Abstract: Apparatus for calibrating a meter prover is disclosed including a chamber taking the form of a substantially perfect right circular cylinder, a piston adapted for rectilinear movement within said cylinder between a first position and a second position, means for moving the piston from its first position to its second position, and an encoder coupled to the piston for providing an output signal indicative of the movement of the piston and thus the volume of fluid displaced by that movement of the piston. The calibrating apparatus comprises an antenna electromagnetic energy to the antenna whereby electromagnetic waves are emanated into the chamber. A detector is coupled to the antenna to detect electromagnetic energy leaving the chamber and is in turn coupled to a resonant detector in the form of a cathode ray tube, whereby a minimum of the level of the electromagnetic energy may be determined.

Abstract: Apparatus for calibrating a flow meter under test is disclosed as including a chamber having an opening to be coupled by a conduit to the fluid meter under test, a piston to be driven by a motor in a first direction and in a second direction. A first valve is disposed within the conduit and inserted between the chamber opening and the fluid meter under test, while a second valve is associated by the conduit to the opening to permit exhaust of the fluid from the chamber. A control circuit including a microprocessor operates in a first mode to energize the motor to drive the piston in the first direction to draw fluid from the meter into the chamber while actuating the first valve to be opened and maintaining the second valve in its closed position.