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About Prover Systems

Reduce costs with automated proving of volumetric or mass meters and ensure ongoing industry compliance & accountability at fiscal measurement operations.

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Proving & Calibration

Ensuring accurate measurement performance – over time – is one of the greatest challenges facing fiscal measurement applications. Because meter performance can be affected by many factors, measurement systems must be regularly verified against a traceable reference to prove compliance to accuracy and repeatability requirements.

Provers ensure a custody transfer system is providing the most accurate measurement possible by offering a stationary or mobile means to facilitate calibration of flow meters before, during or after a transfer.

About Prover Systems

What is a Prover?

A prover is an automated system that provides on-site calibration to ensure flow meters in service for fiscal and custody transfer applications maintain sustainable measurement performance as well as remain in compliance with industry standards.

Since operating (field) conditions can significantly change from the time the flow meter was originally calibrated, proving ensures optimal meter performance over the life of the meter.

Proving Flow Meters

Liquid provers are most often used with flow meters measuring light hydrocarbons to higher viscosity products at varying flow conditions. 

The prover is placed in series with the meter to determine the meter factor during stable operating conditions. This process, known as in-situ proving, is preferable over off-site calibration because it verifies the meter’s performance using the exact product and process conditions that the meter normally experiences during field operation.

It is a recommended practice to periodically use a prover to calibrate each meter in the measurement system to confirm or re-establish the performance of each meter. The prover helps account for changes in meter accuracy as well as verifies the repeatability and linearity of the meter.

Prover Types

Pipe (stationary) and Compact (mobile) are the two most common types of displacement provers in use today.

Various types of pipe provers are available, including bi-directional sphere-type provers and bi-directional piston-type provers, which both combine forward and reverse volumes during a single proving cycle.  Bi-directional piston-type provers are better suited for low temperature applications. 

Smaller size, convenience, and a wide turndown ratio are some of the advantages of compact provers which can be easily mobilized to prove various meters around a site or multiple sites.


Proving lowers the uncertainty of metered volumes to enhance accountability at fiscal measurement operations. In addition to minimizing financial risk, proving enables operators to maintain the accuracy and repeatability of flow meters to reduce maintenance and lifecycle operating costs.

Labor costs are also reduced with a prover by providing automated data logging that improves productivity and diminishes the possibility of human error.


Large volume pipe provers are most often put into service for hydrocarbon and chemical processing applications and are generally best suited for pipeline metering terminals, tanker- and barge-loading facilities, refineries and petrochemical plants, and metering of liquid fuels for power plants. 

Compact provers are commonly used to verify measurement at marketing terminals or in crude and refined product pipelines, FSO and FPSO offloading, ship and barge loading/offloading, railcar loading/offloading, and calibration laboratories.

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A Guide to Optimized Proving Solutions

Meet contractual & regulatory requirements and minimize financial risk.

Download Guide
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