Patent ID: 8352087

Claim:
A method for controlling a flow control valve, the method comprising: measuring a present opening of the valve; measuring a flow through the present opening of the valve; determining a C v value of the valve, using said present opening of the valve, on a C v curve of the valve, wherein the C v value is a flow coefficient value and the C v curve describes C v values as a function of valve openings; calculating a pressure drop across the valve by means of the measured flow and the determine C v value; calculating a flow deviation as a difference between a desired flow set point and the measured flow; integrating said flow deviation; calculating a corrected flow set point by adding the integrated flow deviation to the desired flow set point; calculating a new C v value of the valve by means of the corrected flow set point and the calculated pressure drop; determining a new valve opening, using said new C v value of the valve, on an inverse C v curve of the valve, wherein the inverse C v curve describes valve openings as a function of C v values; moving the valve to a new opening position in response to the determined new valve opening; and continuing said determining of a new valve opening and said moving the valve to a new opening position until the measured flow is set to the desired flow set point.