Static Pressure Calculator

Compute pressure from fluid column height or column height from pressure

 © 2015 LMNO Engineering, www.LMNOeng.com Make Selections: Research, and Software, Ltd. Water at 20 C (68 F) Water at 4 C (39 F) Seawater at 16 C (60 F) SAE 30 oil at 16 C (60 F) Gasoline at 16 C (60 F) Air at 20 C (68 F), 1 atm Methane (natural gas), 20 C, 1 atm Carbon Dioxide at 20 C, 1 atm Nitrogen at 20 C (68 F), 1 atm Helium at 20 C (68 F), 1 atm User Enters Density Compute Pressure Compute Height Pressure, P: atm ft of fluid inch H2O (60F) inch Mercury (60F) kg/cm2 lb/in2 (psi) lb/ft2 (psf) m of fluid mbar mm Mercury (0C) MPa N/m2 (Pa) Height, h: cm m km inch ft mile Mass or Weight Density: g/cm3 kg/m3 N/m3 slug/ft3 lb/ft3

Units in pressure calculator: atm=atmosphere, C=Celsius, cm=centimeter, F=Fahrenheit, ft=foot, g=gram, in=inch, kg=kilogram, km=kilometer, lb=pound, m=meter, mbar=millibar, mm=millimeter, M=Mega, N=Newton, Pa=Pascal

Pressure equation:  P = ρgh   where P = pressure (N/m2), ρ = mass density of fluid (kg/m3), g = acceleration due to gravity = 9.8066 m/s2, h = height of fluid column (m)

(SI units shown in equation, but calculation converts a variety of units)

Introduction
Engineers and others often need a conversion between pressure and height of fluid column. For instance, if a swimming pool is 4 m deep, the pressure at the bottom can be computed. Or, if a fire hydrant must operate at a static pressure of 40 psi, the water column equivalent to 40 psi can be computed. Pressures can also be computed in terms of gas columns, so we have included some built-in values for gas density.

Density must be entered as a positive number. Height and pressure can be entered as negative numbers. The calculator does not check for unrealistic heights or pressures, such as pressure below that of a complete vacuum.

References
All fluid mechanics textbooks discuss static pressure. A sampling of references follows.

Mays, L. W. editor. 1999. Hydraulic design handbook. McGraw-Hill Book Co.

Munson, B.R., D. F. Young, and T. H. Okiishi. 1998. Fundamentals of Fluid Mechanics. John Wiley and Sons, Inc. 3ed.

Streeter, V. L., E. B. Wylie, and K. W. Bedford. 1998. Fluid Mechanics. WCB/McGraw-Hill. 9ed.

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