| 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 (6) 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 (1) are introduced through piping to a differential manometer (12) where the differential pressure is determined and a servomechanism drives the servomotor (17) such that a differential pressure signal will be equal to k(ϝ/2g)V<sp>2</sp> (where, ϝ: 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 (6) at that time is taken out as a flow rate signal by a flow rate transmitter (19). |
