On problems in the definition of the International Temperature Scale arising from the variability of the isotopic composition of some substances used for the fixed-points

Metrologia ◽  
2005 ◽  
Vol 42 (4) ◽  
pp. 194-200 ◽  
Author(s):  
F Pavese
Keyword(s):  
Isotopic Composition ◽  
Fixed Points ◽  
Temperature Scale ◽  
International Temperature Scale ◽  
International Temperature ◽  
Definition Of

scholarly journals The freezing point of platinum

1934 ◽  
Vol 146 (859) ◽  
pp. 792-817 ◽  
Keyword(s):  
Fixed Points ◽  
Temperature Scale ◽  
Freezing Point ◽  
High Standard ◽  
National Physical Laboratory ◽  
Basic Point ◽  
International Temperature Scale ◽  
International Temperature ◽  
Physical Laboratory ◽  
Pure Substances

The International Temperature Scale, which has been in force since 1927, is based on certain values assigned to the boiling and freezing points of pure substances and on specified means of interpolation between, or extrapolation beyond, these points. The highest basic point of the scale is the freezing point of gold, defined as 1063·0° C, while for extrapolation from this temperature use is made of the Wien law of radiation, with a certain value of the constant C 2 . Though any temperature above 1063° C is thus completely defined without reference to further fixed points, determinations of such points are of considerable value. In particular, they serve to indicate the degree of reproducibility of the scale by the various users of it, and, when well authenticated, to provide secondary standards for its realization. Of such fixed points the most important has been the freezing point of palladium (1555° C), but the latest developments in furnace technique and refractory materials should now enable the freezing point of platinum to be used with equal, if not greater, advantage. The qualities of platinum which render it especially valuable in this connection are as follows: its freedom from oxidation; its high standard of purity, for which a convenient electrical test is available; its high freezing point (about 1775° C) which approaches the important zone of temperature covered by the electric fighting industry These qualities also make the platinum point especially suitable as the basis for a standard of fight, as has been proposed by a number of experimenters. It is with the two objects indicated above that the National Physical Laboratory has undertaken an investigation concerning the freezing point of platinum the precise scope of which may be defined as follows:— (1) To determine the value of the freezing point in terms of the International Temperature Scale.

scholarly journals LONG-TERM STABILITY OF Co-C AND Pd-C EUTECTIC FIXED POINTS FOR THERMOCOUPLES CALIBRATION

2021 ◽  
Vol 82 (1) ◽  
pp. 26-29
Author(s):  
Yasser A. Abdelaziz ◽  
◽  
F.M. Megahed ◽  
M. M. Abdel-Aal ◽  
◽  
...  
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Temperature Scale ◽  
Term Stability ◽  
Long Term Stability ◽  
International Temperature Scale ◽  
Definition Of The Kelvin ◽  
Definition Of ◽  
Eutectic Fixed Points

Eutectic fixed points are close to becoming a reference for high temperatures calibration, especially as the new International Temperature Scale (ITS) approach to issue after the re-definition of the Kelvin unit. In this work the long-term stability of Co-C and Pd-C eutectic fixed points were investigated using NIS-Egypt facilities. The eutectic points were measured using Pt/Pd thermocouple. The total exposure to the Co-C and Pd-C melting temperature was about 200 h for the fixed-point cell and 150 h for the Pt/Pd thermocouple. The emfs of the thermocouple at the melting point were observed to drift by about 0.25 °C. Realization uncertainties were estimated to be ~ 0.446 ◦C for Co-C and ~0.742 for Pd-C (k = 2). Results show that Co-C and Pd-C eutectic cells can exhibit long term stability.

The freezing point of zinc as a primary point of the International Temperature Scale

1958 ◽  
Vol 247 (1249) ◽  
pp. 214-224 ◽  
Keyword(s):  
Temperature Scale ◽  
Freezing Point ◽  
Platinum Resistance ◽  
International Temperature Scale ◽  
International Temperature ◽  
Platinum Resistance Thermometers ◽  
Resistance Thermometers ◽  
Accuracy Of Measurement ◽  
Definition Of ◽  
Freezing Point Of Zinc

