Pipe Prover & Small Volume Prover Design
Typical: 80-8400 pulses/bbl (turbine), 20-500 pulses/bbl (Coriolis)
API MPMS Ch. 4: 0.05% for custody transfer
10,000 (turbine), 500-1,000 (Coriolis/ultrasonic)
Understand prover types, meter factor calculations, volume correction factors, and API MPMS proving standards
A meter prover is a calibrated vessel used to verify the accuracy of flow meters in custody transfer service. By displacing a known volume of fluid past the meter, the meter factor (MF) can be calculated as the ratio of true prover volume to indicated meter volume. Provers ensure measurement accuracy within 0.02-0.05% for custody transfer billing per API MPMS standards.
A pipe prover (conventional prover) uses a large-diameter U-shaped or straight pipe loop with a displacer sphere or piston traveling between two detector switches. Displaced volumes are typically 50-5000 gallons. A small volume prover (SVP) uses a precision-machined cylinder with a piston, typically 0.1-50 gallons, requiring multiple passes to accumulate sufficient meter pulses for repeatability.
API MPMS Chapter 4 recommends a minimum of 10,000 pulses per pass for turbine meters to achieve 0.02% resolution. For Coriolis and ultrasonic meters with lower pulse resolution, 500-1,000 pulses per pass may be acceptable. Small volume provers compensate with multiple passes (typically 5-10) to accumulate total required pulses.
API MPMS Chapter 4 requires that consecutive meter factors from a proving run agree within 0.05% (0.0005) for custody transfer applications. This means all individual run meter factors must fall within a range of 0.05% of the mean. If repeatability exceeds this threshold, the proving is considered invalid and must be repeated.