Abstract: The inclusion of one or more tanks in a two-bed pressure swing adsorption system provides for a further reduction in the pressure from which each bed is vented. According to the invention, following a bed pressure equalization step, the bed which is to undergo regeneration is equalized with at least one tank, which is at a lower pressure, in order to transfer part of the gas located in the bed void volume. After the bed is regenerated, it is again equalized with the same tank, now at a higher pressure than the bed, in order to return the conserved gas. This process increases yield by decreasing the loss of gas attributable to bed void volume. The combination of the two-bed process with one or more pressure equalization tanks for conserving void gas for subsequent bed repressurization rather than use as purge gas is unique to the present invention.