Patent ID: 9719686
Date: 2017-08-01
CPC Classifications: F24C,F24F

Claim:
1. A system comprising: an exhaust hood arranged above a fume source in a vertical direction so as to capture fumes from the fume source; a duct connected to the exhaust hood that conveys the fumes captured by the exhaust hood; a flow control device disposed in a section of the duct, the flow control device comprising a plurality of damper blocking elements, each of the damper blocking elements having a major plane, the damper blocking elements being pivotably connected to the section of the duct and movable in a range that is limited to ensure that the respective major plane of each of the damper blocking elements always forms an angle of at least 45 degrees with respect to a horizontal direction throughout the range, the range being such that the plurality of damper blocking elements can selectively, substantially close and open the section of the duct; a motor drive configured to position the damper blocking elements in the section of the duct; at least one sensor that detects a fume load captured by the exhaust hood, the at least one sensor comprising a gas sensor, an optical sensor, a temperature sensor, or a flow sensor; and a controller configured to control the motor drive responsively to a fume load detected by the at least one sensor; the controller further being configured to detect when the fume source is off and when the fume source is on responsively to said at least one sensor 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.