Which type of check valve features a disk that moves in an arc to open or close the valve?

The type of check valve that features a disk moving in an arc to open or close the valve is the swing check valve. This design allows the disk, often shaped like a circular or oval flap, to pivot on a hinge or pin. When the flow of fluid is in the forward direction, the disk swings open, allowing easy passage. Conversely, if the flow reverses, the disk swings back against the seat, effectively preventing backflow. This operational mechanism is particularly effective in applications where the fluid's flow direction can vary, helping to maintain system integrity and preventing potential damage.

In contrast, other types of check valves operate differently: for instance, a ball check valve uses a ball that seals against a seat to prevent backflow, while a diaphragm check valve relies on a flexible diaphragm that moves in response to pressure changes. The butterfly check valve, although it resembles the swing check's movement, utilizes a circular disk that rotates around a shaft for flow regulation rather than hinging to swing open or closed. These distinct designs highlight why the swing check valve is recognized for its arc movement in regulating flow direction effectively.