Road Tunnel Ventilation - Semi-transverse Ventilation

Semi-transversal ventilation uses air ducts to introduce inside the tunnel set flow rates of fresh air so to accomplish the dilution of the pollutants. In case of fire, the fans need to be able to reverse their running direction so to extract the smoke flow rate and grant safe environment to the tunnel users.
The system is normally used for bi-directional tunnels with need of augmented safety.

For Semi-transversal ventilation Systemair offers a wide range of axial fans, sound attenuators and dampers:

Axial fans AXC and AXR

• Unidirectional (AXC) or truly reversible (AXR)
• Diameters from 1.400 to 1.600 mm
• Volume flows up to 150m³/s and 5.000 Pa of pressure using contra-rotating fans in series
• Up to 400°C for 2h operation
• Certified according to EN 12101-3


Sound attenuators

• Cylindrical silencers with or without acoustic pod directly connected to the fan
• Limited acoustic attenuation and low pressure losses
• Should the system require higher attenuations a splitter silencer can be sized,
   the splitters can be fix or moveable types on special rails in order to allow
   the possibility of easy cleaning
• Aerodynamic nose of the splitters (on request) to reduce the pressure losses even more
• Acoustic material fire resistance classified ClassA1 in accordance to ISO EN 13501-1
• Standard finish in neoprene tissue or expanded metal sheet
• Structure material can be pre-galvanized, hot dip galvanized or stainless steel



• Multi leaf dampers with parallel or opposite blades specially designed for
   underground applications
• Made of hot dip galvanized steel after manufacture or in stainless steel
   AISI 304L/316L equivalent to EN 1.4301/1.4404
• Air leakage less than 0.1 m³/sm² at 1kPa
• Blade deflection less than L/180 at 6 kPa
• Operational cycling (open-close) up to 6 million cycling
• Actuators pneumatic, electro-pneumatic, spring return, on/off, modulating
• Supply 230 or 400V, 50 or 60 Hz, 1 or 3 ph
• The entire damper including motor can operate with hot air or smoke
   up to 400°C for 2 h certified in accordance to CETU/PIARC.