NOVELTY - Indexing rotary dual valve comprises a first valve assembly having two stationary sections and a first rotatable valve section, a second valve assembly having third and fourth stationary sections and a second rotatable valve section; indexing drive mechanism for controlling interval of each step in pressure swing adsorption and disposed between the two assemblies, and a rotatable shaft with top and bottom portions secured to respective valve assembly.    USE - For use in PSA system (claimed).    ADVANTAGE - The inventive indexing rotary dual valve permits the PSA system to operate with adsorption cycles including pressure equalization step including product gas flow step, vessel purging step and/or product gas to be backfilled; provides a low cost H2PSA process, which eliminates excess piping connecting the system components, and with improved PSA cycles and efficiencies through the use of indexing rotary valves and control of the individual step times in the PSA cycle, and enhanced PSA process performance.    DETAILED DESCRIPTION - Indexing rotary dual valve for use in a pressure swing adsorption (PSA) system comprises a first valve assembly comprising a first stationary section having apertures adapted so that each aperture accommodates a different gas feed line from a pressure swing adsorption (PSA) bed. A first rotatable valve section has at least2 spaced-apart openings separated at a preselected arcuate degree setting and channel(s) disposed on the first valve section connected to the opening(s) for providing regulation of the pressurization of a gas between PSA beds and a second stationary section and all sections form the first valve assembly having a gas output opening for exiting a gas product. A second valve assembly comprises a third stationary section, a second rotatable valve section having at least2 spaced-apart openings separated at a preselected arcuate degree setting, and a fourth stationary section having aperture adapted so that each aperture accommodates a different gas feed line from a PSA bed and all sections from the second valve assembly having a gas input opening for receiving a feed gas and providing a constant feed flow rate between the PSA beds. An indexing drive mechanism (4) provides a preselected index setting and capable of controlling the interval of each step in the PSA cycle. A rotatable shaft (6) has the top portion secured to the first valve assembly, the bottom portion secured to the second valve assembly, and the indexing drive mechanism secured to the shaft and disposed between the two valve assemblies.    An INDEPENDENT CLAIM is also included for a PSA process comprising providing a source of feed gas, a source of suction force, multiple bed system, and an indexing rotary valve; feeding the feed gas through the indexing rotary valve to a bed for removing an undesired component from the feed gas using adsorbers under pressures and using the indexing rotary valve for providing a constant feed flow rate between the PSA beds, for controlling the depressurization by varying equalization down in one bed and equalization up in another bed to increase a high purity gas product output and purge gas; and using the indexing rotary valve for receiving and repelling the feed gas, controlling the interval of each step in the PSA cycle, for receiving and repelling the purge gas, and for receiving, collecting and dispensing the high purity gas product.    DESCRIPTION OF DRAWING(S) - The figure is a 4-bed PSA process using the rotary indexing valve train driven by a common source.    Four adsorption vessels (1)    Rotary feed multiport valve (2)    Drive mechanism (4)    Shaft (6)    Feed line (7)