Importance

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Abstract

Embodiments described herein relate to methods and structures for controlling a valve. One embodiment provides a valve control comprising a first valve fluidly connected with a first fluid conveying conduit and a second fluid conveying conduit. The first valve is movable between a first position where fluid communicates between the first fluid conveying conduit and the second fluid conveying conduit and a second position where fluid does not communicate between the first fluid conveying conduit and the second fluid conveying conduit. A first source of relatively increased pressure and a first source of relatively reduced pressure are provided. A third conduit fluidly connects the first source of relatively increased pressure and the first source of relatively reduced pressure with the first valve. A third valve is fluidly connected with the third conduit. The third valve is movable between a first position where the first source of relatively increased pressure is fluidly connected with the third conduit and the first valve thereby moving the first valve toward its second position and a second position where the first source of relatively reduced pressure is fluidly connected with the third conduit and the first valve thereby moving the first valve toward its first position. A second valve is fluidly connected with the third conduit between the third valve and the first valve. The second valve is movable between a first position where fluid communicates between the first valve and the third valve and a second position where no fluid communicates between the first valve and the third valve.

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First Claim