How Does DEF Work?
Injected into the exhaust stream of diesel engines (not into the fuel).
At high exhaust temperatures, urea breaks down into ammonia.
Ammonia reacts with NOₓ gases in the SCR catalyst.
The chemical reaction converts NOₓ into harmless nitrogen (N₂) and water vapor (H₂O).
🚛 Why is DEF Important?
Required for many diesel vehicles (trucks, buses, off-road equipment, etc.) made since around 2010 (U.S.) and later in other regions.
Helps vehicles meet Tier 4 (off-road) and EPA 2010 (on-road) emissions standards.
Reduces smog and respiratory pollutants, contributing to cleaner air.
❄️ Storage and Handling
Freezing Point: 12°F (-11°C) – it expands when frozen but can be reused once thawed.
Shelf Life: About 1 year if stored between 12°F and 86°F (-11°C to 30°C).
Contamination Warning: Always use dedicated DEF equipment; even small impurities can damage the SCR system.
