ASHRAE Calculations Dryer-Ell
ASHRAE Fundamentals Handbook has a methodology for calculating the friction loss in ducts and fittings. Based on these formulas, Dryer-Ells can be measured the same as straight pipe. This permits use of the maximum allowed run length. A ten inch radius smooth interior ninety degree bend will only have an equivalent vent length of 1-1/2 feet ...
More details