Biomedical Engineering Reference
In-Depth Information
point at 212 F. The zero point or starting point, 0 F, represents temperature of
certain salt-ice mixture.
C ¼ 5 = 9 ð F 32 Þ
• Kelvin or Absolute scale (K):
It was introduced in 1848 by Lord Kelvin. It has ice point at 273.16 K and steam
point at 373.16 K.
K ¼ C þ 273 : 16
• Rankine scale (R 0 ):
It has ice point at 491.69 R 0 and steam point at 671.69 R 0 . It has 180 degrees
between ice point and steam point just as on Fahrenheit scale, therefore it is also
called as ''absolute Fahrenheit scale''.
R 0 ¼ F þ 459 : 69
• REAUMUR SCALE (R):
It is often used in alcohol industries. It has 0 R as the ice point and 80 R as the
steam point. It was introduced in 1731 and used in few European countries.
An international practical temperature scale has been set up in 1948, in order to
define the temperature intervals on the basis of equilibrium of various substances.
From -310 F(-190 C) to 1,220 F (660 C) temperature scale is defined by the
resistance of a platinum resistance thermometer. From 1,220 F (660 C) to
1,945 F (1,063 C) temperature scales are defined by platinum versus platinum-
rhodium thermocouple. Above 1,945 F (1,063 C) the scale is defined by a for-
mula for the radiation of a black body. Figure 2.4 shows the various types of
temperature scale.
The International Practical Temperature Scale (IPTS) defines six primary fixed
point for reference temperatures in terms of:
Fig. 2.4
Temperature scale
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