techniques for approximating the international temperature ... - BIPM
techniques for approximating the international temperature ... - BIPM techniques for approximating the international temperature ... - BIPM
110 Fig. 11.1: Resistance-temperature characteristic for several commercial resistors: (a) A, thermistor; B, 68 Ω Allen-Bradley; C, 220 Ω Speer (grade 1002); D, 51 Ω Speer (grade 1002); E, 10 Ω Speer (grade 1002) [Anderson (1972)]; (b) various nominal Matsushita carbon resistors of grade ERC-18SGJ [Saito and Sato (1975)].
111 Fig. 11.2: Relative sensitivity versus temperature for carbon (C), carbon-glass (CG), and germanium (Ge) thermometers [Swartz and Swartz (1974)]. 11.3 Thermal Contact Providing good thermal contact is one of the main problems that limits the usefulness of carbon resistors. The heat dissipated in the sensor must flow to the surroundings without causing a relative temperature rise greater than ∆T/T ≈ 10 -3 . At 1 K, for a 220 Ω Speer resistor for example, the maximum power dissipated in the CRT must remain smaller than 10 -7 W for a 1% accuracy in the measurement. The thermal boundary resistance between the unit and the environment depends upon the mounting, but is roughly 10 -2 K/W for an area of 10 -4 m 2 . Different thermal grounding techniques have been proposed [Polturak et al. (1978), Johnson and Anderson (1971 )]. Thermally grounding the resistor via its leads only is not recommended. It is important to bind the unit with a copper housing that is thermally anchored to the device to be studied, with grease, stycast, varnish or other equally good agent. The paint used for color coding the resistor should be removed because it may loosen after several thermal cycles. 11.4 Response Time The thermal response time of a CRT is short; some typical values are given in Table 11.1. Longer time constants (up to tens of minutes) can be observed if the copper
- Page 80 and 81: 60 6. Vapour Pressure Thermometry*
- Page 82 and 83: 62 transitions, but it could be app
- Page 84 and 85: n ∑ i= 2 64 L x [ Π − k ] P =
- Page 86 and 87: 66 Fig. 6.3: Diagram at constant pr
- Page 88 and 89: 68 Fig. 6.4: Schematic construction
- Page 90 and 91: 70 Fig. 6.6: Use of an evacuated ja
- Page 92 and 93: 72 Following this, the connecting t
- Page 94 and 95: 74 Fig. 6.9: (c) N2, CO, Ar, O2, CH
- Page 96 and 97: 76 the Weber-Schmidt equation [Webe
- Page 98 and 99: 78 Table 6.1: Temperature values (K
- Page 100 and 101: 80 into the bulb (hydrous ferric ox
- Page 102 and 103: 82 Fig. 6.12: Effect on the vapour
- Page 104 and 105: 84 the remaining liquid increases.
- Page 106 and 107: 86 Curie constant (C⊥ is about 0.
- Page 108 and 109: 8.1 General Remarks 88 8. Platinum
- Page 110 and 111: 90 For a group of 45 thermometers h
- Page 112 and 113: 92 More recently, Seifert [(1980),
- Page 114 and 115: 94 For thermometers with W(4.2 K) <
- Page 116 and 117: 96 after 500 h at 1700 °C in air,
- Page 118 and 119: 98 normally extends about 50 cm bac
- Page 120 and 121: 100 inhomogeneities result from the
- Page 122 and 123: 9.5 Approximations to the ITS-90 10
- Page 124 and 125: 104 10. Infrared Radiation Thermome
- Page 126 and 127: 106 almost negligible. The final ac
- Page 128 and 129: 108 11. Carbon Resistance Thermomet
- Page 132 and 133: 112 Table 11.1: Typical Time Consta
- Page 134 and 135: 114 calibration after each cool-dow
- Page 136 and 137: 116 12. Carbon-Glass Resistance The
- Page 138 and 139: 118 Fig. 12.1: Resistance-temperatu
- Page 140 and 141: 120 14. Diode Thermometers Diodes c
- Page 142 and 143: 122 2 BT V = E0 − − CT ln ( DT)
- Page 144 and 145: 124 Fig. 15.1: Principal features o
- Page 146 and 147: 126 For a thermometer graduated abo
- Page 148 and 149: 128 rise decreases with time but in
- Page 150 and 151: 130 Fig. 16.1: (a) Fabrication of I
- Page 152 and 153: 132 capillaries of a twin- (or four
- Page 154 and 155: 134 advised to choose the thermomet
- Page 156 and 157: 136 Fig. 16.6: Distribution of the
- Page 158 and 159: 138 and between different thermomet
- Page 160 and 161: 140 therefrom) can then be used wit
- Page 162 and 163: 142
- Page 164 and 165: 144 Fig. 16.8: Tolerances for indus
- Page 166 and 167: 146 Stability on thermal cycling is
- Page 168 and 169: 18.2.1 Type T Thermocouple 148 With
- Page 170 and 171: 150 within ± 0.5 to 0.7 percent. T
- Page 172 and 173: 152 insulation even though it be af
- Page 174 and 175: 154 Table 18.4: Recommended Sheath
- Page 176 and 177: 156 In the case of the Types K and
- Page 178 and 179: 158 temperature is measured with th
110<br />
Fig. 11.1: Resistance-<strong>temperature</strong> characteristic <strong>for</strong> several commercial resistors: (a) A,<br />
<strong>the</strong>rmistor; B, 68 Ω Allen-Bradley; C, 220 Ω Speer (grade 1002); D, 51 Ω Speer<br />
(grade 1002); E, 10 Ω Speer (grade 1002) [Anderson (1972)]; (b) various nominal<br />
Matsushita carbon resistors of grade ERC-18SGJ [Saito and Sato (1975)].
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