Calculating Fluid Flow Rate Through Orifice 2

[KimWonGun]

I am trying to replicate the result of an on-line orifice plate calculator but am apparently overlooking a key point. Can anyone spot my error?

I am using the equation: flow rate = flow coefficient*orifice area*sqrt(2(deltaP)/density)for a fluid.

where flow coefficient = discharge coefficient / sqrt(1-(d2/d1)^4)

inner pipe diameter (d1) = 0.837 in
orifice diameter (d2) = 0.579 in
kinematic viscosity @200F = 1.32 cSt
deltaP = 1 psi
specific gravity@ 200F = 0.9556
discharge coefficient = 0.63

flow coefficient = 0.63/(sqrt(1-0.579/0.837)^4) = 0.718

flow rate = (0.718)*(pi*(0.579)^2/4)*sqrt(2*1/(0.036111/386))

The calculator shows a flow rate of 28.5 cu in/s while my manual calculation shows 47.6 cu in/s. Where is my error? Even though the dimensional analysis works out, I wonder why the viscosity does not play a part in this equation?

 

[ione]

Viscosity plays a role as it enters the Reynolds number, which is used to calculate the coefficient of discharge (as per ISO 5167).

Please take a look here

http://www.flowmeterdirectory.com/flowmeter_orifice_calc.html

and here

http://www.brighthub.com/engineering/civil/articles/63291.aspx

 

[Latexman]

Run your numbers again. I got 27.6 cu in/s using your exact numbers. Plus you left out s.g. in your calculations. With s.g. I got 28.3 cu in/s.

Good luck,
Latexman