Ventilation ducts are a municipal infrastructure that allows air to circulate and reduce the concentration of harmful gases. Ventilation  pipe, duct production and installation of the plate, profiles and other  major finished materials, should meet the design and related products,  the existing national standards, and application of factory inspection  certificate, the material approach should be based on the current  national standards for acceptance. Ventilation  pipe by material points: generally: steel duct (ordinary steel),  galvanized sheet (white iron) duct, stainless steel ventilation pipe,  FRP ventilation pipe, plastic ventilation pipe, composite ventilation  pipe, color steel sandwich insulation board ventilation pipe ,  Double-sided aluminum foil insulation ventilation pipe, single-sided  color steel insulation duct, coated cloth ventilation pipe (such as mine  hairdryer), mining plastic ventilation pipe;