V

n

NATIONAL BUREAU OF STANDARDS REPORT

8367

PERFORMANCE TEST OP TWO "HI-FLOW AEROSOLVE

EXTENDED-AREA, DRY MEDIA, AIR FILTERS

MODELS 43P-45 AND 43P-95

IT

manufactured by

Cambridge Filter Corporation

Syracuse, New York

by

Joseph C. Davis and Paul R. Achenbach

Report to

Veterans Administration

Washington, D.C.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards is a principal focal point in the Federal Government for assuring

maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. Its responsibilities include development and maintenance of the national stand- ards of measurement, and the provisions of means for making measurements consistent with those standards; determination of physical constants and properties of materials; development of methods

for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of standard practices for incorporation in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; assistance

to industry, business, and consumers in the development and acceptance of commercial standards and

simplified trade practice recommendations; administration of programs in cooperation with United

States business groups and standards organizations for the development of international standards of

practice; and maintenance of a clearinghouse for the collection and dissemination of scientific, technical, and engineering information. The scope of the Bureau’s activities is suggested in the following

listing of its four Institutes and their organizational units. Institute for Basic Standards. Electricity. Metrology. Heat. Radiation Physics. Mechanics. Applied Mathematics. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radio Standards Laboratory: Radio Standards Physics; Radio Standards Engineering.** Office of Standard Ref- erence Data. Institute for Materials Research. Analytical Chemistry. Polymers. Metallurgy. Inorganic Materials. Reactor Radiations. Cryogenics.** Office of Standard Reference Materials. Central Radio Propagation Laboratory.** Ionosphere Research and Propagation. Troposphere

and Space Telecommunications. Radio Systems. Upper Atmosphere and Space Physics.

Institute for Applied Technology. Textiles and Apparel Technology Center. Building Research.

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Transport Systems. Office of Technical Services. Office of Weights and Measures. Office of Engineering Standards. Office of Industrial Services.

* NBS Group, Joint Institute for Laboratory Astrophysics at the University of Colorado. ** Located at Boulder, Colorado.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT MBS REPORT

1003 - 30-10630 June 2, 1964 8367

PERFORMANCE TEST OF TWO "HI-FLOW AERO SOLVE"

EXTENDED-A REA, DRY MEDIA, AIR FILTERS

MODELS 43 P-45 AND 43 P-95

manufactured by

Cambridge Filter Corporation

Syracuse, New York

Joseph C. Davis and Paul R. Achenbach

Mechanical Systems Section

Building Research Division

by

to

Veterans Administration

Washington, D s C.

IMPORTANT NOTICE NATIONAL BUREAU OF ST,

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

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

opies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PERFORMANCE TEST OF TWO "HI -FLOW AERO SOLVE"

EXT ENDED-A REA , DRY MEDIA, AIR FILTERS

MODELS 43P-45 AND 43P-95

manufactured by

Cambridge Filter Corporation

Syracuse, New York

by

Joseph C. Davis and Paul R. Achenbach

1 . Introduction

At the request of the Veterans Administration, the

performance characteristics of Cambridge "Hi-Flow Aerosolve Filters", Models 43P-45 and 43P-95.> were determined. These filters were of the deep-bed panel type

employing a replaceable dry media. The filters were

manufactured by the Cambridge Filter Corporation of

Syracuse, New York. The scope of the investigation included the determination of the arrestance of the particulate matter of the laboratory air and of Cottrell

precipitate by the filters, and the pressure drop of the

filters at the rated air flow rate of 1500 cfm as the

dust load was gradually increased from zero to a final

value corresponding to a pressure drop of 0.5 W.G. for

Model 43P-45 and a pressure drop of 1.0 W.G. for Model

43P-95.

2 . Description of Test Specimen

The filters, manufactured and supplied for test purposes by the Cambridge Filter Corporation of Syracuse,

New York, were identified as "Hi-Flow Aerosolve Filters"

Models 43P-45 (a medium glass fiber media) and 43P-95

(a fine glass fiber media). In each specimen the filter

media was secured to a stiff No. 20 glass fiber screen

mesh on the downstream side. The filter mat with its

backing was formed into ten pleats, 20 inches deep and

24 1/2 inches wide presenting an effective filtering

surface of approximately 68 sq. ft. The sides of the

filter cartridge were secured to a rigid metal frame made

of one-inch galvanized angles. The weight of each of the

clean filters was approximately 2824 grams (6 1/4 lbs).

