Please help analyze the reasons for the vibration of the centrifugal pump

Is there a problem with the installation? Is cavitation occurring? This post was last edited by david-2 on 2009-3-25 20:41]

Is it axial vibration or vertical vibration? 1. Confirm whether the medium has been vaporized. 2. Verify that your assembly clearance is set as required. 3. Check whether there is a problem with your vibration meter. And what is the unit you used for measurement? 6.7 mm/s?

Start looking from the most basic: 1. Are the foundation bolts loose? Are the connectors loose? Is the connecting pipeline vibrating? 2. Is the impeller back cap loose? 3. Whether the dynamic balance is out of spec. 4. Whether the shaft is bent. 5. Check whether the clearances are appropriate and whether the rotating parts are subject to uneven wear. Such as whether the shaft sleeve clearance, the clearance between the impeller and the shaft, and the clearance between the coupling gears are too large. 6. Is there a problem with the bearings, and is the motor properly aligned? Whether the distance between the half-couplings is too large or too small, whether there are any issues with the couplings, and whether they are too tight or too loose. 7. Is there a problem with the process? Please take some time to check. This post was last edited by Young Builder on 2009-3-25 20:41]

Agree with the person above. Check again whether parameters such as flow rate, pressure, and current have changed, and whether cavitation might occur.

What the poster is measuring is probably the vibration velocity V (mm/s). If the issues with pipes or cavitation can be ruled out, I think we could consider testing just the motor. Our factory has encountered similar situations as well. At first, we suspected a problem with alignment, but after several attempts to repair it and start the pump, the vibration level remained high. Later, when we inspected the motor, we found that it needed major repairs.

What the poster is measuring is probably the vibration velocity V (mm/s). If the issues with pipes or cavitation can be ruled out, I think we could consider testing just the motor. Our factory has encountered similar situations as well. At first, we suspected a problem with alignment, but after several attempts to repair it and start the pump, the vibration level remained high. Later, when we inspected the motor, we found that it needed major repairs.

It’s not about identifying the cause based on vibration, but rather about determining what possible causes there might be. Please specify which measurement points were tested, and what the horizontal, vertical, and axial vibration displacements, velocities, and accelerations at each point are. If applicable, also indicate the envelope value or impact energy. His vibration unit is definitely mm/s, but it’s suspected that he doesn’t have a vibration analyzer capable of measuring spectra; if he does, it would be best to measure the spectrum at the point where the maximum value is observed. By the way, the testing points are not chosen arbitrarily; they should be as close as possible to the location of the bearings.

Generally, there’s no issue with the installation of the foundation bolts; leakage won’t occur during the first step of starting the pump. It’s likely cavitation

The pump continues to vibrate and has not been fixed, which indicates that there is still some hidden issue that hasn’t been identified. The faults mentioned on the upper floors should have been ruled out by now; it’s best to perform a spectrum analysis. If there is no spectrum, try the following approaches: First, determine whether there is a problem with the process. Excluding a few minor issues, there are problems with the bearing selection, the cover, and the wrong rotation direction. Is the current normal? Check a few more aspects: 1. Verify if there are any issues with the foundation. 2. Test the motor individually to rule out motor faults. 3. In the case of a heat pump, it is necessary to check whether there is significant stress on the piping during operation in hot conditions. 4 Determine whether the impeller is suitable. 5. The bearing housing fit of the single-stage centrifugal pump is out of tolerance and the positioning is insufficient. Is there significant stress due to the misalignment between the bearing housing and the cover? This post was last edited by HaiZhongTian on 2009-3-28 23:41]

It’s best to perform a spectrum analysis; if there is a resonance issue with the pipeline, consider changing its frequency by adding supports or clamps to it, thereby altering the pipeline’s frequency.

Confirm vibration mode； Confirm whether it has been vaporized ； Check if there is a problem with your vibration meter ； Confirm whether resonance was considered during installation.

Check the load on the foundation, motor, and pump. Again

Check that the foundation, motor, and pump are not under excessive load; it is necessary to disassemble them for inspection, as there may be debris inside, or the impeller and mouth ring could be worn out.

Use a vibration meter to start from the foundation and eliminate possibilities step by step; disassemble and inspect the wear condition of the impeller and its ring

After learning it, everyone becomes an expert: lol

Try eliminating the issues one by one as follows: 1. Check the bearings. 2. Check the foundation bolts. 3. Check whether the rotor shaft is bent. 4. Verify that the clearance of the coupling is within the required range. 5. Check if the temperature of the medium pumped by the pump is near its vaporization temperature. 6. Balance the rotor (for most pumps, static balancing is sufficient). 7. Check for any rubbing inside the pump

The people upstairs have provided very comprehensive answers, covering almost all the possible causes of vibration. I would like to add my own opinion: the possibility that the vibration is caused by the inlet and outlet pipes should not be overlooked.