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Calcimator

Damper Sizing Calculator

Damper area from CFM and velocity limits.

Inputs

Results

Damper width (in)

24

Damper height (in)

16

Free area (ft²)2.67
Actual velocity (FPM)1,875
Damper drop (in. w.g.)0.22
Damper authority0.31
Authority rating (0-2)1
Equivalent round dia. (in)22.1
Leakage Class I (CFM)10.7
Leakage Class II (CFM)26.7
Required torque (in-lb)19
How to Use This Calculator
  1. Enter Airflow (CFM), Target velocity (FPM), and System delta P (in. w.g.).
  2. Set Aspect ratio (W:H), Blade Type, and Opposed blade (modulating control).
  3. Adjust Parallel blade (2-position/mixing) as needed.
  4. Review Damper width (in) and Damper height (in).
  5. Use Free area (ft²) and Actual velocity (FPM) to inform your decision.
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