FLUMEC2

• *Force per Area - units include psi, psf , or Pascals
• Unit Pressure or Pressure (P)

  defined as a normal force exerted by a fluid per unit area

  present when dealing with gas or liquid

  • counterpart in solids is the normal stress
• *Pressure units can give an equivalent height of a column of liquid.
• Pascal’s Law

  developed by a French mathematician, Blaise Pascal

  • state that “At any point in a fluid at rest, the pressure is the same in all directions.”
• Atmospheric Pressure - pressure at any point on the earth’s surface from the weight of

  the air above it
• Vacuum or Absolute Zero Pressure - a space that has all matter removed from it

  • can also be described as a region of space where the pressure of 760mm

  (29.9in) of mercury
• VACUUM - - described as the difference between atmospheric pressure and actual

  pressure
• Gage Pressure - pressure above or below the atmosphere and can be measured by

  pressure gauges or manometers
• Absolute Pressure - pressure above the absolute zero (vacuum)
• absolute zero is attained if all air is removed; it is the lowest possible pressure attainable
• • absolute pressure can never be negative
• the smallest gage pressure is equal to the negative of the prevailing atmospheric pressure
• unless otherwise stated, the term pressure signifies gage pressure
• Pressure Head - height of a column of homogeneous fluid of unit weight that will produce an

  intensity of pressure P (meters; feet)