Patent attributes
A gas seal assembly includes a pair of mutually rotatable sealing members, each of which has a front face adjacent a gap between the two members which constitutes a leakage path through the seal assembly. The two sealing member are urged, in use, in a direction to close the gap and a gas bleed arrangement is provided for allowing gas from a high pressure side of the seal to bleed into the gap so as to apply a force tending to separate the members. The gas bleed arrangement includes a bore extending between the front face and a rear face of one of the sealing members, a generally radial groove formed in the rear face of the sealing member and a plate overlying the rear face to cover the groove and thereby define between the rear face of the sealing member and the plate a bleed passage connecting the bore to the high pressure side of the seal. The plate is formed as a shim that is sufficiently flexible to be deflected by the gas pressure into mating contact with the rear face of the sealing member so as to confine the gas flow of the bleed passage to the radial groove.
