| 摘要 |
PROBLEM TO BE SOLVED: To provide a drainage pump device that can suppress reduction in pump efficiency and drainage efficiency under a high flow rate by minimizing a loss of head resulting from a flow bent maximally substantially at 180 deg.. SOLUTION: The drainage pump device inserts a drainage pump 2 in a position offset to one side in a water flow direction x in an open water tank 1 opening upward so that a pump shaft 3 is perpendicular to the water flow direction. In a bottom portion of an inner wall 1A of the open water tank 1 situated in the water flow direction x, the inner wall 1A and a suction bell mouth 4 of the drainage pump 2 form a substantially 180 deg. bent suction passage 7A for bending a substantially vertically downward flow into a substantially vertically upward flow and guiding it to a pump suction opening 5.
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