The calorimeter is the core equipment for accurately measuring the heat of a substance. The gas selection directly determines the accuracy and reliability of the experimental data. There are clear differences in the gas requirements of different experimental scenarios.

Core commonly used gas types: The most commonly used gases in calorimeters are oxygen and nitrogen. Oxygen is mainly used for complete combustion experiments of combustible substances, which can provide a sufficient combustion environment for sample combustion to ensure full release of heat. It is suitable for the determination of calorific value of combustible samples such as coal and chemical raw materials; nitrogen is mostly used in inert protection scenarios to isolate air to prevent sample oxidation, or as a carrier gas in special experiments to ensure the stability of the experimental process.

Gas core requirements: No matter which gas is selected, the purity must be strictly up to standard. The purity of oxygen is usually not less than 99.5%, and the purity of nitrogen must reach more than 99.9%. Impurities can interfere with the combustion effect or cause data deviation. At the same time, the gas needs to be dry and clean to avoid moisture and dust clogging pipelines or corroding equipment, which can affect the normal operation of the instrument.

The key basis for gas selection: the selection of gas should be combined with the purpose of the experiment, the determination of the calorific value of the combustible sample should be preferentially selected oxygen, and the non-combustion experiment or the experiment that needs to isolate the air should be selected nitrogen; in addition, the instrument model should be matched. Some high-end calorimeters have specific parameters for gas pressure and flow, and must be operated in strict accordance with the instrument instructions.

Gas usage specifications: Check the gas pipeline tightness before use to prevent leakage from causing safety hazards; replace the gas cylinder and pressure reducing valve regularly to ensure a stable gas supply; close the gas source in time after the experiment, clean the pipeline, and ensure long-term accurate operation of the instrument.

Mastering the gas selection points of a calorimeter not only guarantees the accuracy of the experimental data, but also prolongs the service life of the instrument, helping to carry out various heat measurement experiments efficiently.