What is cavitation

Cavitation more complicated. As the name suggests , it involves in the liquid of the " hole " or " hollow space " Most of these holes is filled with air , and the air pressure at room temperature and which are dissolved in the liquid . Transparent glass tube still no visible bubbles petroleum oil actually contain about 9% of the dissolved air . At any given temperature, the solubility of air in the oil pressure varies directly with the system (Fig. 1 ) . In the standard atmospheric pressure 2.6Mpa , the fluid containing about 9% of the dissolved air , popular point that air is rushed to the oil and stay there dissolved . Until the pressure is reduced or when the temperature drops ran out . If the atmospheric pressure (2.6Mpa) reduced to half 1.3Mpa), dissolved in 9% of 2.6Mpa air will partly separated. Oil will produce bubbles. If this phenomenon occurs buck suction port of the pump or at the edges of the slide valve , the bubble is called " cavitation ."The solubility of air in the oil . The oil surface pressure of the air dissolved in the oil increases the amount of air is increased. Raising the temperature will further increase the amount of dissolved airIn addition to air , the cavity may also have water vapor. Unless carefully dehydrated oil , no barrel new oil will contain at least a few parts per million of water . To withstand temperature changes in  Hydraulic hose fittings  system used oil generally contains several hundred parts per million of water . The vapor pressure of the water vapor pressure than that of mineral oil thousand times higher . Therefore , at any given vacuum condition , the water will be evaporated and the hole filled with steam .