Abstract: A ball valve disclosed herein is low cost and offers a fast and reliable valve operation. Furthermore, the actuating force the ball valve requires, when it is shut off, is small. The ball valve is capable of fine adjustment of the flow. The ball valve comprises a valve casing defining a flow path of a fluid, a valve seat disposed in the midway of the flow path, a valve element which is in engagement with the valve seat or out of engagement with the valve seat, to shut off the flow path or to regulate the flow rate in the flow path, a control rod inserted into the valve casing and movable upward and downward, and a connecting rod, one end of which is rotatably supported at the inner end of the control rod, and the other end of which is connected to the valve element. The valve element comprises a communication path which communicates with both the upstream side of the flow path and the downstream side of the flow path and an on-off means for opening or closing the communication path.

Abstract: A valve appropriate for both shut-off and flow regulation operations is disclosed here. The valve is easy to handle, suffers from low flow resistance in its fully opened state, and offers excellent choking performance. A variety of sizes of the valve can be manufactured in a low-cost manner. The valve comprises a valve seat disposed in the midway of flow passages, and a valve casing which houses the valve seat and the valve element inside. The valve seat has a tilt angle with respect to the direction of the flow of a fluid. The valve element comprises a planar plate as its substrate, and an elongated hole on the back portion of the planar plate. The valve element is held at an initial tilt angle, smaller than the tilt angle of the valve seat, with respect to the direction of the flow of the fluid. A control rod is operative so that the valve element increases its tilt angle from its initial tilt angle.