NATIONAL BUREAU OF STANDARDS REPORT

£679

PERFORMANCE TEST OF

HI-FLO AEROSOLVE 3P-85 AMD HI- CAP 45 HC1500 FILTERS

manufactured by Cambridge Filter Corporation

Syracuse, New York

by

Charles M. Hunt and Paul R. Achenbach

Report to

General Services Administration

Public Buildings Service

Washington, D.C.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

421.03-30-4215628 August 19, 1965 8679

PERFORMANCE TEST OF

HI-FLO AEROSOLVE 3P-85 AND HI-CAP 45 HC1500 FILTERS

manufactured by Cambridge Filter Corporation

Syracuse, New York

by

Charles M. Hunt and Paul R. Achenbach

Building Research Division

to

General Services Administration

Public Buildings Service

Washington, D.C.

IMPORTANT NOTICE NATIONAL BUREAU OF STA

for use within the Government. I 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

ipies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PERFORMANCE TEST OF

HI- FLO AEROSOLVE 3P-85 & HI- CAP 45 HC1500 FILTERS

manufactured by Cambridge Filter Corporation

Syracuse, New York

by

Charles M. Hunt and Paul R. Achenbach

1 . Introduction

At the request of the Public Buildings Service of the General

Services Administration, the performance characteristics of Cambridge

Hi-Flo aerosolve filters, model 3P-85 , and Cambridge Hi-Cap filters,

model HC1500, were determined. The scope of the investigation included determination of arrestance and pressure drop across the filter at t.he rated flow of 1500 cfm as the dust load was increased from

zero to a final value corresponding to a pressure drop of approximately

1 inch for the Hi-Flo and 0.6 inch for the Hi-Cap filter. Atmospheric

dust was used as the test aerosol in the determination of the arrest- ance of the Hi-Flo filter and Cottrell precipitate with the Hi-Cap

filter

2 . Description of Test Specimens

The filters were supplied by the Cambridge Filter Corporation of

Syracuse, New York. The Hi-Flo 3P-85 filter was of the deep-bed dry

media type, having outside face dimensions of 23 3/8 x 23 3/8 inches

and depth of 21 inches. The measured face dimensions of the test

specimens, not including the mounting frame, was 21 7/8 x 21 7/8 inches.

The filter surface was subdivided into ten vertical pockets. The mea- sured depth of each pocket was 20 inches and the height was 24 inches.

The estimated area of the media was 67 ft^, which is in reasonable

agreement with the nominal area of 70 ff2 given by the manufacturer.

A square metal frame, attached at the upstream end, was an integral part of each Hi-Flo 3P-85 filter. Vertical cross members of the

frame were attached to each pocket at the face of the filter.

The downstream surface of the Hi-Flo 3P-85 filter consisted of a highly porous paper or nonwoven cloth backing. A simple flame test

indicated the material to be cellulosic in nature. It had great tear

resistance which suggests impregnation with a polymer. The body of

the filter itself consisted of glass fibers which were about 3 microns

in diameter.

- 1-

The Hi-Cap HC1500 filter consisted of an extended-area disposable

media cartridge which fit into a permanent frame. The media cartridge

was subdivided into four pockets. A detachable, heavy wire retainer

fitted the convolutions of the filter media on the downstream side.

The filter had outside face dimensions of 23 1/2 x 23 1/2 inches

and a depth of 9 inches. The measured face dimensions, exclusive of

the frame, were 22 7/8 x 22 7/8 inches, and the pockets were about

8 7/8 inches deep with a height of 23 inches. The estimated area of

the filter media was about 15 ft^.

The filter media, according to the manufacturer is a modified

acrylic fiber. Diameters of the individual fibers under the microscope were approximately 75 microns.

The Hi-Cap filter media was coated with an oily adhesive which

imparted an amber color to the filter. Small droplets of adhesive

were visible on the fiber, but there was no evidence of drainage due

to excess adhesive.

