Cavitation results in significant damage to pumps. It can be detected through simple vibration monitoring or for more precise diagnosis, by monitoring the power density in a range of vibration frequencies.
Two types of cavitation are distinguished:
Suction cavitation can occur when a pump is under low pressure or high vacuum conditions. As the pump is not receiving enough flow, bubbles will form on the impeller. When these bubbles carry over to the discharge side of the pump and are compressed with the liquid, they implode.
Discharge cavitation can occur when the pressure during the discharge is excessively high. Due to the high pressure, it becomes hard for the fluid to leave the pump, causing it to circulate inside the pump. This could cause a vacuum and the formation of air bubbles, which in turn causes damage to both the impeller and the pump housing.
Long-term cavitation leads to pumping failures, such as the destruction of the pump’s housing and impeller. Other effects of cavitation are excessive noise and energy usage.
🔎 The integrated vibration sensor in Senquip devices is being used to detect changes in pump vibration that may indicate cavitation. This method, although cost effective cannot distinguish between vibration frequencies associated with cavitation, and those associated with drive misalignment and other faults. I would however argue that is there is a sudden change in magnitude of vibration, it should be investigated immediately no matter the cause.
🔎 For customers wanting more precise diagnostics, a vibration sensor such as the KPV200, connected to a Senquip device, can provide power spectral density (PSD) which describes the power present in the signal as a function of frequency. This makes it possible to distinguish between specific failure modes.
