Thermal/Catalytic Oxidizer Source: Huntington Environmental Systems, Inc. A new Wide Flammability Range (WFR) Thermal/Catalytic Oxidizer offered by the company operates both above and below the flammability range of organic concentrations. A new Wide Flammability Range (WFR) Thermal/Catalytic Oxidizer offered by the company operates both above and below the flammability range of organic concentrations. Process streams which vary in organic content between 25% and 100% of their Lower Explosive Limit (LEL) have traditionally been a problem for environmental engineers. Organic concentrations below 25% are usually handled by a thermal or catalytic oxidizer, whereas concentrations above 100% are typically handled as a fuel and burned in a flare. Neither technology is capable of directly treating process streams whose concentrations vary in and out of the flammability range.