Convert the following temperatures to absolute: (a) 100o C, (b) -50o C, (c) 220o C Convert the following gauge pressures to absolute: (d) -76.4kPa, (e) 2.52 MPa (f) 62.7 Pa.
SOLUTION
Note: On both the Kelvin and Rankine scale 0° is equal to absolute zero. One degree in Rankine is equal to one Fahrenheit degree. One Kelvin degree is equal to one Celsius degree.
°F 1 R °C 1 K 0 °C 273.15 K
100°C 373.15 K 50 °C 223.15 K 220°C 493.15 K
Pressure (P) is the force per unit area.
Atmospheric pressure
Patm 101.3 kPa
Gauge pressure is the amount by which pressure differs from atmospheric pressure Pg Absolute pressure (p)
Pgd 76.4 kPa Pd Pgd Patm Pd 24.9 kPa p Pg Patm Pge 2.52 MPa Pe Pge Patm Pe 2.621 MPa Pgf 62.7 Pa Pf Pgf Patm Pf 101.363 kPa