What is SCR system and how does it work?

Categories: Blog-Adblue Emulators

SCR system is used in heavy goods vehicles to reduce the amount of exhaust emissions. Gases are broken down into various chemicals within the exhaust fumes into mostly water and nitrogen, which are much cleaner and better for the environment. SCR system needs to be supplied with AdBlue fluid, which is a simple, non-toxic solution made with about 32.5% synthetic urea and 67.5% deionised water.

How does it work?

The process is reasonably simple to understand. The main components of the SCR system are the catalytic converter and the injection pump. The vehicle outputs emissions, including nox, these are then filtered by DPF filter to remove any access amounts of soot. When gases reaches a certain point, adblue fluid is sprayed in, which separates nox into ammonia and carbon oxide. This mix will then go into the catalytic converter which in turn creates a chemical reaction where emissions are divided into nitrogen and water. Other SCR system Components such as SCR control unit, NOx sensors, AdBlue pressure sensor, temperature sensor and others are there to control and monitor the system, ensuring that every component is operates correctly.

For SCR system to work properly, the fluid temperature must be at least at 220C, power consumption 20% and the RPM of at least 1000.

NOx sensors are there to constantly monitor the amount of noxious emissions from the vehicle to identify if the SCR system is doing its job. It reports the results to the ECU which in turn controls how much adblue to spray in.

SCR system has its own, dedicated control unit (ECU) the brain behind the whole system if you like. SCR ECU monitors all sensors to analyse and calculate the AdBlue injections amount and type required. SCR ECU also controls the heating process, which brings the gases to an acceptable temperature for the chemical process to take place.

AdBlue pressure sensor measures, records and communicates the pressure of the AdBlue fluid data. This will in turn affect the injection.

The temperature sensor measures and monitors the temperature of the AdBlue and emission gasses, sending the signal to heat it up more if it is not warm enough. If the temperature is off, the fluid will be heated beforehand. Here are the main differences between EURO 4, EURO 5 AND EURO 5 standards.

• Euro 4 standard vehicles will have no NOx sensors
• Euro 5 standard vehicles will normally have single NOx sensor after catalyst (DAF trucks will have two)
• Euro 6 standard vehicles will normally have DPF and 2 NOx sensors, one before and one after the catalyst.

How is the SCR system emulated?

Once our Can Smart emulator is connected, it will emulate/imitate every component with SCR system by sending specific signals to the ECU to indicate that the SCR system and everything within it is working normal/as should. The following components will be emulated:

• SCR control unit
• Injector
• AdBlue pump/doser
• AdBlue level sensor
• AdBlue tank with heating system
• NOx sensors

The values sent are very accurate and precise SCR system performance is emulated, making adblue emulator an ideal choice when the SCR system is not working or is not needed.

Cheaper emulators does nothave same capabilities and have sloppy implementation, which means that the SCR system will not be emulated properly. For example, some emulators rather than emulating a working SCR system completely, it will only emulate the temperature sensors around it or other random components. Very few emulators could boast the same capabilities as our Can Smart emulators.

Bad quality emulators can be harmful to your vehicle, for example if the wrong temperature values are sent, the heating systems may be confused whether to heat it up or cool it down, this in turn can cause major damage such as damage to the tank.

You should always purchase your emulator from reliable source and make sure product comes with proper warranty and guarantees.

Should you have any questions or need some advice in regards to SCR systems, please do not hesitate to contact us.