| 摘要 |
A reverse flow proof control valve having a valve shaft, a valve sleeve and a driving block is intended to effectively prevent dirty water or chemicals produced in a fire fighting process from reversely flowing into a household water system via a shower device dropped in a sink, in a tub or on the ground in a fire accident. The valve sleeve is provided with a number of spaced retaining ribs so as to limit the valve shaft to move in a steady and linear manner in operation. A number of spaced supporting rods, forming a frame-like open structure, extend from the bottom of the valve sleeve and terminate with a hoop member. The valve shaft is provided with an additional flanged portion with a engagement journal defined thereunder and a flat cone-shaped driving block is engaged with the bottom end thereof. The driving block has a flat cone-shaped leakage proof cavity at the bottom side thereof so that the skirt of the driving block can be inwardly or outwardly expanded easily, permitiing the same to stop reverse flow by way of a shower device.
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