Which of the following is a type of hydraulic check valve?

• A. Ball check valve
• B. Relief valve
• C. Metering valve
• D. Poppet valve

Answer: (A)

A hydraulic check valve is meant to let fluid flow in only one direction and stop it from flowing backward. The ball check valve does this with a small ball that sits on a seat. When fluid moves forward, pressure pushes the ball away from the seat, allowing the flow. If the flow tries to go backward, the ball naturally seats against the seat and blocks the path, preventing reverse flow. This simple, reliable one-way action is exactly what a check valve is designed to do, making a ball check valve a classic and common type.

Relief valves are for protecting the system from overpressure by opening to vent excess pressure, not for blocking reverse flow. Metering valves regulate the amount of flow, not prevent backflow. Poppet valves are a broader category used in various valve functions; while a poppet can be part of a check valve design in some contexts, the typical, straightforward hydraulic check valve is the ball type.