Fundamental Characteristics of Fire Rated Ductwork

Fire rated ductwork usually needs to pass through compartment walls or floors that will have a prescribed fire resistance period in terms of the load-bearing capacity, integrity and insulation criteria, for durations of 30 to 240 minutes. It is a requirement that where these compartment walls/floors are penetrated by HVAC ducts or other building services, the fire performance criteria for the penetrated wall or floor are maintained, such that fire in one compartment may not spread to other areas. So, the fire-resisting duct needs to maintain i.e., not compromise the fire resistance of the wall or floor through which it penetrates. The performance of a fire-resisting duct which penetrates a fire resisting/separating element requires careful consideration by specifiers and controlling authorities. The standard periods of stability and integrity should in all cases be at least equal to those required for the penetrated element of construction. – Blue book

The methods followed for the fire resistance of walls and floors penetrated by ventilation HVAC ducts in building regulatory requirements and under the guidance of BS 9999: