High vibration in multi-stage centrifugal pump water pumps? ?
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Hello, our facility has a multi-stage centrifugal pump manufactured by Zhejiang Pump Factory, model D125-25*8. Due to high vibration levels of 8.0 mm/s as measured on site, the bearings and mechanical seals were replaced; however, after restarting the pump, the vertical vibration of the front bearing increased to 18 mm/s. The pump was taken apart for maintenance; the impeller and shaft were replaced. After restarting the pump, the vertical vibration levels on both the front and rear sides rose to around 15.5 mm/s. Now it can only be used as an emergency backup unit. What solutions are available? ? ?
Pumps are supposed to be inspected before leaving the factory; high vibration at the installation site may be related to the installation or the pipelines. As for the situation after the maintenance, it was caused by poor assembly.
This post was last edited by Worker @ on 2015-10-19 21:20. Excessive vertical vibration is caused by issues such as loose footings and loose bearing covers.
Every time a maintenance task is carried out, it’s essential to determine the cause; simply replacing parts isn’t very useful in itself
Check the impeller clearance at the balance disc on the pump shaft.
Send a spectrum for analysis.
Yes, everything is carried out in strict accordance with the maintenance plan; such high levels of vibration should not occur. Check for any play in the shaft and rotor rings, measure the fit dimensions of all relevant parts, perform dynamic balancing, examine whether the rotor is bent by checking the tightness of the impeller cover, check the clearance of the thrust disc, verify the alignment data, and monitor the current level……
There are many reasons for excessive vibration, and to determine the cause it is necessary to consult a fitter to find out what abnormalities exist in the various components during disassembly.
Generally speaking, there are many reasons for vibration: misalignment, imbalance, soft feet, imbalance in couplings, scraping, oil film oscillations, and so on – all of these can lead to excessive vibration. Generally speaking as well, the following suggestions are given: 1. Check the alignment, as this is the most common cause of excessive vibration at the site. To check alignment, it is necessary to examine the alignment of the inlet and outlet flanges, as well as something that is rarely paid attention to: the parallelism of the end faces of the coupling itself ； 2. Check the connection of the foot bolts, including those of the motor, to ensure there are no loose bolts... To determine the exact cause, it is advisable to measure the spectrum, as this can help narrow down the scope of troubleshooting~~~
There are many reasons for pump vibration; sometimes it is due to the quality of assembly or the quality of the components used. Even after replacing the impeller and balance disk, the pump may continue to vibrate more. If your pump is relatively large, it is recommended to purchase a new one, as this will provide greater stability compared to trying to fix it by replacing parts.
What was the condition before repair? What’s the frequency situation? Is the entrance unobstructed? Is the inlet vaporizing? Bearings or bushings? Wait, you need to make things clear first before you can analyze them! ! !