AdBlue is a component of modern diesel engines that plays a critical role in reducing nitrogen oxide (NOx) emissions, helping vehicles meet stringent and urgent emission standards. And its core is the precision and high purity of AdBlue urea content.
AdBlue is a registered trademark of the German Association of the Automotive Industry (VDA). It is commonly referred to as DEF or Diesel Exhaust Fluid in North America, ARLA32 in Brazil, and AUS32 in Australia and New Zealand.
AdBlue is not a fuel or fuel additive, but a high-purity urea solution used in diesel vehicles equipped with SCR systems. It is stored in a separate tank and injected into the exhaust through the SCR system. Its main purpose is to convert nitrogen oxides into harmless oxygen and water vapor, thus significantly reducing the environmental impact of diesel vehicles.
The formula of AdBlue is very precise, consisting of 32.5% high-purity urea and 67.5% deionized water. This specific concentration is not arbitrarily set, but the scientifically validated optimal ratio.
To ensure the quality and performance of AdBlue, strict international standards have been established in ISO 22241. This standard details the physical and chemical properties of AdBlue, such as:
Urea concentration: must be between 31.8% and 33.2%, with 32.5% being the optimal target.
Purity: Strictly limit the content of impurities, such as heavy metals, calcium, sodium, and potassium, as these impurities may damage the SCR catalyst and injection system.
PH value and alkalinity: Ensure the stability and non-corrosiveness of the solution.
Density and refractive index: used for quality control and testing.
Only AdBlue products that comply with ISO 22241 standards can be considered qualified, ensuring the normal operation of the SCR system and vehicle compliance with emission regulations.
There are several key reasons for choosing the concentration of 32.5% at the same time:
High-quality AdBlue is produced by mixing high-purity industrial urea with deionized water in precise proportions. A reputable manufacturer adheres to strict quality control procedures to ensure that the final product meets the ISO 22241 standard. They utilize advanced mixing and measurement techniques to precisely blend ingredients.
However, some low-quality or counterfeit AdBlue products may not be produced with such precision, resulting in incorrect urea content. For example, if the mixing equipment is not properly calibrated or the quality of the raw materials (urea and water) does not meet standards, it may result in an incorrect urea concentration in AdBlue products.
The storage conditions will also affect the urea content in AdBlue over time. AdBlue should be stored in a cool and dry place, away from direct sunlight and extreme temperatures. High temperature can cause slow decomposition of urea in AdBlue, reducing its effective concentration. In addition, if the storage container is not airtight, moisture in the air will enter and dilute AdBlue, thereby altering its urea content.
Freezing is another issue. AdBlue freezes at approximately -11 °C. When it freezes and then melts, urea may separate or precipitate, which can affect the overall urea concentration in the solution. To alleviate these issues, it is recommended to use storage containers made of high-density polyethylene (HDPE), which is resistant to chemical degradation and has good insulation properties.
In a laboratory environment, complex analytical techniques are used to determine the urea content in AdBlue. A common method is titration, where a known concentration of reagent is added to the AdBlue sample until the chemical reaction reaches the endpoint. Then use the amount of reagent to calculate the urea content.
Another technique is high-performance liquid chromatography (HPLC), which can separate and quantify the components in AdBlue, thereby accurately measuring urea concentration. These laboratory tests are very accurate, but require specialized equipment and well-trained personnel.
For car owners and on-site technicians, portable testing kits are also available for quickly checking the urea content in AdBlue. These test kits typically use color change indicators or simple chemical reactions to provide a rough estimate of urea concentration. Although not as precise as laboratory testing, they can be used for on-site inspection to ensure that the AdBlue used is within an acceptable range.
For example, some test strips in test kits will change color when immersed in AdBlue, and the color can be compared with the chart to determine if the urea content is close to the 32.5% mark. However, it is worth noting that these on-site tests serve primarily as a screening tool, and if there are doubts about the accuracy of the results, laboratory testing should be conducted.
SCR system damage: Impurities or incorrect urea concentration can cause SCR catalyst blockage, nozzle crystallization, pump corrosion, or malfunction.
Reduced emission efficiency: unable to effectively convert nitrogen oxides, resulting in vehicles failing emission testing and even triggering the vehicle to enter “limp mode” (limiting engine power).
Increased fuel consumption: The low efficiency of the SCR system may indirectly lead to a decrease in fuel economy.
Warning light on: The AdBlue warning light on the vehicle’s dashboard will illuminate, indicating a system issue.
High repair costs: replacing damaged SCR components, such as catalysts, injectors, or pumps, may cost thousands of dollars.
The accuracy and high purity of AdBlue urea content are the cornerstone of its effectiveness and the healthy operation of the SCR system. The ideal urea content of AdBlue is 32.5% (within the range specified in ISO 22241), which effectively reduces nitrogen oxide emissions, benefiting both the environment and vehicle performance.
Understanding the function of urea, the factors that affect its content in AdBlue, and how to test it can not only ensure that your diesel vehicle complies with emission regulations but also protect the SCR system from damage, thereby avoiding unnecessary maintenance costs and contributing to environmental protection.
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