Granted Patent
Utility
US 4,869,821 · App. 07/187,627
Drainage disc for membrane assembly
Inventor:
Amos Korin
Patented Case
View Patent ↗
Granted: Sep 26, 1989
Filed: Apr 28, 1988
Inventor
Amos Korin
Assignee (at issue)
W.R. Grace & Co. Conn.
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.