What is Selective Catalytic Reduction (SCR) System? Components of Basic SCR System.

SCR: Selective Catalytic Reduction

Selective Catalytic Reduction (SCR) is an exhaust after-treatment device to reduce NOx. SCR spreads aqueous urea solution (AUS 32)/ DEF/ AdBlue into the exhaust stream. The ammonia (NH3) from AUS32)/ DEF/ AdBlue combines with NOx in presence of a catalyst to form by-products Nitrogen and water vapor, which are harmless Particulate Matter (PM) reduction is achieved inside the engine through optimized combustion and electronically controlled injection system. Selective Catalytic Reduction (SCR) - is an advanced technology after treatment to reduce NOx (NO2 + NO) outside the engine.

• Engines expel many harmful /polluting gases & other by-products of combustion through the exhaust.
• NO2 & NO is the most harmful element which contributes to acid rain
• AUS 32 is injected upstream of a catalyst in the exhaust system using a very accurate dosing pump. 
• The amount of AUS 32 injected by the pump is controlled by the engine ECM.

 

SCR SYSTEM COMPONENTS

AUS 32 Injection Nozzle

•   4 holes spraying toward the catalyst
•   SAE quick connector
•   Insulated body to reduce heat build-up

Temperature Sensor

• This sensor is fitted on the EGP inlet.
• It monitors the EGP inlet temperature and sends the information to ECM.

NOx Sensor

• It is located at the outlet of EGP to measure exhaust out NOx concentration.

Air Oil Separator

A filter must be fitted to the air supply line to prevent potential oil & debris

contamination in the air supply to the Doser Pump.

AUS 32 Tank

It is made of a special type of PVC material and it is used to store AUS32

Tank Level & Temperature Sensor

It is used to measure the AUS32 Level and AUS32 Temperature.

Dosing Pump

The Dosing Unit is controlled by ECM directly for injecting the required AUS-32/ DEF / AdBlue & air mixture quantity into the exhaust after-treatment system.