| 摘要 |
PROBLEM TO BE SOLVED: To provide a column type submersible pump which can be operated without sucking air through a suction port even if the minimum water level is reduced to a level lower than the conventional level so as to reduce a residual water quantity in a suction sump to increase the proportion of water retentivity in comparison with the residual water quantity. SOLUTION: A suction bellmouth 16 of a vertical shaft mixed flow pump P is opened to the inside of a suction casing 21 having a closed structure. The height H6 of the ceiling 21a in the casing is set at a position sufficiently higher than the height H7 of a suction port 21d opened to a suction sump 19. An air discharge means 22 equipped with an exhaust pipe 22a, an exhaust valve 22b, an exhaust pump 22c or the like is connected to an air discharge port 21e provided in the ceiling 21a in the suction casing 21. By so doing, the pump P can be operated without sucking air even if the lowest water level of the suction sump 19 is reduced to LWL2 corresponding to 0.5D which is about a height H7 of a suction port 21d. COPYRIGHT: (C)2006,JPO&NCIPI
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