The principle of setting the outlet and inlet diameter of the centrifugal pump: Generally, the outlet diameter is selected according to the economic flow rate, and the outlet diameter is determined based on the flow. Technically, the maximum speed of the water flow should not exceed 2.5 ～ 3.0m / s, and the minimum speed should not be less than 0.6m / s (to prevent sedimentation).
Low inlet flow rate, advantages
1. It is beneficial to increase the NPSHA of the device, and the pump is not easy to cavitation;
2. Small scour on pipelines, especially media containing particles;
3. Not easy to generate static electricity;
4. Low-pressure drop at the inlet filter;
5. Within the same section, the medium flows evenly and the hydraulic loss is small.
Low inlet flow rate, disadvantages
1. At the same flow, large pipe diameter is required, and the pipeline cost is high;
2. For some easy-to-precipitate media, the flow rate is too small, which is likely to cause deposition blockage;
3. Large impeller inlet, large ring diameter and large leakage.
The water inlet of the pump is generally larger than the outlet diameter. Someone asked whether the diameter of the inlet and outlet pipes of the centrifugal pump must be larger than the diameter of the inlet and outlet of the pump itself. This problem requires specific analysis.
For most pumps, the purpose of increasing the diameter of the inlet and outlet pipes is to reduce the flow velocity of the fluid in the pipe to reduce the resistance drop of the pipe and ultimately reduce the power consumption of the pump. However, increasing the pipe diameter is to increase the investment cost of the pipe At the cost, this way, for pipelines with a long distance from the pump outlet, you can consider appropriately increasing the diameter of the pipe to reduce the resistance drop, and for short distances, you do not need to consider; and for the material delivered by the pump inlet is a liquefied gas, the temperature is close Materials that are likely to be cavitation such as boiling point and low suction position should be considered to increase the diameter of the pump inlet pipe to reduce the resistance drop and avoid pump cavitation.
