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Concrete duct static loss

Concrete duct static loss

Concrete duct static loss

(OP)
I want to know how to calculate the static pressure losses in a concrete duct.

Thanks

RE: Concrete duct static loss

(OP)
Thanks very much Chasbean1,

Do you think that I can also calculate the friction loss with the ductulator and the use a correction factor depending on the velocity from HVAC rules of Thumb?



  

RE: Concrete duct static loss

It gets a little hairy between laminar and turbulent flow. The friction factor will affect head loss linearly and the change in friction will be linear with laminar flow. But when flow is turbulent, the relative roughness of the pipe comes into play. Using an equation I have from old notes, f when turbulent is a function of:
1 / [(2 log(relative roughness))^.5]
Maybe try crunching the math using the difference in roughness between galvy and concrete by setting up some values for head loss:
H = (f*L*V^2)/(D*2*g), where L is length of pipe, D is diameter, g is gravity (most of this you can make constant). If you get any results from the comparison, pls. post and let us know.
 

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