- AdBlue
- GreenChem
AdBlue®, a crucial component for the operation of Selective Catalytic Reduction (SCR) systems in diesel engines, is essential for reducing nitrogen oxides (NOx). However, its water-based nature raises a recurring concern as cold weather approaches: the risk of freezing.
Understanding the composition of this additive, its freezing point, and preventative measures is essential to ensuring the continued efficiency of the SCR system and full vehicle uptime, avoiding costly downtime.
AdBlue® Freezing Point
AdBlue® is a solution of high-purity urea (32.5%) and demineralized water (67.5%), compliant with the ISO 22241 standard. This concentration ensures effective NOx reduction and lowers the freezing point of the mixture, which begins to gradually solidify around -5°C and becomes completely solid at around -11°C, the so-called eutectic point.
The Consequences of System Blockage
When AdBlue® freezes, the increase in volume (~7%) can cause structural problems in unsuitable containers. However, the greatest risk is operational:
- SCR System Blockage: Freezing in the tank and supply lines prevents the solution from being injected, effectively blocking the emissions control system.
- Activation of Limp Mode (Reduced Power): Modern vehicles detect this immediately. The on-board electronics activate a safety mode (“Limp Mode”) that drastically limits the vehicle’s power and speed.
- Warnings and countdown timers: Warning lights (AdBlue® system fault) appear on the dashboard of modern vehicles. If left untreated, the vehicle may activate a countdown timer that, once reset, prevents the engine from restarting.
- Fault symptoms: An engine that shudders at idle, hesitates when accelerating, or emits black smoke from the exhaust are signs that the SCR system is not working due to blocked AdBlue®.
Prevention and solutions: maintaining efficiency
Newer-generation vehicles are equipped with heating elements integrated into the tank and fuel lines, designed to thaw the solution and return it to a liquid state. However, in extremely cold conditions or if these heaters fail, preventative and corrective measures are essential. Some products on the market promise to reduce the freezing point of AdBlue® through the addition of specific additives. However, it is necessary to verify whether and how these solutions comply with international standards ISO 22241, which are essential to ensure the safety and optimal performance of the fluid. For this reason, it is crucial to be careful and choose only certified products, avoiding risks to the vehicle and the environment.
1. Proper Thawing:
If AdBlue® is frozen:
- Natural Thawing: The safest solution is to park the vehicle in a heated environment (such as a garage or shed) and allow the AdBlue® to re-liquidate naturally.
- Avoid Direct Heat: Do not use open flames, heat guns, or other artificial heat sources to speed up the process, as this could damage the solution or the tank components.
It is important to note that AdBlue®, once thawed and re-liquidated, does not suffer any loss of quality or concentration, provided it has not been contaminated.
2. Conservation and Storage
For professionals storing large quantities of AdBlue®:
- Protected Environments: Always store the additive in environments with temperatures between -5°C and +25°C.
- Partial filling: When anticipating extreme temperatures, avoid completely filling storage containers to allow for 7% volumetric expansion in the event of freezing.
Proper management of AdBlue® during the winter months is crucial to maintaining the efficiency of vehicles equipped with SCR systems. With the risk of the additive freezing at temperatures below -11°C, it is essential to take preventative measures, such as using in-vehicle heaters. Furthermore, proper storage and conservation of AdBlue®, in protected environments and at appropriate temperatures, helps prevent damage to tanks and system components. By adopting these practices, industry professionals and diesel vehicle owners can ensure their vehicles are always operational, minimizing maintenance costs and ensuring compliance with environmental regulations.
FAQ
At what temperature does AdBlue® freeze?
AdBlue® freezes at around -11°C. Winter temperatures, especially at night, can regularly drop below this threshold.
Can I drive with frozen AdBlue®?
If AdBlue® is frozen, the SCR system cannot function properly. In modern vehicles, the electronics can activate a safety mode (Limp Mode) that temporarily limits the vehicle’s power and speed to protect the engine and emissions system. The ability to restart the engine depends on the model: in some cases, the vehicle continues to run, while in others, it may require the AdBlue® to thaw before restarting.
How long does it take to thaw AdBlue®?
It depends on the conditions: in a heated garage, 2-4 hours may suffice. Outdoors, in the sun, it can take 4-8 hours. If the vehicle is equipped with functioning tank heaters, the time is significantly reduced.
Will the engine be damaged if AdBlue® freezes?
No. Freezing AdBlue® does not cause direct or permanent damage to the engine. The only component that is blocked is the SCR exhaust gas aftertreatment system. Once thawed, the system resumes normal operation.