The calorimeter is the core equipment for accurately measuring the calorific value of a substance. The accuracy of its measurement data directly depends on the scientific and standardized calibration process. Mastering the correct calibration method is the key to ensuring the reliability of the experimental results. The following is a detailed explanation of the core calibration knowledge for you.

First, the core calibration substance: benzoic acid

Calibration calorimeter, benzoic acid is the most commonly used reference material. It has the advantages of stable combustion heat, uniform properties, and easy tablet molding. The standard combustion calorific value is clear, and it can achieve full and stable combustion in the calorimeter, providing an accurate benchmark for calibration. Before use, benzoic acid needs to be dried at 60 ° C -70 ° C for 2 hours to remove moisture, and then pressed into compact tablets to avoid incomplete combustion affecting the calibration accuracy.

Second, the specific operation process of calibration

1. Instrument preparation: Turn on the calorimeter to ensure that the equipment is preheated and stable, check the air tightness of the oxygen bomb, and avoid air leakage leading to combustion failure.

2. Sample loading: Put the dried benzoic acid tablets into the crucible, connect the ignition wire, ensure that the ignition wire is in full contact with the sample, and then place the crucible in the oxygen bomb.

Oxygen filling and testing: Fill the oxygen bomb with 3.0 MPa-3.2 MPa of oxygen, put it into the inner cylinder of the calorimeter, start the test program according to the operating procedures, and record the data after the combustion is complete.

4. Repeated verification: Repeat the calibration 3-5 times under the same conditions, remove the data with excessive deviation, and take the average value as the final calibration result to improve the reliability of the data.

III. Precautions for calibration

The calibration environment needs to be kept at a constant temperature to avoid temperature fluctuations interfering with the measurement; the oxygen purity needs to be up to standard, and insufficient purity will lead to insufficient combustion; before each calibration, the oxygen bomb and inner cylinder need to be cleaned to prevent residual substances from affecting the combustion effect. Regular calibration of the calorimeter can continuously ensure the measurement accuracy and provide accurate data support for the experiment.