To capture fine particulate matter in a gas such as air, a dielectric fluid is directed to the center of whichever face of a rotating disc is exposed to the air flow. The disc is comprised of two or more segments which bear opposite electrostatic potentials. As the dielectric fluid is centrifuged towards the periphery of the rotating disc, the fluid becomes charged to the same potential as the segment over which it is passing. Particulate matter is attracted to the charged segment and is captured by the fluid. The fluid then carries the captured particulate matter to a collection device such as a toroidal container disposed around the periphery of the disc. A grounded electrically-conductive ring may be disposed at the outer periphery of the disc to neutralize the captured particles and the fluid before they enter the container

Peterson, V. S.

Siewert, R. D.

English

NASA Technical Reports Server

nited States Patent [ I ~ I  
Peterson et al. 
[54] FINE PARTICULATE CAPTURE DEVICE 
[75] Inventors: Victor S. Peterson, Brunswick; 
Robert D. Siewert, Sandusky, both of 
Ohio 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 414,042 
[22] Filed: Nov. 8, 1973 
[51] Int. C1.2 ................................................ B03C 3/78 
[52] U.S. c1. ........................................ 55/118; 55/122; 
55/127; 55/155; 55/241; 55/242; 55/360; 
55/407 
[58] Field of Search ................. 55/118, 120, 122, 124, 
55/126, 127, 142, 149, 155, 238, 407, 220, 241, 
242, 360 
[561 References Cited 
U.S. PATENT DOCUMENTS 
2,709,954 6/1955 Baker .............................. 55/126 UX 
2,116,724 1/1957 Goldschmied ......................... 55/124 
3,033,643 5/1962 Janes ............................... 55/122 UX 
3,384,446 5/1968 Ziems et al. ....................... 55/122 X 
3,401,503 9/1968 Bergstrom ......................... 55/122 X 
[111 4,134,744 
1451 Jan. 16, 1979 
3,444,667 5/1969 Mullin ................................ 55/122 X 
3,804,942 4/1974 Kat0 et al. ......................... 55/126 X 
Primary Examiner-Frank W. Lutter 
Assistant Examiner-Kathleen J. Prunner 
Attorney, Agent, or Firm-N. T. Musial; J. R. Manning; 
J. A. Mackin 
1571 ABSTRACT 
To capture fine particulate matter in a gas such as air, a 
dielectric fluid is directed to the center of whichever 
face of a rotating disc is exposed to the air flow. The 
disc is comprised of two or more segments which bear 
opposite electrostatic potentials. As the dielectric fluid 
is centrifuged towards the periphery of the rotating 
disc, the fluid becomes charged to the same potential as 
the segment over which it is passing. Particulate matter 
is attracted to the charged segment and is captured by 
the fluid. The fluid then carries the captured particulate 
matter to a collection device such as a toroidal con- 
tainer disposed around the periphery of the disc. A 
grounded electrically-conductive ring may be disposed 
at the outer periphery of the disc to neutralize the cap- 
tured particles and the fluid before they enter the con- 
tainer. 
9 Claims, 1 Drawing Figure 
https://ntrs.nasa.gov/search.jsp?R=19790009021 2020-03-20T18:21:17+00:00Z
U.S. Patent Jan. 16, 1979 4,134,744 
1 
4,134,744 
FINE PARTICULATE CAPTURE DEVICE 
ORIGIN OF THE INVENTION 
This invention was made by Government employees 5 
and may be manufactured and used by or for the Gov- 
ernment of the United States without the payment of 
any royalties thereon or therefor. 
BACKGROUND OF THE INVENTION 
This invention relates to environmental pollution 
measuring devices and is directed more particularly to a 
device for collecting or capturing sub-micron size gas- 
borne or air-borne particulates. 
centers and elsewhere has become a national concern, 
all levels of Government have enacted laws and estab- 
lished requirements for maximum allowable pollution 
levels of gases and solids. Accordingly, there is a need 
for apparatus for quickly, economically and accurately 20 
measuring pollutants in the air. 
To measure the solid matter of particulates in the air, 
known volumes of air samples are directed through 
filters which capture the particulate matter. However, 
these filters do not capture extremely small particles 25 
and particularly those ,of sub-micron size. Moreover, if 
these sub-micron particles are captured in the conven- 
tional filter, it is dflicult, if not impossible, to remove 
them from the filter element material for analysis. 
