Patent ID: 9702565
Date: 2017-07-11
CPC Classifications: F24C,F24F

Claim:
1. A flow control device, comprising: a duct section with a plurality of damper blocking elements, each having a major plane; the damper blocking elements being pivotably connected to the duct section and movable in a range that is limited to ensure that, when the duct section is mounted in a preferred orientation, each of the damper blocking elements major plane always forms an angle of at least 45 degrees from the horizontal throughout the range; the range being such that the plurality of damper blocking elements can selectively, substantially close and open the duct section; a motor drive configured to position the damper blocking elements; and a controller configured to control the motor drive responsively to a fume load detected by at least one of a gas sensor, an optical sensor, a temperature sensor, and a flow sensor, wherein the plurality of damper blocking elements is two damper blocking elements which are interconnected to pivot in opposite directions such that edges thereof meet in the middle of the duct section when the blocking elements are in a closed position and such that the major planes are substantially vertical when the blocking elements are in an open position, and the damper blocking elements pivot on bearings mounted inside the duct section on one side of the duct section and mounted outside the duct section on an opposite side of the duct section such that the one side has no protrusions.