Granted Patent
Utility
US 5,186,201 · App. 07/678,987
Check valves
Inventor:
William E. Warren
Patented Case
View Patent ↗
Granted: Feb 16, 1993
Filed: Apr 30, 1991
Inventor
William E. Warren
Assignee (at issue)
British Technology Group Limited
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.