To provide a method for operating a vertical shaft pump preventing the suction of air from a suction port and the generation of an air sucking swirl and capable of lowering a pumping shut-off water level as compared with a conventional method.
When the water level is lower then an air water change-over valve close water level La, an air water change-over valve 22 is opened in a state that an impeller 11 is rotated, and preceding stand-by operation sucking air in a suction passage 14 from an intake passage 21 and shutting off pumping is performed. When the water level rises and reaches the air water change over water level La, the air water change over valve 22 is closed and the suction of air into the suction passage 14 from the intake passage 21 is stopped. When the water level rises further and reaches a pumping start water level Lb, pumping is started. When the water level is lowered by pumping and reaches a control water level Ld, a delivery water quantity delivered from a delivery part 16 is made smaller than at the time of rated operation in a zone B from the control water level Ld to the pumping shut-off water level Lc. When the water level drops to the pumping shut-off water level Lc, the air water change over valve 22 is opened and pumping is shut off.
| JPH04103896A | 1992-04-06 | |||
| JPH0599187A | 1993-04-20 |
Yoshihiro Morimoto
Toshiji Sasahara
Yohei Harada