How does a check valve operate?

A check valve is designed specifically to allow fluid to flow in only one direction, which is essential in hydraulic systems to prevent backflow. When the flow of fluid is in the designated direction, the check valve opens, enabling the fluid to pass through. If the flow attempts to reverse, the valve automatically shuts, creating a seal that stops the backflow. This characteristic is critical in applications where it is necessary to maintain the pressure and integrity of a system by preventing reverse flow, which could cause damage or malfunction in hydraulic equipment.

The other options do not accurately describe the function of a check valve. While pressure build-up may occur in a hydraulic system, it is not a direct function of the valve itself. Controlling the flow rate is typically managed by valves designed for throttling, not check valves. Lastly, a check valve does not prevent all fluid movement; it only restricts flow in one direction while permitting it in the other.