A ball check valve is a check valve that is much like a swing check valve but instead of having a gate or guided disk, uses a ball to control flow. The ball is inside the body and free to rotate on the seat. The seat and body are tapered in such a way to guide the ball when the valve sees reverse flow. Because the ball can rotate on the seat, it can clean itself. This is especially useful when using a ball check for dirty services or in viscous applications.
Ball check valves are usually sized two inches or below. As the valve gets larger, the ball gets larger and the amount of back pressure to keep the valve closed increases. Ball check valves are available as metallic or non-metallic valves. If the process fluid is highly corrosive, use of a ball check may be preferable over ordering an alternative design that may require the use of exotic metals.
A ball check valve is a very versatile valve and can be used in virtually every service. This includes gasses, liquids and vapors. As noted above, it can also be used in dirty or viscous applications.
The preferred installation orientation for a ball check valve is vertical in the flow up direction. This uses gravity to help seat the valve. If the valve must be in the horizontal position, there must be enough differential pressure across the valve to hold the valve closed. Vertical installation, flow down is not an acceptable orientation for this valve unless there is a spring to assist closure.