To calculate the emptying time of a tank without the discharge pipe
is quite simple, but mostly the reservoir is connected to a discharge pipe, in these cases
is necessary to keep in advise also the pressure drop of the pipe.
The matter is that the pressure drop, in addition to the kind of pipe and fluid, is also
influenced by the speed of the fluid passing through the pipe, which is determined by
pressure which in turn is related to the level of the tank.
This application evaluates the time necessary executing a number of iterations, until it reaches a quite reasonably correct result. This system integrates Bernoulli's equation, the Colebrook and Whine methods and obtain the flow rate at the exit, at the end it calculates the emptying time.
Circular vertical
 Cylindrical
 Flat bottom
Rectangular or squared
 Parallelepiped
 Flat bottom
Useful diameter . . . D
mm
Useful width . . . W
mm
Useful depth . . . P
mm
Starting level . . . h
mm
Internal diameter . . . d
mm
(optional) Gap . . . h2
mm
Total lenght
mm
Kind of pipe
Absolute roughness internal wall
mm
Selection of the kind of fluid
Viscosity at 20 ºC
cSt
Density at 20 ºC
kg/l
Risultati  
Discharged litres  l (dm^{3})  
Emptying time  s  
Emptying time (equivalent)  min  
Relative roughness of the pipe  r/d  
Reynolds number (average)  Re  
Average friction factor (Colebrook Whine)  
Data related to the maximum level . . . h  
Maximum flow rate of the fluid  l/min  
Maximum speed of the fluid in pipe  


Averaged data  
Fluid flow rate  l/min  
Fluid speed in pipe  

Back pressures and low pressions.
This software is not usable for cases when the tanks or the discharge pipes are subject
to negative or positive pressure, it is developed for system at atmospheric pressure.
Curve, deviazioni e raccordi.
There are not options for pressure drop concentrated due to bends or other links, but
they can equally be considered increasing the length of the pipe.
For instance for normal bend it could be added a length of 4 times the envelope of
the same bend.
The apps about tanks.
The apps about pressure drop.