Granted Patent
Utility
US 4,476,022 · App. 06/474,567
Spirally wrapped reverse osmosis membrane cell
Inventor:
David W. Doll
Patented Case
View Patent ↗
Granted: Oct 9, 1984
Filed: Mar 11, 1983
Inventor
David W. Doll
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.