Elevated tank and piping calculation

[DofascoDave]

Hello,

I am a newbie to the forum, and have a question was hoping to get help with. Seems like there is a lot of good information being exchanged here.
It's been a while since I have used bernoulli's equation so hoping I could get some help.

I have a bulk storage tank that tank sits 2.74m above floor level (floor to bottom of tank). At it lowest running volume, the tank fluid level would be 3.3m above floor level. A pipe connects directly to the bottom of the tank, where it runs 30m to its final destination. The pipe eventally discharges into another tank at a level of 0.3m above floor level. With varouius dips and turns along the way, the pipe has 8-90deg and 2-45deg elbows. What I am trying to determine is what would be a typical volumetric flow rate for different sized pipes.

The solution that is flowing through the pipe has a density of 1360 kg/m3.

We are currently changing the construction material from 1" Stainless pipe (0.96" ID) to a Poly-lined steel pipe due to corrosion issues. The diameters we are considering are 1" (0.66" ID) and 1.5" (1.2" ID). The old stainless pipe took a completely different route than the new poly-lined pipe will take, but a rough estimate of the old flow rate was 20 LPM (varied with seasonal temperature and tank level). We are hoping to get a similar flow rate with the new pipes and pipe run.

Any guidance on what flow rates I can expect from the new 1" or 1.5" poly-lined pipe?
Thanks,
Dave

[admin]

I would suggest you to try with pressure drop calculator at:
pressure drop calculator.

For pressure p1 and p2 use water column elevation unit in m of water.

For minor losses coefficient - K use calculator included for K.

[DofascoDave]

Thanks for the link.

Here is my calculation details (I would just paste the report but it wont let me cut and paste?):

- To simplify things I started with assuming no K losses
- I entered 3.3 mWS as my starting P1 and 0.3 mWs as my P2 (had to enter this indirectly, entered 3 mWS as P1-P2).
- 1360 kg/m3 density, had to hunt down the dynamic viscosity = 32 cP
- used 30m pipe length, 0.027m ID based on 1.25" schedule 40 pipe with a liner (.16" liner thickness)

My velocity result was calculated as approximately 0.7 m/s. I know I am in the ball park as the old velocity ranged between 0.4 m/s and 1.0 m/s, depending on tank volume and seasonal temperature (the dynamic viscosity number used was at 25C).

To validate my understanding of the theory on this one, does the calculator simply use the calculation for velocity in a tube, assuming the dP is the change in elevation and laminar flow? Meaning this equation:

V = dP/(32*u*L) * D^2

where dP = pressure drop
u = dynamic viscosity
L = length of pipe
D = inner pipe diameter

Thanks for your help.

[admin]

Here is how you can enable copy/paste o your side:
https://blogs.oracle.com/kyle/entry/cop ... te_in_java

Also, when you press theory button in calculator web page with used equation will be opened in browser.

I will check your results and tell you more, a bit later.

[admin]

I checked you data and as flow is laminar (very high viscosity fluid you have) the equation is for laminar flow used. Reynolds number is just 801 so you are in laminar zone.
I think you did it right.

[jacob374]

To validate my understanding of the theory on this one, does the calculator simply use the calculation for velocity in a tube, assuming the dP is the change in elevation and laminar flow?

[admin]

You can use calculator for change in elevation, but you have to enter that like pressure difference - like elevation difference of 10 m with water in pipe is pressure difference of 10 mWS.
Flow regime is laminar or turbulent depending on the flow itself. You do not need to worry about it. Calculator will take care.