||Investigation of particulate matter monitoring using contact electricity : final report /
John, Walter. ;
Reischl, Georg ;
Devor, William ;
Wesolowski, Jerome J.
||California State Dept. of Health, Berkeley. Air and Industrial Hygiene Lab.;Environmental Sciences Research Lab., Research Triangle Park, NC.
|| U.S. Environmental Protection Agency, Environmental Sciences Research Laboratory, Office of Research and Development,
Air pollution ;
Electric charge ;
Continuous sampling ;
Air pollution detection ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
||ix, 70 pages : illustrations ; 28 cm.
To better understand the contact electrification monitor for particulate matter, charge transfer by aerosol particles impacting on metal surfaces has been investigated. Monodisperse, uniformly charged or neutral aerosol particles (1-5 micrometer diameter) from a vibrating orifice or fluidized bed generator were bounced on a metal probe. The transfer of precharge from the particles were found to be sensitive indicators of the probe surface condition. A surface preparation procedure was developed which yielded linear charge transfer curves. Measurements were made of methylene blue, potassium biphthalate, sodium chloride and aluminum particles impacting on stainless steel, Inconel, titanium and platinum probes. For insulating materials, the transfer of precharge was independent of particle size while the contact charge was proportional to the cube of particle diameter and directly proportional to impact velocity. The magnitude of the contact charge was strongly dependent on the electrical resistivity of the material. A theoretical model was found to account semi-quantitatively for all aspects of the data. A major remaining difficulty is the lack of knowledge of the contact potential. The implications of these findings for monitoring applications is discussed in detail and the advantages and disadvantages of the monitor are assessed.
Project Officer: John Nader. California Department of Health Services, Air and Industrial Hygiene Laboratory Section "October 1978." Includes bibliographical references. "EPA-600/2-78-212." Microfiche.