Smoke leakage (S): The duct shall not have a leakage exceeding 5 m³/h for every 1 m² of inner area spot. This shall be linked to the surface place in the duct in the perforated plate to the top of the duct because of the inlet nozzles. ROCKWOOL ROXUL Safe® https://grease-tight-extract-duct02345.izrablog.com/37341350/helping-the-others-realize-the-advantages-of-fire-resisting-ductwork-insulation