With the development of the economy, various large-scale and high-rise buildings are increasing day by day. However, the construction of fire protection facilities and fire emergency rescue capabilities cannot keep pace. There are serious safety hazards in the fire safety of high-rise buildings, which brings great pressure to urban fire safety. When a fire occurs in a high-rise building, due to the height of the floors, concentration of people, complex functions, long evacuation routes, and rapid spread, it is difficult to fight the fire and evacuate people, which can easily lead to major accidents causing significant casualties and property losses.
Four Major Challenges of High-Rise Fires
Firstly, the "chimney" effect. The vertical stairwells, elevator shafts, and pipe shafts in tall buildings act like chimneys, exacerbating the spread of smoke and flames during a fire. This greatly increases the difficulty of slow personnel evacuation and aerial firefighting in large and high-rise buildings. In addition, high-rise buildings, especially those with luxurious decorations, often have interior furnishings and decoration materials that are combustible or flammable; when burned, they produce toxic gases. After a fire starts inside a building, the smoke and fire first diffuse upward, then turn horizontally upon reaching the ceiling, and move up and down along the walls. As the air circulates, the fire burns more fiercely. Once the roof, windows, doors, or equipment holes burn through, the fire will quickly spread outward. Tests show that during a fire, the horizontal flow speed of smoke and fire is 0.3-0.8 meters/second; vertically, it is 2.4 meters/second. Without obstructions, smoke can spread from one end to the other of a building about a hundred meters long in just 2-5.5 minutes; in the vertical direction, it can spread dozens of floors in less than a minute, forming a "three-dimensional fire scene."
Secondly, difficulties in evacuating people, which can easily lead to major accidents. Once a fire breaks out in a high-rise building, it is difficult to evacuate people, often resulting in significant casualties. This is because: Firstly, there are concentrated people but few evacuation facilities. Since ordinary elevators can accelerate the spread of smoke and fire, they cannot guarantee safe evacuation, so only stairs can be used for evacuation. High-rise civilian buildings accommodate many people, making it challenging to evacuate everyone within a short time. In the chaos, tragedies such as trampling are inevitable. Secondly, with many floors, tall buildings, and long vertical evacuation distances, the required evacuation time is long. Moreover, the direction of people's evacuation is opposite to the direction of smoke and fire spread, forcing them to evacuate while being baked by smoke and hot air currents, further increasing the difficulty and danger of evacuation. Evacuees may be knocked down by smoke and fire.
Thirdly, insufficient fire protection facilities. Height limitations of elevated vehicles for firefighting. Currently, the highest elevated vehicle in China reaches only 101 meters, but due to factors such as site conditions, weather, and fire intensity, its actual working height is hard to reach its maximum potential. Additionally, the effectiveness of using water guns or water cannons for external attack streams is significantly reduced. When the power supply to the fire elevator is cut off and the elevated vehicle cannot reach the fire floor, firefighters have no choice but to climb upwards along internal evacuation stairs. This would be affected by the smoke-proof performance of the evacuation stairs, and could result in conflicts with the downward-moving crowd, slowing both the evacuation and the firefighter's climbing speed.
Fourthly, limitations in firefighters' ability to ascend heights. During firefighting and rescue operations, firefighters generally carry at least 20 kilograms of equipment while climbing, consuming a lot of physical strength. By the time they reach the fire floor, they may be physically exhausted, reducing their combat effectiveness. Moreover, the oxygen tanks carried by firefighters typically last only about 30 minutes or even shorter, requiring frequent replacements and wasting a lot of time.
Due to the great difficulty in rescuing high-rise fires, prevention becomes particularly important. The following points should be observed:
Firstly, fire protection design should comply with national standards. With the improvement of living standards, people pay more attention to home decoration, using various materials. Fire-prone decoration materials not only help the fire spread but also accelerate the fire situation. Currently, according to technical means, different fire resistance grades, different heights, different usage statuses, and the current state of exterior wall insulation material technology in our country, multiple technical combinations should be adopted to achieve the corresponding fire safety grade while vigorously promoting energy-saving and emission reduction in buildings.
1. For buildings over 60 meters in height, all exterior windows should have a fire-resistant performance of no less than 1 hour, and the combustion performance of their insulation materials should not be lower than B2 level.
When B2 level insulation materials are used, each floor should have a horizontal fire isolation belt.
2. For buildings with a height greater than or equal to 24 meters and less than 60 meters, exterior windows should have a fire-resistant performance of no less than 25 minutes, and the combustion performance of their insulation materials should not be lower than B2 level. When B2 level insulation materials are used, a horizontal fire isolation belt should be set every two floors.
3. For buildings less than 24 meters in height, exterior windows should have a fire-resistant performance of no less than 25 minutes, and the combustion performance of their insulation materials should not be lower than B2 level. Among them, when B2 level insulation materials are used, a horizontal fire isolation belt should be set every three floors.
4. For building exterior windows without window spandrels and sill walls, to prevent inter-floor fire spread, there should be a limitation of fire-resistant performance of no less than 1 hour.
5. When a fire isolation belt needs to be set, A-level insulation materials with a width of no less than 300 millimeters should be set along the floor position. The fire isolation belt should be fully adhered to the wall.
Secondly, maintenance and repair of fire protection facilities in high-rise buildings should be strengthened to ensure normal system operation. High-rise buildings are equipped with relatively complete fire protection facilities, such as smoke exhaust systems, automatic fire alarm systems, automatic sprinkler systems, gas automatic fire extinguishing systems, etc. These facilities can promptly detect fires and quickly extinguish them, reducing losses and casualties, effectively enhancing the self-prevention and self-rescue capabilities of high-rise buildings. Therefore, strengthening the maintenance and repair of fire protection facilities in high-rise buildings is an essential task to ensure fire safety.
Thirdly, responsibilities should be assigned to individuals. (1) Clarify the maintenance managers and their responsibilities for building fire protection facilities; (2) Formulate and implement the maintenance management system for building fire protection facilities; (3) Organize operators of automatic fire protection facilities to undergo fire safety training and obtain certification; (4) Legally manage on-duty shifts, patrols, inspections, repairs, maintenance, archiving, and other maintenance tasks for building fire protection facilities.
Fourthly, conduct practical drills. We often hear about practical drills conducted by the fire department, but residents of high-rise buildings have not organized such practical exercises. High-rise safety concerns everyone, and understanding and mastering necessary fire escape experiences is the most crucial reassurance for people living in high-rises. It is hoped that relevant departments will organize more such drills, allowing everyone to become a firefighter.
Hubei Jiangnan Dongfeng Special Purpose Vehicle Co., Ltd. is a designated production factory by the National Development and Reform Commission, the only manufacturer in the capital of special purpose vehicles with fire truck production qualifications certified by the Ministry of Public Security Fire Bureau, and a supporting modification plant of Dongfeng Motor Corporation. The main products produced and sold include fire trucks, recovery vehicles, aerial work platforms, wing-opening box transport vehicles, water sprinklers, refueling vehicles, chemical liquid transport vehicles, flatbed transport vehicles, mobile power vehicles, garbage trucks, and hundreds of varieties. All models have been listed in the national announcement directory, obtained ISO9001-2000 quality management system certification, and product CCC certification.
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