3 . Test Method and Procedure

The filters were tested at the rated air flow 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. The arrestance measurements of the Hi-Flo

filter were carried out using the particulate matter in laboratory air

as the test aerosol. Arrestance of the Hi-Cap filter was measured

with Cottrell precipitate, except that an initial arrestance measure- ment with the unloaded filter and a final measurement of the fully

loaded filter were performed with 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.

In determination of the arrestance of laboratory air, some of the

values were obtained with the timer and some were obtained with sampling

plates of different area. These devices are commonly used to obtain

- 2

-

dust spots of nearly equal opacity on the upstream and downstream sampling papers, a requirement for accurate arrestance measurements. In

the timer method this is achieved by sampling through the 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 arrestance A, (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.

In the method where sampling plates of different areas were used,

the arrestance was calculated using the following formula:

Sp) AD

A = 1 ”

"Spj x AU x 100

where the symbols A, AU, and AD represent the same quantities as indicated above, and Sy and Sp are the upstream and downstream sampling

areas, respectively.

For determination of the arrestance of Cottrell precipitate, plates

of different area were employed and the latter formula was used for

calculation of arrestance.

Arrestance measurements were made with the unloaded filter and

after increments of test dust were introduced to the filter by dispersion in the upstream air. The loading dust consisted of 96 parts by

weight Cottrell precipitate and 4 parts by weight cotton linters. The

Cottrell precipitate had been previously passed through a 100-mesh

sieve, and the lint was prepared by grinding No. 7 cotton linters in

a large Wiley mill equipped with a screen with 4-mm holes.

The pressure drop across each filter was measured at the beginning

of the test and after each addition of loading dust. The Hi-Flo 3P-85

filter was loaded until a pressure drop of approximately 1 inch W.G. was obtained. This is greater than the final pressure drop of 0.6

inches W.G. suggested for similar filters in Cambridge Bulletin 134

(1962). It was done to provide additional test data, since there is no GSA specification for this type filter. The Hi-Cap HC1500 filter was loaded until a pressure drop of approximately 0.6 inches W.G. was

obtained. This is the recommended final pressure drop for Hi-Cap

filters given in Cambridge Bulletin 150 (1963).

- 3-

Although the Hi-Cap HC1500 filter contained an adhesive, it was

tested with the view of comparing its performance with the requirements for a type-C filter according to General Services Administration

"Standard Airconditioning Specification" of December 1964. This specification calls for a dust-holding capacity of "not less than 275 grams

of dust per 1000 cfm of specified capacity when the resistance to air

flow reaches 0.50 inch water gage". The specified capacity of this

filter is 1500 cfm which corresponds to a dust-holding capacity of 413

grams according to the specification.

The tests of the Hi-Flo 3P-85 filter were performed with a single

specimen. However, initial pressure drop and initial arrestance of

atmospheric dust were carried out on a second filter of the same type.

The tests of the Hi-Cap HC1500 were repeat measurements of this type

filter after an earlier specimen with a different adhesive was found

to have very high dust-holding capacity but had an arrestance with

Cottrell precipitate slightly lower than the specification requirement

of 80%.

4 . Results

The arrestance of atmospheric dust and pressure drop of a Hi-Flo

3P-85 extended-area, dry media filter before and during loading is

given in Table 1. These data are plotted in Figure 1 where the upper

curve represents arrestance and the lower curve represents pressure

drop, both plotted as functions of nominal dust load.

- 4-

TABLE 1

Performance of Cambridge Extended-Area,

Dry Media Hi-Flo Filter, Model 3P-85, at 1500 cfm

Nominal3 Pressure Drop

Dust Load across Filter Arrestance of Atmospheric Dust

(grams) (inches W.G.) (percent

)

Average Time

Filter A Sampling and Variable

Timer Plates Area

0 0.250 67.3 71.5 69.4

208 .282 -- 73.4 -- 500 .346 -- 76.5 -- 812 .450 78.9 80.0 79.6

1021 .590 85.8 85.8 85.8

1229 .802 86.9 88.6 87.7

1396 1.014 88.3 -- --

Filter B

0 0.238 68.1

aNominal dust load is the total weight of precipitate and linters

introduced into the test duct. The actual load retained by the

filter is less by the amount which passes the filter.

