Granted Patent
Utility
US 4,638,972 · App. 06/756,187
Valve apparatus
Inventors:
Marvin R. Jones, Paul E. Helfer
Patented Case
View Patent ↗
Granted: Jan 27, 1987
Filed: Jul 18, 1985
Inventors
Marvin R. Jones
Paul E. Helfer
Assignee (at issue)
Koomey, 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.