| 摘要 |
PROBLEM TO BE SOLVED: To provide a self-priming type centrifugal pump having a structure capable of preventing a staying of water in a bag portion chamber at the time of a stopping of pump operation without increasing the number of part items. SOLUTION: In this self-priming type centrifugal pump, a partition wall 14 has an air removal port (fifth communication port) 14e for communicating a discharge chamber 31 with a bag portion chamber 33 at an upper portion. An impeller casing 13 has a first notch 33a for communicating the bag portion chamber 33 with an impeller chamber 20 at a lower portion of an upper partition wall 22a. Water in the discharge chamber 31 is filled in the bag portion chamber 3 through the air removal port 14e at the time of pumping operation. When a pump operation is stopped, since an air is naturally communicated from a discharge coupling 25 with the bag portion chamber 33 through the discharge chamber 31 and the air removal port 14, water staying in the bag portion chamber 3 returns into the impeller chamber 20 through the first notch 33a as a priming. Therefore, a staying of water in the bag portion chamber 33 can be prevented.
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