Two parallel flow tubes inside the coriolis meter vibrate at their resonant frequency in opposite directions. Any mass flow passing through the tubes delays the vibration at the incoming side and accelerates the vibration at the outgoing side. This causes a small time delay between both ends of the tube. This time delay is measured and is used to calculate the mass flow through the tubes.
By measuring the resonant frequency of the tubes the mass of the medium and - given a constant volume inside the tubes - the density of the medium can be calculated. As both effects are temperature dependent, the temperature is measured via a precise sensor for correcting the temperature effects of flow and density measurement.
As a consequence mass flow, density and temperature of the medium are directly measured. As the mass flow and the specific gravity are known the volume flow can be calculated.