Evaluation of Aerodynamic Particle Sizer and Electrical Low-Pressure Impactor for Unimodal and Bimodal Mass-Weighted Size Distributions

The objective of this study was to investigate the feasibility of the Aerodynamic Particle Sizer (APS) and the Electrical Low-Pressure Impactor (ELPI) to study mass weighted particle size distributions. Unimodal and bimodal liquid test aerosols were produced to a small chamber. Simultaneous measurements were performed with an APS 3320, an APS 3321, an ELPI and a Dekati Low-Pressure Impactor (DLPI) analyzed gravimetrically. ELPI current and mass responses were simulated for lognormal size distributions using a parameterization of the impactor kernel functions. In experiments with a single coarse mode, the mass ratio to the DLPI was between 0.75 and 1.15 for both APS models up to 5 µm and for the ELPI up to 3 µm. For larger sizes the ELPI and APS 3320 overestimated and the APS 3321 underestimated the concentration. In experi-ments with a single fine mode, submicrometer ELPI and DLPI results were in good agreement. However, in contrast to the DLP