Granted Patent
Utility
US 5,279,251 · App. 07/991,197
Bidirectional pipeline pig signaling device
Inventor:
Paul E. Bierman
Patented Case
View Patent ↗
Granted: Jan 18, 1994
Filed: Dec 16, 1992
Inventor
Paul E. Bierman
Assignee (at issue)
TDW Delaware, 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.