| 摘要 |
PURPOSE:To prevent cavitation of a pump, by controlling the air pressure in a surge tank in response to the level of water in a water tank serving as a water supply source, and keeping the gross pump head of the pump at a desired value lager than the minimum pump head. CONSTITUTION:Air in a surge tank 6 is supplied to a water-level detecting pipe 10 via a connecting pipe 11, and the level 10a of water in the water-level detecting pipe 10 is made lower than the level of water in a water reservoir tank 4. The level 10a of water in the pipe 10 is moved upward and downward according to the level 4a of water in the tank 4, and the air pressure in the surge tank 6 is also changed with the level of water in the tank 4, so that drop in the gross head of a pump 5 is prevented. Therefore, it is enabled to prevent occurrence of cavitation in the pump. |
