how much pressure is in a tank?

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reptilerancher

reptilerancher

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Jan 14, 2016
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we all know freshwater weighs 8.36 pounds per gallon, so a 10 gallon will weigh about 84 pounds when filled with just water. I want to know the pressure that is on the front panel of a tank. is there a mathematical formula for the amount of pressure that is on the tanks panels?
 
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Per NASA....

The formula that gives the P pressure on an object submerged in a fluid is:

P = r * g * h
where

  • r (rho) is the density of the fluid,
  • g is the acceleration of gravity
  • h is the height of the fluid above the object

https://www.grc.nasa.gov/WWW/K-12/WindTunnel/Activities/fluid_pressure.html


The pressure on the front panel is not uniform. It varies by depth of the water being strongest at the bottom of the panel.

If you want the (total) pressure on the front panel (from top to bottom and across, as opposed to just the bottom), which is not something most people care about but is technically what you asked, you will likely need to combine calculus with the above equation since g is a non linear variable.
 
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so how would the width of the tank affect this? at a local aquarium the depth is 20 feet but the width is 40 would the pressure from the center column of water be then also pushing out on the tank?
 
sorry if this is a stupid question but that happens to the pressure of the water in the center of the tank?
 
If you used 13 inches for the height of the 10 gallon aquarium and filled it to the brim with fresh water, the psi on the bottom of the tank would be 0.46965472983 pounds per square inch. Pressure exerted on the side would be waaaay more math than I can do, or look up.
 
reptilerancher said:
sorry if this is a stupid question but that happens to the pressure of the water in the center of the tank?
Click to expand...

The pressure is the same everywhere inside the water so long as it's the same depth. It isn't higher or lower based upon where the side of the tank is. Look at the formula. There isn't any variable that relates to the side of a container, wall, etc.

Think of the air on the earth (but ignore weather patterns.) It has very low pressure at 80,000 feet, low pressure at 5,000 feet and standard pressure at sea level. So, if you look at it that way, the pressure at sea level is much higher than at 80,000 feet. The air doesn't push "extra" against houses because houses have a wall. It's the same everywhere whether there is a wall or not.

That's because the nature of a gas is to equalizes itself equally inside a container. Liquids do exactly the same thing. The pressure in the ocean at 10 feet below is the same everywhere (except perhaps due to salinity) regardless of whether it's in the middle of the ocean, or next to a cliff or next to a ship.

So the formula doesn't need to calculate differently for each place because the only thing that matters is the depth. Water pressure in a tank at sea level at 20 inches down is the same no matter where in the tank you are, no matter how wide or long the tank is, no matter what type of tank it is.
 
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Drstrangelove Drstrangelove - great explanation!
 
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