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Equivalent Round Duct Calculator App



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The Eastern Sheet Metal Rectangle to Round Duct Calculator App is used by sheet metal contractors and installers, HVAC engineers and contractors to quickly convert the following duct diameters: rectangular to round, oval to round, or rectangular to oval using the U.S. customary system (inches, feet, etc.).

Duct equivalent diameters and properties will include CFM, inches, and water gauge. As measurements are entered into Eastern Sheet Metal’s Rectangle to Round Duct Calculator app, the equivalent round diameter, air velocity, friction rate, and its total friction are calculated in seconds.


To Calculate Rectangular to Round:
Enter Input Data for the following:
• a = length of one side of rectangular duct (in.)
• b = length of adjacent side of rectangular duct (in.)
• Q = volume flow rate (cfm)
• L = length of duct (ft.)

Output:
• D = equivalent round diameter (in.)
• V = air velocity (ft./min.)
• FR = friction rate (in. w.g./100 ft.)
• TF = total friction (in. w.g.)
Output delivers calculated and nominal outcomes

To calculate oval to round
Enter Input data for the following:
• aminor = minor dimension of flat oval duct (in.)
• amajor = major dimension of flat oval duct (in.)
• Q = volume flow rate (cfm)
• L = length of duct (ft.)

Output:
• D = equivalent round diameter (in.)
• V = air velocity (ft./min.)
• FR = friction rate (in. w.g./100 ft.)
• TF = total friction (in. w.g.)
Output delivers calculated and nominal outcomes

To calculate rectangular to oval
Enter Input data for the following:
• a = length of one side of rectangular duct (in.)
• b = length of adjacent side of rectangular duct (in.)
• aminor = minor dimension of flat oval duct (in.)