techniques for approximating the international temperature ... - BIPM
techniques for approximating the international temperature ... - BIPM techniques for approximating the international temperature ... - BIPM
6 not be repeated here, but several special ways to use fixed points for approximating the ITS-90 are described in Chapter 3. On the other hand, there is some duplication in descriptions of the various sensors since all of the defining instruments are also used for secondary measurements. Except for the standard platinum resistance thermometer, there is a rather fuller description of the sensors in the present monograph. For the platinum 10% rhodium/platinum thermocouple*, in particular, which is one of the most important thermometers for approximating the ITS-90 even though it is no longer a defining instrument of the ITS, the information contained in Chapter 5 of the "Supplementary Information for the IPTS-68 and the EPT-76" [CCT-1983] has been included and substantially augmented here, and has been deleted from the revised "Supplementary Information for the ITS-90" [CCT (1990)]. _________________________________________________________________________ * In this monograph, specific thermocouple designations are written with the positive element first, separated from the negative element by the oblique symbol. Frequently, also, they will be written in an abbreviated form: platinum 10% rhodium/platinum will also be written as Pt10Rh/Pt, for example. Standard international letter designations, such as Type S for Pt10Rh/Pt, are also used of course.
Table 1.1: Summary of Some Properties of Most-Commonly-Used Thermometers Usual Thermometric Typical Thermometer Temperature Quantity Uncertainty Range Germanium 1 K to 100 K elec. resist.* ∆T / T < 2x10-4 Rhodium-lron 0.5 K to 30 K elec. resist.* 0.3 mK Platinum-Cobalt (industrial type) 2 K to 20 K elec. resist.* 10 mK Carbon 0.5 K to 30 K elec. resist.* ∆T / T < 5x10-3 Carbon-glass 0.5 K to 100 K elec. resist.* ∆T / T < 1 x1 0-3 7 Diode 4 K to 300 K junction voltage -50 mK Vapour-pressure various subranges between 0.5 K and 100 K pressure -1 mK Mercury-in-glass -50 °C to 250 °C thermal expansion of mercury 0.1 K Thermocouples 4 K to 2500 °C thermoelectromotive force Type S -50 °C to 1600 °C 0.3 K < 1000 °C 1 K > 1000 °C Type R -50 °C to 1600 °C 0.3 K < 1000°C 1 K > 1000 °C Type B 300 °C to 1800 °C 0.5 K to 2 K Type T -200 °C to 350 °C 0.1 K Type E -200 °C to 870 °C 0.1 K < 300 K 1 K > 300 K Type J 0 °C to 760 °C 0.5 K < 300 °C 2 K > 300 °C Type K -200 °C to 1260 °C 0.1 K < 200 °C 1 K 200-1000 °C 3 K > 1000 °C Type N 0 °C to 1300 °C 0.1 K < 200 °C 0.5 K 200-1000 °C 3 K > 1000 °C W/Re 1000 °C to 2400 °C 3-10 K _________________________________________________________________________ * elec. resist. is the electrical resistance
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- Page 41 and 42: 21 device SRM 767 [Schooley et al.
- Page 43 and 44: 23 Table 3.1 : Current Best Estimat
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6<br />
not be repeated here, but several special ways to use fixed points <strong>for</strong> <strong>approximating</strong> <strong>the</strong><br />
ITS-90 are described in Chapter 3. On <strong>the</strong> o<strong>the</strong>r hand, <strong>the</strong>re is some duplication in<br />
descriptions of <strong>the</strong> various sensors since all of <strong>the</strong> defining instruments are also used <strong>for</strong><br />
secondary measurements. Except <strong>for</strong> <strong>the</strong> standard platinum resistance <strong>the</strong>rmometer, <strong>the</strong>re<br />
is a ra<strong>the</strong>r fuller description of <strong>the</strong> sensors in <strong>the</strong> present monograph. For <strong>the</strong> platinum 10%<br />
rhodium/platinum <strong>the</strong>rmocouple*, in particular, which is one of <strong>the</strong> most important<br />
<strong>the</strong>rmometers <strong>for</strong> <strong>approximating</strong> <strong>the</strong> ITS-90 even though it is no longer a defining instrument<br />
of <strong>the</strong> ITS, <strong>the</strong> in<strong>for</strong>mation contained in Chapter 5 of <strong>the</strong> "Supplementary In<strong>for</strong>mation <strong>for</strong> <strong>the</strong><br />
IPTS-68 and <strong>the</strong> EPT-76" [CCT-1983] has been included and substantially augmented here,<br />
and has been deleted from <strong>the</strong> revised "Supplementary In<strong>for</strong>mation <strong>for</strong> <strong>the</strong> ITS-90" [CCT<br />
(1990)].<br />
_________________________________________________________________________<br />
* In this monograph, specific <strong>the</strong>rmocouple designations are written with <strong>the</strong> positive<br />
element first, separated from <strong>the</strong> negative element by <strong>the</strong> oblique symbol. Frequently,<br />
also, <strong>the</strong>y will be written in an abbreviated <strong>for</strong>m: platinum 10% rhodium/platinum will<br />
also be written as Pt10Rh/Pt, <strong>for</strong> example. Standard <strong>international</strong> letter designations,<br />
such as Type S <strong>for</strong> Pt10Rh/Pt, are also used of course.
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