Granted Patent
Utility
US 5,855,224 · App. 08/680,216
Flapper check valve
Inventors:
Ping-Ting Lin, Rand H. Ackroyd
Patented Case
View Patent ↗
Granted: Jan 5, 1999
Filed: Jul 11, 1996
Inventors
Ping-Ting Lin
Rand H. Ackroyd
Assignee (at issue)
Watts Investment Company
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.