Length separation of fibers.
Baron-PA; Deye-GJ; Fernback-J
Aerosol Sci Tech 1994 Aug; 21(2):179-192
A method was developed for length separation of nonconductive fibers such as chrysotile (12001295) using dielectrophoresis under conditions of high humidity. A chrysotile aerosol was passed between the surfaces of two concentric steel cylinders measuring a 12 to 14 kilovolt peak to peak potential, at a 5.35 liters per minute total airflow with a relative humidity of 72%. The high voltage alternating field between the two cylinders caused fibers to drift to the central cylinder and deposit along ten different length classification segments. Fibers collected within these segments were measured using transmission electron microscopy and formed ten groups of fibers ranging in mean length from 31.3 to 8.48 micrometers. Coefficients of variation within these classification groups ranged from 0.17 to 0.33. The classifier showed promise for generating aerosols composed predominantly of short fibers since the classifier effectively removed most of the long fibers from the discharged aerosol. The discharge aerosol contained only 0.1% fibers longer than 13 micrometers and 0.02% fibers longer than 16 micrometers. The method may not be suitable for collecting large amounts of long fibers since the amount collected is limited by the total aerosol concentration that can be effectively separated within the classifier. In this case the aerosol concentration was limited to only 40% of the total airflow rate. Since only 1.5% of the total fiber concentration was collected on each classification segment, with about 85% of the fibers passing through the classifier, the only way to increase the yield of fibers would be to increase the concentration of the challenge aerosol.
NIOSH-Author; Fibrous-dusts; Asbestos-fibers; Dust-sampling; Aerosol-particles; Dust-collection; Airborne-fibers
Aerosol Science and Technology