Which valve is normally open with sensing at the output side?

Which valve is normally open with sensing at the output side?

• A. Pressure valve
• B. Pressure regulating valve
• C. Aeration
• D. Pressure relief valve (correct)

Answer: (D)

A pressure relief valve is used to protect a hydraulic circuit by venting excess fluid when the pressure on the output side gets too high. It is designed to monitor the pressure after the pump or downstream components and, once that downstream pressure reaches its set point, it opens to discharge fluid back to the reservoir. This keeps system pressure within safe limits and prevents damage to components like seals, hoses, and actuators. Under normal operation the valve stays closed to allow flow to the load; only when the downstream pressure rises above the set value does it open to relieve. The other options don’t perform this protective relief function: a pressure valve or a pressure regulating valve maintains or sets pressures for specific parts of the circuit, while aeration relates to introducing air into the fluid, not relieving excess pressure.

A pressure relief valve is used to protect a hydraulic circuit by venting excess fluid when the pressure on the output side gets too high. It is designed to monitor the pressure after the pump or downstream components and, once that downstream pressure reaches its set point, it opens to discharge fluid back to the reservoir. This keeps system pressure within safe limits and prevents damage to components like seals, hoses, and actuators. Under normal operation the valve stays closed to allow flow to the load; only when the downstream pressure rises above the set value does it open to relieve. The other options don’t perform this protective relief function: a pressure valve or a pressure regulating valve maintains or sets pressures for specific parts of the circuit, while aeration relates to introducing air into the fluid, not relieving excess pressure.