| abstract |
In accordance with different embodiments of the present invention, duckbill check valve 10 , having an orifice 11 , and conical check valve 12 , having an orifice 13 , are responsive to the differential pressure of fluid F as it flows between inlet 14 and outlet 16 . In an innovative aspect of the invention, orifice 11 and orifice 13 each have a variable effective diameter. In one embodiment, the duckbill check valve 10 and conical check valve 12 have a conical end that is aligned with the direction of fluid flow. In another embodiment, the duckbill check valve 10 can have a conical end that faces the direction of fluid flow. A pin may traverse orifice 11 or 13. |