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Methods to Improve Pump Cavitation

Apr. 10, 2024

Pumps that have been running for a long time sometimes have cavitation. The impeller will be damaged by cavitation, affecting the continuity of the medium fluid, greatly reducing the power and flow of the pump, causing the pump to have severe noise and vibration, and further it will It corrodes the appearance of the water pump, so it is necessary to improve the anti-cavitation performance of the water pump. Here are some anti-cavitation measures for the pump.


1. Measures to improve the effective cavitation margin of the water pump liquid inlet device

(1) Change the water pump suction device to a reverse irrigation device;

(2) Reduce the installation height of the pump on the water pump suction device;

(3) Increase the pressure of the liquid level in the liquid storage tank in front of the pump to increase the effective cavitation margin of the water pump.

(4) Reduce the flow loss in the pipeline in front of the pump, such as shortening the pipeline as much as possible within the required range, reducing the flow rate in the pipeline, reducing elbows and valves, and increasing the valve opening as much as possible.


2. Measures to improve the anti-cavitation performance of the water pump itself

(1) Improve the structural design from the suction inlet of the pump to the vicinity of the impeller. Increase the flow area, increase the radius of curvature of the impeller cover inlet section, reduce the rapid acceleration and depressurization of the liquid flow, appropriately reduce the thickness of the blade inlet, and round the blade inlet to make it close to a streamline shape, you can also Reduce the acceleration and pressure reduction of the flow around the blade head, improve the surface finish of the impeller and blade inlet to reduce resistance loss, and extend the blade inlet edge to the impeller inlet to allow the liquid flow to receive work in advance and increase the pressure.

(2) Using a double-suction impeller to allow liquid flow to enter the impeller from both sides of the impeller at the same time, the inlet cross-section will be doubled and the inlet flow rate can be doubled.

(3) A front induction impeller is used to make the liquid flow work in advance in the front inducer to increase the liquid flow pressure.

(4) Use anti-cavitation materials. Practice has shown that the higher the strength, hardness and toughness of the material, the better the chemical stability and the stronger the anti-cavitation performance.

(5) The design working conditions adopt a slightly larger positive angle of attack to increase the blade inlet angle, reduce the bending at the blade inlet, and reduce the blade obstruction, so as to increase the inlet area and improve the working conditions under large flow rates to reduce Flow loss, but the positive angle of attack should not be too large, otherwise it will affect efficiency.

3. Reduce the necessary NPSH

Appropriately increasing the diameter of the impeller inlet and increasing the width of the blade inlet can reduce the critical cavitation margin of the water pump, reduce the impeller inlet speed and relative speed, and reduce the generation of bubbles. The method of installing an induction wheel on a multi-stage pump impeller, induction wheel, etc. The pressure wheels are generated to work together after coaxial assembly. In the process, the pressure of the pump impeller is increased to improve the anti-cavitation performance of the pump.

4. Improve the cavitation resistance of overcurrent component data

Choose water pump material components with strong cavitation resistance to effectively reduce damage to water pump flow parts and extend the service life of the water pump. For example, you can choose manganese, bronze, stainless steel and other materials for casting, and the surface is made of polymer coating or laser spraying. Method, the anti-cavitation ability of the water pump will be enhanced.


5. Improve the anti-cavitation ability of imported equipment

The settings of the pump water inlet equipment and pipeline system are closely related to the cavitation margin. In order to meet the requirements of the dynamic pressure drop of the water pump, excellent water inlet equipment must be planned to increase the cavitation margin introduced by the pump manufacturer as much as possible. Secondly, to reasonably determine the water absorption rate of the pump, the various working conditions that the pump manufacturer may encounter during operation should be fully considered. The determined water absorption rate should meet the water absorption rate requirements under any working conditions. In addition, a reasonable air inlet pipe was selected to minimize the length of the horizontal pump water inlet pipe and unnecessary pipe fittings, and appropriately increased the diameter of the water inlet pipe to reduce the hydraulic loss at the water inlet and improve the cavitation margin at the water pump inlet.

It can be seen from this that the three methods to improve the cavitation resistance of the pump are to reduce the necessary cavitation margin, improve the cavitation resistance of the overflow component data, and improve the cavitation resistance of the water inlet equipment. In addition, during the operation of the pump, according to the specific conditions of the pump station, adjustment methods such as variable valves, variable speeds, and variable angles can be selected to prevent the operating conditions of the pump from differing too far from the planned operating conditions.


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