Granted Patent
Utility
US 5,236,009 · App. 07/821,623
Double check backflow preventer with improved toggle linkage check valve
Inventor:
Rand H. Ackroyd
Patented Case
View Patent ↗
Granted: Aug 17, 1993
Filed: Jan 16, 1992
Inventor
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.