| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem, in a centrifugal pump, in which the water at a conduit portion between an impeller and a diaphragm and at a conduit portion between a shroud and a casing influences on the impeller as a friction resistance to disturb the rotations of the impeller because the impeller rotates in high speed, although the water has no relation with the pumping operation fundamentally. SOLUTION: Very little triangular grooves 14 are formed on a surface on a side of a conduit C between an impeller 7 and a diaphragm of a centrifugal pump, and are formed on a surface on a side of a conduit D between a front shroud 6 and a casing 8. Swirls are generated in the triangular grooves 14 and prevents disturbance of the water flow to reduce the friction resistance, so that the number of rotations of the impeller is increased to improve pumping efficiency and impurities in the water are reduced to prevent the lowering in flow rate.
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