Granted Patent
Utility
US 4,532,989 · App. 06/353,394
Valved plug for packer
Inventor:
James M. Barker
Patented Case
View Patent ↗
Granted: Aug 6, 1985
Filed: Mar 1, 1982
Inventor
James M. Barker
Assignee (at issue)
Otis Engineering 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.