The technique is described of achieving the highest accuracy of measurement with platinum-resistance thermometers at the freezing point of zinc and the boiling point of sulphur. The two points are compared in a series of measurements and it is found that the zinc point is some three or four times more reproducible than the sulphur point. It is concluded that the substitution of the zinc point for the sulphur point as a primary fixed point of the International Temperature Scale would lead to a greater precision in the definition of the scale. The value of the freezing point of zinc is found to be 419∙5055 ± 0∙002°C.

scholarly journals Overview of measurements capabilities in radiation thermometry at CEM (Spain)

2019 ◽  
Author(s):  
M. J. Martin ◽  
J. M. Mantilla ◽  
D. del Campo
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Temperature Scale ◽  
Radiation Thermometry ◽  
Thermodynamic Temperature ◽  
National Standards ◽  
Primary Radiation ◽  
International Temperature Scale ◽  
Definition Of The Kelvin ◽  
Definition Of

CEM (Spanish National Institute of Metrology) is responsible for the maintenance and dissemination of the temperature national standards. Nowadays, the CEM Radiation Thermometry Laboratory disseminates and maintains the International Temperature Scale of 1990 (ITS-90) from the Ag fixed point (961.78 °C) to 2800 °C, using Ag or Cu fixed points as reference and standard radiation thermometers (RTs) working at a wavelength of 650 nm. CEM is also able to provide traceability to the new definition of the kelvin and to perform measurements of thermodynamic temperature from 400°C to 2800°C with different RTs (wavelengths of 650 nm, 900 nm and 1550 nm) using absolute and relative primary radiation thermometry. In addition the Radiation Thermometry laboratory performs calibration of RTs working in the usual infrared ranges (1 μm and 10 μm) from – 40°C to 1600°C.

scholarly journals The freezing-point of rhodium

1939 ◽  
Vol 173 (952) ◽  
pp. 117-125 ◽  
Keyword(s):  
Fixed Points ◽  
Temperature Scale ◽  
Freezing Point ◽  
National Bureau ◽  
Basic Point ◽  
Colour Temperature ◽  
Freezing Points ◽  
International Temperature Scale ◽  
International Temperature ◽  
Pure Substances

The International Temperature Scale, which has been in force since 1927 (Bureau International des Poids et Mesures 1927, 1934), is based on certain values assigned to the boiling- and freezing-points of pure substances and on specified means of interpolation between, or extrapolation beyond, these points. The highest basic point of the scale is the freezing-point of gold, defined as 1063-0° C, while for extrapolation from this temperature use is made of the Wien law of radiation with a certain value of the constant c2. Though any temperature above 1063° C is thus completely defined without reference to further fixed points, determinations of such points are of considerable value. In particular, they serve to indicate the degree of reproducibility of the scale and, when well authenticated, to provide secondary standards for its realization in cases where this is more convenient than a primary calibration. A good example of the use of secondary fixed points is the establishment by the National Bureau of Standards, U.S.A., of a scale of colour temperature (Wensel, Judd and Roeser 1934), based on the freezing-points of platinum (1773° C), rhodium (1966° C) and iridium (2454° C).

scholarly journals The freezing point of palladium

1936 ◽  
Vol 155 (885) ◽  
pp. 301-308 ◽  
Keyword(s):  
Fixed Points ◽  
Temperature Scale ◽  
Freezing Point ◽  
Basic Point ◽  
Freezing Points ◽  
International Temperature Scale ◽  
A Value ◽  
International Temperature ◽  
The Subject ◽  
Pure Substances

The International Temperature Scale, which has been in force since 1927, is based on certain values assigned to the boiling and freezing points of pure substances and on specified means of interpolation between, or extrapolation beyond, these points. The highest basic point of the scale is the freezing point of gold, defined as 1063·0º C, while for extrapolation from this temperature use is made of the Wien law of radiation with a certain value of the constant c 2 . Though any temperature above 1063º C is thus completely defined without reference to further fixed points, determinations of such points are of considerable value. In particular, they serve to indicate the degree of reproducibility of the scale by the various users of it, and, when well authenticated, to provide secondary standards for its realization. Probably the most important of the fixed points referred to are the freezing points of palladium, platinum, rhodium, and iridium. The first-mentioned point has been the subject of considerable investigation in the past and a value of 1555º C has been assigned to it in the list of secondary points given in the appendix to the specification of the International Temperature Scale.

