Granted Patent
Utility
US 5,372,158 · App. 08/130,016
Valve with backflow preventer
Inventor:
Robert C. Berfield
Patented Case
View Patent ↗
Granted: Dec 13, 1994
Filed: Sep 30, 1993
Inventor
Robert C. Berfield
Assignee (at issue)
SHOP VAC 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.