Quantification of the influence of external vibrations on the measurement error of a Coriolis mass-flow meter

• Clear insight into the meter׳s dynamics is obtained by modal decomposition.
• The meter׳s dynamics can be modelled effectively by flexible multi-body modelling.
• The 3D dynamics can be approximated effectively by a 1D modal representation.
• The effect of external vibrations on the flow measurement is understood.
• Effects of external vibrations can be accurately quantified from vibration spectra.

In this paper the influence of external vibrations on the measurement value of a Coriolis mass-flow meter (CMFM) for low flows is investigated and quantified. Model results are compared with experimental results to improve the knowledge on how external vibrations affect the mass-flow measurement value. A flexible multi-body model is built and the working principle of a CMFM is explained. Some special properties of the model are evaluated to get insight into the dynamic behaviour of the CMFM. Using the model, the transfer functions between external vibrations (e.g. floor vibrations) and the flow error are derived. The external vibrations are characterised with a PSD. Integrating the squared transfer function times the PSD over the whole frequency range results in an RMS flow error estimate. In an experiment predefined vibrations are applied on the casing of the CMFM and the error is determined. The experimental results show that the transfer functions and the estimated measurement error correspond with the model results.The agreement between model and measurements implies that the influence of external vibrations on the measurement is fully understood. This result can be applied in two ways; firstly that the influence of any external vibration spectrum on the flow error can be estimated and secondly that the performance of different CMFM designs can be compared and optimised by shaping their respective transfer functions.