Granted Patent
Utility
US 4,461,353 · App. 06/401,005
Well safety valve
Inventors:
Michael B. Vinzant, Steven C. Speegle, Michael Wade Meaders, Robert L. Hilts
Patented Case
View Patent ↗
Granted: Jul 24, 1984
Filed: Jul 22, 1982
Inventors
Michael B. Vinzant
Steven C. Speegle
Michael Wade Meaders
Robert L. Hilts
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.