Meter Proving: Typical methods
Typical methods of meter proving are:
- Static proving tanks a very finely calibrated tank that is connected to meters where the discharge from the tank is compared to the meter reading; or where the meter reading is compared instead to receipt into the tank.
- Mobile proving tanks as above but of lesser capacity such as 1,500 litres. It needs to be jacked up and levelled before use. However, the tanks used must be ones which have been specifically designed for this purpose.
- Reference meters are high grade meters that are connected in line with the meter to be tested and the results compared. The reference meters themselves need to be proved. Corrections need to be made where the pressure goes over 1.5 bars (27 p.s.i.) against an authenticated correction graph produced at the proving of the reference meter. The reference meter must not be used to prove meters at flow rates that the reference meter itself has not been tested at.
- Prover loops a loop in the pipe work that allows the flow to be diverted through a proving meter or device rather than the working meter.
- Pipe provers often work in specially designed prover loops that accommodate a sphere that is started and sensed at a stop point electronically and travels with the flow so that a precisely known amount of oil travelling through the pipe travels through the meter and results are compared. Instead of a sphere, sometimes a piston is used and this process can be run backwards so that the same precisely known amount of fluid can be pushed through in the same direction twice.