What device allows fluid to flow freely in one direction while restricting flow in the opposite direction?

The device that allows fluid to flow freely in one direction while restricting flow in the opposite direction is the orifice check valve. This type of valve is specifically designed to prevent backflow, which is essential in hydraulic and pneumatic systems. When fluid moves in the intended direction, the valve opens, permitting flow. However, if the fluid attempts to flow in the reverse direction, the valve closes, preventing backflow and maintaining system integrity.

In hydraulic systems, backflow can cause damage or inefficiencies, so the orifice check valve plays a crucial role in ensuring the system operates correctly and safely. The design of this valve often incorporates a small orifice that controls the flow rate, providing a balance between allowing fluid passage and preventing reverse flow.

For context, a throttle valve controls the amount of fluid flow but does not inherently prevent backflow. A directional control valve is more about directing flow to different parts of the system rather than restricting reverse flow in a single direction. A pressure relief valve is designed to protect the system from overpressure by allowing fluid to escape, rather than controlling flow in both directions.