Studies on Contamination of Thermocouples Used for Continuous Temperature Measurement of Steel Bath
On the continuous immersion pyrometry of molten steel-II
1962 Volume 48 Issue 2 Pages 105-111
Details
1962 Volume 48 Issue 2 Pages 105-111
In the first report (Tetsu-to-Hagané, 47 (1961) 11, p.1982-1988), the authors described the continuous immersion pyrometry method of molten steel in ladle and some results thereof. In order to establish this method, it was neccessary to keep the degree of contamination of thermocouple elements as low as possible.
To obtain high accuracy of actual measurement, the contamination of every thrmocouple wires used for each measurements is studied by the measurement of the drop of e. m. f., the examination of the distribution of parasitic e. m. f. and the spectrographic analysis etc. And, the tentative method to caluculate the error which was appearing during the actual measurement was considered. The main results obtained by these studies were as follows:
(1) Value of parasitic e. m. f. on the PtRh element is positive. This seems to be the characteristic of the contamination for this case.
(2) The error which is appearing during actual measurement can be caluculated by the next formula:
ΔT=Σi {ΔT1 (EPt1-EPtRh1) /1000F1}
(3) The degree of contamination of thermocouple elements depends on a temperature distribution along the wire, diameter of the wire, the insulating and protecting tube.
(4) To attain to the lower degree of contamination on the thermocouple elements and the lower cost of measurement, it is better to use a wire of smaller diameter.
(5) It is desirable to avoid the successive use of thermocouples for a high-accuracy measurement.
