Road Tunnel Ventilation
Road tunnel ventilation is required to prevent the build-up of vehicle exhaust fumes and maintain air quality for occupants and enable safe evacuation in the event of an emergency by managing smoke generated from a fire.
Road tunnel ventilation is required to prevent the build-up of vehicle exhaust fumes and maintain air quality for occupants and enable safe evacuation in the event of an emergency by managing smoke generated from a fire.
Ventilation systems in road tunnels serve two primary function. Firstly, they manage the pollution generated by vehicles and, secondly, they are an integral part of emergency life safety system to manage smoke generated from a fire. A good ventilation system is fully integrated into the wider fire protection package but is flexible and functional in these dual scenarios.
During pollution mode, Tunnel Fans are often VFD controlled using Carbon Monoxide (CO) and Nitrogen Oxide (NO)detectors to ensure that the tunnel pollutants are monitored and controlled.
In the event of a fire, this same system will provide the ventilation to extract smoke. The system will perform a vital function ensuring occupants can safely evacuate and emergency services can tackle the source of the fire.
We can provide system design services and tailored products for:
Each of the tunnel ventilation systems use either tunnel jet fans, large axial fans or a combination of the two to provide pollution control ventilation and smoke ventilation in the event of a tunnel fire.
Longitudinal ventilation is used where possible, as it gives the lowest installation and operating cost. The most common method is to use Jet Thrust Fans where the relatively high velocity discharge induces a flow of air through the tunnel. As the jet from the fan diffuses, it transfers energy to the tunnel airflow and creates an increase in static pressure, which causes air to flow as in any conventional system.
Large axial flow fans are used for transverse and semi transverse systems where the air is supplied or extracted through ducts from plant rooms. Normally several fans are used in parallel to provide steps in volume flow. Frequently the fans are VFD controlled to provide additional steps in ventilation, a lower operating cost at low levels of flow and low noise levels for night time operation. Often the fans are 100% reversible so that supply fans can also extract. To clear smoke from one side of a fire, reversible fans may be used with the duct system to create a longitudinal flow along the tunnel.
There can also be occasions where a longitudinal system using Jet Thrust Fans is justified in addition to a transverse system as the operating cost at low ventilation rates is much lower. To avoid pollution at the openings of the tunnel, large fans may be used to capture the tunnel airflow and discharge it at a high level.
As electric vehicles and increasing levels of freight traffic (with potentially flammable loads) increase, particular attention needs to be paid to the long-term fire ventilation requirement of the tunnel.
BACK
United Kingdom
United States
Deutschland