NATIONAL BUREAU OF STANDARDS REPORT

7891

PERFORMANCE TEST OF

AN AUTOMATIC RENEWABLE FILTER MEDIA

manufactured by

United States Gypsum Company

Des Plaines,, Illinois

by

Carl W. Coblentz and Paul R. Achenbach

Report to

General Services Administration

Public Buildings Service

Washington 25 , D. C.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set fortli in the Act of Congress,

March 3, 1901, as amended by Congress in Public Law 019, 1950. These include the development and maintenance of the national standards of measurement and the provision of means

and methods for making measurements consistent with these standards; the determination of

physical constants and properties of materials; the development of methods and instruments

for testing materials, devices, and structures; advisory services to government agencies on

scientific and technical problems; invention and development of devices to serve special needs

of the Government; and the development of standard practices, codes, and specifications. The

work includes basic and applied research, development, engineering, instrumentation, testing,

evaluation, calibration services, and various consultation and information services. Research

projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau’s unique competence is required.

The scope of activities is suggested by the listing of divisions and sections on the inside of

the back cover.

Publications

The results of the Bureau’s research are published either in the Bureau’s own series of

publications or in the journals of professional and scientific societies. The Bureau publishes

three periodicals available from the Government Printing Office: The Journal of Research,

published in four separate sections, presents complete scientific and technical papers; the Technical News Bulletin presents summary and preliminary reports on work in progress; and .the Central Radio Propagation Laboratory Ionospheric Predictions provides data for determining

the best frequencies to use for radio communications throughout the world. There are also

five series of nonperiodical publications: Monographs, Applied Mathematics Series, Handbooks.

Miscellaneous Publications, and Technical Notes.

A complete listing of the Bureau’s publications can be found in National Bureau of Standards Circular 460, Publications of the National Bureau of Standards, 1901 to June 1947 ($1.25),

and the Supplement to National Bureau of Standards Circular 460, July 1947 to June 1957

($1.50), and Miscellaneous Publication 240, July 1957 to June 1960 (includes Titles of Papers

Published in Outside Journals 1950 to 1959) ($2.25); available from the Superintendent of

Documents, Government Printing Office, Washington 25, D.C.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1003 - 30-10630 May 27, 1963 7891

PERFORMANCE TEST OF AN AUTOMATIC

RENEWABLE FILTER MEDIA

manufactured by

United States Gypsum Company

Des Plaines^ Illinois

by

Carl W. Coblentz and Paul R. Achenbach

Mechanical Systems Section

Building Research Division

to

General Services Administration

Public Buildings Service

Washington 25,, D*C.

IMPORTANT NOTICE NATIONAL BUREAU OF ST/

for use within the Government, and review. For this reason, the whole or in part, is not authori Bureau of Standards, Washingto

the Report has been specifically |

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

s accounting documents intended

subjected to additional evaluation

listing of this Report, either in Office of the Director, National

the Government agency for which

>pies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PERFORMANCE TEST OF AN AUTOMATIC

RENEWABLE FILTER MEDIA

manufactured by

United States Gypsum Company

Des Plaines, Illinois

by

Carl W. Coblentz and Paul R. Achenbach

1 . Intro duction

At the request of the Public Buildings Service,, General

Services Administration,, the performance characteristics of

an automatic renewable air filter media manufactured by the

United States Gypsum Company was determined. The scope of

this examination included the determination of the arrestanc

and the dust-holding capacity of the media when operated at

a face velocity of 500 ft/min. and at a pressure drop up to

0.50 in. W.G.

2 . Description of Test Specimen

The test specimen was manufactured and supplied by the

United States Gypsum Company of Des Plaines,, Illinois. It

was a roll of a blue fiber glass mat, about 30 in. long and

16 in. in diameter. The mat was designed as an automatic

renewable type filter medium for the G. S. A. designation

type E filter. The media was compressed to approximately

1/4 in. thickness in the roll, but it expanded to about

2 3/4 in. thickness when unrolled. The glass fiber mat was

treated with an organic binder and the mat was denser at

the downstream side than on the upstream. The mat had been

treated with an oily adhesive and weighed about 39 grams/sq.

ft. A microscopic examination showed that the glass fibers

were between 25 and 60 microns thick and several Inches

long.
- 2 -

3 . Test Method and Procedure

The medium was tested at the rated face velocity of 500

ft/mln. The arrestance determinations were made with the

NBS Dust Spot Method described in a paper by R. S. Dill

entitled "A Test Method for Air Filters” (ASHVE Transactions, Vol. 44, p. 379* 1938). The roll of media was

installed in a "Conomatic” roll-filter frame manufactured

by Continental Air Filters, Inc., of Louisville, Kentucky,

for the test. This mechanism was modified for use with

the National Bureau of Standards air filter test apparatus

by providing it with an air-tight enclosure and adapters

to fit the upstream and downstream sections of the test

duct. This roll-filter frame had been used previously

for testing the manufacturer’ s own media and was representative of the apparatus used for this type of media.

The Conomatic frame equipped with the U. S. Gypsum media

was installed in the test apparatus and carefully sealed

to prevent any bypass of air or inward leakage into the

test apparatus, except through the measuring orifice.

After establishing the correct air flow rate through the

filter, samples of air were drawn from the center points

of the test duct two feet upstream and eight feet downstream of the test specimen at equal rates and passed

through known area of Whatman No. 4l filter paper. The

arrestance determinations were made with Cottrell

precipitate Injected Into the air stream at a ratio of

one gram per 1,000 cu. ft. of air.

The light transmission of the sampling papers was measured

before and after the test on the same area of each paper

and the two sampling papers used for any one arrestance

determination were selected to have the same light transmission when clean.

For determining the arrestance of the filter, different

size areas of sampling paper were used upstream and downstream of the filter in order to obtain a similar increase

of opacity on the two sampling papers. The arrestance

was then calculated by the formula:

. A = (i - !§

x * 100
-3-

where the symbols Su and Sp are the upstream and downstream

sampling areas and AU and AD are the observed changes In

the opacity of the upstream and downstream sampling paper,

respectively.

Arrestance determinations were made at the beginning and

at the end of the test of the specimen and at several

intermediate loading conditions. The arrestance determinations were made with Cottrell precipitate only, while

cotton linters were added during the loading process in a ratio of 4 parts to every 96 parts of Cottrell precipitate,

including that amount of Cottrell precipitate used for

arrestance measurements. The Cottrell precipitate had

been previously sifted through a 100-mesh screen and

the lint was prepared by grinding No. 7 cotton linters

through a Wiley mill with a 4-millimeter screen.

The pressure drop across the media was recorded at the

beginning of the test of the specimen, after each

arrestance determination, after introduction of each 20-

gram increment of Cottrell precipitate into the test

duct, and at the beginning and end of each advance cycle.

The advance of the filter media was observed through a window in the test apparatus by determining the position

of a marker, attached to the mat, relative to a yardstick

mounted in the filter housing, adjacent to the mat. A

pilot light connected in parallel with the electric motor

enabled the operator to record the pressure drop across

the medium at the beginning and at the end of each advance

cycle. The pressure switch was adjusted to commence the

advance cycle when the pressure drop reached approximately

0.500 in. W.G.

4 . Test Results

The pressure drop and arrestance values determined for

the test specimen are shown in table 1.
-4-

Table 1

Pressure Drop

Pressure Drop,

in. W.G.

0.140

0.450

0.455

0.470

0.475

and Arrestance

Arrestance

%

64*

76

77

78

78

*initial, with clean medium

It will be noted that the pressure drop of the clean

medium was 0.140 in. W.G. and showed an arrestance of 64

percent. At steady state, i.e., after several advance

cycles, when the pressure drop varied between 0.485 in.

W.G. and 0.440 in. W.G. a series of arrestance determinations produced values ranging from 76 percent to 78

percent, averaging 77 percent. The arrestance values

were approximately proportional to the pressure drop of the

medium and it may be assumed that the average value would

have been about one percent higher if the media had been

operated closer to the 0.500 in. W.G. maximum permissible

pressure drop.

Table 2 presents the cumulative dust weights received by

the 2 ft. wide media, the Individual and cumulative

lengths of mat travel and the pressure drop before and

after each advance cycle.
-5-

Table 2

Dust Load,, Mat Travel, and Pressure Drop of

the U. S. Gypsum Company Glass Fiber Media

Dust Load Mat Travel, in. Pressure Drop, in. W.

Grams Advance Total

Before

Advance

After

Advance

562 4 4 0.480 0.440

625 2 1/2 6 1/2 0.485 0.445

666 2 1/2 9 0.480 0.440

729 1 1/2 10 1/2 0.485 0.445

791 1 1/2 12 0.485 0.445

833 2 14 0.480 0.440

895 1 15 0.480 0.440

937 2 17 0.480 0.445

979 1 18 0.480 0.445

999 1 19 0.480 0.445

1083 2 21 0.485 0.450

1125 1 1/2 22 1/2 0.485 0.445

1167 1 23 1/2 0.485 0.445

The first movement of the media was 4 in. and occurred with

a dust load of 562 grams and at a pressure drop of 0.480 in.

W.G. across the 4 sq. ft. of exposed mat. The two succeeding

advance lengths were both 2 1/2 in. and,, thereafter, ten

further movements advanced the mat between 1 in. and 2 in.

each, a total of 14 1/2 in. The pressure drop at the

beginning of the advance cycles was from 0.480 to 0.485 in.

W.G. and ranged from 0.440 to 0.450 in. W.G. at the end of

the cycles. The average pressure differential was O.O38

in. W.G.

The dust-holding capacity per unit area of the test specimen

was determined as the slope of a straight line that best

fitted the observed values of mat travel and dust load as

plotted in Figure 1 . The graph shows the performance of

the media after the two first advance cycles. It will be

noted that the individual points of observation are scattered

from the straight line to an equivalent of up to 20 grams

dust load which is caused by the fact that the indicated

dust load values are based on an integral number of 20.83

gram increments of dust and lint and, also, that the advance

distances could not be observed on the scale to better than

the nearest half-inch mark. According to the straight line

in Figure 1 , which represents the average advance movement

of the media which would maintain the pressure drop across

the mat between 0.444 and 0.482 in. W.G. on the average
-6 -

all times, it is shown that after 9 in. of mat travel the

dust load was 6J0 g and after 24 in. travel the dust load was

1,180 g. Thus, a mat travel of 24 - 9 = 15 in. was caused

by the introduction of 11,180 - 6J0 = 510 g of dust. The

dust-holding capacity was calculated by dividing the dust

load per foot width by the length of advance in feet, i.e.,

x = 204 g/sq. ft.

