An in situ calibration technique for the determination of large particle aspiration efficiencies of TSP samplers - the stop distance concept

The efficiency of TSP samplers for large particle is determined by inertial effects; instead of using Stokes number for characterizing the instrument, the particle stop distance is chosen. Polydisperse glass beads with aerodynamic diameters between 20 and 120 mym were used as calibration aerosol. The size distribution sampled under in situ conditions as compared to the original size distribution gives the aspiration efficiency, provided that the smallest particle in the test aerosol are sampled with sufficient efficiency.