As air moves from a supply plenum or main duct into a takeoff it changes direction. Airflow has a hard time making turns at high rates of speed, just as we would driving down the interstate. When we ...

In 1948, research by R.G. Huebscher established flow resistance for different shapes of ductwork at equal velocities, which allowed the creation of the duct-sizing calculator or “Ductulator” for ...