New fire safety solution for blocks of flats under test

For further information, please contact:

Raimo Perttunen
Fläkt Woods Oy
+358 40 868 3536
raimo.perttunen@flaktwoods.com 
 
Application page: Fire Safety

According to The Finnish National Rescue Association (SPEK), 90 people were killed in fires in 2007. The figure is significantly lower than that for 2006, which was the worst year for decades with 126 fire victims.

Given the population the figure is among the highest internationally, and there is no downward trend despite the constant introduction of new safety equipment and systems, required by law and enabled by advanced technology. The situation calls for even more decisive action.

A typical fire victim fails, for one reason or another, to escape from an apartment on fire, where the conditions may turn fatal in 2 to 3 minutes, before the arrival of the fire brigade. Others manage to escape from the flames but in doing so inhale a lethal amount of toxic gases.

Pressurisation provides unobstructed exit from an enclosed staircase

According to the National Building Code of Finland, easy-to-open windows and natural ventilators in the staircase, intended for use by the fire brigade, are an adequate smoke ventilation system for a building with a maximum of eight storeys. However, as such a system does not allow smoke ventilation until the fire brigade has arrived; it is not always able to ensure a safe and timely exit in cases where large quantities of smoke are transferred from an apartment on fire to the staircase.

Fläkt Woods has developed, on the basis of new European standards for smoke control, a system for automatic pressurisation of staircases in residential buildings in case of fire. Pressurisation is an effective means of maintaining a safe escape route as it prevents the staircase from filling up with smoke.

The system incorporates a pressurisation fan that starts automatically on a signal from smoke detectors. A frequency inverter sets the rotation speed of the fan to maintain an overpressure of 50 Pa in the stairwell when the doors are closed. The overpressure prohibits smoke and gases from entering the stairwell, but still allows the doors to be opened.

Myllypuro fire tests

Tests on the pressurisation system were scheduled for 20–21 February 2008 on Alakiventie Street in Myllypuro, Helsinki, on a block of flats due for demolition. The tests were conducted by Fläkt Woods Oy, The City of Helsinki Rescue Department, Inspecta Oy and VTT Technical Research Centre of Finland under actual fire conditions to determine the suitability of the pressurisation system for use as a fire safety solution in low-rise residential buildings. Conventionally, pressurisation has only been used in extremely tall buildings.

The tests involved setting fire to a one-bedroom flat with normal fire load to find out, for example, how long the system would be able to keep the staircase clear of smoke in different circumstances. More information was needed about the effects of window opening, among other things. The test plan contained four different fire tests.