Medical Oxygen Generators produce gaseous oxygen from compressed air on site and offer a cost-effective, reliable and safe alternative to traditional oxygen gas supplies such as cylinders or cryogenic liquid. An Oxygen Generator from Oxy wise, has been certified to European Directive 93/42/EEC on Medical Device. Atlas Copco oxygen generators use pressure swing adsorption (PSA) technology. The generator consists of two separate pressure vessels filled with zeolite molecular sieve (ZMS) material that separates the oxygen from the incoming air.