As the core tool of temperature measurement, thermometers come in a wide variety, and each has its unique principle and application scenario.
Mercury thermometer is a classic temperature measuring instrument. It uses the simple and reliable physical principle of mercury's thermal expansion and contraction. The sealed mercury column in the glass tube will rise and fall with changes in temperature. The temperature value is obtained by reading the scale corresponding to the top of the mercury column. The measurement range of mercury thermometers is generally between -39℃ and 357℃. Within this range, it can provide relatively high measurement accuracy. In daily life, we often use it to measure body temperature. In laboratory environments, it is also used for some experimental measurements that require high precision and a suitable temperature range, such as monitoring the storage temperature of certain chemical reagents.
Thermocouple thermometer is based on the Seebeck effect. When two different metal conductors form a closed loop, if the temperatures of the two contact points are different, a thermoelectric potential will be generated in the loop. There is a specific functional relationship between this thermoelectric potential and the temperature difference. By measuring the magnitude of the thermoelectric potential, the temperature value can be calculated. The advantage of thermocouple thermometers is that they have a wide measurement range and can measure a large range from low temperatures to high temperatures. The highest temperature that can be measured exceeds 1000℃. Therefore, in the industrial field, especially in high-temperature production processes such as steel, metallurgy and ceramics, thermocouple thermometers are widely used in measuring temperatures inside blast furnaces and ceramic firing furnaces.
Thermal resistance thermometer uses the characteristic that the resistance of metal or semiconductor materials changes with temperature to achieve temperature measurement. For metal materials, their resistance usually increases with increasing temperature. For example, platinum resistance thermometer has the advantages of high precision and good stability. It is often used for precision measurement in the medium and low temperature range and plays an important role in accurately controlling the production environment temperature in industries such as food processing and pharmaceuticals. Semiconductor thermal resistance thermometer, such as thermistor thermometer, has a more significant change in resistance with temperature and high sensitivity. It is often used in occasions where a fast response to temperature changes is required, such as temperature monitoring of electronic equipment. These different types of thermometers complement each other and meet the diverse needs of temperature measurement in different fields.
