Abstract: The present invention called a patient ventilator oxygen concentration system advantageously utilizes an existing suitable air supply and provides a modular oxygen concentrator that uses the existing air supply and a medical grade air filtration package for providing medical grade using the existing air supply. The oxygen concentrator has multiple bed pairs which can be selectively activated. If one of the multiple bed pairs is not activated, the excess air provided by the existing air supply is filtered and medical grade air is supplied instead of oxygen gas for use with patient ventilators. Advantageously, the present invention obtains a large increase in medical grade air flow at the expense of very little oxygen flow while maintaining oxygen purity using the existing air supply. The present invention provides a pneumatic circuit which is capable due to a modular bed design. Each bed pair uses approximately three SCFM (80 SLPM) to produce five SLPM of oxygen.