Oxygen O2 Industrial Gases CAS No.: 7782-44-7 EINECS No.: 231-956-9 UN No.: UN1072 Purity: 99.995%-99.9997% Dot Class: 2.2 Appearance: Colorless Grade Standard: Industrial Grade, Medical Grade, Electronic Grade. Industry Use: Steel making, non-ferrous metal smelting.Cutting metal material. Medical Use: In first-aid treatment of emergencies such as suffocation and heart attack, in the treatment of patients with respiratory disorders and in anaesthesia. Semiconductor Fabrication: Chemical vapour deposition of silicon dioxide, thermal oxide growth, plasma etching, plasma stripping of photoresist and carrier gas in certain deposition/diffusion operations.