Discussion and inquiries regarding nitrogen protection for flammable systems

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1. Nitrogen protection (inerting) is primarily used to control the oxygen content in systems containing flammable materials, in order to avoid the risk of combustion and explosion. 2. For different flammable liquids, there are various oxygen safety limits (i.e., limit oxygen concentrations). Nitrogen protection involves reducing the oxygen concentration below these limit values; typically, the control level is set 4% lower than the limit oxygen concentration. For example, if the limit oxygen concentration for methanol is 10%, then the control level is an oxygen concentration of 6%. 3. The method of nitrogen protection varies depending on the different systems. For example: 3.1 Storage tanks can be protected by nitrogen sealing valves to maintain a sealed environment; pressure is released when it exceeds a certain level, and nitrogen is supplied when the pressure drops below a certain level ； 3.2 For other relatively airtight systems, vacuum pumping followed by the filling of nitrogen 2–3 times can be used for displacement protection ； 3.3 How then can some non-hermetical systems ensure that nitrogen protection is effective? After the reaction vessel is protected by nitrogen purging, if it is necessary to open the vessel’s lid to add solids or to vent it for subsequent reactions, how is it appropriate to maintain nitrogen protection during these operations? Can protection be achieved by determining the nitrogen flow rate? But given the different diameters of the vent pipes or reaction vessels, how can the appropriate nitrogen flow rate be determined? ?Question 3.3: Seeking advice from experts! If there are any other shortcomings, please feel free to help improve them; thank you!