Does your pump make loud noises? Like it is pumping solid rocks? The reason could be pump cavitation. Cavitation can lead to a number of different problems for your pumping system including excess energy usage and noise pollution.
What is cavitation?
Cavitation is the formation of bubbles in liquids which are developed in low-pressure areas around impellers. When these bubbles implode they cause intense shockwaves inside the pump leading to significant damage to the housing and impeller.
If left unattended, pump cavitation can often lead to:
- Completely destroying the impeller
- Growing vibrations
- Housing failure
- Low flow
- Increasing energy consumption
The two most common types of pump cavitation include discharge and suction cavitation.
When the pump’s discharge cavitation runs at less than 10% of its BEP, cavitation occurs. The intense discharge pressure makes it hard for the fluid to flow out of the pump, leading to excess circulation within the pump. The liquid flows between the housing and impeller at a high pressure creating a vacuum and formation of bubbles at the housing wall.
As it is with cavitation, when these bubbles implode they create an intense shock wave causing wear of the housing and impeller. In worst-case scenarios, the implosion can also end up breaking the impeller shaft.
Discharge cavitation may also be due to:
- Clogging of filters
- Clogging of discharge end pipes
- Inefficient piping design
Suction cavitation occurs when a pump is under high vacuum or low-pressure conditions. The pump may not be receiving enough flow or it may be starved. This leads to the formation of bubbles at the eye of the impeller. As the bubbles proceed towards the discharge end they are compressed and turn into liquids eventually imploding against the impeller face.
Impellers that have been victims to suction cavitation may appear like sponges due to missing chunks of metal.
The causes of suction cavitation include:
- Pipe blockages
- Clogged filters
- Lack of appropriate suction conditions
- Inappropriate piping design
If you are sure that your pumps are experiencing cavitation, inspect the following:
- Reference the pump’s curve
- Inspect strainers and filters
- Re-evaluate the piping design
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