Ultrasonic density sensor for liquids

TLDR

The paper discusses design aspects such as sensor materials and signal‑to‑noise ratio. The study presents an ultrasonic density sensor for liquids that unifies high accuracy with high durability and is suitable for online measurements across a wide range of tube diameters. The sensor comprises a piezoceramic disk transducer mounted between two quartz glass reference rods, a second transducer as receiver, and determines density from the reflection coefficient at the quartz–liquid interface and the transit time between the interface and the receiver, with an internal acoustic reference generated from the rear side of the disk. The sensor achieved high long‑term stability and ±0.1 % full‑scale accuracy, as demonstrated by experimental results. Applications include concentration measurement and ultrasonic mass flow measurement.

Abstract

This paper presents an ultrasonic density sensor for liquids that unifies high accuracy with high durability and is suitable for on-line measurements in a wide range of tube diameters. The sensor consists of a transducer with a piezoceramic disk mounted between two reference rods of quartz glass. Additionally, a second transducer is used as a sound receiver. The density is obtained from the reflection coefficient of ultrasound at the interface between the quartz glass rod and the liquid and the transit time of sound between this interface and the second transducer. Parameters, such as high long-term stability and accuracy of +/-0.1% of full scale, were obtained by an internal acoustic reference measurement. The reference signal is generated using the sound radiated from the rear side of the piezoceramic disk. Design aspects such as sensor materials and signal-to-noise ratio are discussed, and experimental results are given in this paper. Applications of the sensor include concentration measurement, and ultrasonic mass flow measurement.