Before the centrifugal pump starts working, the pump is first filled with liquid, and then the centrifugal pump is started. The impeller rotates rapidly, and the blades of the impeller drive the liquid to rotate. When the liquid rotates, it flows towards the outer edge of the impeller by inertia. At the same time, the impeller sucks in the liquid from the suction chamber. In this process, the liquid in the impeller flows around the blades, and the liquid acts on the blades with a lift force equal in magnitude and opposite in direction. This force does work on the liquid, causing it to gain energy and flow out of the impeller. At this time, the kinetic energy and pressure energy of the liquid increase.
The hazards of cavitation in centrifugal pumps:
The shock wave transmitted to the impeller and pump casing during cavitation, combined with the chemical corrosion of metals by trace amounts of dissolved oxygen in the liquid, can cause surface marks and cracks to appear after a certain period of time, and even gradually detach in a sea like manner; When cavitation occurs, it can also produce noise, which can cause the pump body to vibrate and potentially lead to a decrease in pump performance; At the same time, due to the generation of steam, the apparent density of the liquid decreases, resulting in a decrease in the actual flow rate, outlet pressure, and efficiency of the liquid. In severe cases, it can lead to the complete inability to output the liquid.
The main causes of cavitation are:
1. Excessive resistance or thin pipeline in the imported pipeline;
2. The temperature of the conveying medium is too high;
3. Excessive flow, which means the outlet valve is opened too wide;
4. The installation height is too high, which affects the suction capacity of the pump;
5. Selection issues, including pump selection, pump material selection, etc.
Solution to cavitation:
1. Clean up foreign objects in the inlet pipeline to ensure smooth flow, or increase the diameter of the pipe;
2. Reduce the temperature of the conveying medium;
3. Reduce installation height;
4. Re select the pump or improve certain components of the pump, such as using anti cavitation materials, etc.
