Granted Patent
Utility
US 5,765,815 · App. 08/802,522
Rotary valve with pressurized energized seal
Inventor:
Douglas G. Calvin
Patented Case
View Patent ↗
Granted: Jun 16, 1998
Filed: Feb 20, 1997
Inventor
Douglas G. Calvin
Assignee (at issue)
Keystone International
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.