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Temperature
Kinetic Theory of Gases.

Fluid Power - Intro to Hydraulics, Pneumatics, and how it all works
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Figure  11-1.-Comparison  of  Kelvin,  Celsius,  Fahrenheit,  and  Rankine  temperature. convert  Fahrenheit  to  absolute.  For  Fahrenheit readings  above  zero,  460°  is  added.  Thus,  72°F equals  460°  plus  72°,  or  532°  absolute  (532°R). If  the  Fahrenheit  reading  is  below  zero,  it  is subtracted  from  460°.  Thus,  -40°F  equals  460° minus  40°,  or  420°  absolute  (420°R). The   Kelvin   and   Celsius   scales   are   used internationally  in  scientific  measurements;  there- fore, some technical manuals may use these scales in   directions   and   operating   instructions.   The Fahrenheit scale is commonly used in the United States; therefore, it is used in most areas of this manual. PRESSURE We defined pressure in chapter 2 as force per unit  area.  Remember,  liquids  exert  pressure  on all  surfaces  with  which  they  come  in  contact. Gases,  because  of  their  ability  to  completely  fill containers,  exert  pressure  on  all  sides  of  a container. In practice, we maybe interested in either of two pressure readings. We may desire either the gauge pressure or the absolute pressure. Absolute pressure is measured from absolute zero  pressure  rather  than  from  normal  or atmospheric  pressure  (approximately  14.7  psi). Gauge pressure is used on all ordinary gauges, and indicates   pressure   in   excess   of   atmospheric pressure. Therefore, absolute pressure is equal to atmospheric  pressure  plus  gauge  pressure.  For example,  100  psi  gauge  pressure  (psig)  equals  100 psi  plus  14.7  psi  or  114.7  psi  absolute  pressure (psia).  Whenever  gas  laws  are  applied,  absolute pressures Gases are required. COMPRESSIBILITY  AND EXPANSION  OF  GASES can  be  readily  compressed  and  are assumed to be perfectly elastic. This combination of properties gives a gas the ability to yield to a 11-3







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