Granted Patent
Utility
US 4,432,870 · App. 06/260,888
Sludge removal apparatus
Inventor:
Frederick E. Russell
Patented Case
View Patent ↗
Granted: Feb 21, 1984
Filed: May 6, 1981
Inventor
Frederick E. Russell
Assignee (at issue)
Protectaire Systems, Co.
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.