Consumptive fast reaction thermocouple / thermometry lance / thermocouple rod
TEMPERATURE MEASUREMENT IN LIQUID METAL
Molten metal temperature must be within strict limits determined and required by the metallurgical and quality department, before the heat or melt may be tapped or cast. These acceptance limits are the best compromise between various conflicting factors. A too low temperature gives raise to casting problems. A too high temperature results in extra energy consumption, increased refractory wear, decrease of eutectic cells in iron, different casting problems (break-through, various surface defects, etc.) and time losses due to holding or cooling down the molten metal.
Hence, accuracy, reproducibility and reliability of molten metal temperature measurements directly influence the quality of the end product as well as the productivity of the plant.
To control whether the desired temperature is reached, different techniques are used. Amongst the best-known methods we cite optical temperature measurement and thermoelectric temperature measurement.
Because of the influence of slag, fumes and various border conditions, optical temperature measurement of molten metal is a relatively rough method that cannot guarantee the high accuracy mostly required. Moreover, this method only measures the temperature at the metal surface.
Thermoelectric temperature measurements with noble metal thermocouples dipped in the molten metal bath actually provide the best solution. Nowadays, expendable thermocouples such as shown in fig.1 are the most economical and effective way to fulfil the required accuracy, reproducibility and reliability.