Page 20 - Aeronautical Engineer Data Book

10 Aeronautical Engineer’s Data Book
Table 2.4 Density (#)

Unit lb/in 3 lb/ft 3 kg/m 3 g/cm 3
1 lb per in 3 1 1728 2.768 27.68
2 10 4
1 lb per ft 3 5.787 1 16.02 1.602
2 10 –4 2 10 –2
1 kg per m 3 3.613 6.243 1 0.001
2 10 –5 2 10 –2
1 g per cm 3 3613 62.43 1000 1
2 10 –2

2.3.4 Pressure
2
The base USCS unit is the lbf/in (or ‘psi’).
1 Pa = 1 N/m 2
–4
1 Pa = 1.45038 2 10 lbf/in 2
In practice, pressures in SI units are measured
in MPa, bar, atmospheres, torr, or the height of
a liquid column, depending on the application.
See Figures 2.1, 2.2 and Table 2.5.
So for liquid columns:
O = 25.4 mm H O = 249.089 Pa
1 in H 2 2
1 in Hg = 13.59 in H 2 O = 3385.12 Pa =
33.85 mbar.
1 mm Hg = 13.59 mm H 2 O = 133.3224 Pa =
1.333224 mbar.
O = 9.80665 Pa
1 mm H 2
1 torr = 133.3224 Pa
For conversion of liquid column pressures: 1
in = 25.4 mm.

2.3.5 Temperature
The basic unit of temperature is degrees Fahren­
heit (°F). The SI unit is kelvin (K). The most
commonly used unit is degrees Celsius (°C).
Absolute zero is defined as 0 K or –273.15°C,
the point at which a perfect gas has zero
volume. See Figures 2.3 and 2.4.
5
°C = / (°F – 32)
9
9
°F = / (°C + 32)
5