Thoroughly clean the inside of the constant temperature oil bath to remove residual impurities, oil stains, etc. Use appropriate cleaners and tools to ensure that there is no dirt accumulation on the inner wall of the oil bath, heating elements, and stirring device, so as not to affect the heat transfer efficiency and calibration accuracy.

After cleaning, dry it with a clean cloth or let it air dry naturally to ensure that the inside of the oil bath is dry.

Check the liquid level of the heat transfer oil, which should be within the normal range. If the liquid level is too low, it is necessary to add an appropriate amount of the same type of heat transfer oil to ensure that the heating elements and the temperature-sensing part of the thermometer can be fully immersed when the oil bath operates normally.

Check the quality of the heat transfer oil, such as color, transparency, viscosity, etc. If the heat transfer oil is deteriorated, contaminated, or aged, it should be replaced in time to ensure good heat conduction performance and stability.

Select a standard thermometer with high accuracy, good stability, and calibrated. Its range should cover the working temperature range of the constant temperature oil bath, and the resolution should meet the calibration requirements. Generally, it is recommended to use a thermometer with a resolution of not less than 0.1℃.

Before use, check whether the appearance of the standard thermometer is intact, whether there is damage or blurred scale, etc. At the same time, confirm that the thermometer certificate is within the validity period to ensure its accuracy and reliability.

The calibration work should be carried out in an environment with relatively stable temperature and no obvious air flow interference. The difference between the ambient temperature and the set temperature of the constant temperature oil bath should not be too large, generally controlled within ±5℃, to reduce the influence of the ambient temperature on the calibration results.

Ensure that there are no strong electromagnetic fields, vibration sources and other interference factors around the working area to avoid affecting the normal operation and measurement accuracy of the thermometer and the oil bath.