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23 November 2021

How to Service Your Peripheral or Centrifugal Pump

Centrifugal pumps are highly efficient pumps used all over the world for a variety of tasks, including pumping water, oils, solvents, acids, bases and other fluids. A motor spins an impeller in the casing of the device that draws in fluids towards the suction eye and then ejects it outward via vanes and, eventually, through the discharge outlet.

Why Maintain Your Peripheral Pump?

Maintaining your peripheral pump offers two main benefits:

  1. Reduced operating costs
  2. Longer system life

Consistent maintenance allows you to identify potential issues with your system in advance and prevent costly wear and tear.

The Main Parts Of A Centrifugal Pump

Pumps are made of several interdependent parts. These include:

  • Impeller – the rotor that creates the movement to allow fluids to flow through the device
  • Shaft – the axle for the impeller
  • Volute – the casing or exterior of the unit
  • Motor – the unit that provides power to the shaft, rotating the impeller
  • Bearings – components that reduce the friction between the shaft and other pump components

Basic O-ring Service Instructions

To conduct a peripheral pump service you will need to go through the following steps:

Step 1: Collect Your Tools

For a centrifugal pump service, you will need:

  • A spanner
  • Medium flat screwdriver
  • Fine sandpaper
  • Steel wool
  • Clean cloth
  • Rubber mallet

Step 2: Disconnect The Unit From The Power Supply

To avoid electrocution or injury from unwanted operation, disconnect the pump from the power supply. Physically remove the plug from its socket.

Step 3: Loosen The Front Cover Bolts

Take your spanner and loosen the three bolts on the front cover of the unit. After removing them, place them in a container so that you don’t lose them.

Step 4: Remove The Front Cover

Next, remove the front cover. If you cannot remove it by hand, tap it lightly with the rubber mallet. Loosening it slightly should make it easier to prize from the casing.

Step 5: Clean The Inside Of The Front Cover

Using either steel wool or sandpaper, clean the inside of the front cover. Then remove any debris or excess material with the clean cloth.

Step 6: Clean The Impeller

Do the same for the exposed impeller. Gently rub with a clean cloth to remove any grime, dust or visible particles.

Step 7: Remove And Clean The O-ring

Between the casing and the back plate or under the impeller, you will find the o-ring. Remove it by pulling it over the top of the impeller and then clean with the cloth, removing any dirt. Also clean the locating face, removing any loose material or debris.

Step 8: Replace the O-ring And Cover

Replace the O-ring on the locating face and then align the cover with the rest of the unit, by making sure the holes for the screws align.

Step 9: Replace The Bolts

Replace the three bolts and tighten them with a spanner.

Once you’ve finished servicing the unit, it’s ready for installation and operation.

How Often Should You Maintain Your Pump?

You need to perform pump maintenance tasks on varying schedules. Some are routine, while others are quarterly or annual.

Routine Maintenance Of Peripheral Pumps In South Africa

You need to perform pump maintenance tasks on varying schedules. Some are routine, while others are quarterly or annual.

Step 1: Check Pump Discharge Pressure

You can calculate the head pressure of your pump by observing the difference between the suction and discharge gauges. Check that these are within the manufacturer’s recommended range.

Step 2: Check Vibration Levels

Excessive vibration can be an indication of imminent pump failure. Causes include damaged bearings, improper pump alignment or obstructions in the suction and discharge lines.

Step 3: Check All Seals

Pumps rely on seals to avoid leaks. However, rubber seals can lose quality over time and eventually crack. If there are signs of leakage, it indicates a seal issue. You may need to open the pump and replace those that are worn.

Step 4: Check Bearing Condition

Ensure bearings spin freely and have sufficient lubrication. Lubricants should not bubble. If they do, you may need to add more to dissipate excess bearing heat.

Quarterly Maintenance Of Centrifugal Pumps In South Africa

Step 1: Check Pump Foundation

Pumps can sometimes wriggle loose from their foundations. Check that the unit remains securely mounted and tighten any mounting bolts.

Step 2: Align The Shaft

Pump shafts can also sometimes move out of alignment due to forces from the impeller. Open the unit and then compare the shaft position against the manufacturer’s specification. Check for damage and replace if it is out of alignment.

Step 3: Grease

Grease-lubricated pumps typically require greasing every 2,000 hours. Check your pump manual to see how often the manufacturer recommends greasing.

If you are greasing re-greasing bearings, always use the same type of grease. Do not mix greases. Before greasing, ensure the bearings are perfectly clean. Do not over grease as this can create solids that cause the bearings to operate at higher temperatures.

Step 4: Oil

Oil-lubricated pumps require oil changes every 2,000 hours. However, if your pump is new, you should replace the oil after the first 200 hours (similar to a new car).

When using oil-based lubricants, avoid foaming or detergent-containing varieties. Top up oil levels to the midpoint indicated on your unit’s sight glass. Filling beyond this could increase wear and tear.

Annual Maintenance Of Peripheral Pumps

You’ll need to keep track of your pump’s performance and maintenance issues over time to maximise its longevity.

Step 1: Inspect The Impeller, Casing, Bearing Frame and Foot

Check the pump’s critical components for signs of wear, corrosion and cracks. If there are any cracks on the impeller deeper than ⅛ inch, replace it. Remove any loose material from the unit. If there are any signs of wear or tear deeper than ⅛ inches on any of the other components, replace them.

Step 2: Check The Shaft

The maximum total indicator reading (TIR) should not exceed 0.002 inches. If it does, then you may need to replace the shaft.

Do you still have questions? Give our AQS Liquid Transfer team a call on +27 12 548 7204 or fill out our enquiry form, our friendly team will get back to you with first-hand expertise on how to select a borehole pump for your needs.

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