Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Liquid Flow from Containers - Emptying Time

Calculate liquid velocity, volume flow and draining time when emptying a container for it's fluid.

Sponsored Links

Base Apertures

 

container base apertures

The liquid outlet velocity when draining a tank or a container can be calculated

v = Cv (2 g H )1/2                                (1a)

where

v = outlet velocity (m/s)

Cv = velocity coefficient (water 0.97)

g = acceleration of gravity (9.81 m/s2)

H = height (m)

The liquid volume flow can be calculated

V = Cd A (2 g H)1/2                        (1b)

where

V = volume flow (m3/s)

A = area of aperture - flow outlet (m2)

Cd = discharge coefficient

where

Cd = Cc Cv 

where

Cc = contraction coefficient (sharp edge aperture 0.62, well rounded aperture 0.97)

A = area aperture (m2)

Example - Volume Flow when draining a Container

The height from the surface to the outlet aperture in a water filled container is 3 m. The aperture is sharp edged with diameter 0.1 m. The discharge coefficient can be calculated as

Cd = 0.62 0.97

     = 0.6

The area of the aperture can be calculated as

A = π ((0.1 m) / 2)2

   =   0.008 m2

The volume flow through the aperture can be calculated as

V = 0.6 (0.008 m2) (2 (9.81 m/s2) (3 m))1/2  

   = 0.037 m3/s

For height 1.5 m the volume flow is 0.026 m3/s. For height 0.5 m the volume flow is 0.015 m3/s.

Draining Tank Calculator

This calculator is based on eq. (1b) and can be used to estimate the volume flow and time used to drain a container or tank through an aperture.

The calculator divides the container in "slices" and makes an iterative average calculation for each slice. The accuracy of the calculation can be increased by increasing the number of slices.

Bottom area of tank or container  (m2)

H - height between surface and aperture (m)

A - aperture area (m2)

Cd - discharge coefficient

no. of "slices" or segments (for the iterative calculation)

- results in table below!

Note! - the flow is reduced and the time is increased with reduced height.

Draining tank - flow, time and level - values from default example

Small Lateral Apertures

small lateral apertures

Outlet velocity can be expressed as

v = Cv (2 g H)1/2                                (2a)

Distance s can be expressed as

s = 2 (H h)1/2                               (2b)

Volume flow can be expressed as

V = Cd A (2 g H)1/2                             (2c)

Reaction force can be expressed as

F = ρ V v                                 (2d)

where

ρ = density (kg/m3)  (water 1000 kg/m3)

Large Lateral Apertures

large lateral apertures

Volume flow can be expressed as

V = 2/3 Cd b (2 g)1/2 (H23/2 - H13/2)                                (3a)

where

b = width of aperture (m)

 

Excess Pressure in Container

excess pressure in container

Outlet velocity can be expressed as

v = Cv (2 (g H + p / ρ))1/2                               (4a)

where

p = excess pressure in container or tank (N/m2, Pa)

Volume flow can be expressed as

V = Cd A (2 (g H + p / ρ))1/2                           (4b)

Sponsored Links

Related Topics

Related Documents

Sponsored Links

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

Translate
About the Engineering ToolBox!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

Citation

This page can be cited as

  • Engineering ToolBox, (2011). Liquid Flow from Containers - Emptying Time. [online] Available at: https://www.engineeringtoolbox.com/flow-liquid-water-tank-d_1753.html [Accessed Day Mo. Year].

Modify access date.

. .

close

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

3 30

Sponsored Links
.