Ball valves are a type of quarter-turn valve that uses a hollow, perforated ball to control the flow of liquids or gases through a pipe. The ball has a hole, or port, through its center, which allows the fluid to flow when the port is aligned with the inlet and outlet of the valve. Rotating the ball 90 degrees using the valve handle or actuator blocks the flow of fluid by positioning the solid part of the ball across the inlet and outlet ports.