Simultaneous Measurement System of Liquid Density and Viscosity Using Steel Tuning Fork

Industrial tuning fork densitometer is available in the market, but the tuning fork viscometer is hard to find out. This article proposes a simultaneous measurement of liquid density and viscosity using a steel tuning fork by measuring its resonance frequency and quality factor. Two models, which only vary in liquid viscosity detection, are obtained from theoretical and simulation analysis, respectively. A tuning fork with high sensitivity to liquid density and viscosity is selected by comparing the performance of tuning forks with different fork shapes and vibration modes in simulation. After that, two kinds of tuning fork’s excitation and detection system are designed and compared with each other. Finally, experiments are carried out to validate the above models and test this measurement system’s performance. Results show that it has high accuracy in liquid density detection and also performs precisely when measuring liquid viscosity in the high viscosity range. Compared with a measurement system using a quartz tuning fork, this system is more stable when measuring mixed liquid or liquid with impurities and is easier to be adopted in factories.