| 摘要 |
An arrangement for testing a flow meter which issues a first train of pulses in response to the rotation of a rotatable member thereof includes a measuring cylinder-and-piston unit that has a cylinder, a piston slidably received in the cylinder and displacing a known comparison volume of a fluid out of the cylinder for delivery to the flow meter, and a piston rod which extends to the exterior of the cylinder. A photoelectric sensing arrangement is mounted on the piston rod for joint movement therewith along a stationary volume scale to scan distancing markings of such scale and issue a second train of pulses in response to the detection thereof. A first of such distancing markings is so situated that the sensing arrangement encounters the same only after the piston rod has covered an initial distance corresponding to a running-in distance of the piston. A lug with countermarkings corresponding to the distancing markings is mounted on the piston rod and interposed in the light path of the photoelectric sensing arrangement to mask and unmask the distancing markings and thus to achieve a pronounced light-dark effect. The first pulse of the second pulse train triggers the counting of the pulses of the first pulse train which are correlated to the number of revolutions of the rotatable member of the flow meter, and a correction is made after the termination of a test run for pulse fractions occurring at the beginning and at the end of the testing run.
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