Granted Patent
Utility
US 4,902,304 · App. 07/147,585
Separate low pressure gas storage system
Inventor:
Walter R. Hallen
Patented Case
View Patent ↗
Granted: Feb 20, 1990
Filed: Jan 21, 1988
Inventor
Walter R. Hallen
Assignee (at issue)
Envirex, 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.