These furnaces are generally induction or gas fired furnaces. Here the fume extraction system is generally used to recover fumes, which are a valuable by-product (zinc oxide). In this furnace only primary fume extraction systems are used to collect the zinc powder in the form of zinc and they are collected from the bag filter discharged and packed directly. Outlet emission performance is specified for the process duty and verified under agreed test conditions depending on the pollution control norms at the location.