Meter Prover [1]

A container used to determine the accuracy of a meter [2].

To check a pump meter, an inspector would dispense product from the pump into the proving can. When the pump meter shows that the amount dispensed is 5 gallons, the operator then checks the liquid level in the container to verify that the amount there is, indeed, 5 gallons. Minor variances are permitted and the normal allowed variance is plus or minus 6 cubic inches per 5 gallons of product. This is a variance of 0.5 percent.

If the pump meter records a significant inaccuracy, the pump can be officially removed from service until it is adjusted to accurate condition. Calibration of larger meters, such as those used at loading racks [3], is obtained through use of prover tanks.

See also Prover tank [4].