Granted Patent
Utility
US 4,288,402 · App. 06/033,240
Acid field test kit for refrigeration oils containing a leak detector
Inventor:
Leonard C. Ellis
Patented Case
View Patent ↗
Granted: Sep 8, 1981
Filed: Apr 25, 1979
Inventor
Leonard C. Ellis
Assignee (at issue)
Virginia Chemicals 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.