Dixon packing is a small particle high-efficiency packing made of metal wire mesh, with a diameter equal to its height. The specifications mainly include 2 × 2, 3 × 3, 4 × 4, 5 × 5, 6 × 6, 7 × 7, 8 × 8, 9 × 9, 10 × 10, 11 × 11, 12 × 12, etc.   Due to the capillary action of metal wire mesh, the liquid can be well dispersed and form a film, which is conducive to sufficient mass and heat transfer between gas and liquid, and can significantly eliminate unstable phenomena such as channel flow. The pressure drop of the θ ring packing is related to factors such as gas velocity, liquid spray rate, system density, surface tension, viscosity, and the characteristics of the packing, as well as the amount of pre flooding treatment of the packing.   The hysteresis of dixon packing is greater than that of similar solid fillers, and the surface wetting is also more complete than that of general ceramic rings, resulting in a higher film formation rate and higher separation efficiency. The theoretical plate number of θ ring packing decreases with the increase of packing size and tower diameter, which is more pronounced for packing in small diameter towers.   The increase of tower diameter leads to a significant decrease in the theoretical plate number (when Dr/d>10, HETP=0.8-1.2dr, while when Dr/d>70, the packing efficiency is significantly reduced). It increases with the increase of gas velocity and decreases with the decrease of surface wettability of the packing. θ ring packing is mainly used in laboratory and small batch, high-purity product separation processes. (Compared with single-layer, double-layer has greatly improved mechanical properties and separation efficiency. Generally, double-layer is selected for sizes of 5 × 5 or more.)