Popular Science on Vehicle Urea: Essential Knowledge!

For truck drivers who spend years on the road making a living, vehicle urea is an indispensable part of daily driving. With increasing emissions standards, its usage has grown significantly. Without it, vehicles not only fail emission tests but may also face speed and torque restrictions, severely affecting normal operations. Today, let’s dive into the science of urea!

What is Urea Solution? What Does It Do?

Urea solution, formally known as Diesel Exhaust Fluid (DEF), is commonly called automotive urea, vehicle urea, eco-friendly automotive urea, or diesel vehicle exhaust purification fluid. It is a transparent, colorless liquid primarily composed of urea and deionized water. Stored in a vehicle’s dedicated tank, it is used in SCR (Selective Catalytic Reduction) technology.

Vehicle urea standards include the following key aspects:

1. Concentration: The concentration of vehicle urea solution is typically around 32.5%. GB/T29518 specifies a range of 31.8% to 33.2% (by mass of urea in the solution).
2. Density: At the standard temperature of 20°C (as per GB/T29518), the density must be controlled between 1087.0–1093.0 kg/m³ (1.0870–1.0930 g/cm³).
3. Moisture Content: Moisture should account for 0.3%–1.0%.
4. Total Nitrogen Content: Total nitrogen (on a dry basis) should exceed 46.3%.
5. Biuret Content: Biuret content must be less than 0.5%.
6. Iron Content: Iron (as Fe) should be less than 0.0005%.
7. Alkalinity: Alkalinity (as NH3) should range from 0.01 to 0.03.

Additional requirements for vehicle urea:
● Appearance: Colorless, transparent, and clear liquid.
● Odor: No obvious peculiar smell.
● pH Value: 4.5–8.5.

In a diesel vehicle’s exhaust treatment system (especially in SCR-equipped vehicles), urea solution is injected into the exhaust pipe. At high temperatures, urea decomposes into ammonia, which reacts with nitrogen oxides (NOx) in the exhaust under an SCR catalyst to reduce NOx into nitrogen and water, minimizing environmental pollution. It also optimizes engine performance and fuel efficiency, reducing diesel consumption and enhancing the vehicle’s environmental friendliness.

Urea Consumption and Annual Costs

Vehicle urea has significantly increased operational costs for truck drivers. With emission upgrades, urea consumption has risen. Many drivers report that under China’s National VI standards, urea consumption is approximately 8%–10% of fuel usage; with high-efficiency SCR systems, it can reach up to 14%. Including after-treatment system maintenance and downtime costs, annual urea expenses can even hit ¥20,000–30,000. In today’s tough freight market, this is a substantial financial burden.

Disabling Urea Systems: A Risky Temptation

To cut costs, some drivers disable urea systems or use substandard urea. While this may reduce upfront expenses, it leads to severe long-term consequences:

• Environmental Pollution: Increased NOx emissions harm the environment.
• Hardware Damage:
  1. Urea Injectors: Exposed to high exhaust temperatures, injectors may suffer permanent mechanical damage from lack of cooling during abnormal operation.
  2. Pipe Blockages: Unused urea in the system can solidify or crystallize, causing blockages or irreversible hardware failures, leading to high repair costs.
• Legal Penalties: Violating regulations by disabling emission control devices can result in ¥1,000–5,000 fines from environmental authorities. Manufacturers may also void warranties for such modifications.

How to Identify Quality Urea? Four Essential Tips!

With numerous vehicle urea brands of varying quality, substandard products can trigger fault alarms and damage after-treatment systems.

Four Ways to Check Urea Quality:

1. Inspect Appearance:
   • Check for intact packaging and clear labels (brand name, trademark, barcode, expiration date). Expired urea requires testing before use.
   • High-quality urea is transparent, pure, and slightly blue. Discoloration (yellow/turbid), impurities, or foreign matter indicate substandard products.
   • The engine’s urea quality sensor in the tank will report fault codes for poor-quality urea or low levels.
2. Smell Test: Fresh urea is odorless. A mild ammonia smell after high heat/sunlight is normal, but pungent or strange odors suggest substandard urea.
3. System Self-Check: Monitor for fault codes from the urea quality sensor, indicating low quality or low levels. Replace urea immediately if warnings appear.
4. Refractometer Test: Use a refractometer to measure urea concentration and assess quality accurately.

Note: Cutting corners on urea can lead to costly repairs. Always choose reputable brands to protect your vehicle and comply with environmental standards.