ASME PTC 25 pdf download Pressure Relief Devices safety relief valve:a pressure relief valve character-ized by rapid opening or closing or by gradualopening or closing, generally proportional to theincrease or decrease in pressure. lt can be used forcompressible or incompressible fluids. 2.3.2 Nonreclosing Pressure Relief Device.Apressure relief device designed to actuate and remainopen after operation.A manual resetting means maybe provided....