NATIONAL BUREAU OF STANDARDS REPORT

PERFORMANCE TESTS OF TWO ONE- INCH

THROW-AWAY TYPE "DUST-SFOF’ AIR FILTERS

Manufactured by

Owens-Corning Fiberglas Corporation

Toledo^ Ohio

Bureau of Yards and Docks

Office of the Chief of Engineers

Headquarters U. S„ Air Force

Washington. D. C.

6448

by

Carl W. Coblentz

Paul R. Achenbach

Report to

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions find Activities

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

3, 1901, as amended hv Congress in Public Law 619, 19S0. 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. A major portion of the Bureau's work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic EnergyCommission. The scope 'of activities is suggested by the listing of divisions and sections on the

inside of the back cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agenc> of a particular project or program. Published papers appear either in the Bureau's own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

complete papers reporting technical investigations; the Technical News Bulletin, which presents

summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions,

which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 160, Publications of

the National Bureau of Standards (#1.25) ajid its Supplement (#0.75), available from the Superintendent of Documents, Government Printing Office, Washington 25, D. C.

Inquiries regarding the Bureau’s reports should be addressed to the Office of Technical Information, National Bureau of Standards, Washington 25, D. C.
N AT 1 0 N A L BUREAU OF STANDARDS REPORT

ms PROJECT

1000-12-4801 June 26, 1959

NBS REPORT

6448

PERFORMANCE TESTS OF TWO ONE-INCH

THROW-AWAY TYPE "DUST-STOP" AIR FILTERS

Manufactured by

Owens-Corning Fiberglas Corporation

Toledo, Ohio

Carl W. Coblentz and Paul R. Achenbach

Air Conditioning, Heating, and Refrigeration Section

Building Technology Division

Bureau of Yards and Docks

Office of the Chief of Engineers

Headquarters, U„ S. Air Force

Washington, D. C„

the Office of the Director, N; Standards and Technology (NIST) Such permission is not needed,

n Aiiiowo r tui thn Lrtimrnmont V ^ I f + 1, 4- InLnn

by

to

NATIONAL BUREAU OF ST

intended for use within the

to additional evaluation and

listing of this Report, either

IMPORTANT NOTICE

progress accounting documents

however, by the Government

to reproduce additional copi on October 9, 201 5. prepared If that agency wishes

NBS
.
PERFORMANCE TESTS OF TWO ONE- INCH

THROW-AWAY TYPE "DUST-STOP” AIR FILTERS

by

Carl W. Coblent z and Paul R„ Aehenbach

1. INTRODUCTION

The performance characteristics of a group of cleanable

viscous impingement type air filters were determined to provide

information for evaluating the relative economy of cleanable

versus throw-away types of filters,, This investigation was

requested by the Defense Department through the Tri-Service program of research and development at the National Bureau of

Standards to obtain required data for the preparation of new air

filter specifications.

This report presents the results of the performance test

of two nominally 1-in. thick throw-away filters of a type of

which only the 2-in. thick model had been tested previously at

this Bureau. The performance of a 2-in. thick specimen of this

filter was presented in NBS Report No. 4972 dated January 18,,

1957.

2. DESCRIPTION OF TEST SPECIMENS

The test specimens were manufactured by the Owens-Corning

Fiberglas Corporation of Toledo,, Ohio,, and bore the trade name,

"Dust-Sj3 oj?” . The specimens were obtained for testing from the

NBS storeroom. The filter media consisted of a 1-in. thick pack

of glass fibers and had been treated with an oily adhesive. The

filter media were held in position on both faces by thin brass

sheet retainers, perforated with 1 1/2 in. diameter cut-outs. The

cardboard frames measured 19 7/8 in. square by 7/8 in. thickness

on the outside, leaving an 18 in. square opening corresponding to

2.25 sq ft net face area. The weights of the clean filters were

387 grams and 378 grams, respectively (approximately 13 1/2 oz).
'
-2 -

3. TEST METHOD AND PROCEDURE

The performance of the filters was determined at face velocities of 360 and 540 ft/min, i.e., air flow rates of 8l6 cfm and

1224 cfm, respectively. The arrestance measurements were conducted in accordance with the NBS "Dust Spot Method" as described

in the paper, "A Test Method for Air Filters" by R. S. Dill,

( ASHVE Transactions, Vol. 44, p. 379, 1938).

