China Unicom is mainly used for air circulation pipe between the two places, played the role of ventilation. Currently on the market is the most widely used spiral duct. 

The spiral duct market is generally divided into three categories according to the material: galvanized spiral duct, stainless steel spiral duct and composite spiral duct. Among them, the stainless steel duct best quality, applicability, but the price is high. Currently the most widely circulating on the market spiral duct galvanized sheet. Spiral duct galvanized sheet, stainless steel spiral duct basic features, but the price is relatively only two-thirds of the stainless steel duct or even lower. Composite spiral duct generally used in the external environment than ordinary, not too high for duct places. 

Spiral duct scope is very extensive. Return air duct cleaning system, central air conditioning and ventilation pipes, industrial supply and exhaust ventilation pipes, exhaust pipes suck environmental systems, mine gas drainage pipe, duct and other mine rubberized cloth. 

Spiral duct ventilation because first used to send cold air duct so classified category. It is set according to their use of the name, but it can be used in other places, even for drainage, drain liquid or as a container, which can not call it the duct. By naming structure shall call it the spiral seam bite tube, made of metal as the main helical biting and call it a metal tube seam. If the material is classified by name, probably could have these names: zinc (iron) coil, stainless steel coil, aluminum coil, or in order to distinguish it from the existing stainless steel pipe, stainless steel tube can call it thin, because it is available in 0.3 mm or thinner tape roll is made of stainless steel.