Pump cavitation warning signs and how to avoid it

By "Apollo" Flow Controls September 26, 2018

Pump cavitation is a common problem in many pumping applications. It occurs when air bubbles are created in a liquid being transported because of rapid changes in pressure around a pump impeller. These bubbles develop in the low-pressure zones of the pumping system and can burst when subjected to high pressures. When the bubbles instantaneously explode, they send powerful shockwaves (called cavitation) throughout the system.

Manufacturers and pump operators in petroleum, food processing, and chemical handling industries should factor in the risk of cavitation when designing and running their machinery. Cavitation can cause significant damage to a pump and decrease its overall efficiency with time. The shockwaves put excessive stress on a pump’s components, reducing their overall lifespan. They also result in unwanted noise and vibrations, premature valve failure, damage to components, and reduced flow pressure.

Here are some warning signs that your system may be experiencing cavitation, as well as some tips on how to prevent cavitation in the future.

Warning signs of cavitation

Noise/ vibrations: This is the most identifiable sign of cavitation. When the bubbles within a liquid explode, they make a series of bubbling noises as if tiny pebbles or ball bearings are being thrown around. Most professionals describe the sound as that of pumping marbles, gravel, or rocks. The noise results in vibrations over time, and the little shockwaves can be felt on the equipment when a liquid is being pumped.

Decreased flow or pressure: If the pump is not delivering the amount of flow specified by its manufacturer, cavitation could be the problem.

Erosion of the impeller: If there are eroded pieces of the impeller within your pumping system, that is a sure symptom that the pump is facing cavitation.

Breakage of seals and bearings: Excessive vibration and shockwaves caused by cavitation can cause seals and bearings to break, leading to leakages or malfunctions.

Unpredictable power consumption: Bubbles in a pumping system often start to form when the impeller is not functioning optimally. If you observe that the pump needs more power than usual to transfer the same type of fluid, cavitation could be the problem.

Tips on how to prevent cavitation

• Over-exertion: Make sure that you are not operating your pump beyond your pump manufacturer’s performance specifications. If you push it too hard, such as by running it at above ideal rpms to move fluids at faster rates, it will eventually fail.

• Maintenance: Evaluate your pumping system’s components to ensure that they can handle the volume, flow rate, and properties of the fluid to be transported. Those that can’t should be replaced.

• Temperature: Keep an eye on the temperature of the fluid under transportation. This will help you reduce the chances for vaporization, which increase as liquids heat up.

• Booster pump: Add a booster pump to your system to help take away excess pressure from your primary pump.

• Blockages: Assess the system for any clogging and blockages, and ensure that the check valve is installed correctly.

• Check-ups: Regularly check the state of joints, seals, valves, pipes, and any other point in the system that is likely to fail and result in air being sucked into the system.