Patent ID: 8499783

Claim:
A gate for mounting in a valve body of a resilient seated gate valve, the gate being coated with, or formed from, a resiliently deformable material and comprising two opposed faces spaced from the transverse plane of the gate, at least the upstream face being provided with at least two seals formed from the resiliently deformable material, that each extend around the face, the at least two seals comprising a first upstream seal and a second upstream seal, the first upstream seal being located within the periphery of the second upstream seal, the first upstream seal, in use, permitting fluid leakage when it reaches the limit of its sealing capability for a given compression such that an inter-seal space between the two seals becomes pressurised so that the fluid pressure is stepped and retained across the seals, that is, the fluid pressure between the seals is intermediate the upstream fluid pressure and the downstream fluid pressure, wherein at least four seals are provided, that is, the upstream and the downstream faces each comprise at least two seals, such that in use, the seal compression forces required to seal against a given fluid pressure are further reduced, and the integrity of sealing is further increased, and wherein the seals extend to an underside of the gate, and further wherein the entirety of the seals of the upstream face are spaced-apart from the entirety of the seals of the downstream face.