What determines the size of a safety device in relation to a pressure vessel?

The size of a safety device in relation to a pressure vessel is fundamentally related to the diameter of the vessel. The diameter is crucial because it directly influences the volume of fluid within the vessel and the resulting pressure conditions. A larger diameter vessel can hold more fluid, which may lead to a higher potential for increased pressure in case of a thermal event or other overpressure situations.

Safety devices, such as pressure relief valves, must be adequately sized to relieve excess pressure in order to prevent catastrophic failures. If a safety device is not sized properly in relation to the vessel diameter, it may not be capable of discharging enough volume to protect the vessel from exceeding its maximum allowable working pressure. Therefore, adhering to the proper sizing guidelines based on the diameter ensures that the safety device can respond effectively and protect the integrity of the vessel and the surrounding environment.