Duct Fitting Loss Coefficient

Calculate pressure loss through duct fittings using loss coefficient method for common fitting types.

1=90° Elbow, 2=Tee (branch), 3=Transition, 4=Damper
Velocity in fitting
FPM
Radius/Diameter: Sharp=0.5, Standard=1.0, Long=1.5 (for elbows)
30°, 45°, or 90° (for tees)
degrees

Results

Loss Coefficient (C)-
Velocity Pressure-in wc
Fitting Pressure Loss-in wc
References: ASHRAE Fundamentals Ch. 21, SMACNA HVAC Systems Duct Design, 4th Ed.