Dear all,

We're facing a problem with the Hydraulic Coupling of boiler feeder pump. The absolute vibration taken by CSI2140 is very high at all directions, at the moment, it's more than 10 mm/s. This has happened for a long time and can't find the answer.

- Input:1500 rpm; Output: 5971 rpm

Only 1X of output shaft dominates. The spectrum is below:

But the relative vibration of this shaft (taken by online system) is very small, about 20 um.

If you have any ideal, please help me, all opinions would be welcomed.

Sorry if my English is not clear.

Best Regards

Original Post

More details please: bearings type, mark where exactly was your spectrum taken, any Peakvue spectrum, time waveform? Do you have some measurement history before increase? When did it happen? After some overhaul? Is the vibration level the same when you turn the machine off and back on? 

Without additional information I would say the most possible cause is pump rotor unbalance or coupling unbalance on the pump side half.

Dear all,

Thank so much for your interest. Sorry for reply late because of going business. Please see more information:

1. There are points we take the measurement. We use CSI2140 to measure outside.

All points dominated with 1X like above spectrum, detail:

G1H: 0.398 mm/s     G1V: 2.574 mm/s      G1A: 1.449 mm/s (output shaft)

G2H: 0.492 mm/s     G2V: 6.001 mm/s      G2A: 2.673mm/s (output shaft)

G3H: 8.988mm/s     G3V: 6.497 mm/s      G3A: 12.969 mm/s (input shaft)

G4H: 9.459 mm/s     G4V: 10.55 mm/s      G4A: 10.08mm/s (input shaft)

2. Bearing type is journal bearing. All points mark "12" in the above image are journal bearing. And we have displacement sensors to get orbit spectrum

3. The diagram of whole machine:

The vibration at P1, P2 are bit of high at 1X also:

4. The Timewaveform at highest vibration point G4V:

If you need more information to give an estimation, please post here.

Thank so much for your help!

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