This standard describes the state of the art of downstream dust separators for small and medium-scale firing systems fired with solid fuels in accordance with the scope of the 1. BImSchV (Federal Emissions Protection Act). A distinction is made between the following types of heating: single-room firing systems of all stated performances within the scope of the 1. BImSchV, fired with solid fuels; boilers with a nominal heat output from 4 kW up to 50 kW, fired with wood and coal as fuel; boilers with a nominal heat output up to more than 50 kW up to 1000 kW, fired with wood and coal as fuel; boilers with a nominal heat output from 4 kW up to 100 kW, fired with with fossil fuels of type no. 8 and no. 13 of the 1.BImSchV. The standard defines which efficiency (in this case particularly the separation efficiency) is to be seen as the state of the art for separators for this type of heaters.