Granted Patent
Utility
US 4,625,942 · App. 06/489,252
Valve assembly, seat and seal
Inventor:
Norman A. Nelson
Patented Case
View Patent ↗
Granted: Dec 2, 1986
Filed: Apr 27, 1983
Inventor
Norman A. Nelson
Assignee (at issue)
NL Industries, 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.