Patent ID: 8336628

Claim:
A pressure equalizing system for a subterranean tool operable from a surface through a tubing string, comprising: a housing having a passage therethrough and a movable member operable in said passage to selectively close said passage while defining a downhole pressure zone and an uphole pressure zone with respect to the moveable member, said zones separated by an intermediate pressure zone at the moveable member such that said movable member is subjected to a positive pressure differential of said downhole pressure zone with respect to said intermediate zone; said uphole pressure and intermediate zones separated by at least one seal that is functional for pressure isolation of differential pressure between said uphole pressure and intermediate zones when said movable member selectively closes said passage, whereupon pressure buildup in said uphole pressure zone above a predetermined value said seal is bypassed as pressure is changed in said intermediate zone as flow from said uphole pressure zone into said intermediate zone brings said intermediate zone closer to the pressure in said downhole pressure zone to facilitate movement of said movable member to open said passage.