| 摘要 |
PURPOSE:To cut cost by adopting a vertical shaft pump equipped with a vacuum breakage device which has a vane wheel arranged at the position higher than the min. water level which is characteristic for the pump, as a part of a plurality of vertical shaft pumps. CONSTITUTION:In the ordinary vertical shaft pumps 201 and 301, each position of the suction bell-mouths 214 and 314 is set higher than the min. lowest water level LWL1 of an air suction type vertical shaft pump 101. In the vertical shaft pump 101, a vane wheel 111 is installed at the position higher than the lowest water level LWL1. When the water level lowers below the min. water level LWL1, the vertical shaft pumps 201 and 301 are air-operated by pumping up water by the vertical pump 101. Therefore, the need of adopting a vertical shaft pump equipped with a vacuum breakage device for all the vertical shaft pumps is avoided, and cost cut can be realized.
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