NATIONAL BUREAU OF STANDARDS REPORT

9403

PERFORMANCE TEST OF AN

M- 104 GLASS FIBER RENEWABLE FILTER MEDIA

Manufactured by

American Air Filter Company

Louisville, Kentucky

U. S. DEPARTMENT OF COMMERCE

NATIONAL OUREAU OF STANDARDS

by

Charles M. Hunt
THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANDARDS REPORT

MBS PROJECT

42103-40-4215630

NBS REPORT

9403

September 22, 1966

PERFORMANCE TEST OF AN

M- 104 GLASS FIBER RENEWABLE FILTER MEDIA

Manufactured by

American Air Filter Company

Louisville, Kentucky

by

Charles M. Hunt

IMPORTANT NOTICE NATIONAL BUREAU OF STAI

for use within the Government. Bi and review. For this reason, the | whole or in part, is not authorize Bureau of Standards, Washington

the Report has been specifically pi

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

accounting documents intended

ibjected to additional evaluation

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

le Government agency for which

ies for its own use.

I, S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

Performance Test of An

M-104 Glass Fiber Renewable Filter Media

Manufactured byAmerican Air Filter Company

Louisville, Kentucky

by

Charles M, Hunt

Performance Test of An

M-104 Glass Fiber Renewable Filter Media

Manufactured by

American Air Filter Company

Louisville, Kentucky

by

Charles M. Hunt

1. Introduction

At the request of the Public Buildings Service of the General

Services Administration, performance characteristics of an M-104 roll

filter media were determined. The scope of the investigation included

determination of the arrestance of Cottrell precipitate diffused into

laboratory air, and the nominal dust holding capacity when the face

velocity was maintained at 500 ft/min. and the media was intermittently

advanced in such a way as to maintain the pressure drop across the

filter between 0.45 and 0.5 inches W.G.

2. Description of Test Specimen

The M-104 media was a white fiber glass mat about 2 inches thick.

It was reinforced by longitudinal wires spaced about 10 inches apart

which were cemented to its downstream side. The media was coated with

o adhesive. A section was found to have a weight of 35.3 grams per ft ,

and after three extractions with alcohol it had a dry weight of 15.6

grams per ft , indicating an adhesive content of 19.7 grams per ft .

There was no visible evidence of drainage or excessive liquid on the

media

.
2

3. Test Methods and Procedure

The media was tested at a net face velocity of 500 ft/min.

The arrestance determinations were made using the "NBS Dust Spot

Method for Air Filters" (ASHVE Transactions, Vol. 44, p. 379, 1938).

For the test, the roll of media was installed in a roll-filter frame

constructed to fit the NBS test apparatus. This apparatus provided

an airtight enclosure and adapters to fit the upstream and downstream

sections of the test duct. This roll-filter frame has been used

previously for testing various media of this type.

The frame had two openings, 2 ft x 2 ft, one upstream and the

other downstream from the filter. The roll of filter media was

placed at the top of the frame on a spool and arranged so the media

passed immediately upstream of the downstream opening as it unrolled.

The loaded media was rolled up on a similar spool at the bottom of the

frame. The bottom spool was driven by a motor actuated manually when

the pressure drop across the media reached 0.5 in. W.G. Nine vertical

bars in the downstream opening served to prevent appreciable deflection

of the media under the influence of the air pressure difference. The

edges of the media were enclosed in metal groove-type tracks to restrict

by-pass of air between the media and frame.
-3-

The frame and media were installed in the test duct and

carefully sealed to prevent any by-pass of air or inward flow 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 areas of Whatman No. 41 filter paper.

The arrestance determinations were made with Cottrell precipitate

injected into the air stream with a ratio of approximately one gram

of dust per 1,000 cu ft of air.

The amount of light passing through 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 exposed upstream and downstream of the

filter in order to obtain a similar increase of opacity on the two

sampling papers. The arrestance was calculated by the formula:

A
-4-

where the symbols and are the upstream and downstream sampling

areas and All and AD are the observed changes in the opacity of the

upstream and downstream sampling papers, respectively.

