Pump Seizing
Pump Seizing
(OP)
Hey all,
I am a mechanical seal engineer and in my current role I have been tasked with learning pump troubleshooting.
I have essentially 2 questions:
1.) What are some main factors contributing to centrifugal pumps seizing up?
2.) Is there a good guide online or book that specializes on centrifugal pump troubleshooting?
Thank you!
I am a mechanical seal engineer and in my current role I have been tasked with learning pump troubleshooting.
I have essentially 2 questions:
1.) What are some main factors contributing to centrifugal pumps seizing up?
2.) Is there a good guide online or book that specializes on centrifugal pump troubleshooting?
Thank you!





RE: Pump Seizing
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Pump Seizing
The working point should be as close as possible to the BEP (best efficiency point), but often engineers tends to exaggerate head losses, and take some "safe side" for the head, and the pump is over-design, thus running at the left of their BEP, which means risk of : cavitation, vibrations, overheating, more axial and radial trust, etc...
I think you should knowwell how to design and install a pump, then you can see what is done wrongly. That for you can read the good documents from the pump suppliers like KSB or Grundfoss.
RE: Pump Seizing
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Pump Seizing
The only time I ever saw a pump actually seize up it was a vacuum residue tower bottoms pump. The pump was not designed to transfer 900F oil. The metal clearances were not large enough so when the pump got hot it would seize. Once it cooled off it would run again. It was very hard to figure out because the pump was half way around the world from where I was trying to fix it from my desk.
I agree that there is no substitute for going out to the plant and listening to the pumps on a regular basis. Touch them, feel how they vibrate when there is no problem, note how hot they are, note how hot the
motor is. Make sure the motor fan is actually blowing air over the motor. Things like that.
If you want to get better at centrifugal pump troubleshooting you need to read about them, listen to others, and do some hands on work on the pumps, or at least watch them get torn down and see what is happening. Get a good flashlight. Sometimes the light is not so you can see what is going on, but it focuses your attention on a very narrow spot that can be helpful. It also works as a pointer when talking to the operations staff so you are sure you are on the same page.
Regards
StoneCold.
RE: Pump Seizing
RE: Pump Seizing
Too much unbalanced force can also lead to mechanical contact, damage and seizing.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Pump Seizing
Earlier this year had a 3/4 Hp close coupled inline centrifugal pump fail. A new pump was installed under warranty and it failed just a couple months later. With second pump's failure, did a little digging and learned that the pump was installed with the motor housing in the vertical position. Checked the O&M manual and found that this orientation was not a manufacturer approved orientation. Opening the pump to inspect the impellor, found the impellor shattered (no joke), and a retaining ring bent out of shape. Conclusion was that due to the motor housing being in the vertical position, the impellor and rotor assembly fell out of position via gravity causing the impellor to rub against the pump housing until it eventually destroyed itself; not sure if it ever actually siezed or not.
On a side note, whether due to trying to overcome friction of rubbing with the housing or turning a siezed impellor or no impellor to turn, the motor overheated and wiring in the control housing burned out the connections.
RE: Pump Seizing
RE: Pump Seizing
Confucious say: Very broad, ambiguous question get very broad, ambiguous answer.