Patent ID: 6116270
Filing Date: 2000-09-12
Classification: E21B,Y10T

Abstract:
A non-return foot valve having an open position and a closed position for control of liquid flow, comprising:an outer body having a tubular wall with an inner cylindrical surface, said tubular wall having a blank portion;a piston having a closed lower end surmounted by a hollow sleeve having a sleeve wall with an outer cylindrical surface which is slidably engageable with said blank portion said surfaces containing ports respectively communicating with a space external of said body and a space internal of the sleeve; and,three axially spaced sealing rings interposed between said tubular and sleeve walls, said outer body ports being adjacent to but above the intermediate of said sealing rings, said ports in said sleeve wall lie between the intermediate and lower of said sealing rings when said valve is in said closed position and lie between the intermediate and upper of said sealing rings when the valve is in its open position,said intermediate sealing ring sealing said blank portion of said body inner cylindrical surface by said sleeve outer cylindrical surface when said valve is in its closed position, but slidable movement of said sleeve away from said body blank portion placing said valve in its open position, whereby pressure by a fluid on the closed end of said sleeve effecting said slidable movement of said sleeve.