Calculation for draining a tank 3

[roes]

I would like to know the calculation for finding the time to drain a static, atmospheric tank of water to a pit, which is also at atmospheric pressure. Can anyone help? Please include friction loss and minor losses.

 

[Latexman]

A related post, thread798-58749, gave a website that has a calculator for "Drainage time for vertical tanks". It's here -

http://www.freecalc.com/vessels.htm

Good luck,
Latexman

 

[roes]

Latexman

Thanks for information. I had looked at the site you gave me, but I was also looking for the actual calculation so that I can check the answers by hand.

 

[klem]

ROES,
The FreeCalc linh has a reference to a Chem. Eng. article giving the basis which should fulfill your needs.

Klem

 

[25362]

If you have access to a technical library there are two articles that can be of help:

Chemical Engineering, May 15, 1972 Plant Notebook :"Timing gravity flow from vertical tanks" by E.P. Lynch.

Chemical Engineering, Jan 1989. "Drainig Tanks: How long does it really take ?" by Shoaei and Sommerfeld (with references).

Good luck.

 

[homan0135]

YOU CAN READ FLUID MECHANICS MA GRAW HILL

IN THAT BOOK DESCRIBE TIME DISCHARGE (DRAINING)
PLEASE SEE THAT BOOK

 

[25362]

Formulas fail when vortices form. A vortex may form when:

-The liquid is falling at a rate of more than 1 m/s
-When the outflowing speed is greater than 3 m/s
-When the level is low
-When the drain connection is located away from the tank
walls in large diameter tanks
-When there are large quantities of gas dissolved in the
draining liquid
-When the liquid inlet induces rotation
-When the liquids are near their boiling points
-When Coriolis effects may somehow influence the flow

 

[klem]

If vortices are a problem, a simple breaker of two baffles at 90 degrees attached to the inlet, projecting one pipe diameter (D)above and one D into the inlet has solved the problem for me. The portion above should be about two D wide.

Klem

 

[MariusChE]

So, how do you calculate vortex outflow over a conical nozzle?

remove.marius_che@yahoo.com