Granted Patent
Utility
US 6,648,021 · App. 10/137,078
Gas control device and method of supplying gas
Inventors:
Dao-Hong Zheng, John Irven, Mark George
Patented Case
View Patent ↗
Granted: Nov 18, 2003
Filed: May 2, 2002
Inventors
Dao-Hong Zheng
John Irven
Mark George
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.