Generation of Large, Solid, Monodisperse Calibration Aerosols

During the calibration of four large-particle impactors developed at the University of Florida, techniques were developed for the generation of large, solid calibration aerosols. Using a slightly modified, vibrating-orifice aerosol generator, solid ammonium fluorescein particles of up to 70-μm aerodynamic diameter were successfully generated. When generated under the proper test conditions, the particles were found to be spherical and of uniform size. Although the described generation method requires considerable operator technique, it is felt that the method will be of value in situations where the use of liquid calibration aerosols may be inappropriate.