Defensive fire protection
Subsumed in the defensive fire protection category are measures intended to rescue humans and animals after a fire has broken out.
Smoke and heat exhaust systems (SHE) form integral parts of every preventive fire protection concept.
Fatal fire victims
In actuality, fatal fire victims mostly succumb to injuries caused by smoke. Up to 90 % of all fatal fire accidents can be attributed to suffocation from smoke gas. The causes of these deaths are the toxic and corrosive components of the gas that result in chemical burns in the lungs and respiratory tract, ultimately leading to the death of the victim.
Misconception of time
Curiously, the first impulse driving a person’s behaviour in the event fire is curiosity rather than fear. We ogle and marvel when we should run away and sound alarm. The second phenomenon commonly observed in such instances is the lack of respect people show towards the heat and destructive power the fire unleashes. The third phenomenon of note is that most people are completely oblivious as to how fire smoke merely takes a few minutes to rapidly spread
and engulf every pathway that could be used as an escape route or for rescue and firefighting operations. The fourth phenomenon we observe time and again is the misguided notion to have enough time to escape the fire.
Protection of human beings (active rescue)
Keep escape and rescue routes clear by removing smoke Full visibility for those trying to escape Save human lives.
Firefighting (passive rescue)
RauPathways for firefighting operations with low smoke formation Quick and targeted firefighting operations by the fire brigade Reduced risk to first responders.
Protection of property
Prevention of full-scale and secondary fires Reduction of devastating damage to the building caused by smoke.
Subsumed under the umbrella term SHE are the following systems:
Natural smoke exhaust systems (NSE)
Smoke extraction by natural lift Suitable for stairwells, industrial structures, atriums, and similar types of buildings where thermal lift is capable of discharging smoke.
Mechanical smoke exhaust system (MSE)
Smoke dissipation by fans Suitable for industrial structures, atriums and similar types of buildings where thermal lift is insufficient for smoke extraction and must be bolstered by fans.
Smoke protection pressure system (SPP)
Smoke suppression by exerting positive pressure Suitable for stairwells in tall buildings and for safety stairwells where smoke must not penetrate emergency routes.
Spreading of smoke without smoke removal
A fire breaking out inside a building always progresses in an entirely different way from an outside fire. The measures intended to provide preventive fire protection must take this fact into account. Every fire releases thermal energy and smoke. Hot smoke rises to the top and fills the room. Unless removed by appropriate means, the smoke in combination with the fire and hot gases will eventually destroy the building.
Spreading of smoke with smoke removal
Smoke and heat are discharged quickly by means of convection (heat dissipation) for the following purposes: minimise smoke formation along rescue and escape routes, guarantee full visibility for those trying to escape, i.e. save lives, prevent the “flashover” effect (smoke ignition), and facilitate firefighting operations by allowing the fire brigade to fight the fire in a quick and targeted manner, thereby preventing secondary fires and preserving property.