Even with a primary FES, some fumes escape 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 from the furnace platform, or open automatically 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 it goes to atmosphere thru 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.