Smoke leakage (S): The duct shall not Have a very leakage exceeding five m³/h for each 1 m² of interior surface area area. This shall be associated with the area place of the duct in the perforated plate to the top of the duct with the inlet nozzles. CE https://grease-tight-extract-duct12333.blogvivi.com/37576010/5-essential-elements-for-grease-tight-extract-ductwork