10 meters.
The dryer cloth is made of high-strength polyester glass fiber and is woven into a coated base fabric. PVC is modified as a surface film. It is an effective combination of high-strength base fabric and high-tech surface film. Mainly divided into mining air duct cloth, glass fiber air duct cloth, flame retardant air duct cloth, fireproof air duct cloth, industrial air duct cloth, plastic-coated glass fiber cloth, tunnel air duct cloth, air guide cloth.
Calculation of tunnel ventilation wind pressure: What is the general air friction resistance coefficient (no formula required), and what is the frontal resistance encountered by the wind flow?
1500m air duct for 1500m tunnel construction. According to the query of relevant information, the correct air duct should be selected for the tunnel length. The 500m-1500m tunnel should use 55kwx2 axial flow fan, and the 1500m-2000m tunnel should use 75kwx2 axial flow fan.
The friction coefficient of the air duct is related to many factors, including: the diameter of the air duct, the suspension form and quality of the air duct, the connection form of the air duct, etc. Therefore, the actual air duct during tunnel construction The friction resistance coefficient must be actually measured during the tunnel construction process, and at the same time guide the ventilation work on site. If the measured friction resistance coefficient of the air duct is large, the reasons must be analyzed and improvements and adjustments must be made to ensure normal operation during the tunnel construction process. Ventilation needs. The selection value of the friction coefficient of the air duct can be obtained from the monograph "Ventilation and Dust Prevention in Tunnel Construction" by Professor Lai Diquan of Shijiazhuang Railway Institute and by consulting the relevant "Ventilation Safety" books, but its value cannot be used as the actual wind pressure during on-site tunnel construction. The friction coefficient of the cylinder must be determined through on-site measurement. Otherwise, the calculated results will deviate greatly from the actual site, so that the equipped ventilator and air duct equipment cannot be used. The following is for reference only: 1200mm ventilation hose friction resistance coefficient = 0.00284 NS2/m4, 1000mm ventilation hose friction resistance coefficient = 0.0029 NS2/m4.