The centrifugal pump and the automatic boiler feed pump device null pump

摘要

PROBLEM TO BE SOLVED: To provide a centrifugal pump of a large pumping rate in which a low pressure part is not formed with an extremely slight amount of flow, for reducing operation noises and a running cost, and an automatic water supply pump device using the centrifugal pump. ;SOLUTION: A centrifugal pump has an impeller 7 composed of a front shroud 12, a rear shroud 13, and plural spiral vanes 14 therebetween circumferentially, and plural spiral flow passages 15 formed between the spiral vanes 14. The spiral vanes 20 have projection 20 each, at its front end surface in rotational direction, for throttling a sectional area of each spiral passage 15 over an area where peeling eddy is generated at the time of operation with a little flow. The projection 20 prevents generation of peeling eddy inside the spiral passage 15 is in operation with an extremely slight amount of flow.;COPYRIGHT: (C)1997,JPO