Smoke and heat are a major threat to the safety of people involved in a fire: they hinder the escape and rescue operations.
During a fire, a large amount of smoke and heat is developed, and in very short time invades the environment, reducing the visibility and preventing breathing, increments the internal temperature up to very high values.
The 90% of the victims from fire, in fact, is due to asphyxia, intoxication and breathing of hot fumes.
The development and uncontrolled spread of smoke and heat can lead to increased temperature even in areas far away from the place of ignition and thus generating the phenomenon of fire leap: the objects catch fire by spontaneous combustion and people who fail getting away in time from the fire scene remain trapped.
In this context, the design of systems for smoke and heat control is becoming more and more important as active protection system.
At regulatory level, Italy took its first steps in 1977 with the Concordat Italian Fire (“Systems for evacuation of smoke”), which was followed in 1989 by the UNI-VVF: UNI 9494 – “Heat and smoke evacuators . Features, Sizing and Testing ” (rev. 2007). To date, the UNI 9494 has been updated several times and in 2012 was divided into four parts, each of which addresses different aspects of the theme.
The Smoke and Heat Evacuation Systems are able to maintain a smoke-free layer above the floor by mechanical actions (Forced Evacuation) or taking advantage of natural ventilation (Non Forced Evacuation).
The same code, in fact, distinguishes the natural evacuation systems from the forced, calling both effective: with the same boundary conditions, natural systems and forced systems, although operating according to different principles, guarantee the same level of safety.
It is, therefore, important to have well-ventilated areas to provide effective responses to problems arising from the development of a fire, by acting on it in a preventive way.
Ing. Fabio Spena, Guidi & Partners