Granted Patent
Utility
US 5,037,547 · App. 07/420,929
Dual stage filter cartridge for a reverse osmosis purification system
Inventor:
Bruce D. Burrows
Patented Case
View Patent ↗
Granted: Aug 6, 1991
Filed: Oct 13, 1989
Inventor
Bruce D. Burrows
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.