Check valves are generally installed in pipelines to prevent backflow. A check valve is basically a one-way valve, in which the flow can run freely one way, but if the flow turns the valve will close to protect the piping, other valves, pumps, etc. If the flow turns and no check valve is installed, a water hammer can occur. Water hammers often occur with extreme force and will easily damage a pipeline or components.

Check valves are used in many different applications. For example, they are often placed on the outlet side of a pump, to protect the pump from backflow. Centrifugal pumps, the most common type of water pumps, are not self-priming, and therefore check valves are essential for keeping water in the pipes.