"220V AC Cooling Fan" molecular sieve oxygen plant: is an advanced gas separation technology physical methods (PSA method) to extract oxygen directly from the air, that the system that is used, fresh and natural, maximum oxygen pressure of 0.2 to 0.3 MPa (ie 2 to 3 kg), high-pressure explosive and other dangerous non-existent; chemical oxygen machine: rational use of pharmaceutical formulations in specific situations can indeed meet the urgent need of some consumers but due to poor equipment.... operational problems require a higher investment cost a fee every time oxygen is not suited to continuous use of home oxygen therapy, and many other defects "220V AC Cooling Fan" oxygen membrane oxygen machine:....! this oxygen machine membrane oxygen way through membrane filtration nitrogen molecules in the air, reaching 30% of export concentration of oxygen, with small size, low power consumption advantages. However, using this method of oxygen is obtained in the machine 30% of the oxygen concentration, a long-term oxygen therapy may be used to care, and severe hypoxic condition desired by the medical emergency of high concentrations of oxygen only. I suggest you try the Light molecule "220V AC Cooling Fan" sieve oxygen generator, low noise, high oxygen concentration, imported compressor, high-performance molecular sieve adsorption, both to ensure product quality and prolong life.