Abstract: A single bed reversing blower vacuum swing adsorption air separation unit includes a purge recovery tank. This purge recovery tank is joined to an O2 supply line downstream of the adsorber vessel or directly to the adsorber vessel opposite an inlet thereof. The purge recovery tank collects a purging charge of mostly O2 gas towards the end of a production phase for the air separation unit. This purging charge is held by the purge recovery tank while the reversing blower reverses and the material within the adsorber vessel is recharged. Around the time that the reversible blower is re-reversed to return to a production phase, the purge recovery tank is opened to allow mostly O2 gas from the purge tank to quickly flow back into the adsorber vessel which has a vacuum drawn thereon, to allow the air separation unit to quickly return to its production phase.