The aerosol used for the arrestance determination was Cottrell precipitate which had been sifted through a 100-mesh wire

screen. In order to simulate actual operating conditions when

loading the filters, four percent by weight of cotton linters,

previously ground in a Wiley mill with a four-millimeter screen,

was introduced simultaneously with the Cottrell precipitate. The

pressure drop of the filters was recorded after each increment of

20 grams of dust had been introduced into the test apparatus.

Whereas the arrestance determinations were made with 100 percent

Cottrell precipitate, cotton linters were added to retain the

ratio of four parts by weight to every 96 parts of Cottrell precipitate, including the amount used for arrestance measurements. Arrestance determinations were made at the beginning and at the end

of the loading of each filter and also at several intermediate load

conditions

The filters were loaded with a dust concentration of approximately 1 gram of dust in 1000 cu ft of air until the pressure drop

exceeded 0.5 in. W.G. at 360 ft/min face velocity and 0.8 in. W.G.

at 540 ft/min face velocity.

At the conclusion of each test, the fallout of dust that occurred upstream of the filter was determined by sweeping out this

part of the test apparatus. The ratio of fallout to the total

amount of dust introduced into the test apparatus was then determined. In the evaluation of the test specimen the "Dust Load",

then, was considered as the net amount of dust that had reached

one square foot net face area of the filter, according to the

formula:

Dm

D = __L x F

A

-3-

where: D = net dust load,, g/sq ft

Drji = dust introduced into the test apparatus,, g

A = net filter area,, sq ft

F = one minus the ratio of fallout to total dust introduced during the test

4. TEST RESULTS

The pressure drop and arrestance values determined during the

loading of the two specimens are shown in Tables 1 and 2. These

data are also presented graphically in Fig. 1 as four smooth curves

drawn to approximately fit the individual points of observation.

Table 1

Performance of 1-inch Dust-Stop Filter

at 360 ft/min Face Velocity

Load Pressure Drop . Arrestance

g/sq ft in. W. G.

0 0.100 - 4 0.105 60

54 0.195 60*

103 0.270 60

154 0.365 56

210 0.507 54*

Average of two tests

Table 2

Performance of 1-inch Dust-Stop Filter

at 5^0 ft/min Face Velocity

Load Pressure Drop Arrestance

g/sq ft in. W. G. ~W~

0 0.145 - 15 0.175 54*

90 0.313 51*

155 0.415 45*

202 0.505 45

260 0.615 36*

307 0.737 45*

335 0.840 38

* Average of two tests

-lilt will be noted that the pressure drop of the clean filters

was 0.100 in. W.G. at 360 ft/min face velocity and 0.145 in. W.G.

at 540 ft/min face velocity. The arrestance at 360 ft/min face

velocity remained constant at 60 percent during about half of the

loading and then decreased to 5^ percent. The arrestance values

determined at 5^-0 ft/min face velocity commenced at 5^ percent

and, then, decreased at an unsteady rate - the cause of which could

be that, at this face velocity, considerable dust that was originally captured in the filter, was pulled through as the loading

continued.

The dust loads accumulated by the two test specimens when

the pressure had increased to 0.5 in. W.G. and 0.8 in. W.G'!, respectively, were taken from the lower curves of Fig. 1 and are

presented in Table 3 as the Dust Holding Capacity. Also shown

in this table are the Mean Arrestance values which present the

average arrestance during the period in which the capacity dust

load was accumulated, taken from the arrestance curves of Fig. 1.

Table 3

Dust Holding Capacity and Mean Arrestance

(Determined from Fig. l)

Face Velocity, ft/min

Final Pressure Drop, in. W.G.

Dust Holding Capacity, g/sq ft

Mean Arrestance, percent

360

0.5

208

58

540

0.8

325

46

USCOMM-NBS-DC

OWENS- CORNING "DUSTSTOP" (1 inch thick)

100 200 300

DUST LOAD, grams per square foot

tt. S. DEPARTMENT OK COMMERCE

Lewi* |j. Striuion, St'rrf’tm-y

NATIONAL mmtCAU Of’ STANDARDS

A. V. Afttlll, lyirrctnr

THIS NATIONAL BUREAU OE STANOAWOS

The scope of Activities of the National Bureau of Standards at its hcurl(|Uartcrs in Washington,

0. C., dnd its major laboratories in Boulder, Colo., is suggested in the following listing of tin; divisions and sections engaged in technical work. In general, each section carries out specialized

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the activities, and of the resultant publications, appears on the inside front cover. WASHINGTON, I). C.

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*