Composed of air supply fans, air ducts, air supply outlets, and control systems. It delivers fresh air to protected areas, such as stairwells and lobbies, ensuring that the air pressure in these areas is higher than in adjacent areas, preventing smoke from entering.

Utilizes the openings of the building itself, such as windows and balconies, relying on natural wind and thermal pressure to achieve air circulation, thereby preventing smoke intrusion. This method does not require mechanical equipment, is cost-effective, but is significantly affected by external environmental conditions.

Typically consists of smoke exhaust fans, smoke exhaust ducts, smoke exhaust outlets, smoke barriers, and smoke exhaust fire dampers. During a fire, the smoke exhaust fan activates, drawing smoke into the duct through the exhaust outlet and then expelling it outdoors. Smoke barriers are used to block smoke diffusion within a certain height range, while smoke exhaust fire dampers automatically close when the temperature in the duct reaches a certain value, preventing the spread of fire.

Utilizes the building's external windows, balconies, or dedicated smoke exhaust outlets, leveraging the buoyancy of hot smoke and wind to naturally expel smoke outdoors. It features a simple structure and low maintenance costs, but the effectiveness of smoke exhaust is also limited by building structure and meteorological conditions.

Whether through mechanical pressurized air supply or natural ventilation, the core is to maintain a pressure difference between the smoke prevention area and the surrounding environment. The reasonable setting of positive pressure values is key; generally, the positive pressure value in the stairwell should be higher than that in the anteroom, and the positive pressure value in the anteroom should be higher than that in the corridor, thus forming an air barrier that prevents smoke intrusion during a fire.

The mechanical smoke exhaust system relies on the power generated by the smoke exhaust fan to forcibly expel smoke from the building. The natural smoke exhaust system utilizes the thermal expansion and contraction characteristics of hot smoke, making its density lower than that of the surrounding air, allowing it to rise under buoyancy and be expelled through natural smoke outlets.

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