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Because before starting a centrifugal pump, the space inside the pump casing must be filled with external liquid, and this procedure is known as priming the pump. To prevent the liquid pumped into the pump casing from flowing back into the sump due to gravity, a check valve (foot valve) is installed at the inlet of the pump’s suction line ； If the pump is located below the liquid level in the tank, there is no need to prime the pump at startup. Guide wheels are installed on the periphery of the impeller, resulting in a high efficiency of energy conversion for the liquid inside the pump. The guide wheel is a fixed, bladed ring located on the outer periphery of the impeller. The bending direction of these blades is opposite to that of the impeller blades, and their bending angle is precisely adapted to the direction in which the liquid flows out of the impeller. This allows the liquid to change direction smoothly within the pump casing channels, resulting in minimal energy loss and high efficiency in converting dynamic pressure energy into static pressure energy. The balance holes on the rear cover eliminate axial thrust. The liquid pressure around the impeller is already high; a portion of it seeps behind the rear cover of the impeller. Meanwhile, the liquid inlet on the front side of the impeller is at low pressure, which generates an axial thrust that pushes the impeller toward the pump inlet side. This can easily cause wear at the point where the impeller contacts the pump casing, and in severe cases, it can also lead to vibration. The balance hole allows a portion of the high-pressure liquid to leak into the low-pressure area, reducing the pressure difference before and behind the impeller. But this also leads to a decrease in pump efficiency. The shaft seal device ensures the proper operation of the centrifugal pump. When a centrifugal pump is in operation, the pump shaft rotates while the casing remains stationary. If the gap between them is not sealed or is poorly sealed, external air will penetrate into the low-pressure area at the center of the impeller, resulting in a decrease in the pump’s flow rate and efficiency. In severe cases, the flow rate is zero – gas entrapment. Typically, a mechanical seal or a packing seal can be used to achieve sealing between the shaft and the housing. To prevent the pump from running idle, we can use self-priming, corrosion-resistant self-priming pumps, which can effectively extend the service life of the water pump and motor, avoid leaks at the mechanical seal caused by idling operation, and automatically stop working when there is no water available. It saves labor and economic costs, resulting in significant economic benefits.