Grease or kitchen extract ductwork is normally constructed from metal, usually galvanised sheet steel in a rectangular or spiral-wound circular structure, but can also be constructed from all-welded ‘black iron’ or chrome steel. Kitchen extract systems must be often inspected, analyzed, and cleaned to satisfy European and local basic safety https://fireresistingductwork78900.59bloggers.com/29279198/top-guidelines-of-kitchen-extract-systems