The present disclosure describes a system and method for maintaining oxygen purity in portable oxygen concentrators, even with asymmetric generation of oxygen enriched gas volumes from different sieve beds of the concentration system. The present system and method compensate for asymmetric oxygen enriched gas generation using asymmetric delivery of purge volumes. Purge valves are used to deliver the asymmetric purge gas volumes, enables the system to maintain oxygen purity without additional power consumption, even when a portable oxygen concentrator does not include a product tank. The present system and method are configured such that asymmetry in enriched oxygen generation can be monitored and the asymmetric purge gas compensation can be applied independently from other control mechanisms of a portable oxygen concentrator.