NATIONAL BUREAU OF STANDARDS REPORT

7555

PERFORMANCE TEST OF THE BLUE BALANCE TYPE

AUTOMATIC RENEWABLE FILTER MEDIA

supplied by

Electro-Air Cleaner Company

McKees Rocks , Pennsylvania

by

Carl W. Coblent z and Paul R„ Achenbach

Report to

General Services Administration

Public Buildings Service

Washington 25 * D„C 0

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

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and applied research, development, engineering, instrumentation, testing, evaluation, calibration services,

and various consultation and information services. Research projects are also performed for other government

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.

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in the journals of professional and scientific societies. The Bureau itself publishes three periodicals avail- able from the Government Printing Office: The Journal of Research, published in four separate sections,

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and Technical Notes. A complete listing of the Bureau’s publications can be found in National Bureau of Standards Circular

460, Publications of the National Bureau of Standards, 1901 to June 1947 (31.25), and the Supplement to National Bureau of Standards Circular 460, July 1947 to June 1957 (81.50), and Miscellaneous Publication 240,

July 1957 to June 1960 (Includes Titles of Papers Published in Outside Journals 1950 to 1959) (82.25); avail- able from the Superintendent of Documents,' Government Printing Office, Washington 25, D. C.
NATIONAL BUREAU OF STANDARDS REPORT

MBS PHOJECT MBS DEPOSIT

1003-30-10630 July 20, 1962 7555

PERFORMANCE TEST OF THE BLUE BALANCE TYPE

AUTOMATIC RENEWABLE FILTER MEDIA

supplied by

Electro-Air Cleaner Company

McKees Rocks, Pennsylvania

by

Carl W. Coblentz and Paul R. Achenbach

Mechanical Systems Section

Building Research Division

to

General Services Administration

Public Buildings Service

Washington 25* D c C s

NATIONAL BUREAU OF ST

Intended for use within the

to additional evaluation and 1 listing of this Report, either the Office of the Director, Ne however, by the Government

to reproduce additional copli

IMPORTANT NOTICE

regress accounting documents Approved for public release by the n,0 lb published It Is subjected rv * r-,, xt x- it 1 reproduction, or open-literature Director of the National Institute of .| on | 5 obtained In writing from Standards and Technology (NIST) Such permission Is not needed, on October 9, 2015. P

re P ared lf that a«

ency wishes

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U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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PERFORMANCE TEST OF THE BLUE BALANCE TYPE

AUTOMATIC RENEWABLE FILTER MEDIA

supplied by

Electro-Air Cleaner Company

McKees Rocks, Pennsylvania

by

Carl W. Coblent z and Paul R. Achenbach

1 . Intro ductlon

At the request of the Public Buildings Service, General

Services Administration, the performance characteristics of an

automatic renewable air filter media, identified as Blue Balance

media, was determined. The scope of this examination included

the determination of the arrestance and the dust-holding capacity

of the media when operated at a face velocity of 500 ft/min and

at a pressure drop not to exceed 0.5 in. W.G. The arrestance was

determined of Cottrell precipitate and also of the particulate

matter in the laboratory air.

2. Description of Test Specimen

The roll of filter media was supplied by the Electro-Air

Cleaner Company of McKees Rocks, Pennsylvania. It was produced

by the Standard Electric Company of San Antonio, Texas, and

Identified as the Blue Balance type media for automatic renewable media air filters. The media was supplied in a 3 ft wide

roll, approximately 65 ft long. The mat was made of glass fiber,

of blue color, and was about 1 3/4 in. thick. The fibrous mat

was looser at the upstream face of the media than at the downstream side. The fibers were bonded with an organic binder and

treated with an adhesive, said to be tricresyl phosphate. The

weight of the mat was approximately 32 grams per square foot and

a microscopic examination Indicated that most of the fibers were

between 30 and 50 microns in diameter and several inches, long.

The media was tested on an "Auto Roll" filter frame, manufactured by the Electro-Air Cleaner Company, which had been modified for Installation in the National Bureau of Standards air

filter test apparatus. The modification consisted mainly of a complete sheet metal enclosure which covered the clean roll of

media at the top of the filter frame as well as the loaded media

wound on the lower roll, and two flanges that permitted an airtight connection to the two sections of the test duct. The air

flow passage was 24 in. square and had a vertical stationary
- 2 -

grid on the downstream side of the mat to prevent excessive

deflection of the media. The advance of the filter mat was controlled by a pressure switch which closed an electric circuit

when the pressure drop across the filter approached 0.5 in. W.G.