2

-

The gross face area of each of the filter units was 3.84

ft 2

, but the enclosing edges of the metal frame reduced

the net face area to 21 7/8" by 21 7/8" or 3.32 ft 2 .

At a rated air flow of 1500 cfm, the net face velocity was 452 ft/min and the average velocity through the

filter media was about 22 ft/min.

The manufacturer furnished the welded steel frames

into which the filter units were placed during operation.

The frames had overall dimensions of 24" x 24" x 3".

3 . Test Method and Procedure

The filters were tested at the rated air flow rate

of 1500 cfm. The arrestance determinations of each

specimen 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, page 379* 1938).

The filter under test was installed in the test apparatus

and carefully sealed to prevent any by-pass of air, or

inward flow of air into the test apparatus, except through

a 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. Each sample

of air was passed through Whatman No. 41 filter paper.

Arrestance determinations were made with the particulate

matter in the laboratory air as the aerosol and also with

Cottrell precipitate injected into the air stream at a ratio of one gram per 1,000 cu. ft. of air on the Model

43P-45 filter. On the 43P-95 filter specimen, arrestance

determinations were made only with the particulate matter

in the laboratory air.

The light transmission of the sampling papers was

measured on the same area of each paper before and after

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 areas of filter paper

were exposed in the upstream and downstream samplers. A

similar increase of the opacity of both sampling papers

was obtained by passing the sampling air through the

-3-

upstream filter paper only part of the time while operating

the downstream sampler continuously. This time-proportioning was accomplished by the use of one solenoid valve in

the upstream sampling line and another 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 a 5-minute timer cycle, reversing the position of the

two valves during the remainder of the cycle. The arrestA, (in percent), was then determined with the formula:

A = 100

Where T is the percentage of time during which air was

drawn through the upstream sampler, 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 exposed upstream and downstream of the filter in order to obtain a similar increase of opacity on both sampling papers. The arrestance was then calculated by this formula:

A (1 - Sp

Su

x

AD. -) x 100

Where the symbols A, AU, and AD represent the same quantities as indicated above and Sp and Sp are the upstream

and downstream sampling areas, respectively.

Both types of arrestance determinations were made at

the beginning and at the end of the test and at several

intermediate loading conditions for each specimen as indicated in Table 1 for the 43P-45 filter and in Table 2 for

the 43P-95 filter. The loading was done incrementally,

each increment weighing 80 to 400 grams and consisting

of a mixture of 96 parts Cottrell precipitate and 4 parts

cotton linters by weight. The Cottrell precipitate had

previously been 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.

-4-

The pressure drop across the filter under test was

recorded at the beginning of the test, after each arrestance determination, and after each increment of Cottrell

precipitate and lint that was introduced into the test

duct. The test was terminated when the pressure drops

reached 0.5 in. W.G. and 1.0 in. W.G. across the Filter

Model 43P-45 and Filter Model 43P-95* respectively.

The construction of both filters was such that the

method of mounting was important. To obtain maximum

performance of each filter, it was necessary that the

pleats did not sag materially, that their extension

during the testing was not impeded by faulty fastening

of the media to their frames, and that none of the pleats

remained collapsed after subjection to the air flow. It

is suggested that these precautions be taken during use

of these filters in Government installations.

For each increment of filter loading, two determinations of arrestance were made. The value of arrestance

reported was the averaged obtained from two determinations

Upon completion of the test on both initial filter

specimens, a test without load on the filter media was

performed on another specimen of each model, supplied by

the manufacturer. For this test, an arrestance determination was made using only the laboratory air as the aerosol

The pressure drop across the filter was also observed

under these conditions.

4 . Test Results

The test results obtained on the air filter 43P-45

are summarized in Table 1.

-5-

Table 1

Performance of the Cambridge "Hi Plow

Aerosolve" Filter Model 43P-45 at an Air

Plow Rate of 1500 cfm.

Cumulative Load Arrestance

Cottrell

Precipitate Lint Load

of

Aerosol

Pressure

Drop

Grams Grams Grams Percent A T3 A In. W.G. fD Atmospheric Cottrell

0 0 0 - - .152

4 0 4.0 25.7 85.6 .168

80 3.3 83.3 30.1 86 .

