What is AdBlue / DEF Liquid and SCR Technology

AdBlue Liquid is used in diesel vehicles to reduce harmful gases emission to air. It consists of 32.4% high purity urea and 67.6% deionized water. In the USA AdBlue is known as DEF (Diesel Exhaust Fluid) whereas in Brazil it is known as ARLA32. Good quality AdBlue liquid is ISO-22241 certified.

AdBlue is very easy to use and is a harmless substance. It is not mixed with fuel. Vehicles with SCR technology have a dedicated AdBlue tank. It should be refilled when required. Click this link!! to know in detail about BS6 Technology.

AdBlue Tank
AdBlue Dispensing Equipment

SCR (Selective Catalyst Reduction) Technology

Selective Catalyst Reduction (SCR) technology is uses DEF liquid in BS6 and Euro6 diesel engines.
Working of SCR Technology in Diesel Engines

Selective Catalyst Reduction (SCR) technology uses DEF liquid in BS6/Euro6 diesel engines. AdBlue / DEF in SCR converts harmful NOx in diesel exhaust into nitrogen gas and steam. After the implementation of Bharat Stage 6 norms in India. SCR system in exhaust will become mandatory in diesel vehicles. Following are the main components of the SCR System:

  • SCR Catalyst
  • Injection Control Unit
  • AdBlue Fluid injection Unit
  • Tank For AdBlue

AdBlue / DEF Consumption

This image shows DEF warning symbol.
Low DEF Fuel Warning

Vehicles with SCR technology have a dedicated AdBlue tank. It is refilled when required. A typical car consumes approximately 1.5 ltr AdBlue liquid per 1000 km drive. But DEF fluid consumption can be doubled depending on driving style, road and weather conditions.

Latest Mercedes Benz S-Class in India comes with a 25 Ltr AdBlue tank. Car instrument cluster also indicates when AdBlue top-up is required.

What will Happen if a vehicle runs out of DEF / AdBlue Liquid ?

As per Euro6 and BS6 norms. Vehicle will not restart if it is run out of DEF/AdBlue liquid. Tank needs to be refilled with a minimum 3.6 liter of AdBlue liquid.

What if AdBlue Liquid is added in Fuel Tank and vice-versa?

If accidentally AdBlue is filled in fuel tank or fuel to AdBlue tank. You should not start the vehicle and immediately call the service provider.

To sum up, AdBlue liquid is used in BS6 vehicles equipped with SCR technology. It helps in reduction of NOx gases from exhaust gas. AdBlue is also known as DEF (Diesel Exhaust Fluid).

We will keep updating more details on def liquid used in bs6 engines. Please add your suggestions, comments or questions on DEF liquid used in diesel engines to control exhaust gases.

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