Pressure relief valve

A pressure relief valve is an overpressure-protection device that opens when system pressure reaches its set condition, discharging fluid to a designated safe path to limit further pressure rise. It should reclose as pressure falls in accordance with the selected design. This duty differs from a pressure reducing valve, which modulates during normal operation to control downstream pressure; a relief valve responds to an overpressure event. Fluid phase, credible overpressure scenario, set pressure, backpressure, required relieving capacity, and discharge routing require engineering verification.