SERVO TYPE VOLUMETRIC FLOWMETER

摘要

A servo type volumetric flowmeter having instrumental characteristics improved from low flow rate zone to high flow rate zone. The volumetric flowmeter (1) comprises a pair of first and second rotors (6, 7) rotating by the differential pressure of fluid in a measuring chamber (3) disposed in a casing (2) to deliver a specified volume of received fluid and measures the flow rate from the rotation of the rotors. The first rotor is coupled with a servomotor (17). Pressures at pressure detection ports (10, 11) provided at the inlet (8) and outlet (9) of the volumetric flowmeter are introduced through piping to a differential manometer (12) where the differential pressure is determined and a servomechanism drives the servomotor such that a differential pressure signal will be equal to k(gamma/2g)V2 (where, gamma: density of fluid being measured, V: rotational speed of the rotor, g: gravitational acceleration, k: a constant dependent on the structural dimensions of the flowmeter and the frictional coefficient of the pipe). Rotation of the rotor at that time is taken out as a flow rate signal by a flow rate transmitter (19).