Granted Patent
Utility
US 4,440,164 · App. 06/228,940
Life support system and method of providing fresh air to enclosed areas
Inventor:
Bertil R. L. Werjefelt
Patented Case
View Patent ↗
Granted: Apr 3, 1984
Filed: Jan 27, 1981
Inventor
Bertil R. L. Werjefelt
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.