OBJECTS AND SUMMARY OF THE 
INVENTION 
It is an object of the invention to provide apparatus 
which will capture sub-micron size particulate matter 
from a gas such as air for accurate quantitative and 35 
qualitative analysis. 
It is another object of the invention to provide a 
particular capture device which does not require re- 
newal or replacement of parts after each sample collec- 
tion. 40 
In recent years, since air pollution around large urban 15 
30 
It is still another object of the invention to provide a 
particulate capture device for sub-micron particles 
which may be operated in conjunction with a filter 
which captures the larger particles. 
Yet another object of the invention is to provide a 
particulate collection device which stores the collected 
matter in such a way that it is rapidly and easily re- 
moved for evaluation. 
In summary, the instant invention provides apparatus 
for collecting sub-micron airborne particles which 
would be lost within normal filters and which provides, 
as part of the invention, a container for the collected 
particulate matter. 
BRIEF DESCRIPTION OF THE DRAWINGS 
The single FIGURE is a partially cutaway, oblique 
pictorial view of a capture device embodying the inven- 
tion. 
DESCRIPTION OF A PREFERRED 
EMBODIMENT 
Referring now to the single figure, there is shown a 
fine particulate capture device 10 which includes a disc 
11 disposed at one end of a hollow shaft 12. The hollow 
shaft 12 is rotated by an electric drive motor 13 through 
which shaft 12 extends. A dielectric fluid which is non- 
reactive with the particulate matter of interest and pref- 
erably of low viscosity is directed downwardly through 
45 
50 
55 
60 
65 
2 
the hollow shaft 12 via a rotary union 15 from a source 
of dielectric fluid 14. Suitable fluids include but are not 
limited to hydrocarbons, silicon oils, synthetic oils and 
deionized water. 
Electrostatic potentials as at 17 are directed to the 
disc 11 by means of an electrostatic potential slip-ring 
assembly 16. 
To control the rate of flow of dielectric fluid being 
supplied to disc 11, a throttle valve 18 may be disposed 
between the fluid source 14 and the rotary union 15. 
The throttle valve 18 is adjusted to determine the rate of 
capture fluid flow such that a thin layer covers the 
surface of disc 11 exposed to the contaminated air. The 
fluid and captured particulate matter then is centrifuged 
toward the periphery of the disc 11 which is being 
rotated by the drive motor 13. 
The disc 11 is comprised of a plurality of mutually 
isolated, positive sections 19 and negative sections 20 
having a generally wedge-shaped configuration. The 
sections 19 and 20 are of an electrically-conductive 
material such as metal or various types of conductive 
plastics. It will be understood that materials used for the 
segments 19 and 20 must be inert with respect to the 
dielectric fluid being used. The conductive segments 19 
and 20 are separated by dielectric spokes 21 and sub- 
tended by a peripheral dielectric rim 22. 
The disc 11 may be made by inserting conductive 
segments 19 and 20 into a dielectric spoked wheel com- 
prised of a rim 22 and spokes 21. Preferably, the disc is 
made from a dielectric disc having a thin metal layer 
thereon by utilizing well-known circuit etching tech- 
niques to remove the metal layer in the areas defined as 
spokes 21 and rim 22. 
As mentioned previously, a dielectric fluid flows at a 
rate determined by throttle valve 18. The dielectric 
fluid is dispensed through apertures 9 near the lower 
end of hollow shaft 12 and distributed on the lower 
surface of the disc 11. The rotating speed of the disc 11 
and the flow rate of the capture fluid through the throt- 
tle valve 18 must be adjusted to assure an even flowing 
film of fluid over the entire exposed area of the disc 11. 
The speed of the drive motor 13 and the adjustment 
of the throttle valve 18 depend on the viscosity of the 
selected capture fluid. The centrifugal force imparted to 
the fluid must overcome the forces of gravity that 
would tend to separate the fluid from the disc 11 surface 
area. 
Particles carried in an effluent gas or air sample flow- 
ing in the direction as indicated by arrows 23 are di- 
rected by flow velocity and subsequently attracted to 
the electrostatically charged sections 19 and 20. As the 
particles approach the sections 19 and 20, they contact 
