A fluid feeding apparatus for use in a gas supply system as in semiconductor manufacturing facilities which permits high-precision control of the flow of fluid without causing transient overshooting phenomena of fluid at the start of fluid feeding or fluid changeover.
The fluid feeding apparatus of the present invention comprises a pressure flow controller to regulate the flow of fluid, a fluid changeover valve to open and close the fluid passage on the secondary side of the pressure flow controller and a fluid feeding control unit to control the actuation of the pressure flow controller and the fluid changeover valve, said pressure flow controller including: an orifice 5, a control valve 1 provided on the upstream side of the orifice 5, a pressure detector 3 provided between the control valve 1 and the orifice 5 and a calculation control unit 6 which inputs in a drive 2 for said control valve 1 a difference between a flow rate signal Qc and a flow rate specifying signal Qs as control signal Qy, said flow rate signal Qc calculated with flow rate Qc = KP 1 (K = constant) on the basis of a pressure P 1 detected by the pressure detector 3, wherein the flow rate on the downstream side of the orifice 5 is controlled by regulating the pressure P 1 on the upstream side of the orifice 5 through the opening and closing of said control valve 1.