Regarding the issue of impeller wear

As can be seen in the third image, the outer ring of the impeller front cover is worn.

I can see that the widths of the flow channel outlets are different; as a result, the flow rate becomes unstable. When the flow rate changes, that is, when the pump operates at high or low flow rates, the coordination between the impeller and the volute is disrupted. The fluid flow velocity and pressure distribution around the impeller become uneven, resulting in radial forces acting on the impeller. Could this be the reason for uneven wear of the impeller? Looking forward to other answers

The thickness of this cover plate is uneven, which is due to poor casting of the impeller. I took a look at your impeller; the blades inside it are quite large. Could you provide the flow rate, head, the model of the pump in use, and the diameter of the impeller?

“This caused damage to the silicon carbide bearings (fracturing), the shaft sleeves (wear), and the impeller (wear); after repairs and reinstallation, the pump was tested and passed the acceptance checks. However, when the pump was started again today, it failed to operate properly (with low pressure). Based on the phenomena you described, the problems can be divided into two parts: namely, “the silicon carbide bearings cracked, the shaft sleeves wore out, and the impeller was damaged; after repairs these issues were resolved, the pump was tested and passed the acceptance checks,” and “however, when the pump was started again today, it failed to operate properly (with low pressure).” First is the analysis of the first part: \"It caused damage to the silicon carbide bearings (cracking), wear to the shaft sleeves, and wear to the impeller; after maintenance, everything was restored to normal, and the pump was tested and found to meet the requirements.\" How can a pump like this even pass the acceptance tests? Analysis in Part Two: “But when the pump was restarted today, it was found to not be operating properly (low pressure).” Is this phenomenon related to the material of your substance? For example, do the impurities in the material not meet the requirements for using the pump? Also, is this polished area a trace left by dynamic balancing using the deburring method before leaving the factory? It is recommended to reorganize the questions; for example, was the worn area caused by use or was it present from the start ； Whether the material medium and the operating conditions of the pump are suitable. For reference. It’s amazing that stainless steel parts can be processed in this way; it seems that the company that manufactured this equipment is quite unprofessional.

Quality issue on the part manufactured by the factory; there are two problems: 1. The wall thickness of the front cover plate of the impeller is uneven, which is most likely due to processing errors. It’s impossible for a cast part to have such high levels of unevenness in its wall thickness; the part wasn’t aligned properly during processing, hence this quality issue； 2. Uneven wear of the impeller and the mouth ring, among other issues, can cause the balancing system to fail. There are two consequences: either excessive pressure release with insufficient pressure at the outlet, or an imbalance in axial forces that leads to bearing damage

The impeller thickness should be due to wear; it’s unlikely to be in this condition from the factory. There is uneven wear on both the impeller and the mouth ring; what about the impeller? Can’t see any of it? Wear of the mouth ring can lead to a decrease in flow rate. The impeller is in good dynamic balance; it is said that this does not affect pressure, but it does affect the lifespan of the bearings.

Thank you. What I’m worried about is that bearing damage might result from wear of the impeller; it seems that there is a variation in the internal thickness of the impeller when viewed visually.

Thank you for your advice; your judgment matches my own :)

I’ll answer your first question first: during the reset process, I and the technicians in the workshop insisted on replacing the impeller with a new one. Unfortunately, the spare parts hadn’t arrived yet, and there was no backup pump available on site, so we had to proceed with the reset first. After the reset, the technicians tested the pump on site, and nothing abnormal was detected. Part 2: The material is a liquid refrigerant that vaporizes easily. Based on the phenomena observed when starting the pump today, I initially determined that it was cavitation; despite attempting to release air from the system, the pump still wouldn’t start. That’s why I posted a request for help from everyone. The impeller thickness varies; my guess is that it has been this way since it left the factory. (Unfortunately, I wasn’t present during the last inspection of this equipment, and no one paid attention to whether there was such a problem.)

Thank you for your concern. It’s not possible to provide the pump model as it relates to the supplier, but I appreciate it anyway. I’m friends with Wang Qiang from your company :)