What is def fluid?

DEF Fluid: Diesel Exhaust Fluid Explained

DEF, or Diesel Exhaust Fluid, is a non-toxic, colorless, and odorless liquid used in Selective Catalytic Reduction (SCR) systems to reduce nitrogen oxide (NOx) emissions from diesel engines. It's a crucial component in modern diesel vehicles and equipment designed to meet stringent emissions regulations.

Key Components:

• DEF is a solution made up of approximately 32.5% high-purity urea and 67.5% deionized water. The specific concentration is critical for proper SCR system function.

How it Works:

1. DEF is injected into the hot exhaust stream.
2. The heat causes the urea in the DEF to break down into ammonia.
3. The ammonia then reacts with NOx in the presence of a catalyst within the SCR system.
4. This reaction converts the harmful NOx into harmless nitrogen and water.

Why it's Important:

• DEF helps diesel engines meet strict emissions standards, such as those mandated by environmental agencies.
• Reduces air pollution by minimizing NOx emissions, a major contributor to smog and acid rain.
• Ensures compliance with environmental regulations for diesel vehicle operation.

Important Considerations:

• DEF is not a fuel additive. It must be added to a separate DEF tank in the vehicle.
• Running out of DEF can limit vehicle performance and may even prevent the vehicle from starting in some cases.
• Using fluids other than DEF can damage the SCR system and void warranties.
• DEF has a limited shelf life and should be stored properly to prevent degradation.

Where to Find It:

• DEF is readily available at most gas stations, truck stops, auto parts stores, and online retailers. Look for containers that meet the ISO 22241 standard to ensure quality and purity.