Granted Patent
Utility
US 4,699,357 · App. 06/885,171
Reinforced industrial butterfly valve
Inventor:
David E. Sisk
Patented Case
View Patent ↗
Granted: Oct 13, 1987
Filed: Jul 14, 1986
Inventor
David E. Sisk
Assignee (at issue)
ULTRAFLO 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.