Emptying time for tanks and reservoir.

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

Characteristic of the discharge pipe.

Internal diameter . . . d

mm

(optional) Gap . . . h2

mm

Total lenght

mm

Kind of pipe

New Steel Pipe (dim. GAS) New Steel Pipe (dim. UNI) Rusty Steel Pipe (GAS) Rusty Steel Pipe (UNI) Copper Pipe Plastic Pipe (PE100) Plastic Pipe (PP) Plastic Pipe (PVC) Plastic Pipe (PVDF) Rilsan Pipe Glass Pipe Rubber Canvas Pipe Cast iron pipe (internal cement)

Absolute roughness internal wall

mm

Characteristics of the fluid.

Selection of the kind of fluid

Water Salt water Gasoline HYCOOL 45 Kerosene Water-glycol 42% Diesel fuel for motor vehicles Diathermic oil ISO VG 32 Hydraulic oil H-LP 32 Oil SAE 30

Viscosity at 20 ºC

cSt

Density at 20 ºC

kg/l

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.