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Home » Pumps » Spotting Pump Vibrations – The Key to a Smooth, Trouble-free Operation of your Pump Systems

Spotting Pump Vibrations – The Key to a Smooth, Trouble-free Operation of your Pump Systems

Posted: 13/08/2018
Category: Pump Maintenance , Pumps

Here, at Sintech Pumps, a leading industrial pump manufacturer and supplier in India, we have several years of experience working with pumps of all types and sizes across industries. With our tons of expertise and knowledge in the field, we can state with confidence that we are aware of the wide range of things that can go wrong with pumps. Here, in today’s post, we would like to share that knowledge with you. Very often, we find that a clear majority of pumps that are having operational problems exhibit some sort of vibration issue or other. Here, we explain the six major causes of pump vibration. By being aware of these, you could troubleshoot problems before they become a major issue and nip it in the bud. Failing to recognize vibration issues could lead to expensive downtime and costly repairs. Read on to identify the reason for your pump’s poor performance and learn the tactics to identify vibration issues before they become major ones.

  1. Pump Cavitation
If any kind of strange noises coming from your pump, there’s a good chance cavitation is the problem. Pump cavitation is a critical issue that can befall even the highest-quality pumping equipment. It is the formation and subsequent collapse or implosion of vapor bubbles in a pump. Fluid voids are formed when bubbles burst, the fluid surrounding this void rush in to fill the space. This generates a high pressure concentrated on a very tiny area, the resulting damage is high enough to erode the surface. How does it affect the pump?
  • Decrease flow or pressure.
  • Damage internal components of the pump.
  • Unexpected vibration.
  • Impeller erosion.
  • Seal/Bearing failure.
  • Fluctuating power consumption.
  • Distinctive crackling noise
  1. Bent Pump Shaft
Another main reason for pump vibration is a bent pump shaft which leads to axial phase differences that cause axial vibration. If the bend is nearer to the shaft centre, then a dominant vibration occurs at 1x RPM. On the other hand, if the bend is nearer to the coupling, then the vibration occurs at 2x RPM. Very often, bent pump shafts happen at the spot of the coupling or near to it. You can easily identify bent pump shafts using a dial indicator.
  1. Pump Flow Pulsation
This occurs when a pump is operating close to the shut-off head. When this happens, you can notice fluctuations near the pump’s discharge piping. The valve arm and the counterweight will experience unstable flow. A primary reason for pulsation is the lack of a proper feed. The pumped liquid must be in direct contact with the face of the plunger. If not, the plunger moves forward, causing unwanted pulsation. A suction stabilizer helps to keep the pumped liquid in direct contact with the plunger, thereby preventing pump flow pulsation. Other reasons for flow pulsation are:
  • Multiple pumps on a single header
  • Leaking valves
  • Improper spring rates
  • Worn packing
  • Piping designs the reduce flow
  1. Pump Impeller Imbalance
Sometimes pumps get misaligned due to overheating or bearings that have become worn out. Other reasons for misalignment is because of an imbalance in the pump assembly or other components. Imbalance leads to heat build-up and vibration. Imbalance in the impeller has a direct impact on the life of the pump bearings. Consider the case of a centre-hung pump impeller. Here, force imbalance is a more common effect than couple imbalance. In such instances, the highest vibration occurs radially at the highest point of pump operating speed (typically at 1x RPM). Centre hung impellers make use of balanced axial forces on both the outboard and inboard bearings. If you notice, extensive axial vibration in the impellers, then it’s an indicator of a foreign object that’s obstructing the flow. Here are a few impacts of pump impeller imbalance:
  • Bearing failure
  • Pump seizing
  • Excessive vibration that damages the pump
  • Failure of the packing or mechanical seals
  • Shaft deflection – which leads to uncontrolled resonance or bent shaft, that may cause damage to the entire pump system
  1. Pump Bearing Issues
This is one of the main reasons for pump vibration issues. The reason for this is that an estimated 10 to 30% of ball bearings are overworked to trigger fatigue failure. For instance, a pump may have a work lifecycle of 20,000 hours. It doesn’t mean that the bearings have a similar lifecycle. Bearings can fail due to several reasons like excessive wear, overload, corrosion either due to the weather or the pumped media, overheating, overload, contamination or failure of the lubricant. Another main reason for pump bearing failure is due to poor bearing selection. Make sure that you select the right bearing suited for your specific application. You can overcome most of the issues of pump bearing failure by lubricating the bearings with grease, oil mist or specialty oils.
  1. Shaft Misalignment
Here’s the fact – not all vibration is bad. In fact, it’s common for pumps to experience some vibration. So, if you notice excessive vibration, then you can contact a qualified pump technician to figure out whether the vibration is normal or because of shaft misalignment. Also, the technician would be able to tell you whether the vibration would affect the pump’s reliability and performance. Shaft misalignment is one of the trickiest problems to detect. It cannot be measured externally and there are no sensors that tell you how much force is being exerted on the pump. Look for the following signs to determine if your pump has a misaligned shaft:
  • Excessive radial or axial vibration
  • Loose coupling or coupling failures
  • Excessive oil leaks at the bearings and seals
  • High temperature of the discharge oil
  • High temperatures near the bearings or in the casings
  • Cracks in the shafts or breaking of the shafts near the inboard bearings or coupling hubs
Final Thoughts – Troubleshoot Vibration Issues before they become a Problem Spotting the pump vibration issues in early stages can help you avoid expensive repairs and unplanned down times. If you need any further help diagnosing problems with your pump systems, get in touch with our expert pump specialists, here at Sintech, India’s top pump manufacturers and distributors.

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