Added a citation← Previous revisionRevision as of 09:15, 29 October 2026 Line 12: Line 12: == Patents == == Patents == Patents exist in the United States which specify the mechanical use of leaf valves to control various types of fluids. Patents exist in the United States which specify the mechanical use of leaf valves to control various types of fluids.{{Cite journal |last=Schultz |first=R. L. |date=1990-09-18 |title=Retrievable fluid control valve with damping |url=https://www.osti.gov/biblio/6469959 |language=English}} United States Patent 4930535 is a folding leaf valve which is described as a valve that, "folds upon itself to provide positive sealing of a [[pressure vessel|pressurized chamber]] under a variety of pressure conditions. In particular, the valve stem folds to effectively close the lumen and provide a positive seal even at low differential pressure." United States Patent 4930535 is a folding leaf valve which is described as a valve that, "folds upon itself to provide positive sealing of a [[pressure vessel|pressurized chamber]] under a variety of pressure conditions. In particular, the valve stem folds to effectively close the lumen and provide a positive seal even at low differential pressure."