## 4 Conclusions  
In this paper, the analysis of the air/water flow through the Dn25/50-Pn40 discharge valve was carried out, using CFD simulation and considering four values of the seat-valve distance and three positions of the adjustment nozzle. Standards and norms, used by the manufacturers and operators of safety valves, do not specify the position of adjusting nozzle. Also, there are no studies regarding the correct position of the adjusting nozzle. This work establishes the proper position of the adjusting nozzle considering the main safety valve function--to avoid overpressure in the working system as quick is possible--with a maximum fluid velocity, and with a minimum turbulent kinetic energy. The study, applied to a Dn25/50-Pn40 safety valve, shows the importance of safety valve construction, working fluid and pressure for correct positioning of the adjusting nozzle. The study utilized Computational Fluid Dynamics (CFD) simulations to analyze the air/water flow through the Dn25/50-Pn40 discharge valve. This suggests a reliance on numerical methods for understanding the fluid dynamics involved. The analysis took into account four values of the seat-valve distance and three positions of the adjustment nozzle. This indicates a comprehensive investigation, exploring the impact of different configurations on the valve's performance. The focus on air/water flow implies a consideration of two-phase flow dynamics. Understanding how the valve behaves under different conditions with both air and water has implications for its applicability in diverse operational scenarios. The variations in seat-valve distance and adjustment nozzle positions suggest a sensitivity analysis to evaluate how changes in these parameters affect the overall performance of the discharge valve. This information is crucial for optimizing the valve's functionality. The use of a Pn40 pressure class indicates that the valve is designed to handle relatively high-pressure conditions. This choice of pressure class is likely relevant to the specific applications for which the valve is intended. Analyzing the pressure distribution from Figures 25a and 26a, some negative pressure contours can be observed, due the phenomenon of cavitation in the case of liquids, respectively, of compressibility; in the case of gases, phenomena do not interfere with the purpose of the article, namely to determine the optimal position of the adjusting nozzle depending on the value of the fluid velocity and turbulent kinetic energy. The paper likely provides insights into the engineering aspects of discharge valves, offering valuable information for designers and engineers involved in fluid system design. The performed statistical analysis showed that when dealing with air, the adjusting nozzle position stands out as the most critical factor regarding fluidvelocity, while for water, the seat-valve distance takes precedence. Moving on to the assessment of shear stress and turbulent kinetic energy, the analysis consistently highlights the seat-valvedistance as the factor of greatest significance, for both air and water. These conclusions emphasize the essential role of specific variables in influencing fluid behavior and underline the importance of optimizing these factors to achieve desired outcomes in fluid flow and related parameters. The optimization process has successfully identified the optimal combination of input parameters necessary to attain the desired outcomes in both air and water environments. For the air environment, the \"greater is better\" option for turbulent kinetic energy was achieved by setting S-1/H2, while the \"smaller is better\" option for turbulent kinetic energy was attained with the setting S0/H1. Similarly, in the water environment, the optimization process determined that the combination of S0/H2 results in \"greater is better\" turbulent kinetic energy, while S0/H1 is the ideal setting for \"smaller is better\" turbulent kinetic energy.