According to the calibration plan, set the required calibration temperature points on the temperature controller of the constant temperature oil bath. For example, first set it to 50℃, and then proceed to the next step after the temperature is stable.

When setting the temperature, it should be adjusted slowly to avoid sharp temperature changes that cause uneven temperature inside the oil bath or excessive temperature fluctuations.

Turn on the power of the oil bath, start the heating and stirring devices, and let the oil bath start to heating. During the heating process, closely observe the temperature change, which can be monitored through the temperature display instrument on the oil bath.

When the temperature is close to the set value, appropriately reduce the heating power, and make the oil bath slowly rise to the set temperature and maintain temperature stability. Generally, it is required that the temperature fluctuation is within the range of ±0.1℃ (which can be adjusted according to the actual calibration requirements). At this time, it is considered that the oil bath has reached a stable state.

Insert the standard thermometer and the calibrated thermometer into the oil bath through an appropriate installation method (such as a thermometer socket, bracket, etc.). The insertion depth should meet the requirements. It is usually recommended that the insertion depth is not less than 2/3 of the depth of the oil bath to ensure that the thermometer can accurately measure the average temperature inside the oil bath.

Adjust the position of the thermometer to make it as close to the center area of the oil bath as possible, and avoid contact with the wall of the oil bath, heating elements, and stirring device, etc., to reduce the influence of local temperature differences on the measurement results.

When the temperature of the oil bath is stable, read the indication values of the standard thermometer and the calibrated thermometer at the same time and record them. Repeat the reading every a certain time interval (such as 3 - 5 minutes) and collect 5 - 6 sets of data in total.

When recording the data, ensure the accuracy and integrity of the data, and at the same time indicate the acquisition time, thermometer number and other relevant information.

For each set of collected data, calculate the indication difference between the calibrated thermometer and the standard thermometer, which is the temperature deviation. Through the analysis of multiple sets of temperature deviation data, calculate statistical quantities such as the average value and standard deviation to evaluate the measurement accuracy and stability of the calibrated thermometer.

If the temperature deviation exceeds the allowable range, further analyze the reasons, which may be problems with the thermometer itself, uneven temperature of the oil bath, measurement operation error, etc. For different reasons, take corresponding solutions, such as recalibrating the thermometer, adjusting the working state of the oil bath, standardizing the measurement operation, etc.

After completing the calibration of one calibration temperature point, follow the above steps to operate on other set calibration temperature points in turn. For example, set the oil bath temperature to 70℃, repeat the preheating, thermometer installation, data acquisition and analysis processes until all the calibration work of the calibration temperature points is completed.