The importance of calorimeter recalibration

As a key device for accurately measuring heat, calorimeters are widely used in many fields such as coal and chemical industry. As the use time increases or the use environment changes, the measurement accuracy of the instrument may deviate. Re-calibrating the calorimeter is a necessary means to ensure the accuracy and reliability of its measurement data, which is directly related to the scientificity of the experimental results and the correctness of the production decision.

Preparation before calibration

1. Environmental preparation: Calibration should be carried out in a room with stable temperature (generally controlled at 15-30 ° C) and suitable humidity (relative humidity ≤ 80%) to avoid direct sunlight and strong airflow interference to create a stable environment for calibration.

2. Instrument inspection: Carefully check whether the appearance of the calorimeter is damaged and whether the connections of various components are stable to ensure that the instrument can operate normally. At the same time, prepare standard materials that meet the requirements of accuracy, such as benzoic acid, whose calorific value must be accurately known and stable.

3. Cleaning and maintenance: Wipe the inside of the calorimeter with a clean soft cloth to remove residual samples and impurities to prevent it from affecting the calibration results.

Specific calibration steps

1. Installation and weighing: Put the standard benzoic acid tablet into the combustion dish, weigh it accurately with a high-precision balance, and record the weight. Install the combustion dish into the oxygen bomb of the calorimeter to ensure that the installation is firm and avoid accidents during combustion.

2. Oxygenation operation: Fill the oxygen bomb with an appropriate amount of oxygen, the general pressure is controlled at 2.8-3.0 MPa, and the oxygenation time is not less than 15 seconds to ensure that the sample can be fully burned.

3. Instrument settings: Turn on the power supply of the calorimeter, enter the calibration mode, and set relevant parameters according to the instrument manual, such as the calorific value of the reference material, the weight of the sample, etc.

4. Ignition and measurement: Start the ignition program, and the calorimeter automatically measures and records the temperature change during combustion until the end of the measurement.

5. Data calculation and adjustment: According to the measurement data, calculate the actual heat capacity of the calorimeter. If there is a deviation between the actual heat capacity and the instrument setting value, correct the heat capacity according to the instrument operation process until the specified accuracy requirements are met.

Verification and Precautions after Calibration

After the calibration is completed, it is necessary to use the standard material again for verification experiments to ensure the accuracy of the measurement results of the calorimeter. In daily use, the calorimeter should be regularly maintained and inspected to keep the instrument clean and used in strict accordance with the operating procedures to avoid affecting the performance of the instrument due to improper operation. If abnormal measurement data of the instrument is found, it should be re-calibrated in time to ensure the smooth progress of the measurement work.