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Flow control system for a valve

  • US 20050103382A1
  • Filed: 11/17/2004
  • Published: 05/19/2005
  • Est. Priority Date: 11/18/2003
  • Status: Active Grant
First Claim
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1. A flow control system for a valve comprising:

  • a valve body having a main flow passage connecting a first opening in communication with a first pressure area to a second opening in communication with a second pressure area;

    a first valve with a shuttle piston having a first face in communication with the second pressure area through the main flow passage, a first seal at the first face which is operable to open and close the main flow passage, and a second face in communication with the second pressure area through a first orifice, the shuttle piston being biased to close the main flow passage and operable under differential pressure across the first and second faces to open the main flow passage;

    a backpressure passage extending between the first opening and the shuttle piston'"'"'s second face; and

    a second valve operable between opening and closing the second orifice wherein when the second orifice is closed, the shuttle piston is operable under differential pressure between the first and second pressure areas, and when the second orifice is open, the shuttle piston is operable under differential pressure between the second pressure area and the backpressure passage.

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