The rubber tube is generally composed of three layers, namely the inner layer, the middle reinforcing layer (chemical fiber fabric or steel wire) and the outer layer. The materials used for the third layer should be selected according to actual requirements. The inner layer of glue should be resistant to the corrosion of the medium being delivered, and the outer layer of glue should have mechanical strength and adapt to the environment exposed to the outside. Therefore, the inner and outer rubbers are often not a kind of rubber. Chemical fiber fabrics are mainly used for low pressure pipes, while metal braids are used for high pressure and ultra high pressure pipes. EPDM has been widely used in the inner and outer rubber layers of heating and ventilation pipes, and the outer rubber layer of air-conditioning hoses. This is because the material has good resistance to air, water, ozone, sunlight aging and low-temperature flexibility.