(US4981499-A)      Gaseous mixt. is sepd. by adsorption in at least four adsorbers, the same cycle being repeated with a phase shift of a cycle duration divided by the no. of absorbers. Cycle comprises isobaric prodn. at high pressure; cocurrent decompression by at least one adsorber cecompressing and another recompressing; further cocurrent partial direct decompression into a single storage reservoir; final countercurrent decompression to a low pressure of the cycle. Countercurrent scavenging takes place with gas from the reservoir and is followed by partial and final countercurrent recompressions to the high pressure of the cycle by a flow of gas from the isobaric prodn. flow.    USE -   Sepn. of undesirable constituents from H2, elimination of impurities in the etc. (24pp)p    (EP248720-B1)      Adsorption process for separating a gaseous mixture, of the kind where a cycle of successive operations as follows is carried out on each of at least four adsorbers, the cycles being advanced from one adsorber in relation to the following one with a phase shift equal to the duration of a cycle divided by the number of adsorbers: (a) an isobaric production operation at the top pressure of the cycle, in so-called co-current; (b) a first co-current decompression by means of at least one equilibration between said adsorber in decompression and at least one other adsorber in recompression in counter-current, each equilibration being a ''direct'' equilibration ensuring the transfer of the gas coming from one adsorber in decompression directly and immediately into an adsorber in recompression; (c) a second decompression by partial evacuation in co-current towards a storage reservoir; (d) immediately after stage (c), a third decompression, which is final, in counter-current up the base pressure of the cycle; (e) scavenging in counter-current at said base pressure by the gas derived from the storage reservoir, this taking place for a duration which is greater than that of stage (c); (f) a first recompression in counter-current by means of at least one equilibration of the type according to (b); (g) immediately followed by a final recompression in counter-current until at the top pressure of the cycle by an output of gas taken from the production output; characterised by the combination of the following measures: (h) the sum of the durations of the evacuation according to (c), of the final decompression according to (d), and of the scavenging according to (e) is less than said phase shift; (i) the total number of adsorbers is less than or equal to 1+x+y, x being the number of adsorbers simultaneously in isobaric production, and y being the number of direct equilibrations; (l) during phase (c), the storage reservoir is exclusively connected to the adsorber during the course of being evacuated and during phase (e) said storage reservoir is exclusively connected to the adsorber during the course of being scavenged; (m) an operation of evacuation-decompression by partial evacuation according to (c), which affects one adsorber, is followed, after phase (d), by a scavenging operation according to (e) which affects exclusively the same adsorber.