AdBlue and reducing NOx emissions: a major environmental challenge
Nitrogen oxides (NOx) are harmful gases that cause air pollution and global warming. They are produced mainly by the combustion of fossil fuels, particularly diesel, and represent a major environmental challenge. To limit these emissions, the Euro 6 anti-pollution standard, which came into force in 2015, imposes stricter pollution thresholds for diesel vehicles. These regulations have led to the widespread adoption of the SCR (selective catalytic reduction) system, already installed on heavy goods vehicles since the Euro 5 standard came into force in 2008. All new diesel vehicles, whether agricultural machinery, construction equipment or transport trucks, are now equipped with this technology, made possible by a key additive: AdBlue.
The SCR system
What is the SCR?
The SCR (Selective Catalytic Reduction) system is an anti-pollution technology adopted on all new modern diesel vehicles. Its aim is to effectively reduce NOx, which is responsible for air pollution. To achieve this, SCR uses AdBlue, which is injected directly into the exhaust stream, where a chemical reaction transforms the nitrogen oxides into harmless elements. Thanks to this process, modern diesel engines can significantly reduce their environmental impact while maintaining their performance.
How does the SCR system work?
To fully understand the effectiveness of SCR, you need to understand the various stages, from AdBlue storage to final exhaust gas treatment.
1. The AdBlue tank: This stores the urea solution at a controlled temperature. 2. The metering pump: An electric pump draws in the AdBlue, then sends it to the injector. The quantity injected is adjusted automatically, depending on driving conditions and NOx levels detected by sensors. 3. The particulate filter (DPF): Located upstream of the AdBlue injector, the DPF is responsible for retaining the fine particles present in the exhaust gases. Fitted on diesel vehicles since 2011, it acts like a microscopic sieve to capture solid residues before they are released into the atmosphere. 💡 Depending on the configuration, the DPFS can also be positioned after the SCR catalyst. 4. The AdBlue injector: Placed just after the DPF, it sprays AdBlue into the flow of hot exhaust gases, upstream of the SCR catalytic converter. 5. The SCR catalyst: This is the heart of the system. Under the effect of heat, AdBlue breaks down into ammonia. This compound triggers a chemical reaction with NOx, which is then transformed into nitrogen (N₂) and water vapour (H₂O), both of which are harmless to the environment. This reaction reduces NOx by up to 90%. 6. The NOx sensor: Placed downstream of the catalytic converter, this sensor measures residual NOx emissions to check compliance with the Euro 6 standard. If an excess is detected, the system automatically adjusts the quantity of AdBlue injected to restore a compliant level.
Focus on AdBlue
What is the role of AdBlue?
AdBlue is a solution made up of 32.5% urea and 67.5% demineralised water. In the SCR system, AdBlue is transformed into ammonia under the effect of heat. This reacts with the NOx and transforms it into nitrogen (N₂) and water vapour (H₂O), two non-polluting components.
Behind the name "AdBlue
💡 The term "AdBlue®" is not a generic name, but a trademark registered by the German Association of the Automotive Industry (VDA). The VDA ensures compliance with DIN 70070 and ISO 22241 standards, which govern the manufacture, storage and transport of AdBlue.
Depending on the region of the world, AdBlue may go by other names:
DEF (Diesel Exhaust Fluid) - in North America
ARLA 32 - in South America
AUS 32 (Aqueous Urea Solution) - generic name in accordance with standard ISO 22241
FED (Fluide d'Échappement Diesel) - in French, for more technical purposes.
Whatever its name, it is always a urea solution designed for use in the SCR systems of diesel vehicles.
What are the risks associated with AdBlue?
For the SCR system to work optimally, it is essential to be aware of the risks associated with misuse or tampering with AdBlue.
Lack of AdBlue: If the tank is empty, the diesel engine will not start. This safety feature prevents untreated gases from being released into the atmosphere. So it's vital to monitor the fluid level regularly and top it up in good time.
