NATIONAL BUREAU OF STANDARDS REPORT

4160

PERFORMANCE TESTS OF A DOLLINGER

ELECTRO-STAYNEW PRECIPITATOR

by

Henry E. Robinson

Thomas W. Watson

Report to

General Services Administration

Public Buildings Service

Washington 25 , D. C.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing

of the divisions and sections engaged in technical work. In general, each section is engaged in

specialized research, development, and engineering in the field indicated by its title. A brief

description of the activities, and of the resultant reports and publications, appears on the inside

of the back cover of this report.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instru- ments. Magnetic Measurements. Process Technology. Engineering Electronics. Electronic

Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Engineering Metrology.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenic Physics.

Engines and Lubrication. Engine Fuels.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid

State Physics. Electron Physics. Atomic Physics. Nuclear Physics. Radioactivity. X-rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. AEC Radiation Instruments. Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Fluid Mechanics. Engineering Mechanics.

Mass and Scale. Capacity, Density, and Fluid Meters. Combustion Controls.

Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems.

Analogue Systems.

Cryogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials.

Gas Liquefaction.

Radio Propagation Physics. Upper Atmosphere Research. Ionospheric Research. Regular

Propagation Services.

Radio Propagation Engineering. Frequency Utilization Research. Tropospheric Propagation

Research.

Radio Standards. High Frequency Standards. Microwave Standards. • Office of Basic Instrumentation • Office of Weights and Measures
NATIONAL BUREAU OF STANDARDS REPORT

ms PROJECT NBS REPORT

1000-30-4630 June 20, 1955 4160

PERFORMANCE TESTS OF A DOLLINGER

ELECTRO-STAYNEW PRECIPITATOR

MODEL PJ¥ 102

by

Henry E, Robinson

Thomas W„ Watson

Heating and Air Conditioning Section

Building Technology Division

To

General Services Administration

Public Buildings Service

Washington 25, D. C.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication,

unless permlssio 25,D,C. Such |

caliy prepared I

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 201 5.

or In part, is prohibited

Standards, Washington

report has been speclfireport for Its own use,

PERFORMANCE TESTS OF A DOLLINGER MODEL PJW 102

ELECTRO- STAYNEW PRECIPITATOR

by

Henry E* Robinson and Thomas W. Watson

1 . INTRODUCTION

At the request of the Public Buildings Service,

General Services Administration, the performance characteristics of electrostatic air cleaners were determined

to provide information to assist in the preparation of

new air filter specifications.

The test results presented herein were obtained on

a specimen electrostatic filter unit submitted by its

manufacturer at the request of the Public Buildings Service and included determinations of dust-arresting efficiency with three aerosols (atmospheric air, kerosene

lamp smoke, and Cottrell precipitate), pressure drop,

specific dirt load and cleanability of the specimen,

2 , DESCRIPTION OF THE FILTER SPECIMEN

The cleaner was manufactured by the Bollinger

Corporation, Rochester, New York, and was of the electro

static type. It was identified as an "Elec tro-Staynew

Precipitator", Model PJW 102 , with one cell, rated

velocity 300 feet per minute (1200 cfm total capacity).

The power pack had the following nameplate data:

"Raytheon Precipitator Power Supply 100 watts; Type

Spec, No, 238; 60 cycles ! 115 volts; l.F amps." Accordin

to the manufacturer's Bulletin 400 * the recommended

nominal voltages were ± 6000 volts for the ionizer and

-6000 for the collector plates.

The test unit had a housing with actual outside

dimensions 25 1/8 x 25 l/8 inches and was 20 7/8 inches

long* It was rated as having about four sq, ft, of

transverse area, i,e,

,

1200 cfm air delivery at 300

fpm velocity.

