Granted Patent
Utility
US 4,289,165 · App. 06/039,836
Equalizing ball valve member
Inventor:
John V. Fredd
Patented Case
View Patent ↗
Granted: Sep 15, 1981
Filed: May 17, 1979
Inventor
John V. Fredd
Assignee (at issue)
Otis Engineering Corporation
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.