Types of Fans for Tunnel Ventilation System

Tunnels are an integral part of our transport infrastructure, as they allow the passage of different types of vehicles every day.

For this reason, it is vital to choose the right type of fan for a tunnel ventilation system so that it displays a structure responds to specific requirements. In this way, it is possible to guarantee the utmost level of safety to drivers.

In this article, we will discover:

Why are fans in tunnel ventilation systems essential?
The main types of tunnel ventilation systems
The correlation between tunnel and the type of fan to install
How CBI Fans can help you

Why Are Fans In Tunnel Ventilation Systems Essential To Guarantee High Protection Standards On The Road?

Fans are pivotal in tunnel ventilation systems, as they ensure high-protection standards to drivers on the road. In fact, these solutions play a pre-eminent role in the construction of the tunnel itself as well as during the entire operational life of this type of infrastructure.

In fact, a ventilation device effectively extracts from the air harmful gases and pollutants that can impair visibility, causing a detriment in the overall conditions of the tunnel. As a result, they contribute to mitigating the risks related to volatile components, preventing fires and explosions by controlling the internal temperature of the infrastructure.

Additionally, the cleaning action of these types of fans for tunnel ventilation systems preserve the structural integrity of the construction, extending its usual lifespan and protecting it from environmental damage.

Furthermore, a tunnel ventilation system is one of the most important fire-fighting devices, as it:

Keeps people as long as possible in a smoke-free part of the traffic room.
Pushes smoke to one side of the fire, allowing people to reach a safe place in a reasonably short lapse of time.
Keeps smoke out of the air in non-incident structures (escape routes, twin traffic tube, etc.), enabling firefighters to work in favourable conditions.

The Main Types of Tunnel Ventilation Systems

There are four different types of tunnel ventilation systems.

Natural Ventilation

Natural ventilation refers to a type of tunnel ventilation system which relies on environmental agents, such as wind and air pressure gaps, to extract pollutants and allow air circulation through the tunnel. It is generally beneficial in short pedestrian tunnels, but it can also be used in short tunnels for vehicles.

It is the most cost-efficient solution as it does not need energy supplies.

Transverse Ventilation

This type of tunnel ventilation system uses two parallel ducts: one is to draw fresh air in, whilst the other extracts harmful gases and substances. These fans are usually located at the entrances of the tunnel so that air circulation is always guaranteed.

It is the most suitable solution for medium-length tunnels. Unlike natural ventilation, in this case installation costs and power consumption are higher to allow a continuous airflow in and out of the structure.

Longitudinal Ventilation

Longitudinal ventilation uses jet fans installed across the tunnel’s length. The effect is that airflow speeds up the so that contaminants do not have the time to linger inside the tunnel. The jet fan model is easy to install in an existing structure.

In case of fire, a longitudinal ventilation system keeps the area upstream of the fire smoke-free, which meaning that there should be no need for escape routes. However, emergency exits may be required in order to fight effectively against unpredictable events, such as a fire which becomes unmanageable by the ventilation system, or an explosion.

Underground Ventilation

This type of tunnel ventilation system is specially engineered for underground tunnels. As the setting is unique, fans need to be compact in order to perfectly match the limited space of this structure. Additionally, hazardous gases often stagnate in this environment.

Therefore, underground ventilation, in order to preserve air quality and prevent accidents, is the perfect combination of all the features of the other systems to ensure the utmost safety.

How The Tunnel Working Environment Affects The Choice of The Type of Fan to Install in Your Ventilation System

The environment of a tunnel has a significant influence on the selection of the most appropriate type of ventilation system. Consequently, it is necessary to take some aspects into consideration, such as:

Length, which defines how volatile contaminants linger, expand, and concentrate throughout the tunnel. In fact, long tunnels are more likely to face an air deterioration process. As a result, a more sturdy fan can be the right choice for this ventilation system as it could move larger air volume, being more effective in this type of context.
Usage, as to say if the tunnel is intended for vehicles, trains, or pedestrians. In this case, thorough thoughts about the type and the volume of traffic can be relevant.
Different means of transport produce various levels of pollutants, causing volatile components to permeate air, varying from a setting to another.
Geographical features such as height and temperature could also influence the air quality in the tunnel.

For all these reasons, it is important to find the most suitable type of fan for these ventilation systems based on the infrastructural specifications of the tunnel. Only by carefully selecting these solutions, will it be possible to guarantee the conformity of the structure to strict safety regulations.

Would you like to know more about how CBI Group can help you find the perfect type of fan for your tunnel ventilation system?

CBI Group can help you find the right type of fan for your tunnel ventilation system thanks to a specific series dedicated to the most performing blowers for this context.

The CBJET series has been especially engineered with airfoil blades and a direct drive system to ensure an optimal aerodynamic handling. This fan as thrust capabilities ranging from 500 to 3,000N with flow rates up to 260,000 m³/h. It is the perfect series to handle air extraction and management in a tunnel ventilation structure. The device also acts as an emergency system for forced evacuation of smoke and heat.

Choosing this CBI Group jet fans guarantees a high level of operational flexibility because it can deal with reversible or one-directional airflow requirements, moving air within any tunnel setting. The advanced design of this fan provides excellent aerodynamic efficiency, enhancing performance whilst reducing energy consumption.

Another great series by CBI Group is the AXL model. This solution is ideal for both civil and industrial applications, as well as for tunnel ventilation systems. With airfoil blades and direct coupling, this axial fan is capable of handling pressures up to 5,000 Pa and a flow rate up to 830,000 m³/h. The AXL series is also fully equipped to act as an emergency fan, crucial for the forced evacuation of smoke and heat during fire incidents.

Each CBI Group model is designed and manufactured to perform reliably under the most demanding conditions, with subsequent cost savings over the fan lifespan.

The durability and high-performance of this fan is the result of:

The selection of the highest quality materials for prolonged usage.
The rigorous testing to extreme temperature settings (up to 400°C for two hours) to meet the EN 12101-3 standards and to be compliant with the AMCA and ISO international regulations.

Each unit also comes with aeraulic performance certifications from Notified Bodies (No-Bo).