Design and Performance of the Lovelace Aerosol Particle Separator

Abstract

The Lovelace aerosol particle separator (LAPS) provides a continuous separation of aerosol particles in the micron and submicron size ranges according to their aerodynamic equivalent diameters. This new device uses the principle of centrifugal separation of particles in a spinning spiral duct. The LAPS is essentially a spinning rotor driven by a motor at a desired constant speed. An aerosol sample is drawn into an expanding spiral duct through an inlet at the axis of the rotor and is entrained in a laminar stream of clean air and drawn by negative pressure through the channel. The particles are deposited according to their aerodynamic diameters along a 46.2 cm long collection foil lining the outer wall of the spiral duct and the very small particles on a filter at the exit end of the spiral, thereby providing a continuous separation of aerosol particles in the entire size range of interest. The device is relatively inexpensive, rugged, easy to operate, and can be driven either by an induction-type household motor or by a more elaborate centrifuge drive. It is suitable for separating aerosol particles for a variety of purposes including analysis of aerodynamic particle size distribution, preparation of monodisperse particles, measurement of densities of spherical aerosol particles, and measurement of particle shape factors. Because the centrifugal forces are directed toward the collection foil and cause the collected particles to be held firmly in place, the instrument can be used to collect large samples without significant change in calibration or resolution characteristics.