Damper suitable for liquid aerosol-laden flow streams

An exhaust system comprising:

• an exhaust hood having a recess constructed to capture fumes from a fume source;
• a duct section coupled to the exhaust hood so as to receive captured fumes therefrom, the duct section having a cross-section and a flow direction perpendicular to said cross-section;
• a flow control device having a plurality of damper blocking elements disposed in the duct section, each of the damper blocking elements having a major plane;
• a fume load sensor configured to detect a fume load in the duct section;
• a motor drive which positions the damper blocking elements;
• a first bearing and a second bearing supporting a rotation axle of at least one of the plurality of damper blocking elements, the first bearing disposed outside the duct section and the second bearing disposed inside the duct section;
• a seal surrounding at least a portion of the rotation axle that penetrates through a wall of the duct section;
• and
• a controller coupled to the motor drive and configured to control the motor drive responsively to the fume load detected by the fume load sensor, wherein
• each damper blocking element is movable in a respective range from a first position, where the duct section is substantially closed in the flow direction by the damper blocking elements, to a second position, where the duct section is substantially open in the flow direction,
• the controller further being configured to detect, responsively to said fume load sensor, when the fume source is off and when the fume source is on and to substantially close the plurality of damper blocking elements when the fume source is off to prevent air from flowing through said flow control device when the fume source is off, the controller controlling the flow control devices such that it never fully closes when the fume source is on, and
• each of the damper blocking elements has a rigid construction that maintains its shape.