摘要 |
<p>The unit (10) includes a first valve element (24) that is held within a liquid passageway by a first spring mechanism (40). This spring mechanism is designed to yield under pressure to allow the first valve element to move off a valve seat (26) in the opening to allow liquid to pass through. In order to allow air that is trapped on the downstream side of the valve element to escape, air vents (42) are provided in the first valve element. A second valve element (44) is held under compressive force by a second spring (46) over air vents located in the first valve element.</p> |