Patent ID: 7765879

Claim:
A flow control valve, comprising: a valve element that is pivotally disposed inside a valve body and configured to regulate the flow rate of a fluid that passes through the interior of the valve body; an upstream side seat ring that contacts under pressure a seat part of the valve element; an upstream side retainer that holds the upstream side seat ring; a valve opening degree detector that is configured to detect a valve opening degree of the valve element; a differential pressure detector that is configured to detect a differential pressure between the fluid pressure inside an upstream side pipeline and the fluid pressure inside a downstream side pipeline of the valve body; and a flow rate calculator that is configured to calculate a flow coefficient based on a first measurement value provided by the differential pressure detector and a second measurement value provided by the valve opening degree detector, and is further configured to calculate the flow rate of the fluid based on the measurement values and the flow coefficient; wherein, the differential pressure detector is attached to an outer circumferential surface of the valve body; an upstream side fluid pressure outlet part is provided between an inner circumferential surface and an outer circumferential surface of the upstream side retainer in the vicinity of an upstream side end part so that it passes therethrough; a first conduit has an upstream side end in communication with the upstream side fluid pressure outlet part, the first conduit being formed between an inner circumferential surface of the valve body and the outer circumferential surface of the upstream side retainer; and a second conduit formed in the valve body connects a downstream side end of the first conduit to the differential pressure detector.