Diesel Exhaust Fluid, Let’s Review from the Top

It looks like diesel exhaust fluid or DEF as it is mostly called is here to stay for a while. Now, most of you might already know all of the wonderful world of diesel exhaust fluids and some of you fleet managers are just getting trucks now that need DEF.

To keep everyone informed with what might not be considered cutting edge information. We decided to do a little Q&A since we have been getting some of these questions. Maybe in a few weeks we can do it on some other topic. Football, basket weaving, diesel fuel prices or fuel cards.

What is Diesel Exhaust Fluid?

• Diesel Exhaust Fluid or DEF is a high purity chemical solution containing 32.5% urea and 67.5% deionized water.

What is urea?

• Urea is the active ingredient of DEF. Urea is created from synthetic ammonia and carbon dioxide when subjected to high heat and pressure and can be produced as a liquid or solid. Synthetic urea is used mainly in fertilizers but is also used in plastics, animal feed, cleaning agents, and pharmaceutical applications.

• What would I use Diesel Exhaust Fluid for?

Diesel engines are required to meet stringent emissions requirements in 2010. Many diesel engine manufacturers have chosen a technology called Selective Catalytic Reduction (SCR) to meet these requirements. When added to the exhaust gases Diesel Exhaust Fluid reduces the NOx to the EPA required levels. If you purchase a car, truck, tractor or any diesel powered product with SCR technology it will require DEF.

Do I add the DEF to the diesel fuel?

• No. This is a typical misconception. DEF is a fluid that is atomized into the exhaust stream after it leaves the Diesel Particulate Filter and before it enters the Selective Catalytic Reduction system. In the SCR catalytic converter the ammonia molecules reat and neutralize the NOx molecules converting them to Nitrogen and Water.

Is DEF a hazardous material?

• No, DEF is classified as a non-hazardous product.

How often will refueling of DEF be required?

• The consumption rate of DEF is between 2-4% of the diesel fuel consumption. For example, for every 100 gallons of diesel fuel consumed, between 2 and 4 gallons of DEF will be automatically injected into the exhaust system. The typical DEF tank will be approximately 15 – 20 gallons, thus requiring a fill every 5,000 to 6,000 miles.

Is this product affected by temperature?

• Yes. Storage temperature between 40°F and 80°F is recommended to maintain product shelf life. Storage temperature above 12°F is recommended to avoid crystallization which starts at 11°F. Prolonged storage above 86°F will cause hydrolysis to occur, with the consequent formation of ammonia and pressure rise, and will reduce shelf life and product effectiveness.

Does DEF have a shelf life?

• Yes. The shelf life will depend on the temperature at which product is stored, however product older than one year is not recommended to be used.

What about freezing on the vehicle?

• Diesel equipment has heated tanks and supply lines that are designed to freeze and thaw with no performance issues.

Will DEF be harmed if it freezes and then thaws?

• No, the DEF solution has been formulated so that when thawed after freezing it will not separate or lose performance characteristics/strength.

What advantages are there to DEF and SCR technology?

• In addition to reducing NOx emissions, the use of DEF and SCR technology will typically result in improved fuel mileage for most vehicles. The amount of improvement will vary based on your equipment. Many in the industry feel that 3 – 5% improved fuel economy will be realized using DEF and SCR technologies.

How do I obtain DEF?

• If you are truck driver, DEF will be available at many of the locations where you buy diesel fuel.

How will DEF be stored and dispensed?

• DEF is stored in dedicated containers (must be stainless steel or poly tanks) and dispensed through highly specialized dispensing units. Using substandard equipment can contaminate the DEF and subsequently poison the SCR Catalyst.

How is the quality of DEF assured?

• DEF is manufactured to strict ISO 22241, AUS 32 and DIN 70070 standards. These standards ensure proper manufacturing, testing and handling procedures. DEF should only be purchased from companies that provide proof that they follow these standards.

Look at all of the knowledge you just gained about diesel exhaust fluid. If you need any help, please let us know. 267-482-6159 or contact us