Air duct is made of various metal materials, commonly used including galvanized iron sheet and stainless steel. Composite air duct is composed of various inorganic materials, which can be divided into many kinds according to their composition, but most of them are lightweight, porous and high thermal resistance materials. The composite organic materials used by the air duct should be selected according to the direction of the use of the air duct.

　　In the air duct used for air supply and exhaust in this direction, the use of a relatively large range of places, such as factory workshops, production sites, large gymnasiums, public leisure space, etc., are required to replace the air duct fan. The harmful gases need to be discharged outdoors, and the outdoor air needs to be transported to the indoor. At this time, it is necessary to use a pressurized fan for air transportation. The spiral air duct (the connection mode of air duct) is the most suitable. In general, galvanized iron pipe is used, and stainless steel pipe is used in corrosive and especially humid places. Most of the scenarios need to use thermal insulation wrap, such as the need to pressurize the replacement of air smoke exhaust duct, or even the need to use fire resistance standards of heat preservation and fire prevention materials. This special air duct generally chooses special glass wool for smoke prevention and exhaust, which can protect the integrity of the air duct in high temperature fire scenes, and will not cause combustion or combustion phenomenon because of high fire temperature.

　　And hVAC, air cooling system air duct, mostly central air conditioning, or cold storage storage. In the process of use, this kind of air duct needs high quality thermal insulation material for thermal insulation to avoid cold leakage. And in the heat preservation material, the new generation of material leader: rubber and plastic insulation material, it is a kind of high quality rubber and plastic composite material, through the foaming technology bubble forming internal dense small closed holes. These small holes can effectively prevent temperature infiltration frosting. Rubber and plastic in the use of hVAC duct system, the thermal insulation effect is excellent, far better than the effect of traditional thermal insulation materials. It can also be used in low temperature environment, and is also a common pipe insulation material in high-speed rail, automobile and other fields.

　　Uetersen rubber and plastic raw materials for nitrile rubber, polyvinyl chloride, is b1 class refractory materials; It does not ignite and produces black billows of smoke. Traditional rubber and plastic composite materials are inflammable, so in the production of new materials, rubber and plastic flame retardant will be added to the rubber and plastic, rubber and plastic flame retardant proportion is not correct, the product will be abandoned, can not recycle the material production. Therefore, in the early production of rubber and plastic, some manufacturers used halogen containing flame retardants in order to save costs. According to industry statistics, most substandard rubber and plastics use halogen-based flame retardants that release toxic black smoke when burned. The technology has improved, and it is now flame retardant by increasing the oxygen index. Utson rubber also by adding green and safe smoke reducing agent, reduce the release of smoke.