A decontamination system for a device, such as a lumen device, is provided. The decontamination system includes a terminal package defining a device receiving area. The terminal package includes a fluid inlet through which sterilant fluid can be delivered to the device receiving area. An accumulator apparatus is provided that is configured to switch between trapping sterilant fluid delivered into the device receiving area and delivering sterilant fluid to the device receiving area based on pressure changes in the device receiving area. \y 700