Exhaust systems must be labelled with the valid fire resistance class in accordance with DIN 18160-60. This indicates how long the exhaust system can withstand a fire.
In Germany, a fire resistance period of at least 30 minutes is required for flue gas systems in buildings of building classes 1 and 2 that are operated exclusively with gaseous or liquid fuels and whose temperature class does not exceed T 120. All other systems must withstand a fire for at least 90 minutes.
A distinction is made between the following fire resistance classes for flue gas systems:
L00 = fire resistance of 0 minutes
L30 = fire resistance of at least 30 minutes (fire retardant)
L60 = fire resistance of at least 60 minutes (highly fire retardant)
L90 = fire resistance of at least 90 minutes (fire resistant)
L120 = fire resistance of at least 120 minutes ( highly fire-resistant)
Source: bauwion
