Ultrasonic Particle Sizing

Abstract

The measurement of particle size distributions and particle concentrations is an important task in laboratories and in technical processes that deal with suspensions. Especially the instruments designed for on-line applications in production processes mostly evaluate the interactions of light with the suspended particles, viz. extinction, scattering and diffraction. While the interaction of particles with ultrasonics is essentially the same as with light, the application of ultrasonics offers special technical advantages, which are due to the extremely broad range of wavelengths and the coherent detection of ultrasonic waves. Ultrasonic spectrometry makes possible the on-line measurement of the particle size distribution and particle concentration in suspensions at concentrations of up to 30% by volume without diluting the suspension. This paper is intended to introduce the reader to the fundamentals of ultrasonic particle sizing and to explain present efforts in this field. In the last section, some successful realizations of ultrasonic particle sizing instruments are presented.