Granted Patent
Utility
US 5,193,611 · App. 07/773,932
Heat exchangers
Inventor:
John E. Hesselgreaves
Patented Case
View Patent ↗
Granted: Mar 16, 1993
Filed: Nov 5, 1991
Inventor
John E. Hesselgreaves
Assignee (at issue)
The Secretary of State for Trade and Industry in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
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.