How to calculate the discharge volume of the safety valve at the top of the cold high-pressure fractionator in a hydrogenation unit

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As the title suggests, the reaction system is equipped with only one set of safety valves on the cold high-pressure unit. How should the discharge capacity of these safety valves be calculated? Which operating condition should be used for the calculation? Fire? Export closed? Reaction overheating? Automatic control for replenishing new hydrogen failed? Is it still the settle-out pressure caused by the shutdown of the cyclic hydrogen compressor that leads to overpressure in the cold high-pressure section? How should the vent volume be calculated? Which expert knows how to calculate it? By looking at the design documents of other plants, I find that for some, the discharge volume of the cold high-pressure safety valves is much greater than the flow rate of circulating hydrogen, while for others it is much lower than that flow rate; I’m not sure what’s going on.