The pressure drop of the Hi-Flo 3P-85 filter increased from an initial value of 0.250 inches W.G. with the unloaded filter to a final

value of 1.014 inches W.G. after a dust load of 1396 grams had been

added. The dust load corresponding to a pressure drop of 0.6 inch W.G.,

the final pressure recommended by the manufacturer, was about 1035 grams

The second Hi-Flo 3P-85 filter had an initial pressure drop of 0.238

inches

The initial arrestance of the unloaded filter was 69.4% and the

final arrestance was 88.3%. The calculated average arrestance, based

on the area under the upper curve in Figure 1, was 76.9% up to a pressure drop of 0.6 inch W.G. and 79.2% up to 1 inch W.G. Each of these

values is about 0.2% lower than the estimates made in a letter of

March 22nd to Mr. Donald N. Whitmeyer giving a tentative report of

these test results. This is because they give slightly greater weight

to the arrestance values obtained with the timer than the earlier values

The arrestance and pressure drop of the Hi-Cap HC1500 filter in

the unloaded condition and with increasing dust load is given in Table

2. In Figure 2 the upper curve represents arrestance of Cottrell precipitate as a function of nominal dust load while the lower curve is a similar plot of pressure drop.

- 5

-

TABLE 2

Performance of Cambridge Hi- Cap Extended Area,

Disposable Cartridge Filter, Mod. 45 HC1500

Nominal3

Dust Load

at

Pressure Drop across Filter

1500 cfm

Arrestance of

Cottrell Precipitate

Arrestance of

Atmospheric Dust

(grams) (inches W.G.) (percent

)

(percent

)

0 0.166 70.0 9.4

220 .206 78.0 -- 637 .274 81.8 -- 1062 .354 84.3 -- 1486 .468 86.1 -- 1903 .630 89.0 36.6

a See footnote "a". Table 1.

An initial pressure drop of 0.166 inches W. G. was obtained with

the Hi-Cap HC1500 filter, and a final pressure drop of 0.630 inches

W.G. was obtained after 1903 grams of dust had been fed to the filter.

The dust load corresponding to a pressure drop of 0.5 inch W.G. was estimated to be 1590 grams, or 1060 grams per 1000 cfm of specified

capacity, which is well in excess of the GSA specification requirement

of "275 grams of dust per 1000 cfm of specified capacity when the re- sistance to air flow reaches 0.50 inch water gage".

The arrestance of Cottrell precipitate increased from an initial

value of 70.0% with the unloaded filter to 89.0% after a pressure drop

of 0.630 inches W.G. had been reached. The average arrestance, calculated from the curve in Figure 2, was 82.3% when integrated up to a pressure drop of 0.5 inches W.G. This is within the specification

requirement of 80% arrestance.

An arrestance of 9.4% for atmospheric dust was obtained with the

unloaded filter, but this rose to 36.6% for the fully loaded filter.

USCQMM-NBS-DC

PRESSURE

DROP

(INCHES

W.G.)

ARRESIANCE

OFA

1340

SPHERIC

DUST

(PERCENT)

EXTENDED AREA, DISPOSABLE CARTRIDGE

CAMBRIDGE FILTER

MODEL 3P - 85

1.0

0.9

0.8

NOMINAL DUST LOAD (GRAMS)

PRESSURE

DROP

(INCHES

W„G.)

ARRE

STANCE

OF

COTTRELL

PRECIPITATE

(PERCENT)

EXTENDED AREA, DRY MEDIA

CAMBRIDGE FILTER

MODEL 45 HC 1500

NOMINAL DUST I QAD (GRA S)


\ii