A pressure relief valve is a mechanical safety device that provides protection to a pressurized container, such as a pipeline, by reducing the internal pressure by releasing it outside the container.

A pressure relief valve is a valve designed to open at a predetermined pressure value. Many pressure relief valves are designed as safety features to vent tanks before tank pressure exceeds the tank's tolerance and explodes.

A pressure relief device which is designed to reclose and prevent the further flow of fluid after normal conditions have been restored.

Valve to relieve excess pressure in water storage tanks.

A device mounted on a hot water heater or boiler which is designed to release any high steam pressure in the tank to prevent tank explosions.

A pressure-activated valve which opens automatically at a specified pressure to discharge fluid. Interpretation given in Schedule 2: of the Water Supply (Water Fittings) Regulations and Scottish Water [..]

A valve, which limits the pressure to a pre-determined value by exhausting fluid.

A valve held closed by a spring or other means and designed to automatically relieve excess pressure.

Also called a "pop valve" or a "safety valve," this class of mechanical safety device is designed to operate at a predetermined pressure to reduce the internal pressure of a vessel. The valve is often designed to close again when the vessel pressure is again below the set point. (W. Kent Muhlbauer, Pipeline Risk [..]