||Aerodynamic Classification of Fibers with Aerosol Centrifuges.
Martonen, T. B. ;
Johnson., D. L. ;
||Health Effects Research Lab., Research Triangle Park, NC. Environmental Toxicology Div. ;Army Environmental Hygiene Agency, Aberdeen Proving Ground, MD.
Particle size distribution ;
Aerodynamic characteristics ;
Respiratory system ;
Mathematical models ;
Laboratory tests ;
Occupational safety and health ;
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The constituent particles of many ambient and workplace aerosols of health effects concerns are of fibrous and aggregate geometric shapes. The sites of deposition in the human respiratory system are primarily related to the mass median aerodynamic diameters of inhaled particle size distributions. Therefore, to assess potential exposure hazards it is necessary to have accurate kinetic classifications of airborne particulate matter. Centrifugal spectrometers give direct and continuously graded measures of the aerodynamic size distributions of sampled aerosols. A mathematical description of particle behavior in spiral channel centrifuges has been presented, and substantiated by comparisons with laboratory calibration data using polystyrene latex spheres. Here, the theory is extended to non-spherical forms by incorporating appropriate dynamic particle shape resistance factors in trajectory equations. It is demonstrated how optimum centrifuge performance is made possible by the a priori determination of favorable operating conditions permitting high-resolution characterization; specifically for fibrous aerosols.