NATIONAL BUREAU OF STANDARDS REPORT

7504

PERFORMANCE TESTS OF FARR REPLACEABLE CARTRIDGE FILTERS

TYPES HP 100 AND HP 200

Manufactured by

Farr Company

Los Angeles^, California

by

Carl W. Coblentz and Paul R. Achenbach

Report to

Public Buildings Service

General Services Administration

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 forth in the Act of Congress, March 3, 1901, as amended by Congress in Public Law 619, 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

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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

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July 1957 to June 1960 (Includes Titles of Papers Published in Outside Journals 1950 to 1959) ($2.25); avail- able from the Superintendent of Documents, Government Printing Office, Washington 25, D. C.
NATIONAL BUREAU OF STANDARDS REPORT

lOaRWWBSB May 16, 1962 NBS ****** 7^ oY

i

PERFORMANCE TESTS OF FARR REPLACEABLE CARTRIDGE FILTERS

TYPES HP 100 AND HP 200

Manufactured by

Farr Company

Los Angeles, California

by

Carl Wo Coblentz and Paul R„ Achenbach

Mechanical Systems Section

Building Research Division

Public Buildings Service

General Services Administration

Washington 25* D.C„

IMPORTANT NOTICE

NATIONAL BUREAU OF STANT

intended for use within the Gov

to additional evaluation and revii listing of this Report, either in v the Office of the Director, Natioi however, by the Government age

to reproduce additional copies ft

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

ress accounting documents

iy published it is subjected

oduction, or open-literature

is obtained in writing from

h permission is not needed,

pared if that agency wishes

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PERFORMANCE TESTS OF FARR REPLACEABLE CARTRIDGE FILTERS

TYPES HP 100 AND HP 200

Manufactured byFarr Company

Los Angeles, California

by

Carl W. Coblent z and Paul R. Achenbach

1 . Introduction

At the request of the Public Buildings Service, General

Services Administration, the performance characteristics of

the Farr HP 100 and HP 200 replaceable cartridge air filters

were determined. The scope of this examination included the

determination of the arrestance of particulate matter in the

laboratory air, the pressure drop, and the dust holding capacity of the specimens at the rated air flow rate of 1,000 cfm.

2 . Description of Test Specimens

The filters were manufactured and supplied for test purposes by the Farr Company of Los Angeles, California. The

devices consisted of a replaceable media or cartridge, a retainer made of steel wire and shaped to support the pleats

of the filter medium, a holding frame, and a sealer frame.

The holding frame was made of sheet steel and a number of

these frames could be bolted together to form a filter bank.

The retainers were fastened in the holding frame by means of

spring steel clips. When the filter cartridge had been

installed in the retainer the sealer frame pressed the media

against the holding frame to prevent air from leaking past

the filter medium.

The HP 100 and the HP 200 cartridges could both be fitted

into the same frame. The cartridges were approximately 12 in.

deep and each had an effective filter area of about 42 sq ft.

The rated air flow for either specimen was 1,000 cfm, corresponding to a face velocity of 250 ft/min. at the 2 ft square

holding frame of the filter and about 24 ft/min face velocity

at the filter media.

The filter cartridges were supplied folded and could be

fitted Into the retainer when unfolded. The filter media

were made of a dry glass fiber felt, approximately 1/8 inch

thick.
- 2-

3 . Test Method and Procedure

The filters were tested at the rated air flow rate of

1,000 cfm. The arrestance determinations were made using the

NBS Dust Spot Method described in a paper by R. S. Dill entitled ”A Test Method for Air Filters”, (ASHVE Transactions, Vol.

44, pp. 379, 1938). The filter under test was installed in

the test apparatus and carefully sealed to prevent any by-pass

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 2 feet upstream and

8 feet downstream of the test specimen at equal rates and

passed through known areas of Whatman No. 4l filter paper. The

arrestance determinations were made with the particulate

matter in the laboratory air as the aerosol except for one

measurement on the HP 200 filter using Cottrell precipitate.

The light transmission of the sampling papers was measured

for the same area of each paper before and after the test 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 particulate matter

in the laboratory air equal sampling areas were used in the

upstream and downstream samplers. A similar increase of the

opacity of the two sampling papers was obtained by passing the

sampled air through the upstream paper only a part of the time

while operating the downstream sampler continuously. This was

accomplished by installing one solenoid valve in the upstream

sampling line and another one in a line by-passing the sampler.

The solenoid valves were operated by an electric timer and a relay so that one was open while the other one was closed during any desired percentage of the 5-miuute timer cycle, reversing the position of the two valves during the remainder of the

cycle. The arrestance, A (in percent), was then determined

with the formula:

A = 100 - T x

where T is the percentage of time during which air was drawn

through the upstream sampler, and AU and AD are the observed

changes in the opacity of the upstream and downstream sampling

papers, respectively.

For determining the arrestance of the filter with Cottrell

precipitate as the test dust, different size areas of sampling

paper were used upstream and downstream of the filter in order
- 3

-

to obtain a similar increase of opacity on both sampling papers.

The arrestance was then calculated by the formula:

A = (1 5

x x 100

where the symbols A, AU, and AD are the same as indicated above

and Sjj and S D

are the upstream and downstream sampling areas*

respectively.

