Navigating Pump Cavitation: Causes, Symptoms, Diagnosis, and Solutions

Pump cavitation is one of the more serious issues that can occur with a pump. Cavitation can result in damaged components, operational inefficiencies, overheating, safety issues, unplanned downtime, and other issues. What are the causes of pump cavitation, and why does it happen? What are the main symptoms of cavitation, and how is pump cavitation diagnosed? Finally, what is the best solution for this problem?

How to Identify & Resolve Pump Cavitation 

Cause of Pump Cavitation and Why It Happens

Fluid being pumped can experience inadequate flow rates and pressures, sometimes causing gaseous bubbles to form. In a pump, cavitation occurs when these bubbles first take shape and then collapse within the media being pumped. As the bubbles implode against the pump's inner workings, they damage the metal components inside the pump. 

Though this issue can happen with any type of pump, cavitation most commonly occurs in centrifugal pumps. In a centrifugal pump, cavitation ensues when bubbles develop quickly from the impeller’s center to its outer diameter. The centrifugal force generated by the pump heightens pressure, resulting in a quick collapse or implosion of these bubbles, often with significant force.

The negative impact on a pump’s operation is substantial and can drastically affect the lifespan of components within the pumping system, including the pump itself. However, due to where pump cavitation normally occurs, it typically impacts the impeller most harshly. If not dealt with in time, cavitation will erode the material from which the impeller is made, damaging it beyond repair.

There are numerous reasons why pump cavitation occurs including:

• The pump being too far above the fluid source
• The suction pipe having too small a diameter
• The suction pipe being too long
• Too many fittings on the suction pipe
• Handling a liquid with a low vapor pressure
• Running the pump too fast

Symptoms and Diagnosis of Pump Cavitation

The following symptoms may be used to diagnose pump cavitation: 

• Atypical noises: The implosion of bubbles caused by pump cavitation often produces cracking sounds from inside the impeller’s housing, sounding much like marbles rolling around inside system.
• Component failure: Pump cavitation can cause both bearings and seals to fail, and the latter to leak as well; prolonged pump cavitation can result in catastrophic failure of other parts, or even the entire system.
• Decreased flow: If a pump is not producing the expected flow according to manufacturer parameters, this indicates a problem with pressure that may indicate cavitation.
• Impeller erosion: If fragments of the impeller are found at any point throughout a pumping system, cavitation has likely occurred.
• Increased power consumption: It’s often a sign of cavitation if the pump requires more power to transport media than normal, especially when suction falls and rises inexplicably; once bubbles begin to form around the impeller, fluctuating energy use may indicate imminent impeller failure.
• Unusual vibrations: Pump cavitation often causes equipment to vibrate abnormally, whether for the equipment being used or the media being pumped. The implosions and shockwaves traveling through the pumped media damage the impeller and other pump components.

Solutions for Pump Cavitation

The best solution for dealing with pump cavitation is to contact a knowledgeable and experienced pump distributor. Pump design and installation are often the root causes of cavitation. Having a pump distributor ensure the design can properly handle the system requirements is the best step to avoid cavitation. A pump distributor can also ensure the system is installed correctly to circumvent a situation leading to cavitation. 

Correcting for pump cavitation once it occurs is incredibly difficult for an already existing system. Solutions include difficult options, like relocating the pump or source of the pumped liquid while potentially also removing valves and bends that could lead to pressure dropping. 

Tips that decrease the possibility of pump cavitation in already existing systems include: 

• Pumping enough liquid through the system to avoid pressure differentials in the system.
• Mounting any control valve on the discharge end rather than the suction side of the pump.
• Keeping reducers in a position as close as possible to the pump.
• Installing filters large enough to avoid getting blocked.
• Regularly inspecting filters to ensure they are not clogged.
• Regularly clean parts and pipes
• Using the shortest possible inlet hose.
• Ensuring the inlet hose has the correct diameter recommended by the manufacturer.
• Employing inlet hoses with internal springs to ensure sufficient flexibility prevents them from failing when dealing with symptoms of pump cavitation.
• Elevating the reservoir from which fluids are being sourced so it is gravity-fed and creates a flooded inlet.
• Confirming fittings are properly connected, and other elements that can restrict flow, such as elbows, within the system are kept to a minimum.
• Circumventing any pockets where the accumulation of air or other gaseous vapors might occur.
• Replace any damaged parts or piping

Preventing Cavitation Through Proper Pump Maintenance

Regular maintenance is necessary to prevent pump cavitation and other potential mechanical or structural issues. Routine checks on pump performance and vital components make it easier to identify signs of cavitation before significant damage may result.  

Pump maintenance to circumvent cavitation should include the following: 

• Assessing the system to make certain gravity assists with the flow of media as much as possible.  
• Monitoring pressure sensors to safeguard against pump cavitation.  
• Evaluating pump data regarding pressure within the pump ensures that flowrates are optimized.
• Examining the system for cracks or damaged piping that can interrupt the flow of fluids.
• Regularly check filters and strainers to ensure they remain unblocked to prevent pressure buildup.

To learn more about pump cavitation and how to prevent it, contact the pump system experts at Hayes Pump today.