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 ...

Because of this, prekerfed duct liners, like Spiracoustic Plus®, are often the easiest method for lining spiral ducts. The kerfs (grooves) cut into Spiracoustic Plus are spaced to fit the specific ...