Apparatus for calibrating meter prover encoder

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. Further, a frequency detector in the form of a counter, is connected to the output of the generator to detect the frequencies of the generator output at which the minimum level occurs as observed upon the cathode ray tube corresponding to the establishment of a resonant standing wave within the chamber of the meter prover. The frequencies at which the resonant standing waves are established within the chamber, in turn determine the volumes corresponding to the first and second positions and therefore the difference in volume between the first and second positions corresponds to the displacement volume as would be drawn by the movement of the piston from its first to its second position through the fluid flow meter under test.