Patent ID: 8424567

Claim:
A valve coupled between a first pipe section and a second pipe section and actuatable between an open configuration, wherein fluid flow is enabled between the first and second pipe sections, and a closed configuration, wherein fluid flow between the first and second pipe sections is prevented and fluid is entrapped within an enclosed cavity inside the valve, the valve comprising: a first pressure port in fluid communication with the first pipe section when the valve is closed; a second pressure port in fluid communication with the enclosed cavity when the valve is closed; a first seal isolating the second pressure port from the first pressure port when fluid pressure within the enclosed cavity is less than a pre-selected value and displaceable to enable fluid communication between the second pressure port and the first pressure port when fluid pressure in the enclosed cavity is equal to or greater than the pre-selected value; a spool port extending at least between the first pressure port and the second pressure port and wherein the first seal is disposed within the spool port; and a third pressure port in fluid communication with the second pipe section when the valve is closed and a second seal disposed in the spool port isolating the first pressure port from the third pressure port.