| Zugriffsnummer | 23866 |
| Dokumenttyp | Konferenzartikel in Zeitschrift |
| Peer Review | unbekannt |
| Sprache | Englisch |
| Titel | Thermal radiation effect on SPRT-measurements at the aluminium point |
| Autor(in); Institution |
Fahr, Martin; 7.4, Temperatur, PTB-Berlin; National Research Council, Ottawa, CANADA
Rudtsch, Steffen; 7.4, Temperatur, PTB-Berlin
|
| Quelle/Jahr | Acta Metrologica Sinica: 29 (2008), 4A, 6 S. |
| ISSN | 1000-1158 |
| Verlag | Beijing: Acta Metrologica Sinica Press |
| Konferenzangaben | International Conference on Temperature and Thermal Measurement, TEMPBEIJING 2008, Beijing, 20-23, October, 2008, China |
| Freie Schlagworte | radiation effect ; temperature depression ; aluminium point ; thermometer well ; SPRT |
| Zusammenfassung | It is well known that for fixed-point measurements by means of long-stem SPRTs the propagation of visible and near-infrared radiation along the thermometer well of the fixed-point cell as well as the stem of an SPRT can be a source of systematic measurement error. Consequently, all quartz tubes of SPRTs and fixed-point cells used at temperatures above the tin fixed-point are sand-blasted or blackened on the outer surface to prevent radiative heat exchange. For several reasons, treating the inner surface, instead of the outer one, could be more practical. But, as the experimental results in this paper demonstrate, there is a considerable and so-far unexplained depression of the measured fixed-point temperature in the former case. In order to explain the unexpected difference between the inner and outer surface with regards to the radiative heat transfer, the temperature depression has been investigated at the aluminium point using different types of sandblasted quartz tubes. Based on these experimental results, we discuss a more sophisticated model of the propagation of radiation along the thermometer well of fixed-point cells, explaining all findings, and showing how to minimize the thermal radiation effect. |
