Causes of Cavitation in Screw Vacuum Pump
Cavitation often occurs in the use of screw vacuum pump, which is a high noise and destructive phenomenon often occurring in hydraulic machinery. The occurrence of this phenomenon will not only break the vacuum pump, but also cause impeller perforation to cause serious damage to the equipment.
The mechanism of cavitation is due to the action of liquid dynamics. When the local pressure of moving liquid drops to the vaporization pressure at this temperature, the liquid begins to vaporize and forms bubbles. The bubbles are filled with liquid vapor and a small amount of gas dissolved in the liquid. When the bubbles reach the region where the static pressure exceeds the critical pressure along with the moving liquid, the steam in the bubbles suddenly condenses and the bubbles burst. Because the pressure in the bubbles is always below or near the critical value, and the pressure of the outside liquid is relatively large, when the bubbles burst, the surrounding liquid rushes to the center of the bubbles at a very high speed to form a high-frequency water hammer effect, which produces a high local stress and temperature rise, and produces noise and vibration. Repeated occurrence and collapse of such bubbles will destroy the surface of parts in this area. In addition, chemical and electrochemical corrosion of liquid and parts materials will cause cavitation damage with spongy or honeycomb characteristics.
In addition, even above the critical pressure, the screw vacuum pump may also produce cavitation phenomenon. Because when the pressure decreases, the air and other gases dissolved in the liquid will be analyzed, and at the same time, the vapor of the liquid will be brought out to form bubbles filled with liquid vapor and gas. These bubbles are particularly easy to grow and grow on the surface of moving parts, which are taken away by the liquid and will suddenly condense and burst at high pressure. Cavitation is caused by extinction. However, the critical pressure for cavitation varies with the properties of liquids, temperatures and dissolved gases.
Cavitation phenomenon of screw vacuum pump is mainly produced in the operation of the equipment. More attention must be paid to this problem when finding the reason, so as to ensure the normal operation of the equipment and avoid affecting your normal use.
