Sealing means for pressure relief valves and methods of assembly

摘要

A safety relief valve (12) for a pressure vessel (10) in which the main valve member (28) includes a valve plate or disc (52) and a retainer plate (64) having a flexible membrane or diaphragm (62) stretched therebetween in a taut relation to provide a frusto-conical shape (FIG. 3) for obtaining bubble-tight sealing against valve seat (26). A fluid chamber (116) is provided between valve plate (52) and retainer plate (64) and inlet fluid pressure is communicated through opening (118) of jack screw (106) to the fluid chamber (116) for providing inlet fluid pressure thereto to force valve plate (52) and retainer plate (64) apart for tensioning of flexible membrane (62) into a frusto-conical shape. A jack screw (106) is threaded within a bushing (94) carried by retainer plate (64). Upon rotation of jack screw (106), valve plate (52) and retainer plate (64) are forced away from each other for tensioning flexible membrane (62) into a frusto-conical shape. The initial sealing of main valve member (28) is by contact of flexible membrane (62) with seat (26) and the sealing pressure increases as the inlet pressure increases due to differential pressure across the flexible membrane (62). The method of assembly includes the forcing of valve plate (52) and retainer plate (64) away from each other with manual adjusting means (106) to tension the flexible membrane (62) a predetermined amount into a frusto-conical shape.