Patents Assigned to John H. A. Butler
  • Single use syringe
    Patent number: 4941879
    Abstract: A single use syringe having an interacting piston and cylinder which cooperate to define a variable volume working space, the syringe includes a valve body located in the chamber so as to divide the chamber into a first and second sub-chamber, the valve body has valves which permit a liquid to be initially drawn into the syringe and then injected, but prevent a subsequent liquid being drawn into the syringe.
    Type: Grant
    Filed: July 10, 1989
    Date of Patent: July 17, 1990
    Assignee: John H. A. Butler
    Inventors: John H. A. Butler, Sandy Richardson