Dual-Rotor Subsea Turbine Flowmeter

Exact Flow, a supplier of precision flow measurement, has introduced the Exact Dual-Rotor Subsea Turbine Flowmeter. Providing bearing diagnostic capability and wide flow range performance, the meter targets subsea hydraulic pod valve actuation and topside flow applications in the offshore oil industry. In hydraulic fluid applications, it is packaged in a high-pressure, manifold-mounted system with built-in redundancy.

Subjected to low pressures, hydraulic fluids are often estimated to be incompressible. However, when subjected to high pressures, hydraulic fluid properties vary greatly and have a substantial effect on turbine flowmeter accuracy. The Exact Dual-Rotor Subsea Flowmeter is calibrated to account for the entire range of temperature and pressure conditions. It includes internal temperature and pressure sensors to correct for these effects and provide the best possible system accuracy.

With the Exact Dual-Rotor Subsea Flowmeter, bearing diagnostics can be determined by monitoring the ratio of the rotors to detect wear or cleanliness.Improved accuracy is a result of the clamped internal mounting design eliminating movement in the support system.Pressure compensation contributes to the accuracy of the flow rate, as pressure does affect the viscosity of the fluid. Additional Exact Flow benefits are found in the use of helical rotors, which optimize energy transfer over the entire surface of the blade, enhancing speed of response to step changes in flow rate, the company said.

Exact Flow also offers an embedded pickoff system that is impervious to vibration and minimizes space, allowing for direct coupling of electronics, the company said. Both water-tight embedded and remote electronics are available to process the signal output, including the ExactComp IFC15 flow computer.

Exact Flow Dual-Rotor Turbine Flowmeters have a repeatable flow range of up to 500:1 and a UVC turndown range of 60:1, in contrast to 100:1 and 10:1, respectively, for many single-rotor turbine meters. This allows the user to deploy fewer flowmeters to cover a wide range of flow, according to the company.

All Exact Flow turbine flowmeters are calibrated at Flow Dynamics Inc., in an NVLAP accredited facility, obtaining uncertainties of 0.05% of rate and ±0.012% repeatability. Calibrations are offered in 1.2 cSt solvent, blended oils and water with 10, 20 or 30 calibration data points. UVCs are developed over the min/max temperature range of the process fluid.


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