What is Diesel Exhaust Fluid (DEF)?
Diesel Exhaust Fluid (also known as AUS 32, or generically as urea) is a solution of solid urea dissolved in deionized water to produce a concentration that is 32.5% urea and 67.5% deionized water.
How DEF Works
Controlled amounts of the DEF solution are injected into the engine exhaust stream prior to the SCR catalyst. The temperature of the exhaust converts the urea in the DEF to ammonia. The ammonia and NOx in diesel exhaust react in the presence of the SCR catalyst to convert the NOx into nitrogen (N2) and water (H2O).
Typical properties of a DEF solution with 32.5% urea
Cat® Packaging Options
FAQ / DEF Hot Line phones are:
888 598 8186 or 309-494-7532
or visit your local Cat® Dealer
- DEF Flyer
- DEF FAQ
- Chemtool DEF MSDS
- Selective Catalytic Reduction Animated Slide
- Caterpillar Machine Fluids Recommendations - SEBU6250
- Caterpillar Commercial Diesel Engine Fluids Recommendations - SEBU6251
- Caterpillar On-Highway Diesel Engine Fluids Recommendations - SEBU6385
- Caterpillar Gas Engine Lubricant, Fuel, and Coolant Recommendations - SEBU6400
- Caterpillar 3600 Series and C280 Series Diesel Engine Fluids Recommendations - SEBU7003
Back to 'Machine Fluids Overview' Page»