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Publication numberUS2868318 A
Publication typeGrant
Publication dateJan 13, 1959
Filing dateJun 23, 1955
Priority dateJun 23, 1955
Publication numberUS 2868318 A, US 2868318A, US-A-2868318, US2868318 A, US2868318A
InventorsGrinnell Stuart W, Perkins William A, Schadt Conrad F
Original AssigneeGrinnell Stuart W, Perkins William A, Schadt Conrad F
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Collection of airborne material by electrostatic precipitation
US 2868318 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

w. A. PERKINS ETAL 2,868,318 COLLECTION OF AIRBORNE MATERIAL BY ELECTROSTATIC PRECIPITATION Filed June 23, 1955 Jan. 13, 1959 Yr m w m m mmaw m V1 0 w. AW. d 7 mam lf/f/ll/ll w 2.2032 N\ vN W v 1 V\ p- .ww /M .WHHHJ JW All W 1 mwww F 1 .i {EMF 9 i i Ii I United States Patent COLLECTION OF AIRBORNE MATERIAL BY ELECTROSTATIC PRECIPITATION William A. Perkins, Los Altos, Stuart W. Griunell, Menlo Park, and Conrad F. Schadt, Palo Alto, Calif assignors to the United States of America as represented by the Secretary of the Army Application June 23, 1955, Serial No. 517,664

3 Claims. 01. 183-7) This invention relates to a method of collecting airborne particulate material from a current of air. More particularly, it relates to a device and a method of allowing a current of air to impinge on an anode surface whereby the particles in the air are made to adhere to the anode and can thereafter be examined under a microscope.

In the drawings, Fig. 1 shows a longitudinal section of the precipitator and Figs. 2 and 3 show transverse sections at 2-2 and 3-3 respectively. More particularly, 2 is a transparent tube preferably made of a plastic material such as Lucite. Each end of the tube 2 is fitted with stoppers 4 and 6 which have openings 8, 10 and 12. Opening 8 in stopper 4 receives a smaller Lucite tube 14 within which is a perforated spacer 16 supporting a Bakelite rod 18. This latter rod is the insulator for the cathode 20. In stopper 6 there are two openings, 10 and 12. The latter opening is centrally located and supports the anode rod 22. Anode disk 24 is fastened to the end of this rod perpendicular to it and the cathode. Opening 10 serves as an exit for the air which enters through tube 14. An electrical circuit is completed through a 10 megohm resistor in series with the cathode which assists in maintaining a corona discharge at the cathode.

In operation, air is drawn inthrough tube 14, around anode 24 and out opening 10. A potential of 8,000 to 10,000 volts is maintained between anode and cathode which produces a corona discharge at the cathode. Particulate matter in the air entering through tube 14 impinges on the anode disc 24 and adheres thereto over an area substantially equal to the cross sectional area of tube 14. The volume of air passing through the instrument can be determined by time and velocity of flow and the particulate matter therein which has collected on the anode can be examined under a microscope to determine amount as well as size of particles.

As a practical embodiment, the Lucite tube may be about 2%" internal diameter with a length of 6" and with other dimensions in proportion. With such a tube, having a cathode-anode spacing of 6 mm. and a voltage of 8,000 to 10,000, it was possible to maintain an air flow of 100 liters/min. with a small blower using about 10 watts. With such a rate of flow, at least of all particulate matter in the air is collected, even where the particle size is only but 1 to 5 microns in diameter.

The anode surface is highly polished thereby making it possible to clearly see the nature and amount of the particulate matter under a microscope, using surface illumination.

Several modifications of the instrument: are possible. Thus, several cathodes may be installed around the one anode and the air may be sampled through any one or all of the cathodes and deposited on different. areas. Conversely, the anode surface may be rotated thereby placing new surface areas in front of the cathode. Due to the transparent outer tube of the instrument, it is possible to observe the anode surface at all times thereby preventing an excess of anode deposit to be built up before examination is made.

