Cavitation begins as the formation of vapor bubbles at the impeller eye due to low pressure. The bubbles form at the position of lowest pressure at the pump inlet (see Figure 1) which is just prior to the fluid being acted upon by the impeller vanes, they are then rapidly compressed. The compression of the vapor bubbles produces a small shock wave that impacts the impeller surface and pits away at the metal creating over time large eroded areas and subsequent failure. The sound of cavitation is very characteristic and resembles the sound of gravel in a concrete mixer. Figure 1 Pressure profile in a centrifugal pump As you can see from Figure 1 the pressure available at the pump inlet, which is the pressure that we would measure if we put a gauge at that point, can be reasonably high but still drop considerably as it makes it way into the pump. The pressure may be lowered enough that the fluid will vaporize and will then produce cavitation. The same effect can sometimes be seen in control valves because

This is a list of centrifugal pump system tips or DOS AND DON’TS for pump systems. You may not of thought of some of these and they will help you design and trouble-shoot pump systems and select the proper pump. Also there is information here that is hard to find elsewhere. You can think of this list as GUIDELINES for the pump system designer. 1. Flow and pressure relationship of a pump When the flow increases, the discharge pressure of the pump decreases, and when the flow decreases the discharge pressure increases 2. Do not let a pump run at zero flow Do not let a centrifugal pump operate for long periods of time at zero flow. In residential systems, the pressure switch shuts the pump down when the pressure is high which means there is low or no flow. 3. Use pressure gauges Make sure your pump has a pressure gauge on the discharge side close to the outlet of the pump this will help you diagnose pump system problems. It is also useful to have a pressure gauge on