Figure 1.

The contaminants, which are liquids at room temperature, will be used in the

tests as follows. A nearly saturated mixture of air and contaminant vapor

will be generated for the experiments. The apparatus for this purpose is

shown schematically in Figure 5. It consist of three vessels (Al , A2 and

A3) in series; vessels Al and A2 contain liquid contaminant at room

temperature and vessel A3 is empty. Compressed clean air at room

temperature will .be conveyed to vessel Al through a 3 . 2 mm OD nylon tubing

via a manually operated pressure regulator (PR2) followed by a computer

controlled flow regulator (FR2) for adjusting the flow rate of air. The air

from vessel Al will be sent first to vessel A2 and then to vessel A3.

Passing through the liquid contaminant in vessels Al and A2 , the air will be

nearly saturated with contaminant vapors; vessel A3 will serve to remove any

contaminant droplets which might be entrained in vessel A2 . This nearly

saturated air and contaminant vapor mixture from vessel A3, will be sent to

port PO of the test section via the rotameter FR2

.

3 . 4 Analysis Section

Analysis section consists of a computer controlled gas chromatograph (GC)

with a packed stainless steel column, a ten port automatic gas sampling

valve, and a flame ionization detector (FID). The gas chromatograph can be

operated with two detecting systems. It can also be operated with most

detectors including: electron capture detector (ECD) , flame ionization

detector (FID) , flame photometric detector (FPD) , hot wire detector (HWD)

,

Nitrogen Phosphorus detector (NPD) , and thermal conductivity detector (TCD)

.

Air samples, SI from port PI and S2 from port A2 , will be conveyed to the GC

for analysis via the ten port sampling valve. The flow path that will be

used is shown schematically in Figure 6. The flow path uses one carrier

inlet, one column, and one detector, and two loops; loop LI for sample SI

from port PI, and loop L2 for sample S2 from port P2 . The contaminant

concentration data along with other relevant data will be recorded for

further analysis. The exhaust gases from the GC will be sent to the

laboratory exhaust hood.

6
4. CURRENT STATUS

The test apparatus has been designed, fabricated and assembled. Initial

checking of various parts of the apparatus and instrumentation has either

been completed or is underway. The gas chromatograph has been acquired,

installed and inspected. Three different grades of carbons (filter medium)

have been acquired, and two more carbons, from a different vender, are being

acquired. The gaseous contaminant (n-Butane) to be used in the initial

experiments has been acquired. Development of computer software for

controlling the experiments and analyzing the test data is underway.

5 . PLANNED ACTIVITIES

Most of the experiments will be conducted at room temperature (22-24°C)

using moist air having three different values of relative humidity, about

30, 40, and 50 per cent. Initial tests will be conducted with 2-Butane as the gaseous contaminant and a coal based carbon as the filter medium. The

surface area and bulk density of the selected carbon are 600 to 700 m^/g and

0.55 to 0.60 g/cc respectively. During the initial tests, the test

apparatus, various instrumentation, software, and the testing procedures

will be checked and debugged, and modified if necessary.

The conditioned air (about 30% relative humidity, and 22-24°C) will be

contaminated with 2 -Butane to achieve a concentration level of about 100

parts per million (ppm) ; subsequent tests will be conducted with 2-Butane

concentrations of about 150 .ppm, 75 ppm and 30 ppm. During these

experiments data on the contaminant concentration upstream of the filter

medium (C^) and downstream of the filter medium (C Q ) will be collected as a function of elapsed time. These data will be plotted as penetration (C 0 /C^)

versus dimensionless elapsed time (t/r) as shown in Figure 7. Where r is

the residence time (the time spent by a vapor or gaseous contaminant in a bed of filter media granules).

Subsequently, experiments with other gaseous contaminants and filter media

will be conducted by following the procedure outlined above. Gaseous

contaminants for the experiments will be selected according to their

possible adverse health effects, and their presence in the indoor air.

Selected contaminants will include representatives of various classes of

volatile organic compounds (VOC) . For example: methanol for alcohols;

formaldehyde or hexanal for aldehydes; trimethylpentane for alkane; toluene

for aromatic hydrocarbons; trichloroethane for halo-carbons; 2-butanone for

ketones; etc.

During this work, close cooperation with the ASHRAE technical committee on

gaseous air contaminants and gas contaminant removal equipment (TC 2.3) will

be maintained. The findings of the initial experiments will be shared with

members of this committee; and their suggestions regarding the selection of

filter media and gaseous contaminants will be sought. In this way, it is

expected that the ASHRAE would use the results of this study as a basis for

promulgating a consensus standard.

7
6 . ACKNOWLEDGMENT

This work is sponsored jointly by the National Bureau of Standards and the

Consumer Product Safety Commission.

The author wishes to express his sincere gratitude to:

1. MR. Richard D. Rivers, Vice-president, Environmental Quality Sciences,

Louisville Ky. , for his many valuable suggestions during the design of

the test apparatus.

2. DR. Richard A. Grot for his continued support and many helpful

~ suggestions

.

