NATIONAL BUREAU OF STANDARDS REPORT

8383

PERFORMANCE TEST OF THE FILTREX GLASS FIBER

AUTOMATIC RENEWABLE FILTER MEDIA, TYPE 63 DGC

manufactured by

Drico Industrial Corporation

Passaic, New Jersey

Joseph C. Davis and Paul R. Achenbach

Report to

General Services Administration

Public Buildings Service

Washington 25, D.C„

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

by
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

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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

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

MBS PROJECT MBS REPORT

421.03-30-4210630 July 14, 1964 8383

PERFORMANCE TEST OF THE FILTREX GLASS FIBER

AUTOMATIC RENEWABLE FILTER MEDIA, TYPE 63 DGC

manufactured by

Drico Industrial Corporation

Passaic, New Jersey

by

Joseph C. Davis and Paul R. Achenbach

Mechanical Systems Section

Building Research Division

to

General Services Administration

Public Buildings Service

Washington 25, D.C.

IMPORTANT NOTICE NATIONAL BUREAU OF SI

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

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.

)ss accounting documents intended

; subjected to additional evaluation

i listing of this Report, either in

le Office of the Director, National

r the Government agency for which

copies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PERFORMANCE TEST OF THE FILTREX GLASS FIBER

AUTOMATIC RENEWABLE FILTER MEDIA, TYPE 63 DGC

manufactured by

Drico Industrial Corporation

Passaic, New Jersey

Joseph C. Davis and Paul R. Achenbach

1

.

Introduction

At the request of the Public Buildings Service, General

Services Administration, the performance characteristics of

the "Filtrex" glass fiber roll-type filter media. Type 63

DGC, manufactured by the Drico Industrial Corporation of

Passaic, New Jersey, were determined. The scope of the

investigations included the determination of the arrestances of Cottrell precipitate diffused into the laboratory

air and the dust-holding capacity when the face velocity

was maintained at 500 ft/mi n. and while the media was intermittently advanced under the control of a pressure

switch with a maximum setting for the pressure drop across

the media of 0.5 in. W.G.

2

.

Description of Test Specimen

The roll of filter media was manufactured and supplied

for test purposes by the Drico Industrial Corporation of

Passaic, New Jersey. It was identified as "Filtrex", Type

63 DGC. The media was approximately 3^ inches wide and

2-1/2 inches thick, laminated with blue color on one face

and white color on the other face. The white fibers of the

downstream face were closer spun than the blue fibers on

the upstream face. The media was composed of spun glass

fibers bonded with an organic bonding agent. It was coated

with a fire-retardant oil. Microscopic examination of the

fibers indicated that they were between 30 and 50 microns

in diameter. The length of the fibers in the white face

ranged from about 1 to about 3 inches; the length of the

fibers in the blue face ranged from about 2 to 5 inches.

The approximate unit weight of mat was 40 gram/ft2.

3

,

Test Method and Procedure

The medium was tested at a net face velocity of 500 ft/

min. The arrestance determinations were made with the"NBS
Dust Spot Method For Air Filters" (ASHVE Transact ions,

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 behind the

downstream opening as it unrolled. The expended media was

rolled up in a similar spool at the bottom of the frame.

The bottom spool was driven by a motor actuated by an

adjustable pneumatic switch which sensed the pressure drop

across the media. 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

The frame and Drico media were installed in the dust

spot test apparatus 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 area of Whatman

No. 4l filter paper. The arrestance determinations were

made with Cottrell precipitate injected into the air stream

at a ratio of one gram per 1,000 cu . ft. of air.

The light transmission of 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

- 2

-
calculated by the formula:

A = /I - S D x — )X 100

Sn AU ’

where the symbols Sg and Sg are the upstream and downstream

sampling areas and AU and AD are the observed changes in

the opacity of the upstream and downstream sampling papers,

respectively.

Arrestance determinations were made when the media was

clean at the beginning of the test, and at selected intervals of loading until the intermittent advance of the media

under the control of the pneumatic switch 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 of

4 parts to every 96 parts of Cottrell precipitate, including

the Cottrell precipitate used for arrestance measurements.

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 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 yardstick

mounted in the filter housing, adjacent to the mat. A

pilot light connected in parallel with the electric motor

enabled the operator to note the position of the media and

to record the pressure drop across the medium at the beginning and at the end of each advance cycle. The pressure

switch was adjusted to commence the advance cycle when the

pressure drop reached approximately 0.50 in. W. G. and to

stop when the drop was about 0.45 in. W. G.

