Granted Patent
Utility
US 4,834,621 · App. 07/124,503
Air throttling valve for submerged pump system
Inventors:
Keith Hall, Robert L. Esvang, Jr., Ralph N. DiLorenzo
Patented Case
View Patent ↗
Granted: May 30, 1989
Filed: Nov 24, 1987
Inventors
Keith Hall
Robert L. Esvang, Jr.
Ralph N. DiLorenzo
Assignee (at issue)
APCO Valve and Primer 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.