Performance of a TSI Aerodynamic Particle Sizer

Abstract

Calibration curves of the aerodynamic particle sizer (APS) under different sets of operating conditions (i.e., pressure drop across the nozzle, flow rate, and ambient pressure) were obtained. Materials used included oleic acid (OA), dioctyl phthalate (DOP), polystyrene latex (PSL), and fused aluminosilicate particles (FAP). The effect of particle density on the calibration was not found to be significant among test aerosols (in the density range from 0.89 to 2.3 g/cm³). Calibration curves obtained at reduced ambient pressure were different from the manufacturer's curve, indicating that recalibration of the APS is required if other than standard operating conditions are used. However, all the curves can be consolidated into a unique curve that relates the Stokes number at the nozzle exit to the normalized particle velocity (particle velocity divided by gas velocity). Methods for calculating gas velocity, particle velocity, and other pertinent parameters for the APS were developed and the results are presented. Consequently, these parameters together with the unique curve can be used to generate calibration curves for any set of operating conditions without performing the experimental calibration in the laboratory. The geometric standard deviations of monodisperse aerosols measured by the APS are generally in good agreement (< 2%) with those determined by other methods, thus demonstrating the good resolution of the instrument.