The upstream and downstream faces had flanges 30

inches square matching those of the duct of the test

apparatus. The face openings were approximately 24

- 2 -

inches square both upstream and downstream. The downstream face was adapted to receive a nominal 24x24x2-

inch after-filter which for this unit was a 23 9/16 x 23 9/lb x 2-inch DPV-2 cleanable impingement type air

filter manufactured by the Bollinger Corporation,

The filter cell of the test unit was 23 3/4 inches

in height, 17 5/6 inches in length, and 23 inches in

width, and contained 6l aluminum or steel plates spaced

approximately 5/16 inch apart, presenting a total surface

area of approximately 185 square feet.

The manufacturer furnished an adhesive (a wateremulsifying oil) designed as "Pingene 400 n

> with which

the collector plates were oiled by spraying them from

both the upstream and downstream face. The after-filter

v/ as oiled in preparation for the test by immersing the

filter in the oil and letting the excess drain off with

the filter standing on edge for 18 hours prior to the

test©

The power pack, connected to a 115-volt 60-cycle

supply, was adjusted in accordance with instructions

of the manufacturer to recommended settings prior to

the tests; the ionizer and plate voltages that resulted

were measured by means of an accurate electrostatic

voltmeter. As indicated in the manufacturer’s bulletin,

the total ionizer voltage differential was equal to the

difference of the positive and negative voltages above

ground furnished by the power pack.

3. TEST METHOD AND PROCEDURE

Efficiency determinations were made by the NBS

"Dust-Spot Method" using the following aerosols? (a)

outdoor air drawn through the laboratory without addition

of other dust or contaminant; (b) kerosene lamp smoke;

and (c) Cottrell precipitate. The test method is described in the paper "A Test Method for Air Filters"

by B. S. Dill (ASHVE Transactions, Vol, 44 * T° 379, 1938).

The test duct and arrangement are shown in Figure 1, A

baffle made of two 3 wide slats was located in the

duct about ft downstream of the test assembly to intermix the air discharged from it.

For these tests, the unit was installed in the test

duct and carefully sealed to prevent inleakage of air.

The desired rate of air flow through the air cleaner was

- 3 - established and samples of air w ere drawn from the center

points of the test duct one foot upstream and eight feet

downstream of the air cleaner assembly at equal rates and

passed through known areas of Whatman No. I4I filter paper.

For the atmospheric air and oil lamp smoke tests , the

samples were drawn at equal rates through equal areas of

filter paper ( 3 /4 -inch diameter spots). The downstream

sample was drawn continuously during the test; the upstream

sample was drawn intermittently in a number of one-minute

periods uniformly distributed over the duration of the test,

aggregating one-tenth of the downstream sampling period.

Under these conditions an efficiency of 90 percent would be

indicated if the upstream and downstream dust-spots on the

filter papers had the same opacity, as indicated by the

change in the light transmissions of the dust-spot areas

before and after the sample was drawn, which were determined by means of a photometer using transmitted light.

The filter papers used in the upstream and downstream

positions were selected to have the same light transmission

readings when clean. If the opacities of the dust-spots

differed, the efficiency was calculated by means of the

formula s- -* / "n

Efficiency, percent = 100 1 100 - 10

where Op and O2 were the opacities of the dust-spots upstream and downstream, respectively, and tp and tp were

the aggregate times during which the upstream and

-

' downstream samples, respectively, were drawn.

For the efficiency tests with Cottrell precipitate

as the aerosol, the samples upstream and downstream were

drawn at equal rates and for equal times but unequal dustspot areas were used to obtain opacities that were approximately equal. If the opacities of the dust-spots differed,

the value of the efficiency was calculated by means of the

formula above, with the ratio k^fk-x substituted for the

ratio tp/tp , where A2 and At were the areas of the dustspots downstream and upstream respectively.

The following procedure was employed in these tests.

After the clean and oiled unit had been installed in the

test duct, and all discoverable air leaks into its housing

had been sealed, its input and output voltages were adjusted to values recommended by a representative of the

4

-

manufacturers (input 115 volts; ionizer 13.6 kv total;

plates-6. 8 kv). Three determinations of the efficiency

of the clean unit were made at the rated velocity, using

as the aerosol outdoor air drawl into the test duct through

a nearby open window* A determination of efficiency with

the unit not energized was also made* Following these,

single determinations were made using outdoor air at

velocities 20 percent greater, and 20 percent less than the

rated velocity.

