The Oxygen Concentrator produces concentrated oxygen from room air for delivery to a patient requiring low flow oxygen therapy. The oxygen from the air is concentrated using a molecular sieve and a pressure swing adsorption process. Oxygen Concentrators are used for oxygen provision in healthcare applications, in hospitals, or at home. Especially where liquid or pressurized oxygen is too dangerous or inconvenient, such as in homes or in portable clinics. The basic structure of all models is the same. Each model of the Oxygen Concentrators consists principally of an oxygen concentrator unit, a flow meter, an oxygen purity sensor, and optionally a humidification bottle.