Cavitation Prevention in Pumps

We previously posted on the diminishing performance of water pumps. (https://pumpbiz.com/blog/centrifugal-pump-not-pumping-as-much-water/) A focus of that post was the reduced effectiveness of the impeller. Sometimes impellers are damaged by suspended solids in the fluid. But, even if you are not pumping liquids with solids or high highly viscous fluids, there can still be damage to the impeller and other components of the pump. One of the ways this damage can occur is by cavitation.

Cavitation

From the sound of it, you might think that cavitation in water pumps would be that bad. But, it is. Cavitation occurs as pockets of air, or bubbles, form in the liquid flowing through the pump. This frequently happens when there is a rapid formation and collapse of vapor pockets in areas of the liquid where there is very low pressure.

Pump Damage from Cavitation

The range of issues of from cavitation includes pitting or deterioration. This can degrade the performance of the pump over time. But, it can also be case hydraulic imbalance that creates excessive vibration in the pump. When this happens, shaft or bearing failures are very possible. The cavitation issues range from degraded performance to catastrophic pump failure.

Detecting Cavitation

Cavitation issues may have audible signals, such as sounding like pebbles or marbles are being pumped into the fluid. When your sure the liquid is clear and yet hear what sounds like solids in the pump, you may have cavitation.

Cavitation also has visible signs. Pitting inside the pump (yes, you should inspect the pump periodically), excessive vibration, or increase energy consumption. If your going through more gas the normal, you may have a cavitation issue; pumps with cavitation just don’t operate as efficiently.

What causes cavitation

Suction Cavitation

Suction cavitation happens when the pressure in the flow is diminished, there is an opportunity for air to form in the fluid. This can happen due to clogging, inlet line is too narrow, the pump is too far from the water source, and other conditions that may negatively impact the consistent suction pressure in the system.

Discharge Cavitation

If the discharge pressure is too high, the pump to circulate the fluid within the pump housing at a very high velocity, this will cause a vacuum along the housing wall resulting in vapor bubbles. y

Preventing or eliminating cavitation

The idea of pumping fluids seems simple to some people. This leads to poorly designed pumping systems. To prevent cavitation, systems must be designed with the proper pump, inlet and discharge dimensions, and the proper distance between the pump and the fluid source and the discharge head. Working with an engineer at your pump distributor can ensure that the system is designed properly.

Cavitation is one possible issue with poorly design pumping systems. Preventing problems with a properly designed system can ensure your pump lasts longer, operates more efficiently, gives performs as expected.