Thermal resistance thermometer is a temperature sensing element made of conductor or semiconductor material. Its resistance value is a function of temperature. When it is used with the display instrument cover, it can measure the temperature from - 200 ℃ to 500 ℃. It has the characteristics of high precision and good stability. The heated part of the thermal resistance (temperature sensing element) is evenly twined on the insulating framework with the required metal filaments. When there is a temperature step in the measured medium, the measured temperature is the average temperature of the measured medium. Thermocouple thermometer is a temperature sensing element composed of two conductors with different components. It is usually used together with display, recording and regulating instruments. It can measure the temperature of - 200 ~ 1800 ℃ in the production process. When used with the display instrument, the compensation wire should be connected.