We claim:

1. An electrostatic precipitator comprising a longitudinal tube having an anode surface therein perpendicular to and supported by a central shaft coincident with the axis of said tube, a pointed cathode supported normally and in close spacing to said anode surface and to one side of the center thereof including means to admit air around said anode in a stream confined to a small area of said anode and including electrical means to supply a direct current potential difference of 8,000 to 10,000 volts between cathode and anode.

2. An electrostatic precipitator in accordance with claim 1 wherein the anode supporting shaft is positioned in a stopper in the end of the tube, said stopper containing an additional opening for exhausting air from the tube.

3. An electrostatic precipitator in accordance with claim 1 wherein the anode surface is highly polished and is rotatable to expose new surfaces to the cathode discharge.

References Cited in the file of this patent UNITED STATES PATENTS 1,069,993 Amos Aug. 12, 1913 1,992,113 Anderson Feb. 19, 1935 2,244,278 White June 3, 1941 2,748,887 Osmar June 5, 1956 OTHER REFERENCES Perry: Chemical Engineers Handbook, 3rd ed., Mc- Graw-Hill (1950), pages 1039-1045.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1069993 *Oct 3, 1908Aug 12, 1913Nat Purification CompanyElectrical purification apparatus.
US1992113 *Oct 26, 1931Feb 19, 1935Int Precipitation CoElectrical precipitating apparatus
US2244278 *Mar 1, 1940Jun 3, 1941Research CorpElectrode for electric precipitators
US2748887 *Aug 4, 1952Jun 5, 1956Osmar John JElectric dust precipitator
Referenced by
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US3035445 *Apr 11, 1958May 22, 1962Evans Iii Evan CAerosol sampler
US3485011 *Oct 21, 1966Dec 23, 1969Coe Everett L JrElectrical precipitator and operating method
US3520172 *May 29, 1967Jul 14, 1970Univ MinnesotaAerosol sampler
US3695001 *Mar 24, 1970Oct 3, 1972Nippon Kogei Kogyo CoMethod and system for removing particles of floating dusts produced upon an excavation of a tunnel
US3827217 *Dec 19, 1972Aug 6, 1974Commissariat Energie AtomiqueElectrostatic precipitator for the collection of particles contained in a gas
US3853750 *Dec 19, 1972Dec 10, 1974Commissariat Energie AtomiqueMethod and device for the collection of particles in a gas with particle-size separation
US3957374 *Jan 14, 1975May 18, 1976Carl Zeiss-StiftungApparatus for obtaining samples of dusts for analysis by spectrochemical examination
US4693733 *Sep 9, 1986Sep 15, 1987Kankyo Company LimitedAir cleaner
US5578112 *Jun 1, 1995Nov 26, 1996999520 Ontario LimitedModular and low power ionizer
US6056808 *May 31, 1996May 2, 2000Dkw International Inc.Modular and low power ionizer
US6287368 *Jul 22, 1997Sep 11, 2001Oy Airtunnel Ltd.Apparatus for the purification of air flue gases, or equivalent
US6964189Feb 25, 2004Nov 15, 2005Westinghouse Savannah River Company, LlcPortable aerosol contaminant extractor
US8163235 *Nov 16, 2011Apr 24, 2012Steris CorporationMethod for removing gaseous or vaporous sterilants from a surface
US8202355Nov 16, 2011Jun 19, 2012Steris CorporationApparatus for removing gaseous or vaporous sterilants from a container
US20120055507 *Nov 16, 2011Mar 8, 2012Steris CorporationMethod for removing gaseous or vaporous sterilants from a surface
USRE33927 *Sep 15, 1989May 19, 1992Kankyo Company LimitedAir cleaner
WO2008066966A2 *Jun 25, 2007Jun 5, 2008Sceptor Ind IncElectrostatic collection device
U.S. Classification96/94
International ClassificationB03C3/45
Cooperative ClassificationB03C3/45
European ClassificationB03C3/45