The sentinel-relief valve lifts at how many pounds per square inch (psi)?

• A. 25 psi
• B. 30 psi
• C. 40 psi
• D. 50 psi

Answer: (B)

A sentinel-relief valve is a safety device that opens when system pressure reaches its set value to prevent overpressure. The disc lifts off the seat when the pressure exceeds the spring’s resistance, allowing the fluid to vent and keep the system from being damaged.

In this scenario, the valve is designed to lift at 30 psi. That setting provides a reliable protective margin: it prevents the pressure from climbing high enough to harm components, while avoiding unnecessary venting from small daily fluctuations that might occur at lower pressures. If it were set much lower, like 25 psi, it could vent too often; if set higher, like 40 or 50 psi, the system could experience higher pressures before relief occurs, increasing risk to equipment. Therefore, 30 psi is the best balance for this sentinel-relief valve.