Smoke leakage (S): The duct shall not Have a very leakage exceeding five m³/h for each one m² of inside floor space. This shall be linked to the surface area spot on the duct with the perforated plate to the top of the duct because of the inlet nozzles. Pressurisation https://fire-resisting-ductwork-i45566.idblogmaker.com/36040421/5-essential-elements-for-grease-tight-extract-ductwork