Tutorial – troubleshooting pumps

TUTORIAL – TROUBLESHOOTING PUMPS PT001

Most of the time when we describe pump problems we mean:

  • The mechanical seal is leaking prematurely. S020
  • The bearings are failing prematurely. TBB001
  • The centrifugal pump is not developing enough pressure (Head). PT004
  • The centrifugal pump is not pumping enough capacity. PT003
  • The centrifugal pump is using too much amperage. PT005
  • The pump is experiencing a corrosion problem. You should be especially familiar with corrosion problems aassociated with:
  • The pump has to be primed. Positive displacement pumps are self-priming but centrifugal pumps have to have air removed prior to start up. P036
  • The pump works for a while and then loses suction. PT012
  • The centrifugal pump is cavitating. C021
  • The pump is surging. S116
  • Vortexing is drawing air into the pump suction P015-1
  • There is excessive vibration. V016 You need to know something about vibration readings V018
  • There is too much heat generation in the pump. H009
  • The pump stuffing box is getting too hot       ST018-2
  • The centrifugal pump is making too much noise. N007
  • The pump is running as a turbine P045-1

All of the above problems can fit into three neat catagories:

  • Poor design and specifications practices.  GT002
  • Poor operation practices  GT003
  • Poor shop and maintenance practices  GT004

To be an effective troubleshooter you’ll need to understand some pump basics:

  • The system curve. S111
  • The pump curve. P038
  • You must understand three formulas that link head, pressure and velocity. T012
  • You need to understand three rules that explain shaft deflection. T013
    • Shaft deflection accounts for a great many of the premature seal and bearing failures we experience. This is especially true with Original equipment seals. O003
    • There are several things you should know about shaft deflection:
      • The different types of shaft deflection. S042
      • Axil deflection of the shaft                 A036
      • The problems shaft deflection causes. S044
      • How to reduce shaft deflection. S043
      • Shaft bending, the L3/Dformula predicts if you are going to have a problem with the mechanical seal in your pump. L003
      • Here is some additional shaft deflection information S114

The pump can be supplied with various types of bearings B023.

  • Sleeve or poured type S057
  • Ball bearings, sometimes called precision bearings. B013
  • Roller bearings R018

You should be familiar with impellers. They are a big part of troubleshooting pump rroblems

There are different kinds of maintenance being done in pump shops throughout the world. You should be familiar with some of the preventive maintenance programs being tried.

When it comes to analyzing pump failure you get several opportunities, requiring different troubleshooting techniques:

  • Troubleshooting a running pump. You can learn a great deal by analyzing the problem while the pump is still operating. Noise, leakage and vibration are visible.
  • Troubleshooting a stopped pump. You can also learn how to analyze the problem when the pump has stopped, but has not been taken into the shop and disassembled.
  • Troubleshooting a disassembled pump. You can look at the various damaged components and rub marks after the pump has been disassembled in the shop, and by the marks and damage determine the cause of the problem.

Troubleshooting positive displacement pumps is just as much fun as troubleshooting centrifugal pumps, but there are some differences.

Some more “Troubleshooting” pump Links

  • Analyzing Rub marks, PT014
  • Aspiration is a major cause of moisture entering the bearing case A032
  • Corrosion, Stainless Steel, PT015
  • Centrifugal pump 10 most important features C025-1
  • Pump Loses prime, PT012
  • Noise in the pump, N007
  • Operating window on the pump curve, O013
  • Piping problems P059
  • Power failure problem, P025
  • Rules of thumb for pumps, R023
  • Stuffing box getting hot, ST018_2
  • Stuffing box noise, ST018_3
  • Turbulent flow T026
  • Vibration, V016

Posted

  • On February 18, 2018