There are many ways to detect temperature measuring instruments. According to the different measurement principles and application scenarios, they can be divided into many types. The following are some common temperature-measuring instruments and their detection methods:

1. Contact thermometer
Glass liquid thermometer
Working principle: Use the property that the volume of the liquid changes with temperature to measure the temperature.
Detection method: Usually the detection is carried out by comparison method, that is, the thermometer to be tested and the standard thermometer of known accuracy are placed in the same constant temperature bath at the same time, and the readings of the two are compared.
Resistance thermometer
Working principle: Use the property that the resistance value of a conductor or semiconductor changes with temperature to measure the temperature.
Detection method: Use a bridge circuit or a resistance meter to measure the resistance value, and determine the temperature according to the resistance-temperature relationship curve.
Thermocouple thermometer
Working principle: Use the thermoelectric effect, that is, the conductors of two different materials generate electromotive force under the action of temperature difference to measure the temperature.
Detection method: Compare the thermocouple with the standard thermocouple, or use a thermocouple calibrator for calibration.
Bimetallic thermometer
Working principle: Two metal sheets with different linear expansion coefficients are combined together. When the temperature changes, the two metals have different elongations and displacement occurs, which drives the pointer to deflect to indicate the temperature.
Detection method: Verify by comparison method or using special calibration equipment.
2. Non-contact thermometer
Infrared thermometer
Working principle: The temperature value is obtained by measuring the infrared radiation emitted by the surface of the object.
Detection method: Use a standard black body radiation source for calibration, or compare it with a target object of known temperature to verify its accuracy.
Optical pyrometer
Working principle: Use the relationship between the brightness and temperature of the thermal radiation of the object to measure high temperature.
Detection method: Verify its accuracy by comparison method or comparison with a standard high-temperature source.
3. Special thermometer
Semiconductor thermometer
Working principle: Use the characteristics of the resistance or other electrical properties of semiconductor elements that change with temperature to measure temperature.
Detection method: Use special semiconductor thermometer calibration equipment for calibration.
Liquid crystal thermometer
Working principle: Use the phase change of liquid crystal at different temperatures to change color, thereby indicating temperature.
Detection method: Usually the accuracy is verified by comparing the color change at a known temperature.
4. Comprehensive detection method
Comparison method: Put the thermometer to be tested and the standard thermometer of known accuracy into the same constant temperature bath at the same time, and compare the readings of the two.
Calibration method: Use special calibration equipment to calibrate the thermometer, such as a thermocouple calibrator, resistance measuring instrument, etc.
Standard source method: Use standard sources such as standard black body radiation sources and standard high-temperature sources to calibrate the thermometer.
5. Precautions
When testing the thermometer, the stability and accuracy of the detection environment should be ensured to avoid the influence of external factors on the test results.
Different types of thermometers should adopt different detection methods and standards to ensure the accuracy and reliability of the test results.
Thermometers should be calibrated and maintained regularly to ensure their accuracy and stability in long-term use.
In summary, there are many detection methods for temperature measuring instruments, and the appropriate detection method should be selected according to the specific application scenario and measurement requirements. At the same time, the accuracy and reliability of the detection process should be ensured to meet the needs of production and scientific research.