During pump testing, the pipes at the pump’s inlet and outlet experience severe vibration

Is the pump a reciprocating pump? Possible cause: 1) The reciprocating pump provides driving force ； 2) The pump outlet pipe lacks rigid supports or has insufficient stiffness ； 3) Resonance occurs within the pipeline system itself. Solution: 1) Add a rigid support ； 2) Adjust the pipeline route or layout, and then add rigid supports.

1. The inlet and outlet pipe diameters are equal; does the pressure drop at the inlet meet the requirements to prevent cavitation? 2. When there is a large difference in pressure at the inlet and outlet, a multi-stage or positive-displacement pump must be used. Vibration is inevitable; it depends on the way throttling is implemented at the outlet. If the outlet pressure is normal, then throttling might be the cause of the vibration rather than the pump itself. 3. Consider the opinions from the third floor... Hehe, just a few random remarks: lol

It cannot be determined for sure whether it is a multi-stage centrifugal pump or a positive-displacement pump; it could also be a high-speed centrifugal pump. If it is a reciprocating pump, resonance is likely to occur because the design frequency of the pump outlet pipeline is close to the operating frequency of the pump. Solutions include adjusting the setup of the outlet pipeline supports, changing the frequency of the pipeline, and modifying the position of those supports. Adding buffer tanks is also advisable; in particular, it is important to use more fixed supports. In the case of high-speed centrifugal pumps or multi-stage centrifugal pumps, in addition to the resonance issue, there may also be a problem with vaporization at the inlet. It is not a reasonable design to have the inlet diameter equal to the outlet diameter. It is recommended to increase the diameter of the inlet pipeline or add a booster pump at the inlet. If vaporization is an issue, prolonged operation can lead to the breakage of the pump shaft. Resonance, if persistent, can damage the pipelines, posing safety risks. This pump has a particularly high head, so thorough consideration should be given to its design, taking all relevant factors into account. Additionally, vibration in this pump is inevitable; what’s crucial is to determine the extent of that vibration. Is it within the range permitted by the supplier? This post was last edited by 1681818 on 2008-1-24 at 11:04

For high-pressure pumps (which are generally multi-stage centrifugal pumps), when the pump is started, if both the inlet and outlet are fully open at the same time, the pump operates at its maximum power level (or even under overload), which can easily lead to resonance or problems resulting from the increased load. If it is a volume pump, it might be the opposite – the outlet is restricted.

Possible causes: 1) Large pressure difference between inlet and outlet; 2) Blockage downstream of the pump’s outlet pipe; 3) Insufficient rigidity in the pump’s support structure; 4) Cavitation in the fluid； 5) The operation of the equipment upstream of this pump needs to be checked.

1. Are the foundation and pump compatible?； 2. Are the inlet and outlet pipes properly secured? ； 3. The flow rate is too high (pressure will be displayed) or too low ； 4. Are the motor and pump individually qualified in terms of dynamic and static balance? ； 5. Connection of motor and pump, alignment ； 6. Cavitation Refer to relevant sources

1. It is possible that the inlet pipeline is not aligned with the pump’s inlet during assembly. 2. The gas in the inlet pipeline of the pump before the air pump has not been completely removed. 3. There is a problem with the pump shaft. 4. There is a problem with the pump itself. 5. It is caused by vibration of the motor. 6. The motor shaft is not aligned with the pump shaft. 7. The pipe supports or fixing points for the pump’s inlet pipeline are not properly arranged. 8. The liquid level in the pump’s inlet tank is too low, allowing seal gas to enter the pump

Check for cavitation and verify the alignment of the pump.

It is very likely to be a problem with the inlet and outlet pipelines

Is there a check valve at the pump outlet? Check whether the check valve is stuck. Strengthen the fixing of the inlet and outlet pipes of pump 2. Check if there are any solid particles in the reciprocating pump that could cause it to get stuck; this was the problem we encountered with the piston pump we used last time

Vibration in pumps generally occurs during operation when gas enters the pump chamber; when high-pressure liquid enters this chamber, it combines with the gas to cause surging, which is transmitted to the pump body and leads to vibration in the pump. This vibration is then transmitted to the pipes, causing them to vibrate as well. If all the spaces inside the pump are completely filled with liquid and become solid, then no vibration in the pump or pipes will occur, unless there is frictional vibration caused by an unbalanced installation of the motor.

Generally speaking, it can be difficult to determine how to change the vibration frequency of a pipeline. Is it best to add buffers at the inlet and outlet, as well as corrugated expansion joints, in order to eliminate the vibration of the pump?

In the case of a multi-stage centrifugal pump, check whether the flow rate is too high, exceeding the design limits. I encountered this issue on site; the only difference was that the pump outlet pressure was slightly lower, at 5.5 MPag.

The pump outlet pipe lacks rigid support or has insufficient stiffness

Judge from two aspects: 1. Check whether there are any issues with the quality of installation, such as unreasonable piping design or pumps that aren’t properly aligned； 2. Whether there is vacuuming in the pump.

I suggest you carefully check whether the inlet pipeline has an uneven pattern. Sometimes such a pattern can prevent gas from escaping from inside the pipeline, resulting in a gas blockage. This, in turn, causes the flow rate to fluctuate when the pump is started, leading to severe vibrations in the pipeline. If this is the cause, I’m sure you know how to deal with it

First, determine where the vibration is coming from – whether it’s the inlet pipe or the pump itself. Vibration of the pump itself is due to improper installation alignment or issues with the pump’s quality. Imported vibration is caused by poor suction conditions. As for those that can cause poor inhalation, consider whether the filter is clogged and whether the pipe diameter has been chosen appropriately. I see that the import value is 150 and the export value is also 150. Let’s check whether there’s insufficient import traffic, or if excessive export traffic is causing the low import traffic.