| Zugriffsnummer | 28540 |
| Dokumenttyp | Zeitschriftenartikel |
| Sprache | Englisch |
| Titel | A new attempt on a coulometric trace humidity generator |
| Autor(in); Institution |
Mackrodt, Peter; 3.2, Gasanalytik und Zustandsverhalten, PTB-Braunschweig
|
| Quelle/Jahr | International Journal of Thermophysics: 33 (2012), 8-9, 1520 - 1535 |
| ISSN | 0195-928X (PRINT) ; 1572-9567 (ONLINE) |
| DOI | |
| Verlag | Dodrecht: Springer |
| Freie Schlagworte | Coulometry ; Frost-point temperature ; Generator ; Humidity ; Hygrometry ; Laser spectroscopy ; Trace analysis ; Uncertainty ; Volume fraction ; Water electrolysis ; Water vapor |
| Zusammenfassung | This paper describes the improved PTB coulometric trace humidity generator designed to extend the calibration capabilities at PTB down to 5 nL/L water-vapor volume fraction. The generation of defined water-vapor concentrations is based on the generation of defined quantities of hydrogen and oxygen by electrolysis of water according to Faraday’s law and the catalytic recombination of the generated hydrogen and oxygen back into water, which is then added to a flow of ultrapure or zero gas. The inherent uncertainties associated with the main subsystems are discussed, especially as concern the electrolysis of water. The expanded relative uncertainty of the water-vapor concentration is calculated and shown to be about 0.5 % to 1 % in the range above 100 nL/L volume fraction. For lower concentrations, the expanded uncertainty in volume fraction is about 0.6 nL/L to 0.9 nL/L caused by the blank level of the zero gas. |
