Usually, flexible air duct tubing, lay flat ventilation ducts and rigid duct pipe are applied to ventilation system of tunnel construction.
Flexible air duct tubing is usually designed by lay flat ventilation ducts with steel wire. It is mainly used for negative ventilation and usually applied to short distance ventilation because of heavy wind resistance. It is usually applied to tunnel with some gas because of with anti-flaming and anti-static function.
Lay flat ventilation ducts is usually made up by plastic coated or dipped fabric, which the base fabric is textile fabric like dacryon, vinyl on and others. It is easy to dismount and carry with light weight and has low air leakage. It is suitable for being composed into large caliber air duct and only applied to positive pressure ventilation.
Rigid air duct pipe is usually steel air duct which is connected by flange plate. Also there are FRP air duct, polyethylene-aluminum air duct and glass fiber air duct applied abroad. They usually is sheet material processed in construction site and can be applied to positive and negative ventilation.
Lay flat vent duct with zipper is mostly used for ventilation of tunnel construction. And the main performance index is air leakage, wind resistance, friction factor, resistance to pressure and diameter expanding rate.