How do I select an actuator for airfoil vs. standard damper blades?

Airfoil blades (convex, aerodynamic profile) generate significantly lower pressure drop and lower torque compared to standard flat blades because the streamlined shape reduces the aerodynamic force that the actuator must overcome, particularly at velocities above 2,000 FPM. For the same damper face area and pressure differential, an airfoil-blade damper may require only 60–70% of the actuator torque needed for a standard flat-blade damper, which can mean a smaller and less expensive actuator. However, airfoil dampers are more expensive to manufacture and are typically justified only in large AHU applications (face area >6 ft²) where the torque savings are substantial, or in critical control applications (economizer mixing sections) where the improved flow characteristic improves control stability. When retrofitting, verify the actuator torque requirement against the actual installed damper type — replacing a failed actuator with one sized for flat blades on an airfoil damper is safe (oversized), but using an airfoil-rated actuator on a flat-blade damper will likely result in insufficient torque and failure to close at high differential pressure.