Stop valve a valve in which the flow of water is controlled by a movable spindle which lowers to a fixed seat, thereby restricting the flow through the valve opening; the spindle is fitted with a washer to provide tight closure; usually enclosed in a chamber having a globular shape.
Stop Valve are named for their spherical body shape. The two halves of the valve body are separated by an internal baffle which has an opening forming a seat onto which a movable plug can be screwed in to close (or shut) the valve. In globe valves, the plug is connected to a stem which is operated by screw action in manual valves. Typically, automatically controlled valves are of the sliding stem type. These Stop valves have a smooth stem rather than threaded and are opened or closed by an actuator assembly. When a globe valve is manually operated, the stem is turned by a handwheel.