The pressure switch had a fixed differential setting and operated

an electric motor that was connected to the lower spool.

3 . Test Method and Procedure

The filter media was tested at the rated face velocity of

500 ft/min. The arrestance determinations were made in accordance

with the NBS Dust Spot Method described in a paper by R. S. Dill

entitled n A Test Method for Air Filters” (ASHVE Transactions * Vol.

44, p. 379* 1938). The filter under test was installed in the

test apparatus and carefully sealed to prevent any by-pass of air

or inward air 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 2 feet upstream and 8 feet downstream of

the test specimen at equal rates and passed through known areas

of Whatman No. 41 filter paper. Arrestance determinations were

made periodically 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 1 gram per 1,000 cu ft of air.

The light transmission of the sampling papers was measured

on 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 sampling air

through the upstream paper only 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-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 - T x 45
3

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

through the upstream sampler* and AH 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

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

The arrestance was then calculated by the formulas

A = d - sj x * 100

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

and Sy and SD

are the upstream and downstream sampling areas*

respectively,

Arrestance determinations were made with Cottrell precipitate when the media was clean* at intervals thereafter during

the loading of the initially-exposed section of media* and

several times after incremental advance of the media began. The

media was loaded with cotton linters and Cottrell precipitate

in the ratio of 4 to 96 parts by weight. When ah arrestance

determination was made with Cottrell precipitate* the linters

were not added* but this Interruption in linter addition was

compensated for later to maintain the selected ratio of the two

contaminants. 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 media under test was

observed and recorded after each arrestance determination* after

introduction of each 20-gram Increment of Cottrell precipitate

into the test duct* and at the beginning and end of each advance

cycle.

4. Test Results

The test results are summarized in Tables 1 and 2. Table 1

shows the arrestance values for Cottrell precipitate as the

initially-exposed section of media was being loaded and at a later

time when the media was being advanced incrementally. The pressure drop of the clean mat at the rated face velocity of 500 ft/

min was 0.210 in. W.G. and the initial arrestance of Cottrell

precipitate was 68 percent. It will be noted* that the arrestance Increased with the pressure drop and that the arrestance of

Cottrell precipitate ranged from JQ percent to 82 percent for

pressure drop values between 0.4 and 0.5 in. W.G.* averaging 80

percent. The arrestance of the particulate matter in the
- 4 -

laboratory air at 0.436 in. W.G. pressure drop was 12 percent.

Table 2 shows the mat travel, the dust load, and the pressure drop across the filter before and at the end of each advance

of the media. It was found that the increments of mat travel

varied between 2 1/2 in. and 4 in., averaging 3*16 in.

The cumulative dust load values in Table 2 are expressed In

grams per foot width and represent the amount of Cottrell precipitate and lint introduced into the test apparatus. The "DustHolding Capacity" provides a relative measure of the rate of

media consumption under operating condition. The observed dust

load values were plotted against the cumulative advance of the

media in Figure 1 and the dust-holding capacity was determined

as the slope of a line through the plotted points. The dashed

line in Figure 1 indicates the average dust-holding capacity

obtained by using all of the data for mat travel and dust load

beginning with a mat position of 17 in. and ending with a total

mat movement of 69 1/2 in. The dust-holding capacity for the

over-all operation was 200 g/sq ft.

An inspection of Table 2 shows that the increments of mat

travel were not entirely consistent. Also the change in the

pressure drop caused by advancing the mat varied from 0.052 to

0.100 in. W.G. at different periods during the test. In particular, the increments of mat travel between mat positions of

17 in. and 25 in. and between 58 1/2 in. and 69 1/2 in. were

below the average, and the change in pressure drop during these

same periods was below average. The slope of lines faired

through the plotted points in Figure 1 corresponding to' these

portions of the test is somewhat lower than the dotted line

shown for the entire test. The dust-holding capacities indicated by these flatter slopes are 232 and 238 grams/sq ft.

These results indicate that a pressure switch with a smaller

pressure differential would provide an appreciably higher dustholding capacity in any given case. Discounting the first two

increments of mat travel for this specimen, the average effective

differential of the pressure switch was 0.080 in. W.G. for this

test.

Probably the average dust-holding capacity of 200 grams/

sq ft computed for the mat travel from 17 in. to 70 in. is a more reliable measure of the performance of the test specimen

than the two short periods of better performance.

USCOMM-NBS-DC
Table 1

PRESSURE DROP AND ARRESTANCE OF "BLUE BALANCE" MEDIA

Pressure Drop Arrestance Aerosol*

in. W.G. ' yo

'

0.210 68 C

0.212 69 C

0.348 76 C

0.485 78 C

0.486 82 C

0.436 12 A

0.447 79 C

0.460 8l C

*Aerosol A - Particulate matter in laboratory air.

