The reaction will take place in the vessel. Unless there is two phase flow and unreacted vessel contents are emitted, the moisture in the air should not affect the discharge.
There are no valves except the Level control valve as shown. The water can only enter D228 so the relief case is based on a reaction in that vessel only. The vent lines connecting the vessels remain clear. The overflows could be part filled with liquid.
Hello,
I have to verify the design of a pressure relief vent (2 x 6" bursting discs in series) for a pressure vessel in which a process upset could see water entering the tank and cause a reaction.
The following sketch shows how the vessel is linked to other vessels by vents and overflows...