The requirements specified for the type E media are 75 percent

average arrestance and 200 g/sq. ft. dust-holding capacity.

The performance values determined for the test specimen

were 77 percent average arrestance and 204 g/sq. ft. dustholding capacity.
Travel

,

Inch

p

01

U. S. Gypsum Company Type E Medium

achea

700 800 900 1000 1100 1200

Dust Load,, grams

U. S. DEPARTMENT OF COMMERCE

Luther H. Hodges, Secretary

NATIONAL BUREAU OF STANDARDS

A.'V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C.,and

Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work.

In general, each section carries out specialized research, development, and engineering in the field indicated by

its title. A brief description of the activities, and of the resultant publications, appears on the inside of the

front cover. WASHINGTON, D. C.

Electricity. Resistance and Reactance. Electrochemistry. Electrical Instruments. Magnetic Measurements.

Dielectrics. High Voltage. Absolute Electrical Measurements.

Metrology. Photometry and Colorimetry. Refractometry. Photographic Research. Length. Engineering Metrology.

Mass and Volume.

Heat. Temperature Physics. H&at Measurements. Cryogenic Physics. Equation of State. Statistical Physics.

Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiological Equipment.

Nucleonic Instrumentation. Neutron Physics.

Analytical and Inorganic Chemistry. Pure Substances. Spectrochemistry. Solution Chemistry. Standard Refer- ence Materials. Applied Analytical Research. Crystal Chemistry.

Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Rheology. Combustion

Controls.

Polymers. Macromolecules: Synthesis and Structure. Polymer Chemistry. Polymer Physics. Polymer Characterization. Polymer Evaluation and Testing. Applied Polymer Standards and Research. Dental Research.

Metallurgy. Engineering Metallurgy. Metal Reactions. Metal Physics. Electrolysis and Metal Deposition.

Inorganic Solids. Engineering Ceramics. Glass. Solid State Chemistry. Crystal Growth. Physical Properties.

Crystallography.

Building Research. Structural Engineering. Fire Research. Mechanical Systems. Organic Building Materials.

Codes and Safety Standards. Heat Transfer. Inorganic Building Materials. Metallic Building Materials.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics. Operations Research.

Data Processing Systems. Components and Techniques. Computer Technology. Measurements Automation.

Engineering Applications. Systems Analysis.

Atomic Physics. Spectroscopy. Infrared Spectroscopy. Far Ultraviolet Physics. Solid State Physics. Electron

Physics. Atomic Physics. Plasma Spectroscopy.

Instrumentation. Engineering Electronics. Electron Devices. Electronic Instrumentation. Mechanical Instru- ments. Basic Instrumentation.

Physical Chemistry. Thermochemistry. Surface Chemistry. Organic Chemistry. Molecular Spectroscopy. Ele- mentary Processes. Mass Spectrometry. Photochemistry and Radiation Chemistry.

Office of Weights and Measures. BOLLDEK, COLO.

CRYOGENIC ENGINEERING LABORATORY

Cryogenic Processes. Cryogenic Properties of Solids. Cryogenic Technical Services. Properties of Cryogenic

Fluids.

CENTRAL RADIO PROPAGATION LABORATORY

Ionosphere Research and Propagation. Low Frequency and Very Low Frequency Research. Ionosphere Research. Prediction Services. Sun-Earth Relationships. Field Engineering. Radio Warning Services. Vertical

Soundings Research.

Troposphere and Space Telecommunications. Data Reduction Instrumentation. Radio Noise. Tropospheric

Measurements. Tropospheric Analysis. Spectrum Utilization Research. Radio-Meteorology. Lower Atmosphere

Physics.

Radio Systems. Applied Electromagnetic Theory. High Frequency and Very High Frequency Research. Fre- quency Utilization. Modulation Research. Antenna Research. Radiodetermination.

Upper Atmosphere and Space Physics. Upper Atmosphere and Plasma Physics. High Latitude Ionosphere

Physics. Ionosphere and Exosphere Scatter. Airglow and Aurora. Ionospheric Radio Astronomy.

RADIO STANDARDS LABORATORY

Radio Standards Physics. Frequency and Time Disseminations. Radio and Microwave Materials. Atomic Fre- quency and Time-Interval Standards. Radio Plasma. Microwave Physics.

Radio Standards Engineering. High Frequency Electrical Standards. High Frequency Calibration Services. High

Frequency Impedance Standards. Microwave Calibration Services. Microwave Circuit Standards. Low Frequency

Calibration Services.

Joint Institute for Laboratory Astrophysics- NBS Group (Univ. of Colo.).

USCOMM—NBS— DC
1

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