Despite a primary FES on the AOD furnace, some fumes get escaped while the operation of scrape charging, pouring and additives adding. This fume makes a cloud at the top of the shed. In secondary fume extraction system, we install many hoods at the top of the shed with automatic dampers throughout the shed. These dampers are opened as needed from the furnace platform, or open automatically when fumes are sensed and extract the fume from the top of the shed and take it to the pulse jet bag filter or bag filter or air pollution control system. After filtration of fumes and gases is discharged through the ID fan and stack or chimney. Outlet emission performance is specified for the process duty and verified under agreed test conditions depending on the pollution control norms at the location.