Pump the risk of vaporization

1. Produce noise and vibration

    As the vaporization of the pump vaporizes continuously in the high-pressure zone and is accompanied by a strong water hammer, the danger of the vaporization of the pump is that it generates noise and vibration, and can be heard like a crackling popcorn, The presence of vaporization, in which case a small amount of air can be pumped to buffer the noise vibrations and damage to the metal, is widely used in hydraulic turbines but is seldom used in pumps.

  2. Overflow components cavitation

Pump for a long time under the conditions of work in the vaporization, the pump flow components in some parts of the vaporization will be destroyed, that is, cavitation. This is due to vaporization

In the metal surface occurs, the pump will be the risk of vaporization of the metal surface will be like a sharp knife like a sharp impact, the metal will appear pitting that perforation. Sometimes the metal particles loose and peeling and appear honeycomb, cavitation in addition to the mechanical force, but also accompanied by electrolysis, chemical corrosion and other complex role.

    Practice has proved that the cavitation is the location of the vacuolar rupture. So often in the round after the entrance and pressure water chamber inlet parts found cavitation traces, but the vapor generated at the entrance of the impeller, want to cure the vaporization must prevent the impeller at the entrance to produce vacuoles.

    3. Performance degradation

    The energy exchange between the impeller and the liquid is disturbed and destroyed when the pump is vaporized. The performance of the external characteristic is the head flow curve, the shaft power flow curve and the efficiency curve. In severe cases, the flow in the pump will be interrupted, resulting in the pump not working. However, the performance of the blue line in the early stage of vaporization of the pump did not change significantly, when the performance curve changes, the vaporization has developed to a certain extent.

    The performance curves of different specific speed pumps differ in the form of vaporization. For the low specific speed pump, because the blade flow channel is narrow and long, so in the event of vaporization of cavitation easy to fill the entire flow channel, and thus the risk of water vapor pump is a sharp decline in performance curve form. With the increase in specific speed, the blade flow channel to the trend of wide and short change, so the development of cavitation from the nascent to the entire flow channel has a transition process, the corresponding pump performance curve is slowly declining to a flow Showing a sharp decline. Axial pump performance curve in the entire flow range is only slow down. In addition, the multi-stage pump vaporization is limited to the first level, so the performance degradation than single-stage single-suction centrifugal pump to small.