A pressure swing adsorption system for separating components of a gas mixture includes a first adsorbent module, and a second a adsorbent module coupled to the a first adsorbent module. The first adsorbent module includes a first gas inlet for receiving the gas mixture, at least one bed of first adsorbent material in communication with the first gas inlet for adsorbing a gas mixture component from the gas mixture, and a first gas outlet in communication with the first adsorbent beds for receiving a first product gas therefrom. The second adsorbent module includes a second gas inlet coupled to the first gas outlet for receiving the first product gas, at least one second bed of adsorbent material in communication with the second gas inlet for adsorbing a first product gas component from the first product gas, and a second gas outlet in communication with the second adsorbent beds for receiving a second product gas therefrom. The first product gas substantially excludes the adsorbed gas mixture component, and the second product gas substantially excludes the adsorbed first product gas component. Also, the adsorbent modules are configured for transferring the first product gas between the adsorbent modules over a plurality of discrete pressure levels to maintain substantial uniformity of gas flow therebetween.