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Difference between gas trapping and cavitation: Gas trapping: When a centrifugal pump is in operation, if the pump is not filled with liquid, or if air gets into the pump during operation, the low density of air compared to that of liquid results in insufficient vacuum at the suction inlet, preventing liquid from being drawn into the pump. At this point, although the impeller is rotating, it is unable to pump liquid outward; this phenomenon is known as gas locking. Cavitation: If the pressure at the pump’s inlet is equal to, or even lower than, the saturated vapor pressure corresponding to the temperature of the liquid, the liquid will boil and a large number of bubbles will form. Some gases dissolved in a liquid can also undergo flashing due to reduced pressure, releasing bubbles. As the liquid enters the high-pressure area of the pump, these bubbles burst; each bursting bubble creates a local vacuum, and the surrounding liquid rushes into the space occupied by the bubble at high speed. Its kinetic energy is then converted into static pressure energy, resulting in a very high local impact force in an instant. Due to the continuous formation and breakdown of bubbles, this impact force constantly strikes the impeller and pump casing, causing the pump body to vibrate and produce abnormal noises. It also results in honeycomb-shaped peeling on the surface of the blades, and may even lead to cracking and damage of the impeller. At this point, the pump’s flow rate, head, and efficiency all drop sharply; this phenomenon is known as pump cavitation. In general, gas binding is caused by insufficient venting of the liquid or air leakage. Cavitation occurs when the inlet pressure is lower than the saturated vapor pressure, causing the liquid to vaporize.