Cavitation in water pumps is a feared phenomenon in hydraulic installations. On a test bench, it is presented using a peripheral pump, where a valve is closed to cause cavitation. During this process, the sucked water is gasified, going from a liquid to a gaseous state. The visualization is done through a vacuum gauge and a hose as a viewer.
Cavitation generates tiny bubbles that represent cavities of water vapor. When the valve is closed, the negative pressure increases, and the bubbles implode as they go from low to high pressure areas, generating a wave of energy. In high-pressure environments, these bubbles collapse, impacting pump surfaces, causing damage, especially to impellers.
The phenomenon is related to the phase diagram of water, where atmospheric pressure affects the boiling point. At lower pressure, water boils at lower temperatures. It is highlighted that cavitation is not only due to temperature, but also due to pressure.
Factors such as negative suction, hot liquid, and geographic altitude increase the risk of cavitation. In cities with less atmospheric pressure, such as Quito, La Paz or Bogotá, the risk increases. Prevention involves calculating the NPSH (Net Positive Suction Head) available and comparing it with that required by the pump.
In installations with negative suction and hot water, such as boiler feed pumps, a deaerator tank is used to reduce the risk of cavitation. Understanding these concepts is essential to avoid problems in hydraulic installations and ensure efficient pump performance.
Maximum suction head Peripheral pump Negative suction Atmospheric pressure Absolute vacuum Percentage of total vacuum Working point Suction valve Vacuum gauge Cavitation Air bubbles Vapor cavities Sea level Geographical altitude Manometer Pump discharge Cavitation phenomenon Working range Measuring instrument Circulation of water Pump noise level Implosion of vapor cavities Suction lift management Cavitation damage in pumps Hydraulic performance tests Pump suction sizing Vacuum tests in peripheral pumps Risks of excessive suction Water circulation in the hose