Abstract: A fluid feeding apparatus includes parallel flow passages connected at their downstream side, each parallel passage including a pressure flow controller (C) for regulating the flow of fluid and a fluid changeover valve (D) for opening and closing the passage on the downstream side of the pressure flow controller. A fluid feeding control unit (B) controls the pressure flow controllers and changeover valves so that when a changeover valve is closed a control valve (1) upstream of the changeover valve is also closed to prevent a pressure buildup at the changeover valve. In addition to the control valve (1), each pressure flow controller includes an orifice (5) downstream from the control valve, a pressure detector (3) for sensing pressure (P1) in the passage at a point between the control valve and the orifice, and a calculation control unit (6) for producing a control signal Qy for controlling the drive (2) for the control valve.

Abstract: An orifice for a pressure-type flow rate controller, which can be produced by a simple method at a low cost, that provides a linearity--between the pressure P1 on the upstream side of the orifice and the flow rate--over a wide range of the pressure ratio P2/P1 of the pressure P2 on the downstream side of the orifice to the upstream pressure P1 and that permits adjustment with ease of flow characteristics among a plurality of orifices. The orifice comprises an inlet taper 1 in the shape of a bugle and a short narrowed straight section 2 adjoining the inlet taper 1, both formed by cutting one opening end of a preliminary hole 6 made in an orifice plate D, and further comprises a short inner taper 3 and an enlarged straight section 4 connecting with the taper 3 which are formed by enlarging the preliminary hole 6 at the other opening end, the short inner taper 3 adjoining the narrowed straight section 2 on one side and neighboring the enlarged straight section 4 on the other side.

Abstract: A pressure-type flow rate control apparatus for use especially in the gas supply system in semiconductor manufacturing facilities. The flow control apparatus is provided with a bore-variable orifice, which permits easy switching of the fluid flow rate control range as well as size reduction of the pressure-type flow control apparatus, and offers other advantages including improved gas replaceability, prevention of dust formation, and reduced manufacturing costs of the flow control system.