Coriolis meter density errors induced by ambient air and fluid temperature differentials

Coriolis metering technology is widely applied throughout industry. In addition to the mass flow rate, a Coriolis meter can measure fluid density based on the resonant frequency of the flow tube vibration. There is currently increasing interest in utilising this density measurement capability as the primary process value in applications such as precision control for fluid property conditioning, and fluid contamination monitoring. However, within these applications, ambient temperature variation can be significant. This paper details research data obtained using NEL's ‘Very Low Flow’ single-phase facility. The rig was modified to include a programmable temperature enclosure in which a Coriolis meter was installed. Two commercial meter models from the same manufacturer were tested. Both meters showed fluid density errors when subjected to fluctuations in the surrounding ambient air temperature. The fluid properties of the test medium were confirmed to be stable using NEL's UKAS standard reference instrumentation. Previous temperature effects research for Coriolis meters have focussed on the process fluid temperature and there is little published data on the effects of ambient temperature.