Preparation before calibration

Before calibrating the calorimeter, it is necessary to make full preparations. First of all, make sure that the appearance of the calorimeter is intact, and the components are firmly connected without loosening or damage. At the same time, prepare the reference material, such as benzoic acid, whose calorific value needs to be accurately known and stable, which is the key basis for calibration and calibration. In addition, it is also necessary to be equipped with a balance with the required accuracy for accurately weighing the quality of the reference material, as well as a stable power supply to ensure the normal operation of the calorimeter.

Second, the specific steps of calibration

1. Instrument preheating: Turn on the calorimeter and let it preheat for a certain period of time, usually about 30 minutes, so that the internal temperature of the instrument reaches a stable state and reduces the impact of temperature fluctuations on the measurement results.

2. Weigh the standard material: Use a balance to accurately weigh the appropriate amount of benzoic acid and record its quality. The quality range should meet the calibration requirements of the calorimeter, generally controlled between 0.8 and 1.2 grams.

3. Sampling and ignition: put the weighed benzoic acid into the crucible, then place the crucible in the oxygen bomb, and install the ignition wire to ensure good contact. Fill with oxygen to the specified pressure, usually 2.8-3.0MPa, then put the oxygen bomb into the calorimeter inner cylinder and cover it.

4. Start the measurement: Start the calorimeter, and the instrument will automatically perform ignition, measurement, and other operations to record the temperature change process until the end of the measurement, and obtain the heat released by combustion.

5. Calculation and calibration: According to the known calorific value and weighed mass of benzoic acid, calculate the theoretical heat release and compare it with the measured value of the instrument. If there is any deviation, follow the instrument calibration instructions and adjust the relevant parameters until the measured value matches the theoretical value to complete the calibration.

III. Post-calibration verification and precautions

After the calibration is completed, it is necessary to use the reference material again for verification, and repeat the above steps to ensure that the calibration results are accurate and reliable. During the operation, attention should be paid to the stability of the ambient temperature to avoid external interference; the operator needs to be familiar with the instrument operation process and strictly follow the specifications for each step of operation; each calibration should record the relevant data in detail for subsequent traceability and analysis. Through the standardized calibration calibration process, the measurement accuracy of the calorimeter can be guaranteed, and reliable data support can be provided for experiments and production.