Pressure relief systems are a system of last resort. It is best practise to design the system so that pressure relief device systems are not required. For example specify the vessels with a design pressure higher than any pump can deliver. I noted that you have solvents present so fire may be...
The conservative approach is to assume that there is a sudden tube rupture and in this case the relief device would have to pass the cooling water at a volume rate equal to the gas rate flowing from the ruptured tube.
However an alternative approach is to assume that the leak develops slowly...
