How To Calculate Water Pressure
Water pressure, also known as hydrostatic pressure, when dealing with static or non-moving fluid, can be calculated relatively easily. The type of simple calculation that is shown below can even be applied to oceanic situations as it has been experimentally shown that the waves and movement of the water have very little effect on the water pressure. Does this Spark an idea?
Instructions
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1
Determine at what depth you wish to calculate the water hydrostatic pressure. Express this value in meters.
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2
Using a barometer, obtain the atmospheric pressure at the surface of the water. Express this value in kg/ms². See "Resources" below for an easy and quick conversion factor table.
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3
Use what is generally accepted as the standard values for water density and the earth's gravitational acceleration:
water density = 1000kg/m³
earth's gravitational acceleration = 9.81m/s² -
4
Substitute the values obtained in Steps 1 through 4 into the following equation. Calculate when done.
P = a+l*g*h
where
P = water pressure (hydrostatic)
a = atmospheric pressure at water's surface
l = water density
g = gravitational acceleration. -
5
Use the result as the calculated hydrostatic pressure for the depth used in the equation. Multiply this number by .014 to express this pressure in pounds per square inch units.
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Tips & Warnings
Each cubic foot of water weighs about 62.5 pounds.
References
Resources
- Photo Credit http://www.aircraftspruce.com/catalog/graphics/225M_water_P.jpg
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Comments
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i wonder what is the level of water pressure to a submarine hull dept 100 meters every inch square or every centimeter square?
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lynnux18
Sep 29, 2010
The world became complicated and funny because of dull people! -
mike633
Aug 14, 2010
Thanks. Technically correct, yet unhelpful. The linked table of resources lists pressues as kg/m^2 with 1 atmosphere as about 10,000. There is no mention of kg/ms^2, which from reading elsewhere I see is Pa in SI units, so 1 atm = 10^5. Second error was reading the equation as atm times pgh not plus pgh. My mistake there but a bit of spacing would make it more clear.
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aris00
Aug 06, 2010
No, your units are incorrect: you are expressing the atmospheric pressure in kg/m^2 when you should be using kg/ms^2 as stated in the article (maybe corrected over time?). Additionally check your numeric calculations, with your numbers they should be giving you 109.8 kPa not 98MPa.
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mike633
Jul 07, 2010
This is not right. Lets use 1m depth: 10,000 kg/m^2 atmosphere times 1000 kg/m^3 density times 9.8 g times 1m = 98Mpa or about 980 atmostpheres. Your units are incorrect.
