Pipeline pump selection, should be based on process, water supply and drainage requirements, to be considered from five aspects, namely, liquid delivery capacity, the device head, the nature of the liquid, piping layout and operating conditions. 1, colloid mill flow is one of the important performance data selected pump, which is directly related to the entire plant's production capacity and delivery capacity. Such as the design process can be calculated in the pump normal, minimum, maximum three kinds of flow. Select the pump, based on the maximum flow, take into account the normal flow, in the absence of maximum flow, it is usually desirable 1.1 times the normal flow as the maximum flow. 2. The lift required for the installation system is another important performance data for pump selection. The metering pump is generally sized with 5% to 10% head lift. 3, the liquid properties, including the name of the liquid medium, physical properties, chemical properties and other properties, the physical properties of the temperature c density d, viscosity u, medium particle diameter and gas content, etc., which involves the system lift, effective gas Erosion margin calculation and type of suitable pump: Chemical nature, mainly refers to the liquid medium of chemical corrosion and toxicity Rotor pump, is the selection of pump materials and choose which type of shaft seal an important basis. 4, the installation of piping system conditions refers to the liquid from the height of the liquid into the liquid distance to the suction side such as the lowest level, the highest level of the discharge side of some data and pipe specifications and length, material, pipe specifications, the number , Etc., in order to carry out the Department of combing head calculation and NPSH check. 5, the pump operating conditions are many, such as the operation of the liquid T saturated steam P, suction side pressure PS (absolute), the discharge side of the tank pressure PZ, altitude, ambient temperature operation is intermittent or continuous, the pump position Is fixed or portable screw pump.