What are the conditions for cavitation to occur in a centrifugal pump?

The main issue is that the pressure at the pump inlet is lower than the saturated vapor pressure of the material under those inlet conditions, which leads to vaporization of the material; this usually occurs due to excessively high temperatures of the material at the pump inlet or excessive resistance at the pump inlet.

Prevention methods include increasing the backflow height, lowering the pump’s installation height, reducing the resistance in the inlet pipeline, and decreasing the required net positive suction head of the pump. Methods to reduce inlet pipeline resistance include: enlarging the diameter of the inlet pipeline, reducing the number of bends, shortening the length of the pipeline, opening the inlet valve to its maximum extent, and avoiding the use of \"N\"-shaped pipeline designs, among others

Methods to prevent cavitation: 1. Reduce the pump’s installation height; use reverse flow if necessary. 2. Reduce the resistance in the suction pipeline, such as by increasing the pipe diameter and reducing the number of pipeline accessories, foot valves, elbows, gate valves, etc. 3. Add another booster pump. 4. Lower the temperature of the pumped liquid to reduce the vaporization pressure. 5. Avoid using valves for throttling in the inlet piping. 6. Under the same conditions of flow rate and head, a double-suction pump results in a lower NPSHr value. 7. Improve the surface finish by pumping fluid, and grind and clean the flow channels. 8. Increase the diameter at the inlet of the pump impeller to reduce the inlet flow velocity. 9. Reduce the pump speed. 10. Add an inducer wheel at the pump inlet. 11. The components exposed to excessive current are made of materials resistant to cavitation, such as cemented carbide, phosphor bronze, 18-8 steel, Cr-Ni steel, etc. 12. For mixed-flow pumps and axial-flow pumps with adjustable blades, the method of adjusting the installation angle of the blades can be employed.