What are pump cavitation, causes and solutions?

Not many people know what cavitation is in pumps. This term may only be popular among those who often work in the industrial world. Unfortunately, cavitation occurs not only in the industrial world but also in domestic life, especially for those who have water pump facilities at home.

In this article, we will discuss cavitation and how to deal with it when it occurs.

Read Also: Your water pump just hums and doesn’t spin? This is the cause!

Understanding Cavitation

Cavitation is a phenomenon where liquid flowing through a pump experiences evaporation due to a decrease in pressure below the saturated vapour pressure. Do you understand what that means? Hey

So, the definition of cavitation above may be too academic. To make it easier to understand, look at the image below.

In the picture, you can see a centrifugal pump with suction and discharge lines on the right side and top. There is also an impeller in the middle.

The fluid pressure created in the suction line is different from the pump discharge line. This pressure difference will also cause a temperature difference on the two sides of the suction and discharge. From this explanation, we are getting closer to the definition of cavitation above.

Physics says, that if we heat water at a pressure of 1 ATM (1 atmosphere), then the water will evaporate at a temperature of 100 degrees C. You will find different things when heating water in locations with lower atmospheric pressure, for example above the mountains. At that time, the atmospheric pressure on top of the mountain may be below 1 atm, causing the water you heat to begin to evaporate at temperatures below 100 degrees C.

That’s what happens to water pumps that experience cavitation. The water pressure in the suction line is lower than the discharge line. This causes the water in the suction line to evaporate, forming pressurized air bubbles which then burst against the impeller grille thereby damaging the impeller. Simply put, cavitation occurs because the fluid pressure on the suction side is lower than the discharge side.

Bad consequences of pump cavitation?

Cavitation can cause several bad things to the pump, for example:

• Will cause noise to the pump
• The pump will experience vibrations which can cause damage to the entire pump unit up to the prime mover.
• Over time, it will erode and damage the impeller and channel walls.
• Reduces pump efficiency

How to avoid pump cavitation?

Avoid installing a static head that is too long!

This means that the pump suction line should not be too long, it must be made as close to the pump as possible. If it has to be made long, the suction line is made 1 times larger than the pump output. This means that if at the pump output, we use a 1-inch pipe, then in the suction line, we use 2 inches. This is done to reduce friction losses in the pump system.

Avoid too many bends (Elbows) in the pump suction line!

This will further reduce the pressure on the suction line which allows cavitation to easily occur. Make sure the suction line is straight with the pump.