A medical gas production system produces oxygen enriched air usingfrom air a gas composition having a concentration of oxygen greater than theair forsubsequent respiration by patients. The system includes a pair of treatmenttanks, eachcontaining an adsorbent bed for adsorbing gases from the air and a receivertank forreceiving an oxygen enriched gas mixture from the treatment tanks. A pair oftransfervalves connected between receiver tank and respective ones of the treatmenttankscontrol flow of gas from each treatment tank to the receiver tank, as well asenablingbackflow of the gas mixture from the receiver tank to the treatment tank if ameasuredquality of the gas exiting the receiver tank falls below a prescribedthreshold.
