One type of oxygen concentrator commonly used in hospitals is the fixed nitrogen oxygen concentrator. This is basically a tank with a closed top that contains nitrogen. A hose is inserted into the tank, which carries a continuous supply of nitrogen. The oxygen is then slowly released from the tank into the hose. Because of this method, the oxygen concentration is able to maintain constant oxygen levels, which make it ideal for oxygen therapy. Our OLV-5A Oxygen Concentrator can be used as a nitrogen generator for physical training as well. Users or distributors around the world can order our oxygen concentrators from our website.