Which valve allows flow in only one direction and can be set by a screw?

Which valve allows flow in only one direction and can be set by a screw?

• A. One-way control valve
• B. Flow control valves
• C. Meter-out
• D. Counterbalance valve

Answer: (A)

The key idea is unidirectional flow with adjustable opening. A one-way control valve acts like a safety gate that lets fluid pass in the forward direction but blocks it if pressure reverses, preventing backflow in the circuit. The screw setting is how you tune when it starts to open—the opening or cracking pressure—so you can match the valve’s response to the system’s needs and avoid unwanted backflow when the pump stops or when loads push back on the line.

Other valves don’t primarily enforce a single-direction flow. Flow control valves regulate how fast fluid moves but not whether it can move backward. Meter-out valves throttle flow on the return path, again focusing on rate rather than direction. Counterbalance valves control motion to hold a load, not simply restrict reverse flow. So the one-way valve with an adjustable screw best fits the described behavior.