Ensuring essential accuracy during custody transfer

Paul Boughton

Jeffery Still outlines the only petroleum test facility in the world that can ensure true calibration over a dynamic Reynolds Number range of 100 to 1,000,000.

More than 90 million* barrels of petroleum are produced around the world each day. With that volume of product and the magnitude of commerce it represents, precise custody transfer measurement is the foundation for an orderly global petroleum market.

FMC Technologies' Flow Research and Test Facility in Erie, Pennsylvania is capable of testing meters at the widest dynamic measurement range of any test facility in the world.

Accredited in August 2011 by the US Department of Commerce's National Institute of Standards and Technology (NIST), FMC Technologies' Flow Research and Test Center is the only petroleum test laboratory in the world that can ensure true calibration over a dynamic Reynolds Number** range of 100 to 1,000,000. This significant investment in procedures and equipment has allowed FMC Technologies' Flow Research and Test Center to meet the accreditation requirements of ISO 17025. As a result of the accreditation, FMC Technologies is the only manufacturer of custody transfer meters with an on-site test facility capable of dynamic measurement. Positive displacement (PD) meters, conventional turbine meters, helical turbine meters, and ultrasonic meters can be tested under dynamically similar operating conditions to guarantee performance in any crude oil application.[Page Break]

'Dynamic' quantity measures the volume of moving petroleum. In dynamic quantity determination, meter selection is most important because the meter is the device that registers precise measurement. The objective of the dynamic measurement is to calculate, via a meter, the gross volume of petroleum delivered in a custody transfer. That volume is expressed in barrels-per-hour at specific referenced conditions that account for temperature, density, viscosity, flow, velocity, pressure, sediment and water, among other conditions.

Factory calibration of high performance ultrasonic or helical turbine meters to operating conditions requires a technically capable and highly accurate test laboratory. The National Voluntary Laboratory Accreditation Program (NVLAP), run by the US National Institute of Standards and Technology (NIST), ensures that a laboratory fully meets international laboratory standards defined by ISO/IEC 17025. To gain accreditation all measurements recorded in the lab must be traceable through a National Metrology Institute (NMI) such as NIST. NIST is a member of the International Organization of Legal Metrology (OIML). During the accreditation process for FMC Technologies' lab, the accreditation body, NVLAP, assessed factors relevant to its ability to produce precise and accurate test and calibration data, including the: technical competence of staff; test methods; traceability of measurements and calibration; suitability, calibration, and maintenance of equipment under test; handling and transportation of test items; quality assurance of test and calibration data.

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* Energy Information Administration, US Government Official Energy Statistics.

** Reynolds Number. A dimensionless number which is significant in the design of a model of any system in which the effect of viscosity is important in controlling the velocities or the flow pattern of a fluid; equal to the density of a fluid, times its velocity, times a characteristic length, divided by the fluid viscosity. Symbolized NRe. Also known as Damköhler number V (DaV).

Jeffery Still is with FMC Technologies, Erie, Pennsylvania, USA. www.fmctechnologies.com

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