First, the pipeline characteristic curve When the centrifugal pump is installed in a particular pipeline system, the pump should provide the flow and pressure head according to the requirements of the pipeline. The relationship between the required pressure head and the flow curve of the pipeline called the pipeline characteristic curve, the equation is expressed by the following equation He = A + BQe2 Second, the centrifugal pump operating point When the pump installed in a certain pipeline system, the pump characteristics The intersection of the curve and the pipeline and the curve is the working point of the pump. The flow and indenter shown at the working point are both the flow and indenter provided by the pump and the flow and indenter required for the line. Centrifugal pump only work at the work point, the flow in the tube can be stable. Pump operating point to pump the most efficient area is appropriate. Third, the centrifugal pump flow regulation For a pump, the characteristic curve will not change, while the pipeline characteristic curve variable. When the pump operating point provides the flow can not meet the new conditions required flow, it should seek to change the location of the pump operating point, the need for flow control. Flow adjustment methods are: (1) in the centrifugal pump outlet pipe installed a control valve to change the valve opening, that is to change the pipeline characteristic curve He = A + BQe2 B value, the valve open large, the working point away from the vertical axis The valve is closed and the operating point is close to the vertical axis. The advantage of this method of adjustment is that it is easy and flexible to operate. The disadvantage is that the valve is closed hours, the pipeline resistance increases, the energy loss increases, so that the pump can not work in the most efficient area is not economical. With the method of changing the valve opening to adjust the flow and more used in the flow rate adjustment is not, and often need to adjust the occasion. (2) change the pump speed, that is, change the pump characteristic curve. (3) turning impeller diameter also change the pump characteristic curve. Using the above two methods can change my curve of the pump. With these methods to regulate the flow rate within a certain range to ensure that the pump work in the high efficiency area, more economical use of energy, but not convenient, the flow adjustment range is not large, it is not widely used.