Analysis of influence of mechanical boundary conditions on zero point shift of Coriolis flowmeter

Coriolis flow meters determine mass flow rate by measuring the phase shift of the signal pick-up coils. Therefore, changes in the phase shift amount not related to the flow of the measured medium cause mass flow measurement errors. The article is devoted to the experimental evaluation of the effect of mechanical boundary conditions of the Coriolis flowmeter on zero point shift. Special equipment, allowing changing the stiffness of the pipeline, to which the flowmeter is attached, has been developed. Modal experiments on the Coriolis flowmeter without liquid for different lengths of pipe have been conducted. It has been found out that the maximum zero point shift is observed when the frequency of natural vibrations of the coupled system of the flow meter and piping tubes coincides with the drive frequency of tube vibrations. Tests to assess the influence of external vibration on the zero point shift have been conducted. The maximum zero point shift is observed in the coincidence of the external vibration frequency with the drive frequency of oscillation of tubes.