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Well pump

  • US 4,688,999 A
  • Filed: 04/08/1986
  • Issued: 08/25/1987
  • Est. Priority Date: 09/24/1984
  • Status: Expired due to Term
First Claim
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1. A pump comprising a pump cylinder, a piston within said cylinder, an entrance for fluid below said piston, an outlet above said piston, and means for raising and lowering said piston,said piston comprising a cylindrical body or organic polymer having a diameter such as to fit closely in said cylinder, said piston including a first check valve so constructed and arranged as to permit flow of fluid only upwardly through and relative to said body;

  • said body comprising radially flexible flanges extending upwardly and downwardly from its periphery and extending completely about said periphery in close-fitting engagement with said cylinder;

    said first check valve comprising a substantially planar screen having numerous closely spaced small openings on the top of said body and a thin, flexible disc of organic polymeric material fixed on the upper surface of said planar screen and substantially covering the area bounded by said upwardly extending flange;

    said body being provided with a cavity immediately below and covered by said planar screen member and at least one passage extending from said cavity to the bottom of said body.

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