Dual-rotor turbine flowmeter for subsea and topside applications

Bearing diagnostics and built-in redundancy suited to critical and inaccessible installations.
By Control Engineering Staff May 21, 2009

Exact Flow, a supplier of precision flowmeters for demanding applications, has introduced the Dual-rotor Subsea Turbine flowmeter . With a bearing diagnostic capability and wide flow range performance, the meter is a solution for 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.

The company says the dual-rotor configuration offers performance not obtainable with traditional single-rotor designs. Additionally, the flowmeter offers other benefits such as bearing diagnostics, improved accuracy, pressure compensation, long-life ceramic bearings, and high-shock internals.

One element that Exact Flow says most users overlook is the peculiar characteristics of hydraulic fluids at high pressures. Normally users treat hydraulic fluids as incompressible; however, when subjected to high pressures, fluid properties vary greatly and have a substantial effect on turbine flowmeter accuracy. The 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.

Moreover, helical rotors optimize energy transfer over the entire surface of the blade, enhancing speed of response to step changes in flow rate. Helical rotors also produce less pressure drop across the flow meter, as compared with the traditional flat-bladed rotor design. The company says this reduction, translated into force, reduces bearing wear, which allows the meter to maintain its original calibration over a longer period of time.

The flowmeter family has a repeatable flow range of up to 500:1 and a turndown range of 60:1. This allows users to deploy fewer flowmeters to cover a wide range of applications. All units shipped are calibrated at Flow Dynamics, Inc., in a NVLAP accredited facility, obtaining uncertainties of &0.05% of rate and

Read more on turbine flowmeters .

—Edited by Peter Welander, process industries editor, PWelander@cfemedia.com ,
Control Engineering Process Instrumentation & Sensors Monthly
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