Granted Patent
Utility
US 4,398,557 · App. 06/196,813
Combination vacuum relief valve and pressure relief valve
Inventor:
Richard H. Dugge
Patented Case
View Patent ↗
Granted: Aug 16, 1983
Filed: Oct 14, 1980
Inventor
Richard H. Dugge
Assignee (at issue)
ACF Industries Incorporated
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.