Abstract: A gas separator works on a pressure swing principle. The separator includes multiple sieve beds, preferably five arranged in pentagonal fashion about a centerline, and a control valve. The control valve includes a rotor and a stator. The rotor is mounted for rotation relative to the stator. One part of the rotor allows pressurized gas to flow to the stator and thereon to one or more, and preferably two, of the sieve beds for separation. Another part of the rotor blocks flow of gas through the stator to or from one or more of the sieve beds, and yet another part of the rotor allows waste gas to flow from one or more of the sieve beds back through the stator to an exhaust. The separator may be used as part of a system. In a method of use, sieve beds are cycled between adsorption, de-pressurization, purging, and pre-pressurization phases.