Granted Patent
Utility
US 4,749,003 · App. 07/006,021
Center flow check valve
Inventor:
Hayden Leason
Patented Case
View Patent ↗
Granted: Jun 7, 1988
Filed: Jan 22, 1987
Inventor
Hayden Leason
Assignee (at issue)
Filtertek 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.