Over pressure release valve for a hydraulic installation

Claim 1

An over-pressure release valve for a hydraulic installation, said valve including: a circular seat, a disk having an annular surface on one side which cooperates with the seat, said one side of the disk being subject to pressure of a liquid in a hydraulic installation; a thrust member positioned on the other side of the disk; and means for supporting the thrust member relative to the seat so as to press the disk against the seat, wherein the improvement comprises: said thrust member being substantially cylindrical longitudinally flexible chamber mounted coaxially with the disk and the seat, the thrust exerted by said chamber against the other side of the disk being a function only of gas pressure therein; the means for supporting the thrust member comprising a plurality of circumferentially spaced rods extending parallel to the axis of said chamber and spaced radially therefrom, such that the chamber is laterally unsupported and a substantially unrestricted flow area is provided around the seat between said rods; and the diameter of the disk being from 1.20 to 1.25 times that of the opening in the seat, and the disk being unguided and restrained only by said flexible chamber such that liquid from the hydraulic installation can flow in an unrestricted sheet when the disk lifts off the seat due to a sudden overpressure in said installation.