What is important to consider when choosing smoke ventilation and what is a smoke fan? This is what we will try to clarifiy in this article.
Why is smoke ventilation needed?
Smoke ventilation plays a critical role in the fire protection of buildings and public spaces. By limiting the spread of smoke and heat, this technology protects property and saves lives.
Ventilation can occur passively by utilizing the thermal heat expansion of the fire gases that open, for example, fire gas hatches, or forcefully with the help of smoke exhaust fans.
The goal of all smoke ventilation is to remove fire gases from areas where they can pose a danger to people in buildings or tunnels. In this way, it is ensured that evacuation routes function while also facilitating the work of the rescue services.
What are smoke fans?
Smoke exhaust fans are fans specifically designed to handle the extremely high temperatures and smoke development that occur during a fire. This is achieved, among other things, by:
- Fan impellers with specially adapted (and sometimes reinforced) hubs and blades.
- This means that they can withstand high peripheral speeds even at extreme temperatures.
- Motors with special grease in the bearings
- Without the right adaptation to the heat, motors would seize and fail to continue rotating.
But also through the adaptation of other parts such as motor cables, external junction boxes, frameworks, vibration dampers with fail-safety.
Types of smoke fans
There are several types of fans that can be classified as smoke exhaust fans. Depending on the installation, the choice of fan is adapted to best meet the need. For example, we at FläktComp provide both axial fans for installation in ventilation ducts and jet fans for installation in tunnel spaces.
Both of these fan types can be adapted and certified as smoke exhaust fans.
Operation of smoke fans
Normal operation and fire case
In this mode of operation, the fans are designed to normally handle the general ventilation of the space and, in case of fire, increase the flow and function as smoke exhaust fans.
Simply put, the fans have two modes of operation where normal operation handles the daily ventilation needs and the higher operation mode is in case of a fire.
The advantage of this is that no extra fans need to be installed for smoke ventilation. The downside might be that the fans are optimized for operation in case of fire, and thus do not have a fully optimized efficiency during normal operation.
Fire ventilation only
This type of operation means that the fans are designed to be as effective as possible at ventilating toxic fire smoke as quickly as possible in the event of a fire. The fans are not part of the normal ventilation system.
The advantage of such a system is that the fans are well adapted for the intended fire case, as they are not used in normal operation. Since they are on standby, they are not at risk of being clogged and having problems delivering the right performance in the event of a fire. The downside is that there is a risk that the fans “are forgotten”. It is still important to include the fans in service rounds. The fan wheels must be rotated and test-run regularly, to ensure that the fans work in case of a fire.
Temperatures and certifications
All smoke fans must be certified by an independent organization for a specific temperature and operation time. Without this, the fans may not be sold with their respective certification. Each fan design must be certified as a complete unit. This means, for example, that for certain temperatures and fan designs, our fans are only certified with a motor from ABB, while other designs are certified with a motor from WEG.
When planning and designing fire ventilation, it is important to calculate the temperature that the fans will handle. The temperature is then matched against one of the standards applicable to smoke fans as follows:
- F200 for operation at 200°C for 2 hours
- F300 for operation at 300°C for 2 hours
- F400 for operation at 400°C for 2 hours
These certifications indicate the fan’s ability to operate at high temperatures for a predetermined time – a critical factor in fire protection. Note that the standard for fans differs from other fire protection classifications (e.g., walls and doors which use, for example, EI90) as it solely refers to the temperature of the airflow over a set period.
Test of smoke ventilation in a Hamburg tunnel with jet fans
FläktComp and smoke ventilation
At FläktComp, we are experts in smoke fans and offer a wide product portfolio to meet your needs. When designing and installing smoke ventilation, it is important to consider all technical and safety aspects.
With our knowledge and experience, we can provide you with the right guidance in choosing a smoke exhaust fan.
Or contact us directly.