Patent ID: 6845965

Claim:
A valve for controlling a fluid, the fluid exerting a fluid pressure, the valve comprising: a body, the body including: a fluid passage; a valve seat defining an orifice, and including: a sealing gland including a support surface, the support surface including a notch; a resilient valve seat member disposed within the sealing gland; a valve sealing member disposed within the fluid passage and configured to seat against the valve seat member to effect sealing of the valve sealing member to the valve seat and thereby close the orifice; the notch being configured to facilitate the application of the fluid pressure on the valve seat member to prevent leakage through the orifice and between the valve sealing member and the sealing gland when the valve sealing member is seated against the valve seat member; the valve seat member including: a first pressure responsive surface, exposed to the fluid passage, and including a valve engaging surface portion, wherein the valve engaging surface portion is configured to engage the valve sealing member to effect sealing of the valve sealing member to the valve seat; a second pressure responsive surface configured to receive the application of the fluid pressure; the notch being positioned to face the second pressure responsive surface; and the notch being configured to facilitate the application of the fluid pressure on the second pressure responsive surface to counterbalance applications of forces on the first pressure responsive surface.