C - Cottrell precipitate in laboratory air.
Table 2

MAT TRAVEL, DUST LOAD, AND PRESSURE DROP

OF ’’BLUE BALANCE” FILTER MEDIA

Dust Load Travel of Mat, in. Pressure Drop, in. W. G.

g/ft width Advance Total Before Advance After Advane

208 3 3 0.497 0.445

240 2 1/2 5 1/2 0.495 0.435

281 4 9 1/2 0.500 0.415

333 4 13 1/2 0.495 0.415

386 3 1/2 17 0.490 0.410

438 2 1/2 19 1/2 0.495 0.415

490 3 22 1/2 0.497 0.417

542 2 1/2 25 y 0.495 0.425

573 2 1/2 27 1/2 0.497 0.420

625 4 31 1/2 0.495 0.409

688 3 1/2 35 0.490 0.390

729 3 38 0.489 0.400

781 3 41 0.498 0.410

833 3 1/2 44 1/2 0.490 0.415

885 3 1/2 48 0.488 0.410

937 3 51 0.489 0.410

989 3 1/2 54 1/2 0.500 0.410

1041 4 58 1/2 0.496 0.410

1104 2 1/2 61 0.495 0.425

1156 3 1/2 64 1/2 0.495 0.423

1208 2 1/2 67 0.500 0.430

1260 2 1/2 69 1/2 0.498 0.429
I

i

I

I

I

I

I

II

DUST LOAD

grams per foot width

MAT TRAVEL VS DUST LOAD

Figure 1
.
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 cut 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.

Electricity. Resistance and Reactance. Electrochemistry. Electrical Instruments. Magnetic Measurements

Dielectrics. High Voltage.

Metrology. Photometry and Colorimetry. Refractometry. Photographic Research. Length. Engineering Metrology.

Mass and Scale. Volumetry and Densimetry.

Heat. Temperature Physics. Heat Measurements. Cryogenic Physics. Equation of State. Statistical Physics.

Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiological Equipment.

Nucleonic Instrumentation. Neutron Physics.

Analytical and Inorganic Chemistry. Pure Substances. Spectrochemistry. Solution Chemistry. Standard Refer- ence Materials. Applied Analytical Research. Crystal Chemistry.

Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Rheology. Combustion

Controls. Polymers. Macromolecules: Synthesis and Structure. Polymer Chemistry. Polymer Physics. Polymer Characterization. Polymer Evaluation and Testing. Applied Polymer Standards and Research. Dental Research.

Metallwgy. Engineering Metallurgy. Microscopy and Diffraction. Metal Reactions. Metal Physics. Electrolysis

and Metal Deposition,

Inorganic Solids. Engineering Ceramics. Glass. Solid State Chemistry. Crystal Growth. Physical Properties.

Crystallography.

Building Research. Structural Engineering. Fire Research. Mechanical Systems. Organic Building Materials. Codes and Safety Standards. Heat Transfer. Inorganic Building Materials. Metallic Building Materials. Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics. Operations Research. Data Rocessing Systems. Components and Techniques. Computer Technology. Measurements Automation.

Engineering Applications. Systems Analysis.

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Instrumentation. Engineering Electronics. Electron Devices. Electronic Instrumentation. Mechanical Instru- ments. Basic Instrumentation. Physical Chemistry. Thermochemistry. Surface Chemistry. Organic Chemistry. Molecular Spectroscopy. Molecular Kinetics. Mass Spectrometry.

Office of Weights and Measives.

BOULDER, COLO.

Cryogenic Engineering Laboratory. Cryogenic Equipment. Cryogenic Processes. Properties of Materials. Cryogenic Technical Services. CENTRAL RADIO PROPAGATION LABORATORY

ionosphere Research and Propagation. Low Frequency and Very Low Frequency Research. Ionosphere Research. Prediction Services. Sun-Earth Relationships. Field Engineering. Radio Warning Services. Vertical Soundings Research.

Radio Propagation Engineering. Data Reduction Instrumentation. Radio Noise. Tropospheric Measurements.

Tropospheric Analysis. Propagation-Terrain Effects. Radio-Meteorology. Lower Atmosphere Physics.

Radio Systems. Applied Electromagnetic Theory. High Frequency and Very High Frequency Research. Modulation Research. Antenna Research. Navigation Systems.

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Standards. Millimeter-Wave Research.

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

Center.