Cavitation, or the implosion of air bubbles in the hydraulic system, is the second most common cause of hydraulic system and hydraulic pump failure. This means it is vital for anyone who works with a hydraulic pump outlet or system to understand what causes cavitation in a hydraulic system.
It is also important to have an awareness of the signs and symptoms of cavitation so that if cavitation occurs, it can be quickly dealt with before the cavitation erosion compromises the efficient operation of the hydraulic pump or even causes catastrophic failure of the entire system.
This post will explain, in simple terms, the common causes of cavitation in hydraulic systems and what clues to look out for that suggest that your system has a cavitation issue.
Causes of Cavitation in a Hydraulic System
Inadequate Fluid Supply
If a hydraulic pump is not receiving enough fluid, it will pull air from the hydraulic fluid itself. These air bubbles will then implode when they reach an area with higher atmospheric pressure.
Inadequate fluid supply can be caused by blockages in the supply hose or suction line which can be, in turn, a problem with the supply flow or suction line filters. It can also stem from an incorrectly sized hose or the wrong oil level.
High Fluid Temperature
Monitoring temperature with a hydraulic system is key to preventing cavitation as excessive heat will mean the hydraulic fluid is less viscous and so won’t perform as well, leaving the pump under-lubricated. Temperatures and proper viscosity that are too low can also be a cause of cavitation as high oil viscosity creates lower pressure in lines and flow restrictions. Ensuring the system is not overloaded and installing a heat exchanger component can help maintain the correct working temperature and optimal fluid viscosity.
Excessive System Pressure
It is when vapour bubbles are exposed to high pressure or a rapid pressure drop that they implode. The result of static pressure when the vapour bubbles collapse is a shock wave that causes damage to the hydraulic system parts.
Mechanical Issues
Poor system design, lack of regular maintenance by skilled hydraulic engineers, poor plumbing and worn and damaged parts within a hydraulic system can cause low-pressure regions, and the introduction of air inside the system (through leaky seals and joins) can all cause cavitation.
Symptoms of Cavitation in a Hydraulic System
Some of the signs to look out for that suggest the cavitation process might be occurring within your system are listed below.
Unusual Noise and Vibrations
Cracking, whining, popping, or rumbling noises can all signify cavitation of vapor bubbles. It can also sound like pebbles or rocks are passing through hydraulic pumps. The implosion of the bubbles also causes vibrations.
Reduced Hydraulic System Performance
Although the reduced pressure and system performance can be a result of things other than cavitation damage, it is one of the most common causes of poor performance, damage and system failure and so is worth eliminating as a source of any problems along with contamination as soon as problems occur.
Erosion and Pitting
The intense power blast from every implosion of vapour bubbles can cause erosion and pitting of parts of the system. This is often evidenced by metallic debris in filters.
Increased Fluid Contamination
If you find metallic debris in the filter element that is a sign that your system might have cavitation. As it causes other parts of the system to erode, cavitation can also increase other types of hydraulic oil contamination as dust and other contaminants can enter the system.
Conclusion
Now you know some of the most common causes, you should have a clear idea of how to help prevent cavitation in a hydraulic circuit. Knowing the signs will also help to catch this common issue early so you can get a hydraulic engineer to come and remedy the situation before it becomes too costly or causes you hours, days or even weeks of lost production if your system fails.
As with all hydraulic system problems, they are often preventable with regular serving and maintenance.