The position of the media at the beginning of each

advance cycle was recorded as well as the corresponding

cumulative dust load at the time of advance. Prom 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, ten more determinations of

advance as related to load were made, from which it was

possible to draw a straight line from which the dust-holding

capacity in grams/ft2 was determined.

- 3-
The pressure drop across the media was recorded at

the beginning of the test* after each arrestance determination, after introduction of each 20-gram increment of

Cottrell precipitate and lint into the test duct, and at

the beginning and end of each advance cycle.

4 . Test Results

The test results obtained on the specimen Filtrex media

at the design air flow rate of 2000 cfm are summarized in

Tables 1 and 2.

Table 1

Performance of the "Filtrex" Roll Filter Media,

Type 63 DGC at an Air Flow Rate of 2000 CFM

Cumulative

Dust Load

Total Advance

of Media Pressure Drop Arrestance*

Grams Inches In. W.G. Per Cent

0 0 .130 70.5

1726 • 34 .456 83.5

1892 38 . 494 83.8

2059 41 1/2 .480 84.1

2225 45 .506 84.2

2267 45 . 468 83.0 • 2330 47 .442 84.5

* Cottrell precipitate in the laboratory air

It will be noted that the arrestance of the clean filter

medium was 70.5 percent and the average arrestance under

steady-state conditions was 83-9$ using Cottrell precipitate

in the laboratory air as the aerosol.
Table 2

Dust Load, Mat Travel; and Pressure Drop

Of "Filtrex" Glass Fiber Media; Type 63 DGC

Dust Load Mat Travel Pressure Drop; In. W.G.

Grams Inches Before After

Advance Total Advance Advance

0 _ _ 0.130

1465 2 28 0.495 0.460

1570 2 30 0.495 0.435

1664 2 32 0.510 0.455

1726 2 34 0.515 0.455

1809 2 36 0.515 0.460

1892 2 38 0.520 0.465

2017 2 40 0.525 0.480

2142 1 1/2 43 0.505 0.460

2225 2 45 0.505 0.450

2330 2 47 0.505 0.445

The first movement of the media was approximately 3

inches and occurred withl a dust load of 542 grams and at a pressure drop of 0.390 in. W.G . The pneumatic control was

adjusted to the desired cut-in pressure as the first 28

inches of the roll of media were advanced into the air

stream

.

The pressure drop at the beginning; of the advance

cycles after steady-state conditions had been reached (at

1465 grams

)

ranged from 0.495 to 0.525 in. W.G . The

average was O. 5 O9 in. W. G. At the end of the advance cycL

under these conditions; the pressure drops ranged from

0.435 to 0 . 480 in. W.G. with an average of 0.457 in. W.G.

The graph of Fig. 1 shows the performance of the media

for the 10 observations taken after steady state conditions

were established. It will be noted that some of the individual points of observation do not lie in the straight line.

These deviations occurred partly because the advance distance

could only be observed on the scale to the nearest half-inch

mark; and because the pressure control switch did not always

open and close at exactly the same pressure levels. Based

on the best-fitted straight line through the observed data

- 5-
in Figure 1^ it is shown that after 28 in. of mat travel

the dust was 1460 grams and after 47 in. travel, the dust

load was 2310 grams Thus a mat travel of 19 inches was

caused by the introduction of 850 grams of dust The dustholding capacity of the media was calculated by dividing

the dust load increment by the incremental length of advance

in feet and by the width of the media.

Dust-holding capacity = —— x — = 268 grams/sq. ft.

2 19

The performance values determined for the test specimen

were 83-9 percent average arrestance and 268 grams/sq. ft.

dust-holding capacity. The current requirements specified

for the type E media are 75 percent average arrestance and

200 grams/sq . ft . dust holding capacity using Cottrell precipitate as the test dust.

- 6 -
MAT

TRAVEL,

INCHES

MAT TRAVEL VERSUS DUST LOAD

FILTREX MEDIA, TYPE 63 DGC

w*

grams

Position "1 Position \2

1'46'CT

DUST LOAD, GRAMS

FIGURE 1

T!-i •- ;[-ryr

*T— • T

‘ -IV . •1-1 —; fi:[

yr: . ! t;


i

i-