Granted Patent
Utility
US 4,660,646 · App. 06/802,656
Failsafe gas closed safety valve
Inventor:
William A. Blizzard, Jr.
Patented Case
View Patent ↗
Granted: Apr 28, 1987
Filed: Nov 27, 1985
Inventor
William A. Blizzard, Jr.
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.