Smoke leakage (S): The duct shall not Have got a leakage exceeding 5 m³/h for each one m² of internal surface area place. This shall be associated with the surface area space in the duct within the perforated plate to the end in the duct via the inlet nozzles. Pressurisation https://grease-tight-extract-duct90011.spintheblog.com/37494365/the-basic-principles-of-grease-tight-extract-ductwork