Coriolis Mass Flowmeter

A Coriolis meter vibrates one or two tubes that carry the process fluid. The mass flowing through the vibrating tubes twists them by the Coriolis effect, and the phase shift between the inlet and outlet sensors is directly proportional to mass flow. The resonant frequency of the tubes gives density, and a built-in RTD gives temperature, so one instrument reports mass, volume, density, temperature and, from those, concentration, °Brix, °API or net oil.

Because it measures mass directly, the meter needs no compensation for pressure, temperature or composition, and it works on liquids, gases and slurries from crude oil to food sauces. Accuracy of a few tenths of a percent and long-term stability make it the meter of choice for custody transfer, loading, blending, batching and reactor feed. Approvals for legal metrology are available.

Sizes are model-dependent up to 14", with welded, flanged or wafer connections, for flows from 35 kg/h to 3,500 t/h, pressures from full vacuum to 250 bar and temperatures from −196 to +400 °C. Wetted parts are 304, 316 or 316L stainless steel, Hastelloy, duplex or titanium. Outputs are 4–20 mA HART, pulse, FOUNDATION Fieldbus, PROFIBUS, Ethernet or Modbus, with integrated fluid-property tables.

Coriolis meters are found in oil and gas, petrochemical, chemical, food and beverage and pharmaceutical plants; their main limitation is cost and pressure loss in the largest line sizes.