3. Messrs Douglas Pruitt, William S. Dols, and Steven J. Nabinger for

their valuable contribution during assembly of the test apparatus.

7 . REFERENCES

1. ASHRAE 52-76, "Method Of Testing Air-Cleaning Devices Used In General

Ventilation For Removing Particulate Matter," ASHRAE , Atlanta GA 30329.

2. Hayward, D. A. and Trapnell, B. M. W. " CHEMSORPTION " Butterworths

,

Washington, D. C.,1964.

3. Nelson, G. 0. and Correia, A. N. /'Respirator Cartridge Efficiency

Studies: VIII. Summary and Conclusions," Am. Ind. Hyg. Assn." J.37:

514-5.25, 1976.

4. Nelson, G. 0. and Harder, C. A.," Respirator Cartridge Efficiency

Studies: V. Effect of Solvent Vapor," Am. Ind. Hyg. Assn. J. 33:391,

1974.

5. Freeman, G. B., and Reucroft, P. J. ," Adsorption of HCN and H2 O Vapor

Mixture By Activated and Impregnated Carbons," Carbon Vol 17: 313-

316,1979.

”

6. Hanna, G. F. and Kuehner, R. L. , "Critical Factors in Odorant Measurement and Control," ASHRAE Symposium "Odors and Odorant: The Engineering

View" Atlanta GA 30329, 1969.

7. Jonas, L. A., Tewari, Y. B., and Sansone, E. B. ," Prediction of

Adsorption Rate Constants of Activated Carbon for Various Vapors, " Carbon Vol 17: 345-349, 1919.

8. Jonas, L. A. and Svirbely, W. J., "The Kinetic of Adsorption of Carbon

Tetrachloride and Chloroform from Air Mixture by Activated Carbon," J.

of Catalysis 24: 446-459, 1972.

9. Jonas, L. A., Sansone, E. B., and Farris, T. S.," Prediction of

Activated Carbon Performance for Binary Vapor Mixtures," Am. IND. Hyg.

Assn. J. 44:716-719, 1983.

8
10. Department of Interior, Bureau of Mines: Respiratory Protective

Devices: Test for permissibility. 30 CFR 11, Sub-parts I and L.

11. MIL-C-13724: Charcoal, Activated, Impregnated, ASC. Naval Publications

and Forms Center, Philadelphia, PA 19120.

12. MIL-STD-282: Filter Units, Protective Clothing, Gas-Mask Components and

Related Products: Performance Test Methods, 1956.

13. ASTM D3803, Radioiodine Testing of Nuclear-Grade Gas-Phase Adsorbents,

ANNUAL BOOK of ASTM Standards Part 30, ASTM, Philadelphia, Pa 19103.

14. ASTM D3467, Carbon tetrachloride Activity of Activated Carbon, Annual

Book of ASTM Standards , Part 30. ASTM, Philadelphia PA 19103

15. ASTM E544, Referencing Suprathreshold Odor Intensity. ANNUAL BOOK of

ASTM Standards Part 30. ASTM, Philadelphia PA 19103.

16. Ostajic, N. ,"Test Method for Gaseous Contaminant Removal Devices,"

ASHRAE Transactions 1985, Vol 91 Pt.2.

17. Rivers, R. D ., "Practical Test Method For Gaseous Contaminant Removal

Devices," Proc . Indoor Air Quality Workshop, NBS . Gaithersburg Md

20899, 1986.

18. Rivers, R. D., Vice-President, Environmental Quality Sciences,

Louisville KY, Many personal communications.

9
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BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 87 3666

2. Performing Organ. Report No. 3. Publication Date

-

4. TITLE AND SUBTITLE

A Method for Measuring the Effectiveness of

Gaseous Contaminant Removal Devices

5. AUTHOR(S)

Bal M. Mahajan

6. PERFORMING ORGANIZATION (If joint or other than NBS, see in struction s)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most si gnificant in formation. If document includes a si gn i fi cant

bi bl iography or literature survey, mention it here)

A research effort to develop test methods for measuring the effectiveness of gaseous

contaminant removal devices is underway. The objectives of the initial phase of the

research effort were to devise or select a practical test method, design a test

apparatus suitable for this purpose, develop techniques that would permit automation

of all aspects of the testing scheme, and conduct preliminary experiments to demonstrate

the viability of the testing scheme. Various aspects of the testing scheme include:

supply of conditioned air at constant flow rate with a constant value of relative

humidity for the duration of the tests; safe means of contaminating the conditioned

air with known gaseous contaminants at desired concentrations; and mean's for measuring

the contaminant concentration both upstream and downstream of the filter media.

This progress report briefly describes the test apparatus designed for measuring the

effectiveness of filter medias , various components of the test loop, instrumentation,

and contaminant concentration measuring techniques. The report also describes various

aspects of the planned testing scheme that will be followed to accomplish the goals of

this research project.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semi colon s) apparatus; contaminants; device; effectiveness; filter; gaseous; media; method;

removal; sorber; test

13. AVAILABILITY

[jj^Unl i mi ted For Official Distribution. Do Not Release to NTIS

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20402.

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