APS (Aerodynamic Particle Sizer)

Contact: Lucy Chisholm (lucy.chisholm@ec.gc.ca)

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The TSI Aerodynamic Particle Sizer (APS) - Model 3321, measures number concentrations of particles between 500 nm and 20 microns. The APS uses time-of-flight technology to size the particles according to their aerodynamic diameter. Aerosol is brought into the instrument and into a near-vacuum equipped with two lasers separated by a distance. The aerosol passes through the line of the first laser, and then the second, and the time between the two laser detections is recorded. This travel time is related to the aerodynamic size of the aerosol; longer times for larger particles due to aerodynamic drag. The particles are then sized and counted in the same moment, and the results are displayed as a size distribution for particles between 0.5 and 20 microns, in 52 size channels, at approximately 11-minute resolution.

Together the 3321 and the 3031 provide size-resolved aerosol number concentrations for particles with diameters between 0.020 and 20 microns, quantifying the size spectrum of the aerosol.

Using chemical composition information to infer a density, a mass distribution can be calculated from the number distribution.

Further information on the instrument can be found on the TSI website.