What type of check valve uses a spring to control flow direction?

The type of check valve that uses a spring to control flow direction is the spring check valve. This valve is designed to prevent backflow in a piping system by utilizing a spring mechanism that keeps the valve closed when there is no flow. When fluid pressure exceeds a certain level, it overcomes the spring tension, allowing the valve to open and permit flow in the desired direction. Upon a decrease in pressure or flow reversal, the spring forces the valve to close, effectively preventing backflow and protecting the system.

In comparison, other types of check valves operate on different principles. The pressure check valve relies on differential pressure across the valve to open and close, rather than a spring mechanism. The ball check valve uses a ball that moves up and down in the valve body to either block or allow flow, responding solely to fluid dynamics rather than a spring. An inline check valve typically refers to its installation type, allowing flow in one direction, but may utilize various mechanisms that do not include a spring specifically.