Suction is too large :
Some of the water is deep, some of the surrounding terrain is relatively flat, while ignoring the pump allows suction process, resulting in less water absorption or not the result of water suction. To know that the vacuum degree of the pump suction mouth is limited, the absolute vacuum suction process is about 10 meters high water column, while the pump can not establish an absolute vacuum. And a large vacuum, easy to make the pump water vapor, the pump work. Therefore, the centrifugal pump has its maximum allowable suction process, generally between 8.5 - 3 meters. The installation of the pump can not only facilitate simple drawings.
The resistance loss of water flow in the inlet and outlet pipe is too large:
Some users have been measured, although the water tank or water tower to the vertical distance the water is slightly less than the pump head, but a little water or no water. The reason is that the pipe is too long, the water pipe bends more, the water flow in the pipeline resistance loss is too large. The reason is that the pipe is too long, the water pipe bends more, the water flow in the pipeline resistance loss is too large. Under normal circumstances 90 degree elbow than 120 degree elbow resistance, each 90 degrees bend head loss of about 0.5-1 meters, meters per 20 meters of resistance can make the head loss of about 1 meter. In addition, some users are free to pump inlet, outlet pipe diameter, which has a certain impact on the head