Arrastanee d«t«rmiMti®ns were mad® when the media was clean

at the beginning of th© test, and at selected intervals of loading

until th© intermittent advance of the media became representative

of a steady-state operation. The arrestance determinations were

made with Cottrell precipitate only, while cotton linters were added

during the loading process in a ratio ©f 4 parts to ©very 96 parts

o£ Cottrell precipitate. Each loading increment consisted of 20 grams

Cottrell precipitate and 0.83 grams of cotton linters. 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 large

Wiley mill with a 4-millimeter screen.

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 scale mounted in the filter housing. The

advance cycle, which was actuated by a manually operated switch,

began when the pressure drop across the filter reached approximately

0.50 in. W.G. and stopped when the drop was about 0,45 in. W.G.
-5-

The position of the madia at the beginning of each advance

cycle was recorded as well as the corresponding cumulative dust load

at the time of advance. From this information a plot was made of the

advance of the media vs. dust load, and when the relation between the

two parameters became very nearly linear, enough additional determine"

tions of advance as related to load were made to develop the bestfitted straight line through the plotted data, from which the nominal

dust-holding capacity in grams/ft^ was determined.

The pressure drop across the media was recorded at the beginning

of the test, at selected intervals during the dust loading process, and

at the beginning and end of each advance cycle.

4. Test Results

The results of tests with the American Air Filter M-104 filter

are summarized in Tables 1 and 2. From Table 1 an initial arrestance

of 68 percent was calculated from the three initial values in the

table. The average arrestance after steady state conditions were

reached was estimated to be 81.4 percent. A final arrestance, not

shown in the table, was obtained as fresh media was unrolled into the

airstream. A value of 80.0 percent was obtained. From this it is

concluded that very little dirt was dislodged into the airstream during

movement of the filter.
- 6

-

Table 1

Performance of American Air Filter M»104 Roll-o-matic Filter Media

at 2000 cfm

Total fltetst fed

(gram©)

Total advance

of media

(inches)

Pressure

drop

(inches W.G„)

Arrestance

of Cottrell

precipitate

(percent)

0 0 0.180 69.0,69.4,64.1

262 0 0.358 75.0

433 0 0.505 81.4

791 15.3 0.498 81.6

1170 25.8 0.506 80.9

1465 34.3 0.506 81.2, 81.7

Table 2

Total Dust Fed, Advance of the Media, and Pressure Drop of American

Air Filter M-104 Roll Filter Media Tested at 2000 cfm.

Total Dust

Fed

(grams)

Advance of a Media

(Inches)

Pressure Drop (Inches W. G.)

Before After

Advance Advance

0 0 0.180

116 0 .262 —

220 0 .330 —

433 0 .505 0.447

499 5.1 .500 .450

583 8.1 .510 .448

645 10.7 .498 .448

728 12.9 .508 .448

795 15.3 .504 .446

878 17.8 .502 .452

941 19.8 .500 .440

1024 21.8 .502 .450

1086 23.8 .500 .448

1170 25.8 .506 .450

1236 27.8 .498 .446

1320 30.3 .504 .450

1382 —.500 .450

1465 34.3 .506 .450

1532 36.5 .502 —

a. The values in this column were taken just before advance to the

next position.
-7-

Table 2 shows the advance of the filter media required to

keep the pressure drop between 0.45 and 0.5 inches W.G. as dust was

fed to the filter. The advance of the filter media is plotted in

Figure 1 as a function of total dust fed, and a line is drawn through

the points representing steady state conditions. Nominal dust holding

capacity was calculated from the slope of the line by the relationship:

12

Nominal dust holding capacity ® SW s

where S is the slope of the line in inches advance per gram of dust

load, and W is the width of the test duct where it meets the downstream

side of the filter, which in this case is 2 ft. A nominal dust holding

2 capacity of 213 grams per ft was obtained. In Table 3 the average

arrestance in the steady state and nominal dust holding capacity are

compared with requirements for a type-E filter according to General

Services Administration Air Conditioning Standard of December 1964.

Table 3

Performance of American Air Filter M-104

renewable media compared with GSA requirements for a type-E filter

Nominal dust holding capacity Ml 04 Requirement

(grams per square foot of media media type-E media

leaving the air stream) 213 200

Average arrestance of Cottrell

precipitate in steady state

(percent) 81.4 75

USCQMM-N1S-DC

Total Dust Fed to Filter (Grams)