Vibration of circulating water pump
Thread Content
The company has a single-stage, double-suction volute pump manufactured by Shanghai Liancheng Group. Upon receipt, it was found that the originally designated installation location was insufficient; therefore, the orientation of the inlet and outlet ports had to be reversed in order to install the pump. The installation position of the pump’s impeller was then adjusted, changing the original inlet direction to an outlet direction. The pump operated normally when rotated, but vibration began to occur when its frequency was increased to above 40Hz. The inlet pressure is 0.1 MPa and the outlet pressure is 0.4 MPa. What could be the reason?
Provide more detailed information – what are the vibration levels, both vertical and horizontal? Just mentioning vibration levels isn’t enough.
The measured bearing position was 4.2 mm/S horizontally and 3.5 mm/S vertically; when the frequency was below 40 Hz, it was around 2.7 mm/S. However, the vibration at the inlet and outlet connection points was particularly noticeable; I can’t remember the exact data, and adjusting the outlet valve had almost no effect.
First of all, it is necessary to clarify whether the pump foundation meets the requirements for the pump’s installation conditions. Are pipe compensators required for the connection of inlet and outlet pipes, and are there any relevant design requirements? It is recommended to send a few photos of the scene; visuals make things clearer and can serve as a reference.
Is the pipeline installation in compliance with the specifications, and have all the necessary pipeline supports been installed?
Variable-frequency pumps are highly likely to resonate at 40-50Hz. This can be resolved using a non-contact coupling to change the natural frequency of the shaft system.
The original vibration was over 40 microns; with a non-contact coupling, it is now at most 12 microns
Are there flexible connections at the pump’s inlet and outlet?
A total of 4 units were purchased at that time; for 3 of them, no problems occurred since the direction of the impellers wasn’t changed. I think it’s not a problem with the couplings