Granted Patent
Utility
US 4,688,593 · App. 06/809,645
Well reverse flow check valve
Inventors:
Ronald E. Pringle, Arthur J. Morris
Patented Case
View Patent ↗
Granted: Aug 25, 1987
Filed: Dec 16, 1985
Inventors
Ronald E. Pringle
Arthur J. Morris
Assignee (at issue)
Camco 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.