The pump impeller has a hole in it – how to fix it?
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Dear experts, there are three circulating water pumps on site. According to the design specifications provided by the design institute, the pumps should operate under positive pressure. However, after being in use for some time, holes appeared in the low-pressure areas of the impellers (see the pictures; these pictures show cast steel impellers that have been in use for about 40 days), and in severe cases, the blades even became perforated! Have you ever encountered this situation? How to solve it?
I’m attaching another photo showing a perforation in the cast-iron impeller after 6 months of operation; please help take a look!
It is possible to take a look at the other side of the blade, that is, the working surface of the blade; a small mirror can be used to examine the area between the two blades. If there are many holes or honeycomb-like depressions, this is caused by cavitation, and the problem can be resolved by increasing the pressure at the pump inlet or reducing the temperature of the medium. If none of these conditions can be met, then it is necessary to choose a pump with better cavitation resistance.
1. Upgrade the impeller material to 316 austenitic stainless steel. 2. Improve the manufacturing process to increase the pump inlet pressure and reduce cavitation
It’s better to use stainless steel; there are many impurities in your water, so electrochemical corrosion is quite severe
This post was last edited by wanyiwan on 2018-2-14 09:07. It’s caused by cavitation! Suggestion: Increase the pump inlet pressure!
Replace it with a 304 stainless steel impeller, while increasing the inlet pressure or liquid level.
It seems to be caused by cavitation; it is recommended that the poster upgrade the material of the impeller, and also find ways within the processing process to increase the pressure at the pump inlet as well as optimize the heat exchange process. If nothing else works, remove the insulation from the pump inlet pipes to lower the temperature of the fluid – the main goal being to prevent cavitation.
Cavitation may be the cause in the pump; as the pump rotates, water continuously strikes the impeller (water hammer). There are also manufacturing defects in the impeller itself, and under these effects, honeycomb-like holes form in the impeller.