I am confronted with the problem of sizing an actuator for a butterfly-like type of air damper in HVAC control. Experienced colleagues and vendors just gave me tables to look into, but I am more interested in knowing the theory behind calculating the required torque to operate a damper, given the duct size and shape, the differential pressure across the damper, and the air flow. Does anybody know of any articles or books on this? I'd appreciate very much your replies.
I would try the website Belimo.com they are the manufacturer of damper actuators and have a nice torque calculator you could use.