Which valve prevents backflow in a hydraulic line?

Which valve prevents backflow in a hydraulic line?

• A. Metering valve
• B. Check valve
• C. Relief valve
• D. Pilot valve

Answer: (B)

Backflow prevention in a hydraulic line is achieved with a check valve. It allows fluid to flow in the intended direction but seals off when flow reverses. The valve contains a movable element—often a ball, poppet, or disc—that seats against a seal when reverse pressure occurs, stopping any backward movement. Many check valves are spring-assisted to ensure a quick seal when forward flow drops. This is distinct from metering valves, which regulate how much fluid passes through rather than preventing reverse flow; relief valves, which open to relieve excessive pressure, do not block reverse flow by design; and pilot valves, which control other valves with a pilot signal rather than providing a one-way block in the line.

Backflow prevention in a hydraulic line is achieved with a check valve. It allows fluid to flow in the intended direction but seals off when flow reverses. The valve contains a movable element—often a ball, poppet, or disc—that seats against a seal when reverse pressure occurs, stopping any backward movement. Many check valves are spring-assisted to ensure a quick seal when forward flow drops.

This is distinct from metering valves, which regulate how much fluid passes through rather than preventing reverse flow; relief valves, which open to relieve excessive pressure, do not block reverse flow by design; and pilot valves, which control other valves with a pilot signal rather than providing a one-way block in the line.