The UAE boasts some of the most architecturally advanced cities in the world, with Dubai alone boasting 20 of the world’s tallest 100 towers. These inspirational structures have prompted engineering breakthroughs that have changed construction forever, allowing buildings to reach unbelievable heights of over 2,900 feet.
In recent memory, however, we have seen many cities all over the world suffer catastrophic fires within high-rise structures, bringing safety measures back into the spotlight.
In high-rise buildings particularly, a protected means of escape is enormously important. The maximum height that the fire brigade ladder platforms can reach is 30m. Anything above this is not practical for rescue from the outside, which leaves many occupants needing to make their own way to safety. The stairs and their lobbies become arguably the most important life-safety feature in tall buildings.
In the Middle East, the American National Fire Protection Association (NFPA) standards and legislation requires that buildings must have:
- The required fire escape routes and fire exits.
- Measures in place to ensure the safety of fire escape routes, which include systems preventing the spread of fires and smoke.
- Stairs above specified heights need to be pressurised.
Importance of smoke and heat control in fire escape routes
Many believe burns to be the leading cause of death in fire victims. Statistics, however, indicate that smoke inhalation causes between 50% and 80% of fire-related deaths. Burns primarily affect specific parts of a person’s body, whereas smoke inhalation affects all organs. Incorporating a stairwell pressurisation system in a multi-storey building ensures that fire evacuation routes are free of smoke and heat.
Fire smoke is highly toxic, consisting of gases such as carbon monoxide and hydrogen cyanide. The toxicity increases the longer a fire rages. Respiratory distress, loss of consciousness, asphyxiation and organ failure are some of the effects of smoke inhalation.
Experts estimate that approximately 73% of fire survivors suffer long-term and lasting effects. The non-fatal, chronic consequences of smoke inhalation include numerous respiratory ailments such as emphysema, chronic obstructive pulmonary disease and asthma.
Stairwells are the primary fire escape routes in multi-storey or high-rise buildings. Smoke-filled escaped routes, without a pressure relief damper for the staircase, endanger lives. The installation of stair pressurisation systems is crucial for facilitating evacuation, preserving human lives, and reducing property losses in fire outbreaks.
Purpose of stairwell pressurisation
The pressurisation of stairwells is engineered to prevent smoke and heat from leaking past closed doors and infiltrating stairwells. 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.
Air pressure parameters
It is essential that the installed staircase pressurisation system establishes and maintains the correct minimum and maximum air pressures in the stairwell. The standard on smoke and heat control systems (BS EN 12101-6:2005) prescribes the air-pressure parameters to be maintained in pressurised stairwells.
The air-pressure parameters should be sustained between 50Pa and 60Pa to ensure that smoke is kept out and doors can still be easily opened. Properly designed and installed air-pressure relief vents are one of the best methods to establish and maintain these air pressure parameters.
How a stairwell pressurisation system works
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, ensuring the air pressure in the emergency escape route (stairwells, in high-rise buildings) is greater than the air pressure in the adjacent 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, stairwell doors are opened for entry and exit purposes. The increased air pressure counters the flow of smoke and heat, preventing both from entering the stairwell.
Installing specialised and approved pressure relief vents
Specially designed pressure relief vents – also known as dampers – establish and control these air-pressure requirements. If the stairwell air pressure is too low, smoke and heat will enter the protected area. If the stairwell air pressure is too high, people will not be able to open stairwell doors.
Apreco’s PRV-123 and the PRV-Fℑ pressure relief vents meet all the requirements to prevent the over pressurisation of a stairwell.
Apreco – experts in pressurisation systems – provide services, including advice and guidance, during the tender, design and development phases of high-rise building projects. All Apreco pressure relief vents comply with the required standards, including the BS EN 12101-6:2005. Specialist balancing ensures these vents open when a pressure of 50Pa is reached.
The importance and necessity of pressure relief vents in the pressurisation of stairwells cannot be overstated. These systems prevent smoke and heat from entering escape routes, providing evacuees with the means and time to escape fires. In addition, the vents provide protected entrances for firefighters, and they also delay the spread of fires.
For more information, go to www.apreco.com