The agitator is a good selection method with two conditions. One is that the selection result is reasonable, and the other is that the selection method is simple, and these two points are often difficult to have at the same time. Since the viscosity of the liquid has a great influence on the stirring state. Therefore, the selection of the agitator according to the viscosity of the agitating medium is a basic method. Several typical agitators have different ranges of use depending on the viscosity. The various mixers with increasing viscosity are selected in the order of propulsion, turbine, paddle, anchor frame and ribbon. The following figure shows the fineness of this selection order, and proposes a low-speed for large-capacity liquids and a high-speed for small-capacity liquids. The agitator selection chart does not absolutely define the limitation of using the paddle type. In fact, the usage range of various paddle types is overlapped. For example, the paddle agitator can improve the flow pattern by using the baffle plate because of its simple structure. Low viscosity is also more commonly used. Turbine is a turbine-type agitator because of its convective circulation capacity, turbulent diffusion and shearing force.
According to the purpose of the agitation process and the flow state caused by the agitator, the agitator to which the process is applied is judged, which is a relatively suitable method. This type of selection method is to divide the agitator paddle type into two types: fast type and slow type. The former operates in a turbulent state and the latter operates in a laminar state. When selecting, the paddle type and the baffle condition are determined according to the purpose of mixing and the flow state, and the flow state is determined by the viscosity of the stirring medium. Low-viscosity homogeneous liquid mixing is a difficult process of mixing, which is difficult only when the volume is large and the mixing time is short. Because the propulsion type has strong cycle capability and consumes less power, it is the most suitable, and the turbo agitator has high shearing capacity due to its high power consumption. However, it is not necessary for this mixing process, so it is unreasonable if it is used in the mixing of large-volume liquids.