Granted Patent
Utility
US 4,945,947 · App. 07/357,121
Ball-type check valve
Inventors:
Lubbert Westra, Brent J. Lirette
Patented Case
View Patent ↗
Granted: Aug 7, 1990
Filed: May 26, 1989
Inventors
Lubbert Westra
Brent J. Lirette
Assignee (at issue)
Chromalloy American Corp.
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.