| 摘要 |
<p>A backflow valve (10) has a closure gate (28) that is pivotally mounted for movement between an open position in which the closure gate is positioned on a plane substantially parallel to a longitudinal axis (21) of a flow passage and a closed position in which the closure gate is positioned transverse to the longitudinal axis. The closure gate has a midsection positioned pivot axis (34) and is unbalanced with greater weight being toward the first end (30). A rotational stop (36) limits pivotal movement when the closure gate is in the open position. A float (38) is secured to the first end of the closure gate. The greater weight at the first end biases the closure gate by force of gravity against the rotational stop and into the open position. The float causes the closure gate to pivotally move to the closed position in response to liquid (40) rising in the flow passage.</p> |
