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NATIONAL BUREAU OF STANDARDS REPORT

8674

PERFORMANCE TEST OF

"KLEEN-AIR" GLASS FIBER AUTOMATIC RENEWABLE FILTER MEDIA

manufactured by the

B & M Filter Sales and Service, Inc.

Houston, Texas

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 DUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Th- 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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NATIONAL BUREAU OF STANDARDS REPORT

NSS PROJECT NBS REPORT

421.03-30-4215628 August 18, 1965 8674

PERFORMANCE TEST OF

"KLEEN-AIR" GLASS FIBER AUTOMATIC RENEWABLE FILTER MEDIA

manufactured by the

B & M Filter Sales and Service, Inc.

of Houston, Texas

by

Charles M. Hunt and Paul R. Achenbach

Building Research Division

to

General Services Administration

Public Buildings Service

Washington, D„C,

NATIONAL BUREAU OF S' for use within the Government-! and review. For this reason, tl whole or in part, is not authc Bureau of Standards, Washing

the Report has been specificall

IMPORTANT NOTICE

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

ess accounting documents intended

s subjected to additional evaluation

e listing of this Report, either in he Office of the Director, National y the Government agency for which

copies for its own use.

I. S. DEPARTMENT IF COMMERCE

NATIONM MEAD OF STANDARDS

PERFORMANCE TEST OF

"KLEEN-AIR" GLASS FIBER AUTOMATIC RENEWABLE FILTER MEDIA

manufactured by the B & M Filter Sales and Service, Inc.

of Houston, Texas

by

Charles M. Hunt and Paul R. Achenbach

1 . Introduction

This report describes the results of tests obtained with a "KleenAir" roll-type filter media manufactured by the B and M Filter Sales

and Service, Incorporated, of Houston, Texas. Earlier tests of similar

media manufactured by the same company were reported in NBS Report 8571

dated November 2, 1964. The previously tested media was found to have

a satisfactory arrestance, but the dust-holding capacity was below the

requirement of 200 g/ft 2 cited in the Standard Air-Conditioning Specification, dated December 1964, of the General Services Administration.

The present media was modified in an attempt to meet both the arrestance

and dust-holding capacity requirements.

These tests were undertaken at the request of the Public Buildings

Service of the General Services Administration. The tests include the

determination of arrestance of Cottrell precipitate diffused into laboratory air and the dust-holding capacity. They were performed at a face

velocity of 500 ft/min while the media was intermittently advanced during loading to maintain a pressure drop between 0.45 and 0.5 inches W.G. across the filter.

Two media were submitted, one heavier than that described in Report

8571 and one of comparable weight but of slightly more open construction

according to Mr. Weaver of the B & M Company. This report gives only

data on the latter media, because tests on the other were discontinued

when it became evident that dust-holding requirements would not be met.

2 . Description of Test Specimen

'The present filter media resembled the original material in weight

and appearance. It was 32 inches wide, 2 inches thick, and blue in

color. On the downstream side it was attached to a square-weave scrim

reinforcement of approximately four mesh per inch.

According to the manufacturer the fibers were coated with an adhesive consisting of tricresyl phosphate and a thickening agent.

Analysis showed 9.2 g/ft 2 of a liquid of low volatility which was ex- tractable with alcohol. In addition, about 2 grams of easily charred

solid matter separated from the alcohol extract on evaporation. There was no evidence of drainage from the filter due to excessive adhesive.

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3. Test Methods and Procedure

The methods of test were similar to those used in the previous

tests of "Kleen-Air" filter media.

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 re- strict by-pass of air between the media and frame.

The frame and 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. 41 filter paper. The arres- tance determinations were made with Cottrell precipitate injected into

the air stream with a ratio of one gram of dust 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 calculated by the formula:

- 2

-

where the symbols Sy and Sp 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 became representative of a steadystate 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.

Each loading increment consisted of 20 grams Cottrell precipitate and

0.8 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 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 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.

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. 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 determinations

of advance as related to load were made to develop the best-fitted

straight line through the plotted data, from which the dust-holding

capacity in grams/ft^ was determined.

The pressure drop across the media was recorded at the beginning

of the test, after each arrestance determination, after introduction

of each increment of Cottrell precipitate and lint into the test duct,

and at the beginning and end of each advance cycle.

4 . Test Results

The arrestance of the filter media in the initial state and as test dust was added is given in Table 1. The cumulative advance of

the media and the pressure drop at the times the arrestance measurements were made are also given in the table.

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Table 1

Performance of the Modified "Kleen-Air" Roll

Filter Media at an Air Flow Rate of 2000 cfm

Nominal

Dust Load—'

Total Advance Pressure

of Media Drop Arrestance^/

(grams) (inches

)

(in. W.G.) (per cent)

0 0 0.170 67.8

554 0 0.506 83.2

953 17 1/2 0.502 84.5

1187 23 1/2 0.500 84.5

1482 31 1/2 0.504 84.9

1559 33 1/2 0.452 84.8

a/—Nominal dust load is the total amount of Cottrell precipitate

and lint introduced to the filter. A certain fraction of dust

passes through, so that the net load retained by the filter is

less than the nominal dust load. —/Arrestance was determined with Cottrell precipitate dispersed

in air.

The filter had an initial arrestance of 67.8% and an average

arrestance of 84.7% after steady-state conditions were reached.

In Table 2 the advance of the media required to keep the pressure

drop between 0.45 and 0.5 inches W.G. is shown periodically during the

time the dust load was increasing from 804 to 1559 grams.

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-
t

•
Table 2

Nominal Dust Load, Advance of the Media, and

Pressure Drop of Modified '"Kleen-Air" Roll Filter ]Media

Nominal Advance of

Dust Load^-/ Media Pressure Drop (inches W.G.

)

(grams) (inches ) Before After

Increment Total Advance Advance

0 0 0 0.170 - 804 2 13 1/2 0.500 0.450

887 2 15 1/2 0.504 0.450

953 2 17 1/2 0.502 0.450

1016 2 19 1/2 0.496 0.446

1099 2 21 1/2 0.500 0.448

1187 2 23 1/2 0.506 0.450

1249 2 25 1/2 0.496 0.450

1312 2 27 1/2 0.498 0.450

1395 2 29 1/2 0.502 0.448

1482 2 31 1/2 0.506 0.454

1559 2 33 1/3 0.502 0.452

Average 2 0.501 0.450

—/ See footnote a / , Table 1.

In Figure 1, advance of the media has been plotted as a function

of the nominal dust load. Nominal dust-holding capacity was calculated

from the slope of the line in the figure by the relationship,

Nominal dust-holding capacity = ,

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. In this example, W = 2 ft, and the calculation gives

12 ^ Nominal dust-holding capacity = q 2 66 x 2 = 226 •

2 This capacity is higher than the requirement of 200 g/ft , and the

average arrestance of 84.7% with Cottrell precipitate is in excess of

the required arrestance of 75%, incorporated in the December 1964 revision of the GSA "Standard Air-Conditioning Specification".

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36

34

32

30

28

26

24

22

20

18

16

14

12

ADVANCE OF FILTER VS. DUST LOAD FOE

"KLEEN-AXR" GLASS FIBER AUTOMATIC

RENEWABLE FILTER MEDIA

DUST LOAD (GRAMS) FIGURE 1


1.<