Granted Patent
Utility
US 4,856,580 · App. 07/114,837
Heat exchanger
Inventor:
Richard A. Ley
Patented Case
View Patent ↗
Granted: Aug 15, 1989
Filed: Oct 30, 1987
Inventor
Richard A. Ley
Assignee (at issue)
Berwind Corporation
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.