Cavitation is caused by a lack of appropriate net positive suction head, or NPSH at the inlet of your pump. NPSH is a measure of the suction-side pressure at the pump inlet, relative to the vapor pressure of the liquid being pumped. It is an important parameter for the proper operation of centrifugal pumps, as it determines the suction conditions that the pump must operate under. These parameters can be found in the pump curve from manufacturer.
What is NPSH?
Net Positive Suction Head, or NPSH for short, can be broken down into two measurements. first, let’s discuss NPSH required, or NPSHr. NPSHr is the minimum NPSH that the pump must have at the inlet in order to operate without cavitation. Cavitation is a phenomenon that occurs when the pump inlet pressure drops below the vapor pressure of the liquid, causing bubbles to form in the liquid. These bubbles can then collapse when they reach higher pressure regions within the pump, causing damage to the impeller and other components.
Now that we know what NPSHr is, we can look at NPSH available, or NPSHa. To ensure that a pump operates without cavitation, the NPSHa at the pump inlet must be greater than the NPSHr. The NPSHa is the difference between the suction-side pressure at the pump inlet and the vapor pressure of the liquid, and it is influenced by factors such as the elevation of the pump, the height of the liquid in the suction tank or sump, and the frictional losses in the suction piping.
How to Prevent Your Pump From Cavitating
To prevent cavitation and maximize the lifespan of your pump, it is crucial to maintain the right NPSH balance. Regularly monitoring and adjusting the NPSHa and ensuring it exceeds the NPSHr will help keep your pumps running efficiently. Additionally, selecting the right pump for your application, installing the correct pipe sizes, and maintaining the proper operating conditions are key steps to preventing cavitation-related issues. If you’re facing challenges with cavitation or need guidance on optimizing your system, our team of experts at Southeast Pump Specialist is here to help. Contact us today to learn more about how we can ensure your pump system operates at its best.
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