Output Power
BHP = Q x SP / (6356 x Fan Ef f.)
Where
• BHP = Break Horsepower
• Pt = Total pressure, in-WG
• Q = Air flow rate in CFM
• SP = Static pressure in-WG
• FAN EFF = Fan efficiency usually in 65–85% range
Fan Motor Horsepower
Motor HP = BHP / MotorEFF
Where
• BHP = Break Horsepower
• MotorEFF = Motor drive efficienc y usually 80-95%
Tip Speed
Ts = 3.14 x D x N
Where
• Ts = Fan tip speed, FPM
• D = Fan diameter, ft
• N = Fan speed, RPM
V-belt Length Formula
Once a sheave combination is selected we can calculate approximate belt length. Calculate the approximate V-belt length using the following formula:
L = 2C + 1.57 * (D+d) + (D-d)2/ 4C
Where
• L = Pitch Length of Belt
• C = Center Distance of Sheaves
• D = Pitch Diameter of Large Sheave
• d = Pitch Diameter of Small Sheave
