
Flexible Spiral Round Ventilation Air Duct Pipe for Underground Tunnel Project. Customizable Dimensions: Diameter 200-3200mm and Length 10-300m available upon request. High Tensile Strength: Warp and weft directions guarantee durability and strength. Fire-Retardant & Anti-Static: Meets safety standards with flame-retardant and anti-static options. Wide Temperature Range: Operates effectively from -40 to 80 degrees Celsius. Eco-Friendly Material: Made from PVC composite polyester fiber, odorless and safe. Versatile Color Options: Available in Yellow, Black, Orange-Red, and Green. Multiple Connection Methods: Supports Zipper, Steel Ring, and Velcro connections. Superior Airflow Design: Double-sided PVC coating ensures low friction and minimal leakage.