Two rotors are better than one for meter

Edited by the Engineeringtalk editorial team Aug 14, 2008

Novel dual-rotor turbine flowmeter provides high accuracy, lower costs and extended flow range performance compared with traditional single-rotor turbine meters.

Exact Flow has introduced the DX-DL dual-rotor turbine flowmeter.

This advanced flow metering solution provides high accuracy, lower costs and extended flow range performance not obtainable with traditional single-rotor turbine meters.

Exact Flow's dual-rotor turbine design extends the lower flow range far below what has been possible before.

As fluid passes through the meter, the dual rotors become hydraulically coupled due to their counter-rotation.

This allows the rotors to overcome the inertia and drag that affects all single-rotor turbine flowmeters.

Exact Flow's extra flow range capability often eliminates the need for manifold systems, which simplifies installation and lowers cost.

The exceptional performance provided by the dual-rotor meter enhances universal viscosity curves (UVCs) and extends the usable measurement flow range.

Flow straighteners are not required to control process fluid swirl, as the dual-rotor system cancels out rotor acceleration effect.

With flow straighteners, bearing diagnostics can be determined by monitoring the ratio of the rotors to detect wear or cleanliness.

Additional Exact Flow benefits are found in the use of helical rotors.

Helical rotors are designed to minimise the resistance to flow, while imparting flow energy to the blades evenly.

In other words, the energy transfer is optimised over the entire surface of the blade, rather than at only one specific point.

Helical rotors also produce less pressure drop across the flowmeter, as compared with the traditional flat-bladed rotor design.

This reduction, translated into force, reduces bearing wear, which allows the meter to maintain its original calibration over a longer period of time.

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.

It also lowers the initial purchase cost, as well as simplifying system integration and future maintenance.

Exact Flow offers a unique pickoff system for the DX-DL that is impervious to vibration and minimises space, allowing for direct coupling of electronics.

Both integral and remote electronics are available to process the signal output, including the ExactComp IFC15 flow computer.

In addition to its standard dual-rotor turbine flowmeters, Exact Flow delivers a diverse range of integrated flow, temperature and pressure sensor systems in lightweight, compact packaging.

These unique flowmeter systems provide accuracies of 0.25% of reading with extended range performance and superior UVC flow ranges.

All Exact turbine flowmeters are calibrated at Flow Dynamics in a NVLAP accredited facility, obtaining uncertainties of +/-0.05% of rate and +/-0.012% repeatability.

Calibrations are offered in 1.2cSt solvent, blended oils and water with 10, 20 or 30 calibration data points.

UVCs are developed over the minimum/maximum temperature range of the process fluid.