Abstract: Tobacco cut filler is volume expanded using the DIET process and equipment. During depressurization of a pressure vessel containing a mixture of cut filler impregnated with liquid carbon dioxide, gaseous carbon dioxide is bubbled through the mixture to provide a mixture of decreased density and decreased integrity. Liquid water is introduced into the sublimator region of the equipment in order to act as a heat sink, causing tobacco cut filler in that region and related equipment components to not experience overly high exposure to heat. A vertically extending duct in the sublimator region has a relatively large inner diameter so as to allow adequate residence time of the tobacco cut filler in the expansion region. A spray of water applied to the expanded tobacco cut filler and atmosphere in the post expansion region of the DIET equipment moistens the cut filler and reduces the temperature experienced thereby.