1. Errors caused by poor insulation

For example, too much dirt or salt slag on the insulation protection tube of the thermocouple and the wire drawing board leads to poor insulation between the thermocouple JI and the furnace wall, which will not only cause the loss of thermoelectric potential but also introduce interference, and the error caused by this may sometimes reach Baidu. .

2. Thermal resistance error

At high temperature, if there is a layer of coal ash and dust on the protective tube, it will increase the thermal resistance and hinder the conduction of heat. At this time, the temperature indication is lower than the true value of the measured temperature. Therefore, the outside of the thermocouple protection tube should be kept clean to reduce errors.

3. Errors caused by improper installation

The space between the protective sleeve of the thermocouple and the wall is not filled with insulating material, which will cause the heat to overflow or the intrusion of cold air in the furnace. Therefore, the gap between the protective tube of the thermocouple and the hole of the furnace wall should be blocked with insulating material such as refractory mud or asbestos rope to avoid cold. Hot air convection affects the accuracy of temperature measurement;

The cold end of the thermocouple should not be too close to the furnace body so that the temperature exceeds 100 °C.

4. Errors introduced by thermal inertia

Because the thermal inertia of the thermocouple makes the indicated value of the instrument lag behind the change of the measured temperature, this effect is particularly prominent when making rapid measurements. Therefore, a thermocouple with a smaller thermoelectric JI and a smaller protective tube diameter should be used as much as possible.

When the temperature measurement environment permits, the protective tube can even be removed. Due to the measurement lag, the amplitude of the temperature fluctuation detected by the thermocouple is smaller than that of the furnace temperature fluctuation. The larger the measurement lag, the smaller the amplitude of the thermocouple fluctuations and the larger the difference from the actual furnace temperature.