Four ways to control pump flow: Method one: the outlet valve opening adjustment In this method, the pump and outlet pipe valve in series, its actual effect as a new pump system, the maximum pump The output pressure head has not changed, but the flow curve has attenuated. Method 2: Bypass valve adjustment In this method, the valve and pump are connected in parallel. The actual effect is the same as using a new pump system. The maximum output pressure head of the pump changes. At the same time, the characteristics of the flow curve also change. The flow curve is more linear . Method three: adjust the impeller diameter This method does not use any external components, flow characteristics with the diameter of the curve changes. Method 4: Speed ​​Control The change of impeller speed directly changes the flow curve of the pump. The characteristic of the curve does not change. When the speed decreases, the curve becomes flat and the pressure head and the maximum flow rate decrease. The overall efficiency of the pump system outlet valve regulation and bypass regulation methods have increased the pipeline pressure loss, the pump system efficiency are greatly reduced. Impeller diameter adjustment has little effect on the entire pump system efficiency, speed control method does not affect the system efficiency, as long as the speed is not lower than 50% of normal speed. Energy consumption levels: Assuming that the pump output flow rate is adjusted from 60m3 / h to 50m3 / h and the output power is 60% at 60m3 / h by the above four methods (at this time the head pressure is 70m), then several kinds of control How does the flow rate affect the power consumed by the pump? (1) The opening of the outlet valve is adjusted to have a power consumption of 94% and consumes a large amount of power when the flow rate is low. (2) bypass adjustment, the bypass valve reduces the pump head pressure to 55M, which can only be achieved by increasing the pump flow, resulting in a 10% increase in energy consumption. (3) adjust the impeller diameter, reduce the diameter of the impeller pump output flow and pressure are reduced, reducing energy consumption to 67%. (4) speed control, lower speed, pump flow and head pressure are reduced, energy consumption reduced to 65%.