Water Tank Design: Pressure Calculation

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SUMMARY

The discussion centers on calculating pressure at the vertical wall of a cylindrical water tank using the formula Pressure = Density * gravity * height, where height is measured from the water surface to the calculation point. Participants confirm that while this formula applies to fluids like water, the situation changes when substituting water with dry sand due to differences in material behavior. Factors such as moisture content and grain size significantly influence the pressure calculations for dry sand. Additionally, the nature of the pressure vessel—whether static or dynamic—affects design considerations, particularly regarding stress concentration and fatigue strength.

PREREQUISITES
  • Understanding of fluid mechanics principles
  • Familiarity with pressure calculations in engineering
  • Knowledge of material properties, specifically for granular materials
  • Basic concepts of static vs. dynamic pressure systems
NEXT STEPS
  • Research the impact of moisture content on pressure calculations for granular materials
  • Study the differences between static and dynamic pressure systems in engineering design
  • Learn about stress concentration factors in pressure vessels
  • Examine the flow behavior of granular materials and its implications on pressure calculations
USEFUL FOR

Civil engineers, mechanical engineers, and anyone involved in the design and analysis of pressure vessels or granular material behavior.

Su Solberg
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Hello, everyone.

I am trying to calculate the pressure acting at the vertical wall of a cylinder water tank.

I am wondering whether the presure acting on the wall is as follow:

Pressure = Density * gravity * height

where height is from the water surface to the calculation point.


Also, I am wondering whether the situation is the same when i replace the water with dry sand.

Thank you very much for your help.
 
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Su Solberg said:
Hello, everyone.

I am trying to calculate the pressure acting at the vertical wall of a cylinder water tank.

I am wondering whether the presure acting on the wall is as follow:

Pressure = Density * gravity * height

where height is from the water surface to the calculation point.

Yes.

Su Solberg said:
Also, I am wondering whether the situation is the same when i replace the water with dry sand.

I'm not 100% sure, but I believe it would essentially be the same given that the sand particles are very small and would probably give a pressure field equivalent to that of a liquid.

CS
 
the math is right for a fluid, but...
since sand is not actual fluid,
I don't know it the math for a fluid would work
(if I pour a bucket of sand on the floor, it won't disperse flat)
so that seems to tell me surface tension may be a factor, not sure
there may be other variables to consider, too

I am intrigued how to figure that

dr
 
Su Solberg said:
Also, I am wondering whether the situation is the same when i replace the water with dry sand.

I would bet that the equations for dry sand will be different, but I'm not a civil engineer. I know that it will depend heavily on moisture content, and probably grain size (or some measure of it's flow-ability).
 
Su Solberg said:
Hello, everyone.

I am trying to calculate the pressure acting at the vertical wall of a cylinder water tank.

I am wondering whether the presure acting on the wall is as follow:

Pressure = Density * gravity * height

where height is from the water surface to the calculation point.


Also, I am wondering whether the situation is the same when i replace the water with dry sand.

Thank you very much for your help.

depend on weather the pressure vessel has the fluid inside in it has static or dynamic in nature...

cause if the sand is continuesly coming in and going out of the vessel; then in that case the design will b different and very critical...in that case stress concentration will come in picture ... consider notch sensitivity factor and dynamic factor for fatigue strength...

if it is static .. then it will not affect a lot...design can b same as that of water...

i think...
 
The analogies are similar - see equation 8 w/9:

http://www.mec.utt.ro/~tm/SIPA_05/Part1/Ola2_G.pdf

If you have "flow" then things change as per that paper.
 
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