First, clarify the core basis for the calibration of the calorimeter American standard

The calibration of a calorimeter requires strict compliance with relevant American standards and specifications. The core is based on ASTM (American Society for Testing and Materials) standards, which commonly involve ASTM D5865, ASTM E711, etc. These standards clarify the accuracy requirements, calibration conditions, and operation procedures of the calorimeter. They are the fundamental principles of calibration work and ensure that the calibration results are authoritative and versatile.

II. Necessary preparations before calibration

1. Equipment calibration verification: First check the main unit of the calorimeter, oxygen bomb, temperature sensor and other key components to ensure that the equipment is trouble-free and has stable performance. At the same time, calibrate the supporting weighing equipment and standard materials to ensure accurate measurement data.

2. Control of environmental conditions: Calibration should be carried out in a constant temperature and humidity environment, with the ambient temperature controlled at 15-30 ° C and the humidity maintained at 40% -60% to avoid temperature and humidity fluctuations affecting the accuracy of the calibration results.

3. Standard material preparation: Use standard benzoic acid that meets the requirements of the American standard, and its purity must reach more than 99.99%, and it must be certified by an authoritative organization to ensure the traceability of energy release during the calibration process.

III. Core calibration operation process

1. Oxygen bomb assembly and sealing: put the weighed standard benzoic acid into the oxygen bomb crucible, connect the ignition wire to ensure that the ignition wire is in good contact with the benzoic acid, and then tighten the oxygen bomb cover to test the airtightness to ensure that the oxygen bomb seal is leak-free and the pressure meets the calibration requirements.

2. Sample loading and equipment settings: Put the sealed oxygen bomb into the inner cylinder of the calorimeter, add an appropriate amount of distilled water, cover the outer cylinder, and set the parameters of the calorimeter according to the requirements of the American standard, including temperature compensation, ignition delay time, etc., to ensure that the operating parameters of the equipment match the standard.

3. Ignition and data collection: Start the calorimeter ignition program, monitor the temperature change in real time, record the whole process data of ignition to the highest temperature, and obtain the complete temperature-time curve after the temperature is stabilized to provide core data support for subsequent calculations.

IV. Calculation and verification of calibration results

According to the collected temperature data, combined with the known calorific value of standard benzoic acid, the heat capacity of the calorimeter is calculated according to the American standard formula. The calculation formula must strictly follow the ASTM standard requirements to ensure that the calculation process is standardized. After the calculation is completed, it needs to be verified repeatedly, calibrated 3-5 times in a row, and the relative standard deviation of the calculation result should be controlled within the range specified by the American standard. If it exceeds the range, it needs to check the cause and re-calibrate until the result meets the standard.

V. Calibration records and follow-up maintenance

After the calibration is completed, the calibration time, environmental conditions, reference material information, calculation results and other key data are recorded in detail to form a complete calibration report archive. At the same time, a regular calibration system for the calorimeter is established, and it is re-calibrated every six months or after equipment maintenance according to the requirements of the American standard to ensure that the calorimeter is always in accurate operation and ensure the reliability of the detection data.