Oxygen generator - 99% purity On Site Gas’ industrial oxygen generators have been producing 99% oxygen using PSA technology for over 25 years. Our company holds a patent for this breakthrough. Every day, our systems are meeting the need for medical O2 in China, Portugal, Brazil and other countries where hospitals and health care providers use only 99% oxygen. These systems provide oxygen just as reliably and with equally low maintenance as our standard-purity models. We also developed a compact 99% oxygen system for NASA to use aboard the International Space Station. It used to be that this kind of purity only came from bulk suppliers, but times have changed. How it works The 99% oxygen generator is a multi-stage system that starts with a 95% oxygen generator. The 95% oxygen is then processed through a second stage to produce 99% oxygen, and again through an oxygen booster in the final stage. The gas is then stored in a tank at the desired pressure, ready to feed applications requiring the highest purity of oxygen.