Engineering Aspects of Ultrasonic Process Control—Flow, Temperature and Liquid Level Applications

Abstract

The interaction of ultrasonic waves with solid, liquid, gaseous, or multiphase media offers many opportunities for accurate process control, but users risk disappointment because of the influence of “unwanted” variables. The present paper illustrates the use of ultrasonic transit time or amplitude measurements as a basis for calculating flow, temperature, and liquid level. The interrogating wave types include longitudinal, extensional, Rayleigh, transverse shear and torsional modes, at frequencies on the order of 0.1 to 1 MHz. Buffer techniques, special paths, or other means are illustrated for minimizing, avoiding, or compensating for the influence of undesired variables.