Pressure Loss Calculations

[Superfly257]

Hello,

I am trying to calculate the major pressure loss in my system, and I just want to make sure I've done the calculations right.
I'm not sure I'm getting entirely accurate numbers.
Just so you know, the piping is circular, and the fluid being pumped is 15W40 engine oil... the density and viscosity are based off of physical measurements of 15W40 taken in the lab.
Anyway, here are my calculations:

Givens:
½” Piping Dh=0.0127 m
10 ft of tubing = 3.048 m
Max Flow Rate (21 L/min)
Viscosity at 20°C is ? = 357.38 cSt = 0.00035738 m^2/sec
Density = 818 kg/m^3

Pipe Area= ?(0.25)^2= 0.19635 in^2

Volumetric Flow Rate=21 L/min =1281.5 in^3/min =21.36 in^3/sec

Flow Velocity=(Volumetric Flow Rate)/Area= 21.36/0.19635
=108.78 in/sec = 2.763 m/sec

Reynold's Number= (V* D_h)/? =
((2.763)(0.0127))/0.00035738 = 98.187 (Laminar)

?= 64/Re = 64/98.187 = 0.6518

Pressure Loss= ?(L/D_h )((?*V^2)/2)=0.6518(3.048/0.0127)[((818) ?(2.763)?^2)/2]= 488,439.4 Pa

I think this looks a little high, is all this correct, or did I botch it up somewhere?

Thanks,
Superfly

 

[katmar]

Looks right to me. 2,7 m/s is a high velocity for such viscous material in a 1/2" pipe.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[Superfly257]

Okay, good.

So there are no numbers that look totally out of place? I'm just not very familiar with appropriate viscosities and velocities and piping sizes, things like that.

Thanks a lot!
Superfly

 

[vpl]

Any valves in the system? And is it piping or tubing? (You use both words and it makes a difference on the actual inside diameter.

Is this a school problem -- why are you converting back and forth from metric to Imperial units?

Patricia Lougheed

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[Superfly257]

Hi,

Its not a school problem, I am converting between units because I am much more comfortable doing the analysis in metric units (because of the viscosities and densities and such) but my boss wants to see imperial units on my calculations.

Anyway, I was only looking to calculate major pressure loss with this, which is why I didn't include any of the valves or elbows.

I am now trying to calculate the minor pressure loss and I just posted a thread on that, because I am again unsure of the numbers I am getting.

Also, sorry for the mix up, its all piping.

Thanks,
-Superfly