What Is The Principle of A Density Meter?

Digital density meters is based on Archimedes' principle, combined with the microelectronics technology. The liquid sample is placed into an oscillating U-tube, and measure/calculate the density of sample.

The measurement is started since the exciting vibration of the U-tube, and the frequency is measured by a piezoelectric or electromagnetic device with conversions. Since the U-tube oscillation frequency will be related to the mass of sample. When the vibration frequency and the density is simply a  linear relationship, so, measuring the vibration frequency of oscillating U-tube result the accurate density value.

Oscillating U-tube in A Density Meter