Flowmeter Calibration Without the Need for Intermediate Turbine Meters

Independent tests carried out in the Middle East have consistently demonstrated that Rheonik Coriolis large size flowmeters from GE’s Measurement & Control Solutions (USA), can now be calibrated on compact provers without the need for intermediate turbine meters to validate use for custody transfer.

Pipe provers have been used in the oil and gas industry for many years to prove meters to custody transfer and fiscal standards. Over the past twenty years, small volume or compact provers have proved a viable alternative but experience has shown that certain types of meter do not calibrate well because of the small volumes used in compact provers.

Coriolis meters have been particularly difficult to prove using this equipment because Coriolis meters, which measure mass flow, use a sampling and calculation system which integrates data over a short period and produces an output that lags behind the actual flow at any point in time. If this integration period is not compatible with the time taken for the piston of a small volume prover to complete its pass between detectors, then errors will occur. Historically, one way around this problem has been to first prove a turbine meter over the required flow range and then use this proven meter as the transfer standard for the Coriolis meter.

The latest tests have been carried out using only a compact prover, an OMNI flow computer and a density meter. The configuration involved setting up the flow computer to accept the density measurement at the flow meter outlet connection. The verified results show an average stable meter factor and a repeatability of less than +/- 0.1% and the flowmeters proven ranged go up to 12”.

As Uwe Hettrich, product manager for GE’s Rheonik product line, explains, “The Rheonik Omega tube Coriolis meter is one of the most versatile meters on the market. It offers very high accuracy and fast response. It is unaffected by viscosity, density or pressure changes, it can be used in extremely wide range of line sizes, pressures and temperatures and has hazardous area approvals covering most of the world. Its ability to be calibrated by a compact prover, without the need for an intermediate turbine meter, further extends its versatility.”