0

.172

180 7.5 187.5 33.2 86 . l .176

380 15.8 395.8 36.3 87.6 .180

780 32.4 812.4 35.1 88.2 .206

1180 49.0 1229.0 37.5 92.5 .252 C

.246 D

1580 65 . 6 1645.6 41.2 91.3 .320 c .316 D

2300 95.5 2395.5 48.7 93.7 .470 c .432 D

2660 110.0 2770.0

1

—

1

1

—

1

LP\ 92.4 .544 C

.504 D

Second Filter

0 0 0 23.7 .168

A - Atmospheric-Aerosol is the particulate matter in the

laboratory air

B - Cottrell-Aerosol is Cottrell precipitate in laboratory air

C - Pressure drop at close of day's testing

D - Pressure drop at beginning of next day of testing

- 6 -

When the load on Filter Model 43P-45 was about 1000

grams or greater, the pressure drop decreased over night

when the test apparatus was shut down. For example, at

a loading of 1229 grams and at the completion of the day's

testing, the pressure drop was 0.252 in. W.G. The following morning when the filter was subjected to an air flow

at the same specified rate of flow, the pressure drop was

.2-46 in. W.G. This effect became more marked as the

testing progressed and the load increased. At a loading

of 277° grams, the pressure drop was 0.544 in. W.G. at

the close of the day's testing and the following morning

at the beginning of testing it was 0.504 in. W.G. This

effect was not appreciable during the testing of Filter

Model 43P-95.

It will be noted that the pressure drop for the first

specimen of Model 43P-45 increased from 0.168 in. W.G.

with a clean filter to 0.544 in. W.G. or (0.504 in. W.G.)

after a dust load of 2770 grams had been reached for the

filter. The arrestance of the dust in the atmospheric

air increased from 25.7 percent to 51.1 percent during

the loading period and averaged approximately 42 percent.

On the basis of the lower pressure drops observed each

morning during the latter part of the test, the dust load

of Cottrell precipitate and lint corresponding to a pressure drop of 0.5 in. W.G. was 835 grams/ft 2 of net

face area and about 40.8 grams/ft 2 of filter media. The

arrestance values determined with Cottrell precipitate

increased from an initial value of 85.6 percent to a value of about 93 percent. Average arrestance for Cottrell precipitate was 91.4 percent.

The test results obtained on the air filter Model

43P-95 are summarized in Table 2.

-7-

Table 2

Performance of the Cambridge "Hi Flow

Aerosolve" Filter Model 43P-95 at an Air

Flow Rate of 1500 cfm.

Cumulative Load

Cottrell

Precipitate Lint Load

Arrestance of

Atmospheric

Aerosol

Pressure

Drop

Grams Grams Grams Percent In. W.G.

0 0 0 86 .

6

.434

200 8.3 208.3 89.5 .500

500 20.8 520.8 92.2 .630

880 36 .

6

916 .

6

95.0 1.020

Second Filter

0 0 0 85.6 -=}

-=t 00 •

It will be noted that the pressure drop on the first

specimen of the Model 43P-95 filter increased from .434

in. W.G. with a clean filter to 1.020 in. W.G. after a dust load of 916.6 grams had reached the filter. The

arrestance of the dust in the atmospheric air increased

from 86.6 percent to 95 percent during the loading period

and averaged about 91.4 percent. The dust load of Cottrell precipitate and lint corresponding to a pressure

drop of 1.0 in. W.G. was 270 grams/ft 2 of net face area

and about 13.5 grams/ft 2 of filter media.

The values shown in Tables 1 and 2 are graphically

presented in Figures 1 and 2. In these figures the arrestance of particulate matter in the laboratory air, the

arrestance for the Cottrell precipitate and the pressure

differences are all plotted against the dust load.

U SC0MM“N 8S-DC

PRESSURE

DROP,

IN.

W.G„

ARRE

STANCE,

PERCENT

performance curves for Cambridge filter

MODEL 43 P-45

DUST LOAD, GRAMS

PRESSURE

D

ROP

IN

. W

. G

ARRESTANCE,

PERCENT

PERFORMANCE CURVES FOR CAMBRIDGE FILTER

MODEL 43 P-95

PARTICULATE !-M ATTER

IN ^LABORATORY : AIR

FIGURE’

“;40Q

DUST LOAD, GRAMS