Disclaimer – this is my note as of 2016. Hasn’t been updated since then.
Generally there are 2 prover design.
- Displacement prover
- Master-meter prover
There are 2 type of displacement prover
- Conventional pipe prover
- Small volume prover
This would include a calibrated section in which a displacer (prover ball) travels with flow, hence, activates detection devices, which then will
All type of displacement prover systems operate on a principle of repeatable displacement of known volume of liquid hydrocarbon from a calibrated section of pipe between 2 detectors.
The displacement of liquid volume is achieved by an oversize ball or piston travelling through the pipe.
Conventional Pipe Prover
A conventional pipe prover shall be preferably be bi-directional with quick opening and closing for sphere removal.
This type of prover is typical design consideration for conventional pipe prover shall include
- Displacer velocity shall not exceed 3m/s
- Connection shall be downstream to meter
- Designed such that its repeatability during calibration of the volumes, where 5 proving runs (meaning: 5 consecutive runs are performed and be within ± 0.01% of average volume.
- Shall be equipped with temperature and pressure measuring elements (PT – Pressure transmitter; TT – Temperature transmitter)
- 4-way valve: the valve shall be motorized and provided with local and remote actuator with manual override hand-wheel.
Note: This is off course not an all inclusive design criteria.
Small Volume Prover
Its performance is critically dependent on the mechanical precision of its tube bore and movable element position detecting system, measurement of accuracy and stability of temperature and pressure, tightness of moving parts and ratio between the diameter of the tube and the actual displacement of the movable elements.
Typically used for facilities where the footprint and weight is an issue, for offshore operation for example.
- installed downstream of meters
- repeatability during calibration of its volumes, where 5 consecutive runs are performed and be within ± 0.01% of average volume.
- Elements that form the parts of the small volume prover:
- A precision cylinder;
- A displacer piston, spheroid or other liquid hydrocarbon separation devices;
- Displacer detectors;
- A valve arrangement that allows liquid hydrocarbon to flow whilst the displacer complete its travel.
- Pressure and temperature (PT,TT) measurement and indication devices.
- Instrumentation with timers, counters and pulse interpolation capabilities.
- During proving of a turbine or positive displacement meter, the displacer velocity shall not exceed 1.5m/s.
- The calibrated or swept volume of the small volume prover located between displacer-position sensors shall be free from any tapping,vent, or drain point.
Master-meter prover is an indirect proving device that has been proved by a direct prover (pipe or tank prover).
However, a meter with exceptional linearity and repeatability is selected to serve as the master meter. This master meter need to be calibrated annually.
Shall also has temperature and pressure measurement.
Categories: Oil & Gas Notes