Granted Patent
Utility
US 4,521,213 · App. 06/465,375
Liquid drainage system with hinged cup-shaped valve
Inventor:
Carl J. Steigerwald
Patented Case
View Patent ↗
Granted: Jun 4, 1985
Filed: Feb 10, 1983
Inventor
Carl J. Steigerwald
Assignee (at issue)
The Kendall Company LP
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.