On-line ultrasonic density sensor for process control of liquids and slurries

Abstract An on-line ultrasonic density sensor is described in which six transducers are mounted upon a plastic wedge, the base of the wedge being in contact with a liquid or slurry. Ultrasonic beams striking the base at several angles are reflected. The amount of reflection at the plastic–liquid interface depends upon the density of the liquid ρ, the speed of sound c in the liquid, and wedge parameters. By determining the reflection coefficient at two angles, ρ and c can be determined. The sensor can be mounted in a pipeline configuration or submerged for tank applications.