Crystallization: AdBlue can crystallize if exposed to open air or wide variations in temperature. This leads to the formation of cyanuric acid, a solid residue that can damage the injectors or the SCR catalyst, even bringing the vehicle to a standstill. What are the signs of a clogged system? Loss of power and higher fuel consumption. In this case, rapid intervention is required.
Contamination: During filling or storage, dust, residues or other foreign bodies may contaminate the AdBlue. Injected into the SCR system, these elements can cause breakdowns, costly repairs or even the complete stoppage of the vehicle.
💡 HIFI FILTER® offers filtration solutions designed to prevent AdBlue contamination and effectively protect the SCR system, ensuring fluid purity throughout the circuit.
AdBlue HIFI FILTER® solutions
A complete range for every point in the SCR circuit
At HIFI FILTER®, we offer specific filtration solutions for each key point in the AdBlue circuit. Our filters are compatible with a wide range of vehicle makes and systems. They are designed for :
Retain solid contaminants such as dust and urea crystals
Protect sensitive system components, such as the metering pump, injector or catalyst
Prevent clogging and limit premature wear
And so guarantee the reliability and longevity of the SCR system
Here is an overview of our main solutions:
At the reservoir inlet: Our screen filters block contaminants during AdBlue refuelling.
In the tank: Our filter bags capture impurities from the atmosphere or filling pumps.
Between the tank and the dosing pump: We also offer pleated media filters adapted to the latest equipment.
At the inlet and inside the dosing pump: Our pre-filters and pleated media filters effectively protect sensitive system components. The result: reliable, long-lasting SCR system performance.
And much more besides! Our catalogue also includes complete kits (filters, housings, seals, etc.) to meet every need. Consult our online catalogue to discover our full range.
✅ Protecting and extending the life of the SCR system AdBlue filters are essential on machines subject to extreme conditions, such as construction or agricultural machinery. Dust, sand, temperature variations... these are just some of the factors that can contaminate AdBlue. By effectively filtering the fluid, our solutions protect the metering pump, injector and SCR catalyst, reducing premature wear.
✅ Reduce maintenance costs By limiting fouling of the system, you avoid costly breakdowns and reduce the downtime required to clean or replace SCR components.
✅ Complying with environmental standards By preserving the quality of the AdBlue, the filter guarantees precise injection of the solution, ensuring optimum NOx reduction in line with Euro 6 requirements.
Maintenance tips
Replace AdBlue filters regularly
⚠️ An AdBlue filter in good condition is essential for the SCR system to work properly. When it is clogged, it can allow contaminants to pass through, altering the quality of the solution and compromising the effectiveness of the SCR system against NOx. The filter should be replaced periodically, depending on the number of hours the machine is used. This frequency varies according to a number of criteria: the model of machine, its use (intensive or occasional), working conditions (dust, extreme temperatures, humidity, etc.) and even the quality of fuel used. To find out the correct maintenance frequency, refer to the manufacturer's recommendations in the user manual.
Store AdBlue properly to preserve its quality
Improperly stored AdBlue can easily become contaminated, compromising the entire SCR system. To avoid this, follow these best practices:
Store it away from sun and rain, in a suitable container: plastic or stainless steel only.
Avoid freezing: the freezing point of AdBlue is -11°C. Store it at a stable temperature, above this threshold.
Keep the storage area clean: even the smallest amount of dirt (dust, residue, oil, etc.) can contaminate the AdBlue, especially during filling.
Why choose HIFI FILTER® for your AdBlue solutions?
Expertise: Nearly 50 years' experience in filtration to guarantee reliable, high-performance products.
Compatibility: With over 70,000 references, you'll find the right filter for your vehicle, whatever the make: Bomag, Caterpillar, Claas, Cummins, DAF, Hitachi, Iveco, John Deere, New Holland, Volvo, and many others.
Personalised support: Our technical teams are on hand to help you choose and use your filters, by phone, e-mail or in the field.
Global presence: Our international distribution network means we can respond quickly to your needs, anywhere in the world.
💬 Do you have a question or a specific need? Our experts are here to advise you.
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