Definition and classification of AF foam pump is a machine for conveying and lifting liquid. It converts the mechanical energy of the prime mover into the energy of the conveyed liquid, so that the liquid can obtain kinetic energy or potential energy. Because the pump is widely used in various sectors of the national economy, the variety series is numerous, and the classification methods are different. According to its working principle, it can be divided into the following three categories: (1) vane pump: its pressure delivery of liquid is completed by the high-speed rotation of the impeller often equipped with blades, including centrifugal pump, axial flow pump, mixed sedimentation pump, etc. (2) Positive displacement pump: its pressure delivery of liquid is completed by changing the volume of the pump chamber. Generally, there are two ways to change the volume of the workroom: reciprocating motion and rotary motion. Belonging to the category of reciprocating motion, such as piston reciprocating pump, plunger reciprocating pump, etc. Those belonging to the category of rotary motion, such as rotor pump, etc. (3) Other types of pumps: This type of pump refers to special pumps other than vane pump and positive displacement pump, which mainly include screw pump, jet pump (also called water jet pump), water hammer pump, hydraulic pump and airlift pump (also called air lift pump). Except that the screw pump uses the principle of screw propulsion to improve the potential energy of the liquid, the characteristics of the above pumps are to use the kinetic energy or momentum of high-speed liquid flow or air flow to transport the liquid. In the water supply and drainage engineering, the application of such special pumps to transport water or chemicals (coagulants, disinfectants, etc.) in combination with specific conditions often has a good effect. The scope of use of the above types of pumps is very different. Figure 1-2 shows the general type spectrum of several common types of pumps. It can be seen from the figure that the scope of use of various vane pumps that have been finalized for production is quite wide, and the scope of use of centrifugal pump, axial flow pump, mixed flow pump and reciprocating pump has different performance. The use scope of reciprocating pump focuses on high lift and small flow. The use scope of axial flow pump and mixed flow pump focuses on low head and large flow. The use range of centrifugal pump is between the two, the working range is the widest, and the product range, series and specifications are also the largest.