Ball Valves:

A ball valve is a rotational motion valve which uses a ball-shaped disk to start or stop fluid flow. The ball, displays in Figure, performs the similar function as the disk within the globe valve. While the valve handle is turned to open the valve, the ball rotates to a point whereas the hole by the ball is within line along with the valve body inlet and outlet. While the valve is shut, the ball is rotated so in which the hole is perpendicular to a flow openings of the valve body and the flow is stopped.

Many ball valve actuators are of the quick-acting type that needs a 90° turn of the valve handle to operate the valve. Another ball valve actuators are planetary gear-operated. This category of gearing permits the use of an associatively small handwheel and operating force to operate a fairly large valve.

A few ball valves have been established along with a spherical surface coated plug which is off to one side within the open position and rotates inside the flow passage until it blocks the flowpath fully. Seating is accomplished through the eccentric movement of the plug. The valve needs no lubrication and could be used for throttling service.

Figure: Typical Ball Valve