Safety - pressure relief device is intended to rupture disk with

摘要

A safe pressure relief assembly of the rupture disc type guards against pressure differentials beyond a predetermined range extending both above and below zero and includes a positive relief disc which is perforated to permit negative flow without rupturing, a sealing disc normally blocking the perforations, a cutting member positioned in spaced relation to the sealing disc and extending a substantial transverse distance thereacross and a sealing disc support member having a stay arrangement projecting into negative supporting engagement with the sealing disc, the stay arrangement having a resistance to collapse sufficient to retain the sealing disc out of contact with the cutting member only up to a predetermined negative pressure. The subcombination of sealing disc, stay arrangement and cutting member is separately useful, especially as a very low pressure relief device.