Next, three efficiency determinations were made at

rated velocity, using as the aerosol outdoor air with

addition of kerosene smoke generated by an open lamp flame

near the inlet to the test duct.

Following these, three efficiency determinations were

made at rated velocity, using as an aerosol outdoor air in

which was dispersed Cottrell precipitate at a concentration

of one gram per thousand cubic feet of air. When these,

had been obtained, the process was begun of loading the unit

with a mixture of four percent cotton lint and 96 percent

Cottrell precipitate, by weight, separately dispersed into

the air stream. The lint used for this purpose was No* 7

cotton linters previously ground in a Wiley mill with a 4 millimeter screen; the lint was dispersed into the air

stream through an aspirator operating at approximately 35

psi inlet air pressure* At suitable periods as loading

progressed, the efficiency of the unit was determined

using 100 percent Cottrell precipitate in outdoor air. In

these tests, and during the loading process, the rate of

feed of the dispersant was one gram per thous and cubic feet

of air. The pressure drop and the ionizer and plate voltages of the unit were recorded at intervals during the

tests. The dirt-loading process was continued until about

dll grams of the lint and Cottrell precipitate mixture

had been fed (i,e„, 2/3 gram per CFM of unit rating).

At suitable periods as the dirt-loading process progressed, strips of transparent cellophane adhesive tape (3/I4

inch wide) were stretched vertically across the test duct

near its axis, with the adhesive side facing upstream.

Tapes were located at three positions ( 1 ) 12 inches upstream,

(2) 15 inches downstream, and (3) eight ft downstream, of the

test unit; the tapes at stations (1) and (3) were in the

same longitudinal, positions in the test duct as the inlets

to the upstream and downstream sampling tubes „ The adhesive

surface of such a tape captured a sample of the particulate

- 5 - matter in the air flowing past it, and after suitable times

of exposure to the aerosol, scrutiny of the tapes by eye and

with a microscope afforded considerable information as to

the vertical distribution, and the nature, number, and size

of the particles caught at the various stations. Photographic enlargements (10X) by transmitted light were made

of sections of the tapes corresponding to a position at

mid-height in the test duct.

At the end of the tests, the filter cell was removed

from the test unit and cleaned by mean’s of a stream of cold

water from a high pressure hose nozzle, directed at and

into the cell plates from both ends of the unit.

4. TEST RESULTS

A summary of the test data, giving efficiencies in

percent with the three aerosols, and the pressure drop of

the' complete unit including the after-filter, in inch

W.G., at rates of air flow corresponding to various face

velocities, is given in Table 1 , Also, a summary of the

test data obtained in the dirt-loading test conducted at

the rated face velocity of 300 fpm is given in Table 2,

Photographs No. 1, 2 and 3 included in this report are

10X enlargements of the center 3 /hxl-inch section of each

of the cellophane tapes located at the three similarlynumbered stations described under Test Method and Procedure, The tapes were exposed at their respective stations

simultaneously during the dirt-loading test for a period in

which 124 grams of mixture were fed to the test unit. This

exposure was during the interval in which the dirt-load increased from 38 to 162 grams, as shown in Table 2. After

exposure, the tapes were carefully removed from the test

duct for photographing and microscopic study.

Throughout the tests with atmospheric air there were

only four observed incidents of electrical sparking or

flashing in the unit audible to the ear. There was no

instance of sparking or flashing during the kerosene

lamp smoke tests. However, during the Cottrell precipitate and lint loading test electrical sparking occurred

intermittently, the frequency increasing from two to

three times per hour at the start to as much as £0 to 100

times per hour at 300 to ^00 grams of load, and reducing

to about 20 to 3 ^ times per hour at the end of the loading

te st

.

