Stack damper

Abstract

A damper comprising a duct defining an air flow path, opposing damper blades pivotally mounted within the duct, each damper blade having an end that is pivotally mounted in cantilevered fashion in the duct so that an opposing end is free to move within the duct, wherein each damper blade is planar in shape, cooperating flow straightening members disposed centrally in the air flow path, an air flow sensor for generating a signal cooperatively disposed between the flow straightening members, and an actuator for pivoting each damper blade within the duct in response to the signal from the air flow sensor to vary the damper blade position and thereby maintain a desired velocity of air exiting the damper.

1 . A damper comprising:
 a duct defining an air flow path;   opposing damper blades pivotally mounted within the duct, each damper blade having an end that is pivotally mounted in cantilevered fashion in the duct so that an opposing end is free to move within the duct, wherein each damper blade is planar in shape;   cooperating flow straightening members disposed centrally in the air flow path;   an air flow sensor for generating a signal cooperatively disposed between the flow straightening members; and   an actuator for pivoting each damper blade within the duct in response to the signal from the air flow sensor to vary the damper blade position and thereby maintain a desired velocity of air exiting the damper.   
     
     
         2 . A damper according to  claim 1  wherein said actuator comprises a pneumatic piston engaged with a damper blade shaft. 
     
     
         3 . The damper according to  claim 1  further comprising a controller operatively connected to the sensor and the actuator for automatically controlling pivotal movement of each damper blade in response to the measured change in the air flow so as to maintain a substantially constant discharge air velocity.