| 摘要 |
<p>A non-return valve ( 10 ), typically of commonly called duckbill valve shape, comprising a valve body ( 12 ) and a valve membrane ( 14 ). The valve body ( 12 ) is generally tubular and includes an elongate passageway ( 16 ) with inlet ( 18 ) and outlet ( 20 ) at opposing ends. The valve membrane ( 14 ) is of a generally conical-shaped diaphragm formed integrally with the valve body ( 12 ). The diaphragm ( 14 ) has a collapsible opening or aperture ( 22 ) located at or adjacent the cones apex. The conical diaphragm ( 14 ) is oriented with its apex pointing downstream. The resiliently flexible material from which the diaphragm ( 14 ) is constructed, ensures that the diaphragm ( 14 ) in a collapsed condition obstructs or closes the aperture ( 22 ) to prevent fluid flowing in a reverse direction, i.e. backflow towards the inlet. Pressurisation of fluid within the passageway ( 16 ) on the inlet ( 18 ) side of the diaphragm ( 14 ), deflects the diaphragm to open the aperture ( 22 ) so that fluid can flow through the passageway from the inlet ( 18 ) to the outlet ( 20 ) only. A membrane permeable in one direction only can also be made from a panel or sheeting incorporating many such collapsible non-return duckbill valves on the surface of the panel or sheet.</p> |
