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Hygrostat and system

  • US 5,794,848 A
  • Filed: 07/16/1996
  • Issued: 08/18/1998
  • Est. Priority Date: 12/30/1994
  • Status: Expired due to Fees
First Claim
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1. A hygrostat adapted for burial in soil, comprising:

  • a frame having a first end portion and a second end portion, and defining substantially unobstructed openings extending between the first and second end portions;

    a water flow-control valve, supported by the second end portion of the frame; and

    a hygroscopic element formed from a coherent synthetic polymer and arranged between the first end portion of the frame and the water flow-control valve,wherein the hygroscopic element expands and contracts upon uptake and release of water, expansion and contraction thereof controlling operation of the device water flow-control valve; and

    wherein the hygroscopic element has two principal opposing surfaces that comprise a majority of the surface area thereof, the principal surfaces being exposed through the frame openings so that both principal surfaces are adapted to directly contact the soil through the frame openings upon the hygrostat being buried in soil.

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