Fume extractor hood , comprising a flow generator for providing a forced flow in an active mode of the flow generator , an exhaust duct for guiding an exhaust flow , a cleaning device for cleaning a recirculation flow , a splitting device for splitting the forced flow in the exhaust flow and the recirculation flow , wherein in the active mode, the splitting device is in a first fixed state with a first opening area to the exhaust duct so that the forced flow is split in the exhaust flow and the recirculation flow through the cleaning device , characterized in that in a passive mode, in which the flow generator is inactive, the splitting device is in a second fixed state with a second opening area to the exhaust duct for preventing the recirculation flow and for allowing a basic flow , wherein the splitting device is a mechanical device and comprises at least one flap and/or one slider and/or one plate and/or one fin, which is movable for setting the first opening area and second opening area , wherein a movement is achieved by an actuator or electronical and/or mechanical means triggered by a control unit , and wherein the first and/or the second fixed state of the splitting device is/are set up, preferably by mechanical or electronical means, during installation and/or the start-up of the extractor hood based on the pressure and/or the flow of the forced flow , exhaust flow and/or basic flow measured within the extractor hood and/or the exhaust duct , wherein a measuring device is arranged upstream and/or downstream the splitting device for measuring the pressure and/or the flow of the forced flow , exhaust flow and/or basic flow within the extractor hood or in the exhaust duct , wherein the measuring device comprises a test valve, which is preferably arranged in the splitting device and/or at an inner wall of the extractor hood or the exhaust duct , and a measurement unit, which is removable or permanently connected to the test valve. a flow generator for providing a forced flow in an active mode of the flow generator , an exhaust duct for guiding an exhaust flow , a cleaning device for cleaning a recirculation flow , a splitting device for splitting the forced flow in the exhaust flow and the recirculation flow , wherein in the active mode, the splitting device is in a first fixed state with a first opening area to the exhaust duct so that the forced flow is split in the exhaust flow and the recirculation flow through the cleaning device , characterized in that in a passive mode, in which the flow generator is inactive, the splitting device is in a second fixed state with a second opening area to the exhaust duct for preventing the recirculation flow and for allowing a basic flow , wherein the splitting device is a mechanical device and comprises at least one flap and/or one slider and/or one plate and/or one fin, which is movable for setting the first opening area and second opening area , wherein a movement is achieved by an actuator or electronical and/or mechanical means triggered by a control unit , and wherein the first and/or the second fixed state of the splitting device is/are set up, preferably by mechanical or electronical means, during installation and/or the start-up of the extractor hood based on the pressure and/or the flow of the forced flow , exhaust flow and/or basic flow measured within the extractor hood and/or the exhaust duct , wherein a measuring device is arranged upstream and/or downstream the splitting device for measuring the pressure and/or the flow of the forced flow , exhaust flow and/or basic flow within the extractor hood or in the exhaust duct , wherein the measuring device comprises a test valve, which is preferably arranged in the splitting device and/or at an inner wall of the extractor hood or the exhaust duct , and a measurement unit, which is removable or permanently connected to the test valve. <EOS>