When tunnels are in the project embryo phase, the study of ventilation systems are of significant importance, inasmuch they represent a pivotal air aspiration and purification system, but also have a sanitary purpose and protection function in case of emergency.

In these axial ventilation systems, the filtered air is forced to a movement that is parallel to the main shaft around which the blades rotate; they perform at a more elevate speed and present a narrower diameter with respect to centrifugal fans.

However, they have a higher dynamic pressure, a lower efficiency and performance, and this translates into a higher energy consumption, and significantly lower dimensions and costs.



The most used version of industrial ventilation systems is the one where the rotor is inserted into a cylindrical case, which made them know as “axial intubated fans”; this “accommodation” allows to have an interference between the rotos and the blades, resulting in an air flow higher efficiency. These fans are mostly used when great air volumes are required to mid-to-high pressures, and they represent the best solution from an energy consumption point of view.

We can identify three main functions these ventilation systems perform:

  • Reduction and maintenance of the levels of polluted atmospheric agents released by vehicles to a minimum;
  • Reduction and dilution of the presence of fog or smoke, allowing to maintain a prominent level of visibility;
  • In case of fire, they guarantee a possible escape for hot fumes, allowing the necessary visibility to highlight the emergency exits, and reduce the temperature inside the tunnel

Depending on a series of parameters, including the length and area of the tunnel, the expected volume of traffic and the weather conditions in situ, a longitudinal or transverse ventilation system can be chosen. Longitudinal ventilation aims at a single-sided, longitudinal discharge of fumes and pollutants; on the contrary, a transverse ventilation bet on the naturally upward motion of the fumes, as these tend to remain in the upper part of a space.

This leads to the creation of ventilation ducts that allow the discharge of fumes, and at the same time the intake of clean air through multiple ducts placed few meters away. The first type of ventilation represents the majority of the systems used in tunnels, for their conformation, and for the reduced construction and maintenance costs.

OMZ supplies complete groups of industrial fans, consisting of main shafts (fixed organ), rotors on which the blades are placed, which can be backward-turned or tilted curve, and rotors, of which we take care of the balancing, or their barycentric adjustment coinciding with the center of rotation, which aims to reduce as much as possible the eccentricity of the same.

For any info or quotation, please contact the sales department



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