Granted Patent
Utility
US 4,887,942 · App. 07/246,658
Pressure exchanger for liquids
Inventor:
Leif J. Hauge
Patented Case
View Patent ↗
Granted: Dec 19, 1989
Filed: Sep 2, 1988
Inventor
Leif J. Hauge
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.