Granted Patent
Utility
US 4,295,487 · App. 06/090,232
Cleanout apparatus for flow control valves
Inventor:
Robert M. Purton
Patented Case
View Patent ↗
Granted: Oct 20, 1981
Filed: Nov 1, 1979
Inventor
Robert M. Purton
Assignee (at issue)
Dresser 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.