Granted Patent
Utility
US 4,890,643 · App. 07/306,692
Bi-directional sealing valve
Inventor:
John P. Oliver
Patented Case
View Patent ↗
Granted: Jan 2, 1990
Filed: Feb 6, 1989
Inventor
John P. Oliver
Assignee (at issue)
Mogas Industries, Inc.
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.