Abstract: Disclosed is a testing device for at least one flow meter installed in a pipeline. The device includes a calibration container connected to the pipeline across a switch-over valve. A measuring piston is guided for reciprocating movement in the container between a starting and a terminal position. The measuring piston supports two signal releasing rings which are spaced apart from the other about a distance which when multiplied by the inner clearance of the calibration container determines a calibration volume of the measuring path of the piston. At least one signal generator is installed in the wall of the calibration container and cooperates in a contactless manner with the first and second signal releasing rings so as to produce start and stop pulses for one measuring cycle. The flow meter is connected to a pulse generator responsive to the flow rate and connected to an evaluation circuit which after completion of a measuring cycle compares the counted pulses with the calibration volume.

Abstract: A prover detector comprising a barrel having a longitudinal bore formed therethrough to receive a proximity switch mounted in one end thereof and a piston mounted in the other end thereof to extend from the barrel bore into the prover. The proximity switch is of the type that is responsive to the proximity of an unmagnetized, ferromagnetic mass near the end thereof disposed within the barrel bore for closing a set of contacts in the proximity switch and the piston has a cylindrically symmetric portion at the end thereof nearest the proximity switch, such portion centered on an axis of movement of the piston relative to the proximity switch defined by the barrel bore, so that the position of the piston for which the contacts in the proximity switch close depends only upon the distance between the proximity switch and the piston.