ACCURACY OF OPTICAL PYROMETRY IN THE RANGE 800 °C TO 4000 °C

1958 ◽  
Vol 36 (10) ◽  
pp. 1397-1408 ◽  
Author(s):  
D. R. Lovejoy
Keyword(s):  
Standard Deviation ◽  
Temperature Scale ◽  
Primary Standard ◽  
Secondary Standard ◽  
Optical Pyrometer ◽  
Optical Pyrometry ◽  
International Temperature Scale ◽  
International Temperature ◽  
Carbon Arc ◽  
Temperature Standard

A pair of secondary standard tungsten strip lamps have had a luminance temperature – current calibration, in the range 800 °C to 2200 °C, at a number of national laboratories. An analysis of the calibration results confirms estimates of the accuracy of optical pyrometry in the range 800 °C to 2200 °C and supports the extension of these estimates to 4000 °C. The standard deviation uncertainty of optical pyrometry is shown to be about 1 °C at 800 °C rising to 2 °C at 2200 °C and 10 °C at 4000 °C, being about double this for the calibration of commercial pyrometers unless certain described precautions are taken.The reliability of the secondary standard lamps, when used under well-defined conditions, is confirmed and it is shown that they have a standard deviation calibration uncertainty of about 1 °C for the vacuum-type lamps in the range 800 °C to 1500 °C and 2 °C for the gas-filled lamps in the range 1500 °C to 2200 °C. Most of this uncertainty is due to primary standard optical pyrometer calibration errors. Attention is drawn to the fact that a carbon arc fulfills the requirements of a secondary luminance temperature standard at about 3514 °C.Recent determinations of the gold point and the second radiation constant indicate that the 1948 International Temperature Scale is lower than the thermodynamic scale by an amount varying from 0.8 °C at 800 °C to 12 °C at 4000 °C. This is already greater than the calibration errors of optical pyrometry and, in view of the still greater accuracies presaged by photomultipliers, a revision of the International Temperature Scale is suggested.

scholarly journals A large-area blackbody for in-flight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research

2018 ◽  
Vol 11 (8) ◽  
pp. 4757-4762 ◽  
Author(s):  
Friedhelm Olschewski ◽  
Christian Monte ◽  
Albert Adibekyan ◽  
Max Reiniger ◽  
Berndt Gutschwager ◽  
...  
Keyword(s):  
Temperature Scale ◽  
Environmental Research ◽  
Large Area ◽  
Atmospheric Measurements ◽  
Calibration Source ◽  
Aperture Diameter ◽  
International Temperature Scale ◽  
International Temperature ◽  
Long Duration ◽  
Better Than

Abstract. The deployment of the imaging Fourier Transform Spectrometer GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on board a long-duration balloon for stratospheric research requires a blackbody for in-flight calibration in order to provide traceability to the International Temperature Scale (ITS-90) to ensure comparability with the results of other experiments and over time. GLORIA, which has been deployed onboard various research aircraft such as the Russian M55 Geophysica or the German HALO in the past, shall also be used for detailed atmospheric measurements in the stratosphere up to 40 km altitude. The instrument uses a two-dimensional detector array and an imaging optics with a large aperture diameter of 36 mm and an opening angle of 4.07∘ × 4.07∘ for infrared limb observations. To overfill the field of view (FOV) of the instrument, a large-area blackbody radiation sources (125 mm × 125 mm) is required for in-flight calibration. In order to meet the requirements regarding the scientific goals of the GLORIA missions, the radiance temperature of the blackbody calibration source has to be determined to better than 100 mK and the spatial temperature uniformity shall be better than 150 mK. As electrical resources on board a stratospheric balloon are very limited, the latent heat of the phase change of a eutectic material is utilized for temperature stabilization of the calibration source, such that the blackbody has a constant temperature of about −32 ∘C corresponding to a typical temperature observed in the stratosphere. The Institute for Atmospheric and Environmental Research at the University of Wuppertal designed and manufactured a prototype of the large-area blackbody for in-flight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research. This newly developed calibration source was tested under lab conditions as well as in a climatic and environmental test chamber in order to verify its performance especially under flight conditions. At the PTB (Physikalisch-Technische Bundesanstalt), the German national metrology institute, the spatial radiance distribution of the blackbody was determined and traceability to the International Temperature Scale (ITS-90) has been assured. In this paper the design and performance of the balloon-borne blackbody (BBB) is presented.

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