Granted Patent
Utility
US 4,330,031 · App. 06/074,899
Ceramic tube recuperator
Inventor:
Paul K. Shefsiek
Patented Case
View Patent ↗
Granted: May 18, 1982
Filed: Sep 12, 1979
Inventor
Paul K. Shefsiek
Assignee (at issue)
Holcroft 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.