The Stefan diffusion tube is modeled with the recently developed binary friction model (BFM), and it is shown that this model can describe all kinds of vapor flow regimes from Stefan diffusion to pure pressure-driven flow but also Knudsen and (diffusive) slip flow. From the BFM simple criteria are derived for the transition between various regions, the criteria of which are also relevant to the fields of gas adsorption, heterogeneous catalysis, and drying of porous materials. For isobaric counterdiffusion the BFM shows where the limits of Graham’s law are. equimolar counterdiffusion analogously the area of applicability of the Bosanquet equation is derived from the BFM and an extended equation is given.