preparatory work

Before calibrating the Huatai calorimeter, it is necessary to ensure that the instrument is in a stable operation state, the ambient temperature is controlled at 15-30 ° C, the humidity is maintained at 40% -70%, and direct sunlight and strong airflow interference are avoided. At the same time, the standard benzoic acid (purity ≥ 99.99%), special ignition wire, oxygen (purity ≥ 99.5%) and cleaning tools are prepared with metrology certification. All equipment needs to be preheated for more than 30 minutes in advance.

Reference material selection and weighing

Accurate selection of reference materials is the core premise of calibration. Huatai calorimeter needs to match the corresponding range of standard benzoic acid and needs to be used within the valid period. When weighing, use an analytical balance with an accuracy of 0.1mg to press benzoic acid into a tablet with a uniform thickness. The weight is controlled between 0.8-1. 2g to avoid overweight or underweight affecting the combustion effect. Record the exact weight after weighing for backup.

Calibration operation core steps

1. Sampling and sealing: Put the weighed benzoic acid sheet into the crucible, connect the ignition wire to ensure that the ignition wire is in full contact with the sample, and then place the crucible smoothly into the oxygen bomb, tighten the oxygen bomb cover, and check the sealing performance to prevent air leakage.

2. Oxygenation and installation: Fill the oxygen bomb with oxygen, the pressure is set to 2.8-3 MPa, and the oxygenation time is not less than 15 seconds. After completion, put the oxygen bomb into the inner cylinder of the calorimeter, connect the electrodes, and close the outer cover of the instrument.

3. Parameter setting and start-up: Enter the weight of benzoic acid, the calorific value of the ignition wire and other parameters on the instrument operation interface, and start the calibration program. The instrument will automatically complete the ignition, temperature measurement, calculation and other processes without manual intervention. After the program is completed, the calibration results will be recorded.

Validation of calibration results and precautions

After the calibration is completed, it is necessary to perform three consecutive parallel calibrations. The relative standard deviation of the calculated results should be less than or equal to 0.2%. If it exceeds the range, it is necessary to check the environment, operation or standard material problems and re-calibrate. In addition, it is strictly forbidden to touch the instrument during the calibration process to avoid vibration interference. After each calibration, the oxygen bomb and inner cylinder should be cleaned to prevent residual substances from affecting the accuracy of the next calibration.

Mastering the calibration method of Huatai calorimeter can not only ensure the accuracy of the instrument detection data, but also prolong the service life of the instrument and provide reliable support for the experimental detection work.