A well's bottom hole is 20 meters from the ground, we put a diameter of 50mm (mm) water pipe to the bottom, the water surface of the well is 12 meters from the ground, that is, water depth 8 meters, pipe (diameter 50mm) immersed in the well 6 meters, if there are three motor pumps, a pumps of the largest lift is 12 meters, a pumps of the largest lift is 14 meters, and the other a pumps of the largest lift is 16 meters, I should choose which water pump to the most effective pumping to the ground?
The first consideration in this problem is not the pump's head, the head refers to the water pump at the beginning of the level can be elevated to the height, that is, the lift is based on the need to lift the height to determine;
And here is to consider the suction path problem, that is, water pump can absorb much water, take the centrifugal pump as an example, the impeller high-speed rotation to reduce the pressure in the pump, therefore, the external atmospheric pressure will water through the suction pipe "pressure" into the pump, and then sent by the impeller, even if the pump can reduce the pressure of the pump to 0 (internal and external pressure difference of 1 atmospheres), under this condition the pressure of the atmosphere can not be 12 meters high,
So, the three-lift centrifugal pump installed on the ground, it is not possible to extract water from the well, even if the small pipe absorbs water for the flow resistance, unless the pump installation position is lowered to less than 10 m from the water surface, or a pump (such as a submersible pump) that works in other ways can be used to lift water to the ground.
Suction process This calculation, as long as the 1 of atmospheric pressure to the height of the water column can be known in the ideal situation can only reach how high.