Cavitations

If in a pump installation is used high suction head or if peripheral velocity at inlet side of impeller is too high, so it is possibly happened high enough local vacuum condition at inlet side of impeller. It may cause water vaporization, so that bubbles will appear. This phenomena is called cavitations. Cavitations often happen at area where atmospheric pressure decreased, for instance at mountains area, where water boils at lower temperature than lowland area. The bubbles that occurred will flow together with water flow. If at once upon a time, the bubbles reach a high pressure region, so the bubbles will collapse and disappear. If bubbles appearance and bubbles collapse occurs continuously, pump will noise and it may cause vibration. But, worse than that, cavitations may cause erosion and impeller damage. In worst condition, finally pump can not works anymore.
To prevent that trouble, low suction head should be used, suction pipe dimension to be determined in such a manner so that loss friction that happened can be made as low as possible, suction pressure is higher than vapor pressure of water pumped temperature.