Cavitation occurs when the pump suction is under a low pressure/high vacuum condition where the liquid turns into a vapor at the inlet of the pump. This vapor is carried over to the discharge side of the pump where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the pump rotors, gears etc. Rotors, screws, gears, etc. that have been operating under a suction cavitation condition have large chunks of material removed from their faces causing premature failure of the pump.