Granted Patent
Utility
US 4,765,893 · App. 06/886,102
Coiled membrane filter cartridge
Inventor:
Robert Kohlheb
Patented Case
View Patent ↗
Granted: Aug 23, 1988
Filed: Jul 16, 1986
Inventor
Robert Kohlheb
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.