| 摘要 |
PURPOSE:To complete residual water disposal by separating the peripheral bottom edge of a cup-shaped resilient membrane from a bottom plate and holding a gap between the upper peripheral edge of the membrane and a suction cover thereby opening a passage when a swing valve is operated to be turned up, and closing the passage when the swing valve is operated to be turned down. CONSTITUTION:Since a negative pressure is generated under the impeller of a submersible pump when the pump is started at a water level l1, a swing valve 7 is operated to be turned up, the lower peripheral bottom edge 13 of a cup-shaped resilient membrane is separated from a bottom plate 4, and a given gap (g) is held between the upper peripheral edge 15 and a suction cover 2. In result, a passage 17 from the bottom edge, of an annular seat portion 11 to the suction opening 3 of the pump is opened and the water sucked from narrow gaplike passages 12...12 provided in extremely low positions is discharged from a discharge opening (not shown) via the passage 17 and the inside of a pump casing 1. And, when the submersible pump is stopped at a water level l2 whereat drainage is completed, the swing valve 7 is operated to be turned down by the pressure of return water in the pump casing 1 and a piping for the drainage, the peripheral bottom edge 13 of the valve 7 is brought into close contact with the upper surface of the bottom plate, thus enabling the water to be prevented from making backflow.
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