The Core Principle of Calibration Degree of calorimeter

The essence of calorimeter calibration is to calibrate the heat measurement system of the instrument through the reference material with known calorific value to ensure that it can accurately reflect the heat released by the combustion of the substance. The accuracy of calibration directly determines the reliability of experimental data and is a key prerequisite for ensuring the accuracy of subsequent detection.

Required preparations before calibration

1. Selection of reference materials: Benzoic acid is preferred as a reference material, with a stable and uniform calorific value. It is necessary to ensure that benzoic acid is dry and pure to avoid moisture or impurities affecting the calibration results.

2. Instrument status inspection: check the tightness of the oxygen bomb of the calorimeter to ensure that there is no air leakage; clean up the residual material on the inner wall of the oxygen bomb to avoid the residue burning interfering with the heat measurement; at the same time confirm that the power supply, temperature sensor and other components of the instrument are operating normally.

3. Environmental condition control: Calibration should be carried out in a constant temperature environment, and the ambient temperature fluctuation should be controlled within ± 1 ° C to avoid temperature changes affecting the heat balance of the instrument.

Calorimeter degree calibration detailed steps

1. Standard material weighing: use a high-precision balance to accurately weigh an appropriate amount of benzoic acid, the weight must meet the requirements of the instrument manual, generally controlled between 0.8-1 g, and record the weighing value.

2. Sample filling and oxygen bomb assembly: Press the weighed benzoic acid into pieces, put it in a burning dish, connect the ignition wire, and ensure that the ignition wire is in full contact with the sample. Then put the burning dish into the oxygen bomb, tighten the oxygen bomb cover, fill it with enough oxygen, the pressure needs to reach 2.8-3 MPa, and let it stand for 1 minute to check whether it is leaking.

3. Instrument calibration operation: put the assembled oxygen bomb into the inner cylinder of the calorimeter, add an appropriate amount of distilled water to ensure that the water surface covers the top of the oxygen bomb. Start the instrument, enter the calibration mode according to the prompts of the operation interface, enter the calorific value, weight and other parameters of the standard material, and start the calibration procedure. The instrument will automatically complete the ignition, heat measurement and data calculation, and record the calibration coefficient displayed by the instrument after the calibration is completed.

4. Repeated verification: In order to ensure the calibration accuracy, the calibration needs to be repeated 2-3 times. If the relative deviation of the calibration coefficients does not exceed 0.2%, the calibration is qualified; if the deviation is too large, the cause needs to be investigated and re-calibrated.

Key considerations for the calibration process

During operation, it is necessary to strictly abide by the instrument operating procedures to avoid collisions and vibrations of the instrument and to prevent it from affecting the measurement accuracy.

The distilled water used for calibration should be brought to room temperature in advance to avoid heat calculation errors due to differences in water temperature.

After the calibration is completed, it is necessary to clean the oxygen bomb and inner cylinder in time, properly store the reference material, and prepare for the next calibration.

Mastering the calibration method of the calorimeter can not only ensure the measurement accuracy of the instrument, but also provide reliable data support for subsequent experimental testing. Strictly follow the above steps to complete accurate calibration and ensure that the calorimeter is always in the best working condition.