According to relevant statistics, 80% of the deaths in the fire are caused by the inhalation of toxic smoke, therefore, the effective discharge of toxic smoke not only provides a clear line of sight and breathing space required for escape, reduce casualties, but also allows firefighters to create better conditions for extinguishing the fire. As the key component of the fire control system, the fire resistance of the smoke exhaust duct can not be ignored.

The fire resistance time of the smoke exhaust duct is determined according to the position set by itself. According to the relevant provisions of the Technical Standards for Smoke Control and Exhaust Systems in Buildings, the fire resistance limit of smoke exhaust ducts set up in independent Wells, suspended ceilings, garages, spare rooms, etc., should not be less than 0.5h, and the fire resistance limit of smoke exhaust ducts passing through fire zones and indoor areas should not be less than 1h.

Of course, the fire resistance time of the smoke exhaust duct is not unchanged, but is affected by a variety of factors. Architectural design specifications, material selection, installation process and other factors will have an impact on its fire resistance. Therefore, these factors need to be considered comprehensively when determining the fire resistance time of the smoke exhaust duct.

At present, metal air ducts are commonly used on the market as smoke exhaust air ducts, but these air ducts cannot meet the relevant requirements. Therefore, it is necessary to use refractory materials to increase the fire resistance of these air ducts, such as the use of glass wool, rock wool, fire retardant board and other class A non-combustible materials to fireproof the smoke exhaust duct to provide its fire resistance.

The fire resistance time of smoke exhaust duct is very important. In the event of a fire, a long enough fire resistance time can ensure the continuous and stable operation of the smoke control and exhaust system, and provide necessary support for fire suppression and personnel evacuation. Therefore, in the design and selection of smoke exhaust duct, the fire resistance requirements should be fully considered, and effective measures should be taken to improve the fire resistance time.