Granted Patent
Utility
US 5,644,921 · App. 08/651,311
Ultra high purity delivery system for liquefied compressed gases
Inventor:
Naser Mahmud Chowdhury
Patented Case
View Patent ↗
Granted: Jul 8, 1997
Filed: May 22, 1996
Inventor
Naser Mahmud Chowdhury
Assignee (at issue)
Air Products and Chemicals, 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.