The first section selection principle Pump is a wide range of general-purpose machinery and equipment, widely used in petroleum, chemical, power metallurgy, mining, ship selection, light industry, agriculture, civil and defense departments, occupy an important position in the national economy. The electricity consumption of the pump accounts for more than 21% of the national electricity consumption. Therefore, reducing the pump energy consumption, the use of energy conservation is of great significance. In recent years, our pump industry has designed and manufactured many energy-efficient products such as IS, IB, IH, S, D, DG, JC, GMZ and QJ pump products, which have played a positive role in reducing pump energy consumption. However, at present, in all fields of the national economy, due to the irrational selection, many pumps are in an unreasonable operating condition, and their operation efficiency is low, thus wasting a lot of energy. Some pump because the selection is not reasonable, can not be used, or the use of maintenance costs increase, low economic benefits. Thus it can be seen that the rational selection of pumps is equally important for energy conservation. The so-called rational election pump, is to take into account the pump unit and pumping station investment and operating costs and other comprehensive technical and economic indicators, to make it in line with economic, security and applicable principles. Specifically, there are the following aspects: (1) Flow and lift requirements must be met, ie the point of operation of the pump (point of intersection of the device characteristic curve with the pump performance curve) is often maintained in a high-efficiency range so that both mechanical and mechanical damage is not expected. (2) The selected pump should not only small size, light weight, low cost, but also have good characteristics and high efficiency. (3) Good anti-cavitation performance, which not only can reduce the depth of excavation of the pump house, but also make the pump cavitation, smooth operation and long service life. (4) According to the selected pump built pumping station, less investment, low operating costs. The second section selection steps First, list the basic data: 1, the characteristics of the media: media name, specific gravity, viscosity, corrosive, toxic and so on. 2, contained in the media due to the body particle diameter, content how much. 3, medium temperature: (℃) 4, the required flow General industrial pumps in the process can ignore the leakage in the pipeline system, but must consider the impact of process changes on the flow. Agricultural pumps if the use of open channel water, but also must consider the leakage and evaporation. 5, pressure: suction tank pressure, drainage tank pressure, pressure drop in the piping system (head loss). 6, the piping system data (diameter, length, type and number of pipe fittings, water tank to the pressure tank geometric elevation, etc.). The device characteristics should also be made if necessary. In the design and layout of the pipeline, we should note the following: Reasonable choice of pipe diameter, pipe diameter, the same flow, the flow rate is small, the resistance loss is small, but the price is high, the pipe diameter is small, will lead to a sharp increase in resistance loss, so that the selected pump lift, with With increased power, cost and operating costs have increased. Therefore, it should be considered technically and economically. Table 7-1 shows the maximum flow limits for various pipes. Intertech Machinery Inc. , https://www.taiwanmouldmaker.com