What is NPSH and why does it matter?
NPSH stands for “Net Positive Suction Head” and sometimes is referred to “Not Pumping So Hot”. NPSH is the net suction pressure available at the pump inlet. If the available NPSH is less than that required by the pump, many serious problems can result. Excessive vibration can occur when sections of the impeller are handling vapor and the other sections handling liquid. Probably the most serious problem is pitting and erosion of the pump parts, resulting in reduced pump life. This is caused by the collapse of vapor bubbles as they pass to the regions of higher pressure. Excessive noise and vibration usually accompany this cavitations phenomenon. As the vapor bubbles collapse, the adjacent walls are subjected to a tremendous shock from the inrush of liquid into the cavity left by the bubble, This shock actually flakes off small bits of metal and the parts take on the appearance of having been badly eroded. This erosion shows up not at the point of lowest pressure where the bubble is form
