engineering fundamentals Hydrostatics: Manometer Example
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Manometer Pressure
Manometers measure a pressure difference by balancing the weight of a fluid column between the two pressures of interest. Large pressure differences are measured with heavy fluids, such as mercury (e.g. 760 mm Hg = 1 atmosphere). Small pressure differences, such as those experienced in experimental wind tunnels or venturi flowmeters, are measured by lighter fluids such as water (27.7 inch H2O = 1 psi; 1 cm H2O = 98.1 Pa).

To calculate the pressure indicated by the manometer, enter the data below. (The default calculation is for a water manometer with a 10 cm fluid column, with the answer rounded to 3 significant figures.):

Inputs
  Height of fluid column, h:    
  Fluid density, r:    
Answers
  Manometer Pressure, Dp:  981  Pa
 
Equations used in the Calculation
The pressure difference between the bottom and top of an incompressible fluid column is given by the incompressible fluid statics equation,
where g is the acceleration of gravity (9.81 m/s2).
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