Fan Power Equation
Fan Power Equation
(OP)
What is the correct type of pressure (static or total) used in the compressibility factor, KP, when calculating fan power? Howden's Fan Engineering book seems to indicate total pressures should be used, but I also have a PDF from Howden that indicates static pressures should be used. Online searching has also shown mixed answers. For my calculation, I did it both ways and the difference was small enough to be considered negligible by engineering judgement, however, I would still like to know the correct





RE: Fan Power Equation
RE: Fan Power Equation
RE: Fan Power Equation
RE: Fan Power Equation
RE: Fan Power Equation
The power equation for a fan is:
H = (Q*PT*KP) / (6356*NT)
Where,
H = fan shaft power [hp]
NT = fan total efficiency [%]
Q = fan inlet volumetric flow [acfm]
PT = fan total pressure [in. w.c.]
6356 is a conversion factor
KP = compressibility factor
ProcessHVAC
Good heads up info. The pressures used in the compressibility factor equation are absolute fan inlet and outlet pressures. So far I haven't seen the words "external" or "total" paired with "static." Just "total" or "static" used seperately.