ASME PTC 25:1998 pdf free download Special Addenda to ASME PTC 25-1994 Pressure Relief Devices
burst pressure — the value of inlet static pressureat which a rupture disk device functions
chatter – abnormal rapid reciprocating motion ofthe movable parts of a pressure relief valve in whichthe disk contacts the seat
closing pressure – the value of decreasing inletstatic pressure at which the valve disk reestablishescontact with the seat or at which lift becomes zerocoefficient of discharge – the ratio of the measuredrelieving capacity to the theoretical relieving ca-pacity
cold differential test pressure – the inlet static pres-sure at which a pressure relief valve is adjusted toopen on the test stand. This test pressure includescorrections for service conditions of superimposedback pressure and/or temperature
constant back pressure – a superimposed backpressure which is constant with time
cracking pressure — see opening pressure
flow capacity – see measured relieving capacityflow-rating pressure – the inlet static pressure atwhich the relieving capacity of a pressure relief de-vice is measured
flow resistance – a dimensionless term (such asused in para. 5.5.7) which expresses the number ofvelocity heads lost due to flow through a rupturedisk device (where velocity head is one-half the ve-locity squared divided by the acceleration of grav-ity)
flutter – abnormal, rapid reciprocating motion ofthe movable parts of a pressure relief valve in whichthe disk does not contact the seat
leak pressure – see start-to-leak pressure
leak test pressure – the specified inlet static pres-sure at which a quantitative seat leakage test isperformed in accordance with a standard proceduremarked breaking pressure – the value of pressuremarked on a breaking pin or a shear pin device orits nameplate
marked burst pressure – the value of pressuremarked on the rupture disk device or its nameplateor on the tag of the rupture disk and indicates theburst pressure at the coincident disk temperaturemarked set pressure – the value or values of pres-sure marked on a pressure relief device
ASME PTC 25:1998 pdf free download
