PURE OXYGEN CONCENTRATOR, CHAD Drive, Models CH5000 and CH5000S
Post-market surveillance for Pure Stationary Oxygen Concentrators model CHSOOO and CHSOOOS demonstrate an aggregate complaint/service rate greater than 35% for low oxygen purity (output oxygen below the published specification).
worldwide
https://www.accessdata.fda.gov/scripts/ires/index.cfm?Product=Z-0407-2018