Definitions of Aftertreatment System (ATS) Terms

Refer to the following list of definitions of ATS terms and components.

• Aftertreatment System (ATS)—the entire exhaust system from the turbocharger to the tail pipe, including the Selective Catalytic Reduction (SCR) components.

• Aftertreatment Device (ATD)—a device that removes pollutants from exhaust gas after the gas leaves the combustion chamber.

• BlueTec®—Daimler's proprietary SCR technology.

• Diesel Oxidation Catalyst (DOC)—a flow-through device that enhances the oxidation of hydrocarbons in the ATD.

• Diesel Particulate Filter (DPF)—a component in the ATD that traps particulate matter from the exhaust gas.

• Diesel Exhaust Fluid (DEF)—the chemical agent that reacts with the exhaust gases in the SCR to reduce NOx.

• DEF Pump—filters and supplies DEF to the DEF metering unit.

• DEF Tank—holds DEF and regulates its temperature.

• DEF Metering Unit—mixes DEF with compressed air, and meters this mixture into the exhaust flow via an injection nozzle.

• SCR Catalyst—the housing containing a treated ceramic flow-through block where the DEF and exhaust gases undergo selective catalytic reduction.

• Selective Catalytic Reduction (SCR)—a process used to reduce NOx emissions.