Smoke leakage (S): The duct shall not Possess a leakage exceeding five m³/h for every 1 m² of inside surface area space. This shall be relevant to the surface area space with the duct from your perforated plate to the end of your duct through the inlet nozzles. ROCKWOOL ROXUL https://fireresistingductworkinsu46778.therainblog.com/35779118/fire-resisting-ductwork-insulation-an-overview