In 2022, 1,504,500 fires resulted in 3,790 civilian deaths and 13,250 injuries. In addition, there were 96 on-duty firefighter deaths. Apartment structure fires account for 12.4% of deaths and 20.8% of injuries.
While sprinkler systems will help control the spread of fire in the office or living areas - wet, slippery stairs pose a hazard of their own. The best alternative is to pressurize the staircase.
Stair pressurization systems are a common choice for providing the required smokeproof enclosures in high-rise and underground buildings. Stair pressurization is considered a smoke control system and must comply with the requirements of IBC 909, including the provision of a rational analysis and special inspections.
In the event of an emergency, it takes longer to evacuate high-rise buildings; they are likely to have far more people trying to get out using routes that generally only accommodate a handful of people at a time. People in the higher floors have further to travel to reach safety and, the lower they get, the more people will be using the same route. Installing effective measures to keep emergency escape routes smoke- and heat-free for as long as possible is therefore essential to give everyone time to get to safety. It also reduces panic which can result in falls and crush injuries.
Fire and rescue services employees are also less at risk if there are safe areas from which to fight fires and to escape if needed.
Incorporating a stairwell pressurization system in a high rise building ensures that fire evacuation routes are free of smoke and heat. These specialized systems also assist with the containment of fires and provide firefighters with access to areas to extinguish fires.
The installation of stair pressurization systems is crucial for facilitating evacuation, preserving human lives, and reducing property losses in fire outbreaks.
The pressurization of staircases is engineered to prevent smoke and heat from leaking past closed doors and infiltrating stairwells. The systems control air pressures to restrict smoke and heat movements.
These systems keep emergency exit routes clear of smoke and fire in the event of an outbreak by controlling the air pressure in an escape route. The air pressure differences between the area on fire and the stairwell ensure a smoke and heat-free emergency escape route.
It is essential that the installed staircase pressurization system establishes and maintains the correct minimum and maximum air pressures in the stairwell. The basic design criteria for a stairway pressurization system is to provide a minimum of 0.10 inches of water pressure differential and a maximum of 0.35 inches of water pressure differential in the stairway, relative to the rest of the building.
A stair pressurization system is mechanically designed to establish air pressure variations between adjoining areas – such as an emergency escape route and a burning room. These air pressure differences (or variations) ensure that one side of a wall has positive and the other negative air pressure.
Combined air injection, air pressure relief, and air release from the area on fire are necessary for the effective functioning of a pressurization system. This is established by injecting air into the staircase, using a powerful fan, ensuring the air pressure in the emergency escape stairwells is greater than the air pressure area where the fire is raging. The stairwell’s positive (or greater) air pressure prevents smoke and heat from leaking into the escape route.
In the event of a fire, as emergency exit doors are opened , the increased air pressure pushes back smoke and heat, preventing both from entering the stairwell. Fire Dampers or vents prevent the pressure from getting too high – which would make opening doors difficult – while a smoke extraction system in the areas on fire will draw smoke and heat away to the outside.
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