The present disclosure is directed to a method and system for detecting activation of a pressure relief device connected to a storage tank containing a pressurized gas. The method includes calculating a pressure relief device release rate based on a set of inputs, wherein the set of inputs includes at least one of a storage tank volume, a pressure relief set point, an orifice size of the pressure relief device, a gas density, and a reseat point for the pressure relief device. The method further includes monitoring the pressure within the storage tank and calculating a differential pressure reading over time, comparing the differential pressure reading over time to the pressure relief device release rate, and detecting a pressure relief device activation based on the comparison result.