## 4 Discussion  
For the calculation method of inflow volume, a step-by-step adjustment strategy is adopted to ensure the CO\({}_{2}\) concentration preferentially and the subsequent gas introduced always contains the target proportion of CO\({}_{2}\) so that the CO\({}_{2}\) concentration remains unchanged during the time of adjusting the O\({}_{2}\) concentration because of the importance of CO\({}_{2}\) concentration. For the intermediate concentration of O\({}_{2}\), the theoretical calculation value (C\({}_{\text{o1}}\)) is used during the process instead of the measured value for the convenience of calculation, while the measured value will be susceptible. Meanwhile, when changing the gas concentration, since the relief valve is positioned downstream of the gas mixer and upstream of the chambers to avoid the effect of chamber tightness when new gases pass into the mixer, the equal volume of original gases is discharged into the atmosphere from the relief valve, theoretically. Therefore, if the total gas \begin{table}
\begin{tabular}{c c c c c c} \hline \multicolumn{1}{c}{**Target Concentration**} & \multicolumn{2}{c}{**Measured Concentration**} & \multicolumn{2}{c}{**Deviation**} \\ \hline CO\({}_{2}\) & O\({}_{2}\) & CO\({}_{2}\) & O\({}_{2}\) & CO\({}_{2}\) & O\({}_{2}\) \\ \hline \multirow{8}{*}{5\%} & 5\% & 5.01\% & 4.99\% & 0.01\% & \(-\)0.01\% \\  & 8\% & 4.97\% & 7.87\% & \(-\)0.03\% & \(-\)0.13\% \\  & 13\% & 4.92\% & 12.71\% & \(-\)0.08\% & \(-\)0.29\% \\  & 18\% & 4.93\% & 17.65\% & \(-\)0.07\% & \(-\)0.35\% \\  & 23\% & 4.96\% & 22.90\% & \(-\)0.04\% & \(-\)0.02\% \\  & 28\% & 4.96\% & 27.73\% & \(-\)0.04\% & \(-\)0.27\% \\  & 33\% & 4.92\% & 32.50\% & \(-\)0.08\% & \(-\)0.50\% \\  & 38\% & 4.90\% & 37.50\% & \(-\)0.10\% & \(-\)0.50\% \\  & 43\% & 4.90\% & 42.70\% & \(-\)0.10\% & \(-\)0.30\% \\  & 48\% & 4.91\% & 47.50\% & \(-\)0.09\% & \(-\)0.50\% \\  & 53\% & 4.90\% & 52.82\% & \(-\)0.10\% & \(-\)0.18\% \\  & 60\% & 4.95\% & 59.88\% & 0.05\% & \(-\)0.12\% \\  & 70\% & 4.92\% & 69.51\% & \(-\)0.08\% & \(-\)0.49\% \\  & 80\% & 4.93\% & 79.81\% & \(-\)0.07\% & \(-\)0.19\% \\ \hline \end{tabular}
\end{table} 
Table 1: The gas concentration measured and deviation in different scenarios. Figure 13: (**a**) Concentration changes of CO\({}_{2}\) and O\({}_{2}\) after lids open (**b**) gas consumption during each adjustment. inflow volume does not exceed the total capacity of the mixer during each adjustment, a good \"new for old\" can be realized, which satisfies the theoretical calculation model. This method is effective for small concentration changes, maintaining CO2 levels while gradually increasing O2 concentration. However, for large-scale adjustments, multiple adjustments are needed due to more gas discharge, resulting in longer adjustment times and higher gas consumption. Despite these challenges, gradual improvements in reducing gas concentration deviations are observed after several adjustments. For each subsequent adjustment, the gas concentrations of the system will approach the target value, and, thereafter, the interval of stabilization between adjustments depends on the acceptable deviation. Sealing is a critical factor in ensuring the proper functioning of the gas system and minimizing gas consumption. Theoretically, as long as the chamber lid is closed, no gas will be consumed in a breezing state. However, in the actual situation, poor sealing leads to an amount of air entering the system due to the negative pressure in the chambers, resulting in longer adjustment time, more gas consumption, and even failure to reach the target value. Therefore, better sealing helps to maintain longer concentration stability and lower gas consumption. In terms of gas consumption, the system is in a state of minimal gas usage under good sealing conditions. As air gradually enters the system, the O2 concentration increases and the CO2 concentration decreases.