The Ball valves as name suggests is having a ball type spherical body. They are stop valves that use a ball to stop or start the flow of fluid. The ball performs the same function as the disk in the globe valve.
This rotational-motion valve uses a ball-shaped disk with a hole bored through to stop or start fluid flow. When the valve handle is turned to the open position, the
ball is rotated so that the hole lines up with the valve body’s inlet and outlet.
When the ball is rotated so the hole is perpendicular to the flow, the valve is closed. Because the ball moves across the seats with a wiping motion, ball valves can handle fluids with suspended solids.
When the valve is shut, which requires only a 90-degree rotation of the handwheel for most valves, the ball is rotated so which is divided in two parts by a baffle. Flow direction is steeply changed in this type of valve so the controlling of flow is better by the movement of restriction element.
Most ball valves are of the quick-acting type (requiring only a 90-degree turn to operate the valve either completely open or closed), but many are planetary gear operated. This type of gearing allows the use of a relatively small handwheel and operating force to operate a fairly large valve. The gearing does, however, increase the operating time for the valve. Some ball valves contain a swing check located within the ball to give the valve a check valve feature. Ball valves are normally found in the following systems aboard ship: seawater, sanitary, trim and drain, air, hydraulic, and oil transfer.
Ball valves are available in Venturi, reduced and full-port patterns. The full-port pattern has a ball with a bore equal to the inside diameter of pipe. Most ball valves instead have a reduced bore with a Venturi shaped flow passage of about three quarters the nominal valve size.
Uses a large lever to turn a ball that closes or opens the flow with one quick quarter turn.
Ball Valves are mainly used in fluids containing solids.
Ball Valves have lower pressure drops.
Are the standard for natural and LP gas, replacing the older plug valves that were traditionally used as gas valves. Now Ball Valves are standards for gas service also replacing Plug Valves.
Available in either metal or plastic, threaded or non-threaded types.
Ball valves with double-stem seals provide greater durability.