- 6

5o SUMMARY

A. Performance

The efficiency of the air cleaner in arresting the

particulate matter existent in atmospheric air drawn

through the unit varied considerably with the face velocity at which it was operated, as shown in Table 1, At

the rated velocity (300 fpm), the average efficiency on

atmospheric air (91«2 percent), and that on oil lamp smoke

(91 o 6 percent), were very nearly the same. The efficiencies are reported to three significant figures obtained

from the test data. In reporting thus, however, it is

considered desirable to point out that an uncertainty on

the order of one or two percent is possible in determining

efficiencies, although in these results the differences between comparable efficiency values were consistently of

lesser magnitude with only one exception.

It is noted in Table 2 that in the dirt-loading test,

the pressure drop of the complete unit increased by 0,023

inch W.G. for a total input dirt-load of 8ll grams. This

rise was due chiefly to an increase in the pressure drop

of the after -filter , as a result of an accumulation of

cotton lint and of comparatively large particles of

Cottrell precipitate on its media.

As recorded in Table 2, the ionizer voltage showed

a decrease of 0,8 kv and the plate voltage a decrease of

1,2 kv at about 5^0 grams of load, however, as the dirt

load was increased further, the ionizer and plate voltages Increased to approximately their initial values.

The efficiency of the unit with Cottrell precipitate as

the aerosol remained at a high level, never falling below

97 ok percent and ending with a value of 98.3 percent,

approximately equal to that at the start of the loading

test. An efficiency determination made with atmospheric

air at the end of the dirt-loading test indicated that

the unit was approximately as efficient (within about two

percent) on this aerosol when heavily laden with dirt,

as it was when clean®

Bo Cleanability

The filter was subjected to the cleaning process

^described under Test Method and Procedure. No difficulty

was experienced in thoroughly cleaning the ionizer and

collector sections of the unit, using moderate care.

General

On completion of the dirt-loading tests r the unit was

removed from the test duct and examined., The ionizer

structure and bars, and the insulators, were generally

coated with a moderate layer of dust and lint. Dirt

deposits were heaviest on the upstream edges and first

two or three inches of the collector plates, the thickness of the deposits being up to about 1/32 inch. The

heaviest deposits were observed on the leading edges of

the negative plates, A continuous, but thinner, layer

of dirt was deposited over the remaining area of the

collector plates, extending to the aft edges. Considerable

bridging of lint fibers from one collector plate to another,

spanning the gap between them, was obaerved; such bridging

appeared to be most extensive from the center of the unit

downstream to the aft edges of the plates.

The upstream face of the after-filter revealed considerable deposits of lint, somewhat concentrated in six

vertical strips each about two inches wide. The afterfilter media was approximately uniformly darkened by a dust deposit on its upstream face, and slightly darkened

by dust visible on its downstream face.

The dirt (dust) deposits on the electrostatic unit,

and on the after-filter appeared to be well saturated with

oil. After the unit had been removed from the test duct,

the section downstream of the unit was carefully swept

out with a fine brush. The amount of material obtained

from this sweeping was 0.3 gram.

The cellophane tape samples obtained at stations ( 1 ),

( 2 ) and ( 3 ), as shown in Photographs No. 1 , 2 and 3, respectively, indicate in a general way the performance of

the complete unit. Photograph No.l shows many particles

under five microns in actual size, and a distribution of

larger particles up to a few as large as I4.OO microns, as

well as many fibers of lint. (In these photographs, l/l6

inch corresponds to an actual dimension of about 160

microns). Photograph No, 2 , for the tape 15 inches downstream of the unit, shows a few large particles up to about

150 microns in size, but very few fine dust particles considering their number upstream of the unit. Photograph No. 3,

for the tape eight feet downstream of the unit, shows an absence of the larger particles of Photograph 2 , which apparently settled out of the air stream.