the flowing fluid and are captured thereby. Thus, the 
particles are centrifuged towards the periphery of disc 
11 in the dielectric fluid and are collected in a torus 
container as will be described presently. 
As the particles are centrifuged with the dielectric 
fluid, they may obtain varying degrees of electrostatic 
potentials. This is undesirable in that particles that have 
opposite charges would attract to form an agglomerate 
mass. This would spoil the analysis as to population 
density and size of the particles. Accordingly, it is desir- 
able to neutralize the captured particles before they are 
collected. To this end, an electrically-conductive ring 
24 is disposed at the rim of disc 11 and serves as a charge 
neutralizer means. The ring 24 is connected to a ground 
neutral as at 26 via a connective wire (not shown) and 
the slip ring assembly 16. 
4,134,744 
3 4 
In order to collect the particulate-bearing centrifuged 
fluid, a hollow torus 27 is attached by bolts or other 
suitable means to the neutralizing ring 24, as shown by 
means of an upper, inner rim 6 which is attached by 
bolts or other suitable means to an annular mounting 5 
ring 28. A lower, inner rim 8 of the torus is spaced 
below the lower surface of the disc 11 to form an annu- 
lar slot 5 which receives the centrifuged fluid from the 
disc. Torus 27 forms an annular chamber 7. 
from the disc 11 into the torus the disposition electrically conductive material disposed at the periph- 
of the fluid in the torus is indicated at 30. 31 ery of said disc in spaced relationship to said sections to 
indicates the direction of rotation of the disc 11 and the neutralize the dielectric liquid and any charged particles 
torus 27 although it will be obvious that the torus and 15 c o ~ ~ ~ ~ ~ ~ ~ ~  of claim wherein said ring is at an 
the disc can rotate in the opposite direction. electric potential intermediate the opposite potentials of 
the respective sections, 
means for directing a dielectric collector fluid to the 
center of said disc; 
means for controlling the flow rate of said dielectric 
fluid such that it flows in a continuous film toward 
the edge of said disc, and 
means for collecting the fluid being centrifuged from 
said disc, said dielectric fluid being inert with re- 
spect to said sections and non-reactive with respect 
to said particles. 
The arrows 29 indicate the direction of the fluid flow 10 2. The apparatus of claim 1 and a ring Of 
From the foregoing, it will be seen that the invention 
provides apparatus for 
from a gas by flowing a 
disc having charged 
Particulate matter 
fluid across a rotating 
4. The apparatus of claim 1 wherein said dielectric 
fluid is selected from the group consisting of hydrocar- 
which attract particulate 20 bons, sficon oils, synthetic oils and deionized water. 
matter. This causes the particulate matter to be cap- 5. The apparatus of claim wherein said sections 
tured in the fluid and centrifuged into a container dis- comprise foils attach& to a dielectric material. 
posed around the periphery of the rotating disc. 6. The apparatus of claim 1 wherein said means for 
It will be understOOd that those skilled in the art may collecting the dielectric fluid comprises a torus having 
change or modify the invention as dt%akd above 25 annular slot defined by a lower inner rim and the disc, 
without departing from the Spirit and Scope Of the in- 
vention, as set forth in the claims appended hereto. 7. The apparatus of claim 6 wherein said torus is 
8. The apparatus of claim 6 wherein said torus is at an 
30 electric potential intermediate the respective opposite 
potentials of the sections comprising said disc. 
9. The structure of claim 1 wherein said sections are 
wedge-shaped, each section being of a polarity opposite 
to the polarity of each adjacent section. 
the periphery of said disc being inside said toms. 
What is claimed is: 
1. Apparatus for C W k g  particles in a gas, said 
apparatus comprising: 
a disc including at least two sections, each section 
bearing an electrical potential of opposite polarity 
to an adjacent section; 
means for rotating said disc about an axis perpendicu- 
lar to its surface; 35 
attached to and rotates with said disc. 
I * + + +  
45 
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Fine particulate capture device

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