What is a Prover?
A Prover is a device with a "known traceable volume" designed to calibrate or prove a liquid flow meter's accuracy and repeatability under actual operating conditions. Provers can be stationary or por¬table devices used to calibrate and verify the accu¬racy and repeatability of both volumetric and mass flow meters. Provers are commonly used in the hydrocarbon industry for custody transfer or fiscal applications, where accuracy is critical.
A Prover Establishes:
- The K-Factor (pulses per unit volume) of a meter
- The Meter Factor (factor used with a meter to correct accuracy for flow conditions)
- The Linearity over the calibrated flow range for the meter
- The repeatability for the meter system
How to Obtain a Meter Factor:
The meter factor is obtained by dividing the prover test volume by the indicated volume of the meter. Once the meter factor is established, it is used as a volume correction in the calculation for the standard net volume of a receipt or delivery of liquids.
Why is It Important to Prove a Flowmeter?
Simply stated, to provide an accurate measurement.
In addition, proving is critical for financial transactions and custody transfer applications to maintain profitability and reduce financial uncertainties.
Flow meters are generally calibrated in a factory using clean and consistent factory conditions; once they reach the field, they are subject to various conditions in the field. Over time these product and process variations can lead to accuracy shifts known as drifting.
FMD's Small Volume or Unidirectional Captive Displacement Provers use the known volume of the prover in comparison to the output of the flowmeter to calculate a correction factor allowing the user to adjust the flowmeter accordingly for a truly accurate representation of flow rates.