Granted Patent
Utility
US 4,941,809 · App. 06/829,398
Valveless positive displacement metering pump
Inventor:
Harry Pinkerton
Patented Case
View Patent ↗
Granted: Jul 17, 1990
Filed: Feb 13, 1986
Inventor
Harry Pinkerton
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.