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Flow Dynamics has brought out the Positive Displacement Calibrators, Liquid (PDCL) primary standard flowmeter calibrators.

The latest PDCL 10, 60 and 400 Series calibrators enable the most precise liquid-flow calibrations available, ranging from 0.01 GPM (0.04 LPM) to 400 GPM (1514 LPM) with an uncertainty of +/-0.05 per cent and a repeatability of 0.01 per cent of reading.

Utilised at the National Institute of Standards and Technology (NIST) flow calibration laboratory in Gaithersburg, MD, as well as other government calibration labs around the world, the PDCL is a precision volumetric device displacing an exact, known volume of fluid, which passes through the flowmeter under test while compensating for fluid viscosity and temperature.

The PDCL Series is capable of performing NIST-traceable calibrations on most common flowmeters, including turbine, differential pressure orifice plate, rotameter, variable area, coriolis or any other type of meter that has a visual, pulse or analogue output.

The PDCL calibrator consists of a precision-honed and polished cylinder assembly, with a piston mechanically connected with a displacement shaft.

The travel of the piston is measured with a high-resolution linear encoder.

One side of the piston is actuated pneumatically, while the other side displaces a controlled amount of fluid through the meter under test.

The flow is regulated by three control valves – coarse, medium and fine – to obtain the exact flow-rate required.

The fluid is collected in a reservoir tank and returned to the cylinder, bypassing the meter under test.

A temperature-control system maintains the fluid temperature to create the desired calibration conditions.

The calibrator can be fully automated to establish the flow rates and collect calibration data.

Additional automated features consist of an automatic fluid air bleed; servo-driven, telescoping flowmeter section; and flowmeter clamping fixture.

The PDCL’s low fluid usage supports the need to reduce hazardous fluids, while keeping fluid costs to a minimum.

Blending fluids is made easy with an automatic cycling feature for mixing the fluid while in the machine.

A telescoping test section adjusts to enable installation of different-size flowmeters.

The calibrator’s fluid-catch pan incorporates a filter system and drain pump to return the fluid to the reservoir.

Equally as important, the piping loop helps to drain fluids out of the system and facilitate flushing to clean the residual fluid out of the piping.

The electronic output from the calibrator’s encoder, temperature sensors, and the meter under test are signal conditioned and collected with a computer data-acquisition system.

The computer uses Flow Dynamics’ Windows-based ‘Flo-Cal’ software to graph and produce calibration data reports.

The software-graphics display visual aids and real-time calibration data.

Calibration files are automatically stored for calibration history and can be recalled for comparison with the current calibration.

An integral part of the PDCL system is the ‘Flo-Cal’ Windows-based software program, which collects, reduces, plots, prints and stores calibration data.

This program allows the user to change screen displays, data sheet formats and data-reduction equations on line, without using source code or compilers.

As new requirements for calibration processes, data or correlations arise, the program may be changed by the user to meet these requirements.

Cox Instruments

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