- 8 - Comparison of the numbers of particles on the upstream

and downstream tapes indicates, in an obvious way, a high

order of efficiency for the unit in arresting Cottrell

precipitate, as is also indicated by the discoloration test

results presented in Table 2, The latter results show a considerably higher efficiency for the unit when Cottrell precipitate was being received in the air stream than when the

aerosol was outdoor air or kerosene lamp smoke . The overall

efficiency of the unit on particles of the sizes found in

Cottrell precipitate appears therefore to be better than

on the finer particles in outdoor air or kerosene smoke.

Nevertheless, the downstream tapes, and the deposits on

the after-filter, show that a few quite large particles

of dust escaped beyond the electrostatic unit a Whether the

large particles were passed through the unit because they

were not arrested at all, or were caught and later dislodged

from the collector plates by electrical sparking, is not

known from these tests.

As the photographs show, a few large particles passed

unarrested through the after-filter. Assuming that one of

the functions of the after-filter is to arrest as much as

possible of the material escaping the electrostatic unit,

the arrestance characteristics of the after filter are of

major importance in determining the presence or absence,

in the air leaving the complete unit, of such particulate

matter as is shown in the downstream tape photographs.

Table 1

Total

Face Inlet Ionizer Plate Pressure Duration

Velocity Aerosol# Voltage Voltage Drop of Test Efficiency

fpm kv kv inch W.G. minutes percent

300 A 0 0 O.O83 35 12 . 5##

300 A 13o6 6.8 O.O83 180 90.0

300 A 13.6 6.8 .083 180 91 o 9

300 A 13.6 6 e 8 .083 180 91 o 6

36O A 13.6 608 .113 180 67 0 2

2I4O A 13*6 6.8 o 059 180 94«9

300 S 13o6 6.8 0O8I4 180 91.7

300 a 13« 6 6 . 8 .0 84 180 91.8

300 s 13*6 6<>8 .084 180 91.4

300 c 13.6 6.8 .083 12 97.5

300 c 13o6 6.8 .O83 10 99 0I4 300 c 13o6 6.8 .083 10 98.4

#A = Particulate matter in atmospheric air at NBS.

S = Kerosene lamp smoke in atmospheric air.

C = Cottrell precipitate in atmospheric air (1 gram/1000 CF).

## Since unit was not energized, the efficiency was chiefly that

of the after-filter.

Table 2

Face

Velocity

fpm

300

Dirt

Load-*

Total

Ioniser

Voltage

Plate

Voltage

Pressure

Drop Efficiency-**

grams kv kv inch W.G. percent

13.6 6. 8 0.0 814 98.14 (avg)

175 13 o 6 6,8 .089 98.3

3149 13 c 8 6.9 .090 98.3

361 13 o 0 6.1 .088 97o 8

52k 12 o 8 5o6 o091 97 .U

6i|9 13o7 6.7 .093 98.1

761 13 d 5.9 .099 - 811 13.8 6.9 ol07 98.3

811 13,8 6.9 .107 89 . 2-*-**

mixtures 3»9%

'lint, 96.1$ Cottrell precipitate

by wei ght

.

^Efficiency determined with 100% Cottrell precipitate.

-*#*-Efficiency determined with atmospheric air (aerosol A)

as in Table 1, with the unit dirty

.

Orif i c

O

_ i OJ

j.

cj

IfTTid) Nj

I i

Up Stre am Duct

VERTICAL SECTION

-4 Ilf< -X Filter Frame

Down Stream Duct

VERTICAL SECTION

Air Filler Test Apparatus

Fig. 1
i ' *-


Photograph h .

* J

Photograph i. • 3

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 with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

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

various consultation and information services. A major portion of the Bureau’s work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic Energy

Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project

or program. Published papers appear either in the Bureau’s own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

complete papers reporting technical investigations; the Technical News Bulletin, which presents

summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions,

which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.25) and its Supplement ($0.75), available from the Superintendent of Documents, Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of Standards, Washington 25, D. C.