Granted Patent
Utility
US 5,639,384 · App. 08/596,548
Apparatus and method for improving gas backwash in lateral underdrains
Inventors:
Marvin A. Brown, Eugen O. Bergmann, Richard Hsieh
Patented Case
View Patent ↗
Granted: Jun 17, 1997
Filed: Feb 5, 1996
Inventors
Marvin A. Brown
Eugen O. Bergmann
Richard Hsieh
Assignee (at issue)
THE F.B. LEOPOLD COMPANY 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.