Each year fire outbreaks result in numerous injuries and deaths across the United Kingdom. Fire and rescue services attended more than 180k fire incidents in England during the year ending September 2022 which resulted in 276 fire-related fatalities.
UK legislation requires that commercial buildings must have:
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 pressurise the stairwell.
In the event of an emergency, it takes longer to evacuate multi-storey 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 higher floors have further to travel to reach safety and, the lower down the building they get, the more people they will encounter using the same route. Installing effective measures to minimise smoke and heat within emergency escape routes, for as long as possible is therefore essential to give everyone time to get to safety. Such measures will also reduce panic, which is another potential cause of falls and crush injuries.
Fire and rescue services employees will also be exposed to a lower level of risk if there are safe areas from which to fight fires and to escape if needed.
While sprinkler systems will help control the spread of fire in office or living areas - wet, slippery stairs pose a hazard of their own. The best alternative therefore is to pressurise the stairwell.
Incorporating a stairwell pressurisation system in a multi-storey building ensures that fire evacuation routes are free of smoke and heat. These specialised systems also assist with the containment of fires and provide firefighters with access to areas to extinguish fires.
The installation of stair pressurisation systems is crucial for facilitating evacuation, preserving human lives, and reducing property losses in fire outbreaks.
The principle of pressurising stairwells is to prevent smoke and heat from leaking past closed doors and infiltrating stairwells. These systems are designed to control air pressure at key points within the building to restrict movement of smoke and heat.
There is a legal requirement for architects and developers to incorporate a stairwell pressurisation system into the design and construction of multi-storey buildings. These systems are designed to minimise smoke ingress into emergency exit routes, in the event of a fire outbreak, by controlling the air pressure within each escape route. Air pressure differences between the fire zone and the stairwell, ensure that emergency escape routes have minimal levels of smoke and heat present.
It is essential that the installed staircase pressurisation system establishes and maintains the correct minimum and maximum air pressures in the stairwell. The relevant standard for smoke and heat control systems (BS EN 12101-6:2005) prescribes that air pressure should be controlled between 50 Pa to 60 Pa to ensure that smoke is kept out and doors can still be easily opened. It should be noted however that other countries may have different design limits.
A stairwell pressurisation 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 pressurisation system. This is established by injecting air into the stairwell, using a mechanically driven air movement fan, ensuring that the air pressure within the emergency escape stairwells is greater than the air pressure area within the fire zone. The stairwell’s positive (or greater) air pressure minimises the amount of smoke and heat leaking into the escape route.
In the event of a fire, as stairwell doors are opened for entry and exit purposes, the increased air pressure actively pushes back smoke and heat, helping prevent 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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