How much PSI does it take to move water one vertical foot?

Answer 1

In the explanation that follows, the reader should note the difference between the pound-mass (lbm) and the pound-force (lbf). The general formula is pressure = density x gravitational constant x height, or p = dgh. English units are usually kind of weird, but they work out nicely in this one. The density of water, d, is around 62 lbm/ft3. The gravitational constant, g, is 32.2 ft/sec2. We'll say height, h, is in feet. So, p = 62* 32.2 * h (lbm/ft-sec2). The conversion factor that makes all those weird units go away is 1 lbf/32.2 lbm-ft/sec2. p = 62 * h lbf/ft2, where h is in feet. (To put it in pounds per square inch (psi), divide by 144.) So, p = 0.43 psi for every foot in height of the water tower. The reciprocal of that (1/0.43 = 2.33) gives you how many vertical feet of water are required to exert a pressure of one pound on an area of one square inch. We know that a cubic foot of water weighs about 62 pounds. We also know that a cubic foot contains 1,728 cubic inches (12 x 12 x 12). So, a narrow of column of water that is one inch wide by one inch deep by 1,728 inches high will weigh 62 pounds and exert a pressure of 62 pounds on the one-square-inch area under it. But the questioner wants to know how tall the column has to be to exert just one pound, not 62. Dividing 1,728 by 62, yields 27.871 inches, which is approximately 2.33 feet.

Answer 2

The pressure at the bottom of a column of fluid is (rho)gh, where rho is the density of the fluid g is the acceleration due to gravity (9.8 m/s2 or 32.2 ft/s2) h is the height of the column Water has a density of about 56 pounds-mass per cubic foot, so a 1 foot high column has a pressure at the bottom of 62 lbm/ft3 * 32.2 ft/s2 * 1 ft = 1803 lbm/ft-s2. The magic conversion constant is 1 lbf-s2/32.2 lbm-ft and we could have saved some trouble by doing it up front 62 lbm/ft3 * 32.2 ft/s2 * 1 ft * 1 lbf-s2/32.2 lbm-ft = 62 lbf/ft2 If we divide this by 144, we get 0.43 psi. I never trust calculations in English units, so The density of water is 1000 kg/m3, so the pressure at the bottom of a 0.305 m tall column of water is 1000 kg/m3 * 9.8 N/kg * 0.305 m = 2989 Pa. Since 1 atmosphere = 14.696 psi = 101325 Pa, the pressure at the bottom of your column is 2989 Pa * 14.696 psi/101325 Pa = about 0.43 psi. Now that I think of it, we could have multiplied the first equation by

Answer 3

Pressure is measured in many different units of measure, e.g. pounds per square inch(psi), standard atmospheres(ATM) and millimeters of Mercury(mm Hg).

To calculate the pressure in mm Hg, convert 10 feet of water(exact measure) into millimeters of water using 1 inch = 25.4 mm:

10 ft H2O = 10 * 12 in/ft * 25.4 mm/in = 3048 mm H2O. (retain all digits in the intermediate calculation)

Now, convert mm H2O to mm Hg using the specific gravity of mercury(13.6):

3048 mm H2O * 1 mm Hg / 13.6 mm H2O = 224. mm Hg. (only 3 significant digits)

Now one can use the following equivalences to convert to any other measure of pressure.

760 mm Hg = 1 ATM = 14.7 psi

Thus,

10 ft H20 = 224. mm Hg = 0.295 ATM = 4.33 psi

Answer 4

A foot of water has a cubic mass of 62.4 pounds per foot

Answer 5

.433 pounds per square inch per foot of head

Answer 6

Nearly one atmosphere.

Answer 7

13

Answer 8

2.31