Patent ID: 8307845

Claim:
A flow rate controller comprising: a differential pressure flow meter, wherein an orifice is disposed between a pair of pressure sensors provided in a straight piping section of a main fluid channel, the differential pressure flow meter carrying out flow rate measurement by converting a pressure difference obtained from two pressure values detected by the pressure sensors to a flow rate; a flow-rate adjusting valve that is provided in the main fluid channel and whose degree of opening is controlled such that the difference between a measured flow rate value of the differential pressure flow meter and a preset flow rate value determined in advance falls within a predetermined range; and a control unit that controls the degree of opening of the flow-rate adjusting valve upon receiving as inputs the pressure values detected by the pressure sensors, wherein the control unit compares the preset flow rate value and the measured flow rate value of the differential pressure flow meter and automatically determines that there is a clog fault in the orifice when a flow rate difference equal to or greater than a predetermined value continues for a predetermined period of time or longer under controlled conditions.