Granted Patent
Utility
US 4,357,021 · App. 06/208,287
Ferrofluid rotary-shaft seal apparatus and method
Inventors:
Kuldip Raj, Alan Schwartzman
Patented Case
View Patent ↗
Granted: Nov 2, 1982
Filed: Nov 19, 1980
Inventors
Kuldip Raj
Alan Schwartzman
Assignee (at issue)
Ferrofluidics Corporation
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.