Arrestance determinations were made at the beginning and

at the end of the test* and at several Intermediate values of

dust loading. The filters were loaded with a mixture of

Cottrell precipitate and cotton linters in a ratio of 4 parts

of cotton linters to every 96 parts of Cottrell precipitate

by weight. 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 filter under test was recorded

at the beginning of the test of each specimen* after each arrestance determination* and after every 20-gram increment of

Cottrell precipitate had been introduced into the test duct.

The tests were terminated when the pressure drop across the

HP 100 type reached 0.7 in. W.G. and across the HP 200 type*

0.9 in. W.G.

4. Test Results

Whereas only one specimen of the HP 200 type filter was

tested and was found to perform as claimed by the manufacturer*

four specimens of the HP 100 type filter were installed in the

test apparatus* of which two were loaded to capacity . whereas

the other two were removed after initial arrestance determinations showed that they would probably not perform as expected.

Several cartridges were damaged during installation in the

retainer and had to be discarded.

A summary of the results obtained during the tests of the

two specimen HP 100 filters is presented in Table 1 and the

results for the model HP 200 filter are shown in Table 2.

The "Dust Load" shown in these tables is the amount of

Cottrell precipitate and lint received by the filters. It is

the weight of dust introduced Into the test apparatus diminished by the percentage of dust fallout upstream of the filter.

The dust fallout was determined* at the conclusion of the test
TABLE X

PERFORMANCE OF FARR MODEL HP 100 AIR FILTER

AT 1000 CFM AIR FLOW RATE

Dust Load

g

Pressure Drop Arrestanee**

%—

SPECIMEN NO, 1

0 0.185 65.7*

201 0.219 80.3*

403 0.244 73.5*

604 0.285 71.4*

806 0.344 75*4*

1002 0.407 78.9*

1248 0.570

1370 0.693 86.6*

SPECIMEN NO. 2

0 0.190 72,5*

143 0.210 89.2*

285 0.234 90.9

468

‘ 0.264 94.7*

671 0.330 95.5

915 0.464 84.3*

1099 0.679 91*7

^Average of two or three arrestance determinations.

**Particulate matter In the laboratory air used as aerosol
TABLE 2

PERFORMANCE OF FARR MODEL HP 200 AIR FILTER

AT 1000 CFM AIR FLOW RATE

Dust Load

g

Pressure Drop

' in. W.G.

Arrestance

%—

0 0 . 12 0 . 112 0 . 265 0 . 427 0 . 548 0 . 650 0 . 792 0 . 938 0 .

405

88.0*

410 98.5*

439 89.4*

475 91.3

510 91.7

549 93.3*

608 93.3

728 94.1

906 94.2

*Average of two tests.

**The aerosol in this test was Cottrell precipitate, all other

arrestance values were determined with the particulate

matter in the laboratory air.
-4-

by sweeping out the test duct upstream of the test specimen

and calculating the ratio of fallout to the total dust introduced.

Table 1 indicates that the arrestance of the particulate

matter in the atmospheric air for the first specimen of the

HP 100 type filter increased from 65-7 percent to 86.6 percent

while the pressure drop increased from 0.185 in. W.G. to

0.693 in. W.G. due to a dust load of 1370 grams of Cottrell

precipitate and lint. The average arrestance of the second

specimen of this type was appreciably higher than that of the

first one, starting at 72.5 percent with a clean filter and a pressure drop of 0.190 in. W.G. The arrestance of the second

specimen increased to 95*5 percent at a pressure drop of 0.330

in. W.G., then dropped sharply to 84.3 percent at 0.464 in. W.G.

but recovered at the end of the test to 91-7 percent. The

dust load of this filter was 1099 grams and the final pressure

drop, 0.679 in. W.G.

Figure 1 is a graph of the values shown in Table 1. The

upper section shows the observed arrestance values for the two

specimens connected by straight lines and a dotted smooth curve

which approximates the average arrestance values of the two

specimens. This latter curve indicates an average arrestance

of approximately 83 percent based on the observations made on

the two specimens. It will be noted that the pressure drop

of the first specimen, having the higher arrestance of the two,

increased faster than that of the other filter.

Table 2 summarizes the test results obtained with the HP200 model air filter. The arrestance of the particulate matter

in the laboratory air by this filter was initially 88.0 percent

at a pressure drop of 0.405 in. W.G. An arrestance determination with Cottrell precipitate following the initial arrestance

determination with airborne particulate matter in the laboratory

air as the aerosol showed 98.5 percent. Thereafter, the arrestance of the particulate matter in the laboratory Increased

steadily as the dust load was increased to final values of 94.2

percent arrestance and coincident dust load and pressure drop

values of 936 grams and 0.906 in. W.G., respectively as shown

in Figure 2. Assuming that this filter was operated until its

pressure drop at the rated air flow rate had increased by 0.5

in. W.G., the approximate average arrestance would be 92 percent .

USCOMM-NBS-DC
Farr Company, Type HP-100

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mzm,
Farr Company

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.

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Office of Weights and Measures. BOULDER, COLO.

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Standards. Millimeter- Wave Research.

Circuit Standards. High Frequency Electrical Standards. Microwave Circuit Standards. Electronic Calibration Center.
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