| 摘要 |
<p>A valve device for use with a drain provided with a pipe having an entrance for collecting liquid leading to a P-trap beneath the entrance. The device comprising an open vessel, in use positioned at the entrance of the pipe, having walls and a floor defining an internal chamber, the floor having an opening for permitting liquid collected in the chamber to pass into the pipe. The device is provided with a valve arranged to seat in the opening from below and is movable between a closed position sealing the opening against gas and liquid flow from the pipe to the chamber and an open position spaced from the opening beneath the floor. A float is positioned in the internal chamber and a linkage transfers buoyancy force exerted on the float by liquid collected in the chamber to the valve to cause the valve to move from the closed position to the open position when the liquid exceeds a certain depth in the chamber. The device provides an effective way of preventing backflow of gases and liquids from the drain, but overcomes problems caused by gas pressure build-up between the P-trap and the valve that would otherwise prevent the valve from opening properly.</p> |
