Effect of Mechanical Vibrations on Coriolis Mass Flow Meters

Abstract

An analytical study of the response of a simple Coriolis meter subjected to external mechanical vibrations and corresponding finite element studies of three commercially available meters are presented. These show that vibrations produce additional components in the meter sensor signals but that these components are only at the frequency of the vibrations. The results show that errors reported in vibration experiments, using any frequency except the meter drive frequency, are due to failure of the determination of the phase difference between the sensor signals. The results also show that external vibrations at the meter drive frequency produce a meter error regardless of the phase detection algorithm.

Vibration isolation for coriolis mass-flow meters

“…The result is an significant extension of the work of Cheesewright [13], not only the frequencies are shown where the CMFM is sensitive for external vibrations, but also a quantitative estimation of the expected mass-flow error is given, based on the modelled transmissibility function.…”

“…The experimental results correspond well on a quantitative level with the modelled results. The result is a significant extension of the work of Cheesewright [13], since it not only shows the frequencies to which the CMFM is sensitive for external vibrations, but it also provides a quantitative estimation of the expected massflow error, based on the modelled transmissibility function. The agreement between model and measurements implies firstly that the influence of any external vibration spectrum on the flow error, with some limitations due to linearity of the model, can be estimated.…”

“…These vibrations create additional components in the CMFM sensor signals [14], those additional components can introduce a measurement error. The effect of mechanical vibrations on the sensor response of a CMFM is also studied by Cheesewright [12,13]. The analytical study showed that external vibrations at the meter's drive frequency produces a measurement error, regardless of the flow measurement algorithm.…”

“…Furthermore, external stresses and vibrations may affect the measurement value [12,14]. External vibrations at the meter's drive frequency produce a measurement error, regardless of the flow measurement algorithm [13]. Before starting this project, experimental results showed an increased sensitivity for external vibrations, especially when scaling down the nominal flow range (<1 kg/h).…”

“…Measuring the tube displacements allows measuring the massflow. Besides an effect of the mass-flow on the modeshape, external vibrations can introduce motions that cannot be distinguished from the Coriolis force induced motion [13,14], thus introducing a measurement error. The influence of external vibrations on the measurement value can be estimated quantitatively as shown in Chapter 2.…”