Reference: thread403-82316: Fan Horsepower equation derivation
I seem to lose out on this subject. Please note the following:
Fan BHP = (cfm x static press "w.c.) / (6356 x fan efficiency)
Fam Motor HP = fan bhp / motor efficiency
Following are values from a propeller fan manufacturer's catalog for a particular fan:
Static press. = 0.125"w.c. , cfm = 11,207 Fan motor HP = 1.437
By using the above formula fan BHP = (11,207 x 0.125) / (6356 x .7) = 0.31
Motor HP = 0.3148 / 0.9 = 0.35
There is enormous discrepancy between calculated Fan Motor HP of 0.35 and the fan OEM catalog value of 1.437 HP. This is typical of all fan OEM catalogs I see.
Can somebody shed some light?
Thank you and have a great day!