Patent ID: 8387647

Claim:
An overpressure indicating disk apparatus for indicating an over pressure condition in a pressurized system, comprising: a) a body having first and second end portions and a bore, the first end portion configured for attachment to the pressurized system and in pressure communication therewith so that a pressure in the bore is the same pressure as a pressure of the pressurized system; b) a reverse buckling disk having an annular peripheral portion and a concave convex dome portion that has a concave side and a convex side, said annular peripheral portion surrounding said dome, the disk annular peripheral portion mounted to the body and closing the bore at said first end portion; c) an indicating ring affixed to a combination of the body and the reverse buckling disk, the indicating ring having an annular peripheral portion that aligns generally with the annular peripheral portion of the reverse buckling rupture disk; d) a movable central tab portion inside the indicating ring, the central tab portion having an arc shaped peripheral edge that extends less than 360 degrees around the central tab portion, a scored portion being provided in between said arc shaped peripheral edge and said annular peripheral portion of said indicating ring; e) a hinge that connects the central tab portion to the indicating ring; and f) wherein the concave side of the reverse buckling disk faces the central tab and the convex side of the reverse buckling disk faces the pressure inside the bore so that when the pressure in the bore exceeds a preselected maximum pressure value, the disk reverses to engage and displace the central tab thereby indicating an overpressure condition within the bore.