Ball Valves
Ball Valves are so-named because their closing mechanism is ball-shaped.
The ball, shown here, performs the same function as the disk in gate valves. As the valve handle is turned to open the valve, the ball rotates to a point where part or all of the hole through the ball is in line with the valve body inlet and outlet, allowing fluid to flow through the valve.
When the ball is rotated so the hole is perpendicular to the flow openings of the valve body, the flow of fluid stops. If the hole through the ball is the same size as the pipe it is controlling, the valve is called a "full-port" ball valve.
The ball in most water valves is made of stainless steel, and it rotates in a neoprene liner for smooth operation. Ball valves have fewer moving parts than gate valves and are considered more reliable. Most ball valves are the quick-acting type, meaning they require only a 90-degree turn to either completely open or close the valve. Some ball valves also contain a swing check located within the ball to give the valve a check valve feature.
The figure at the left shows a cross-section of a typical ball- valve like the one shown above Most residential ball valves use lever handles as shown, but other models are available with handwheels. In addition to those shown, there are three-way ball valves that are used to supply fluid from a single source to one component or the other in a two-component system.
Ball valves are available in IPS and sweat styles. They’re also available for PVC.
