Which type of valve prevents backflow in liquid systems?

The check valve is specifically designed to allow fluid to flow in only one direction, effectively preventing backflow within liquid systems. This is crucial in various applications, such as maintaining system pressure and ensuring that the fluid does not return to a previously filled area, which could lead to contamination or failure of the system.

Check valves operate using a hinged mechanism or spring that opens when fluid flows in the intended direction and closes automatically if the flow reverses, thereby protecting the integrity of the system. This function is essential in refrigeration and other liquid transport systems where backflow could disrupt operations or cause damage.

In contrast, gate valves, ball valves, and globe valves serve different purposes. Gate valves are primarily used for on/off service with minimal pressure drop, ball valves offer quick shut-off capabilities, and globe valves are suited for regulating flow but not for preventing backflow. Thus, these other valve types do not provide the necessary one-way flow protection that check valves do.