Ball

A ball valve is a rotational motion valve that uses a ball-shaped disc to stop or start fluid flow. The ball performs the same function as the disc in the globe valve. Ball valves are used to control the flow of a liquid or gas. When the valve handle is turned to open the valve, the ball rotates to a point where the hole through the ball is in line with the valve body inlet and outlet. When the valve is shut, the ball is rotated so that the hole is perpendicular to the flow openings of the valve body and the flow is stopped. Most ball valve actuators are of the quick-acting type, which requires a 90° turn of the valve handle to operate the valve. Other ball valve actuators are planetary gear operated. This type of gearing allows the use of a relatively small handwheel and operating force to operate a large valve.