Patents by Inventor Marvin L. Ledtje

Marvin L. Ledtje has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Check valve
    Patent number: 5002662
    Abstract: An improved liquid flow check valve using a ball and seat wherein the seat is made of sintered ceramic. The improved valve will operate in an environment of acetonitrile and water without sticking shut, thereby providing more stable liquid flow rates in liquid chromatography systems.
    Type: Grant
    Filed: March 3, 1989
    Date of Patent: March 26, 1991
    Assignee: Spectra-Physics, Inc.
    Inventors: Marvin L. Ledtje, Aubrey D. Long, Jr.
  • Check valve
    Patent number: 4862907
    Abstract: An improved liquid flow check valve using a ball and seat wherein the seat is made of sintered ceramic. The improved valve will operate in an environment of acetonitrile and water without sticking shut, thereby providing more stable liquid flow rates in liquid chromatography systems.
    Type: Grant
    Filed: September 7, 1988
    Date of Patent: September 5, 1989
    Assignee: Spectra-Physics, Inc.
    Inventors: Marvin L. Ledtje, Aubrey D. Long, Jr.