Reasons for excessive vibration in the outlet pipeline of a Roots blower

I’m not entirely sure about the specific setup in your case, but the main reasons for excessive vibration in the fan are as follows: 1. Loose foundation bolts, which is manifested as significant vertical vibration. 2. The alignment of the coupling is not satisfactory, and this is manifested in three ways: first, there is significant axial vibration; second, the bearings located near the coupling experience high vibration levels; third, the degree of vibration is closely related to the load applied. 3. The fan foundation has poor stiffness, and the fault characteristics are as follows: first, the vibration frequency is at the power frequency, and the vibration time-domain waveform is sinusoidal; second, the vertical vibration velocity is abnormal. 4. The piping connected to the fan is improperly configured; mainly, the vibration-damping joints connecting the fan are worn out, resulting in resonance between the piping and the fan. 5. A large meshing clearance in the synchronous gears, along with insufficient precision in tooth surface contact, can also lead to excessive horizontal vibration. 6. The rotor is unbalanced, and the vibrations are characterized as follows: first, there is significant vibration in the horizontal direction, with the vibration frequency matching that of the rotational speed; second, the amplitude of the vibrations is independent of the unit’s load. 7. Bearing damage and loose shafting components are manifested mainly in the following ways: first, the bearings run at high temperatures and produce abnormal noises; second, there are abnormalities in horizontal, axial, and vertical vibrations. You can check each of these possible causes one by one.

Reply to 1# zfqljq: If the equipment vibrates normally but only the outlet pipe vibrates severely, the main cause is likely excessive outlet pressure. Your current level should also be high. If there is a vent pipe, opening it slightly should reduce the vibration. This is the case with the rotary pumps I have here; especially at the beginning of operation, things improve once the load is applied

The ones on the 3rd floor are experts; they can be trusted completely. {:1_90:}

I agree with the view from the 3rd floor; let’s all exchange ideas, thank you

A fairly comprehensive summary of fan vibrations on the third floor has been provided. However, for low-speed pumps such as Roots pumps and water ring vacuum pumps, due to their low operating frequency, even when the fans and pumps are working properly, their vibrations can still cause resonance in the outlet pipelines or water seal tanks, resulting in significant vibration and noise. In such cases, it is necessary to check the vibration isolation devices or adjust the stiffness of the pipelines