| 摘要 |
<p>A valve system (200) comprising a valve design in which the valve is normally closed is disclosed. The normally closed valve can comprise a circular valve seal face (215) formed by the underside of a rim of an elastomeric valve boss (210) and a circular valve seat (220), which is formed by the rim of a through hole (225) molded into, for example, a plastic cassette (150), such that the valve seal face, the valve seat, and the through hole are concentric. The valve boss can be a hollow "mushroom" shaped valve boss, or a conical-shaped valve boss. If no force is applied to the inside surface (240) of the valve boss, no fluid can pass through the valve as the valve seal face rests against the valve seat as a result of the steady free state load created by the stretch of the valve boss over the slightly longer through hole. When a force (246) is applied to the inside surface (240) of the valve boss (210), the valve seal face (215) is displaced from the valve seat (220), allowing fluid between the valve seal face and the valve seat and then to pass between the valve boss and the inside surface of the through hole.</p> |
