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Diesel Exhaust Fluid (DEF)

What is DEF?

Diesel Exhaust Fluid (DEF) is a non-toxic solution that transforms harmful Nitrogen Oxide (NOx) emissions into harmless water vapor and nitrogen for America’s diesel-powered vehicles that use Selective Catalytic Reduction (SCR).

What is SCR?

Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF). The DEF sets off a chemical reaction that converts nitrogen oxides into nitrogen, water and tiny amounts of carbon dioxide (CO2), natural components of the air we breathe, which is then expelled through the vehicle tailpipe.

DEF Usage

How much DEF will a truck consume?
DEF consumption is expected to be approximately 2 to 3% of fuel consumption, depending on vehicle operation, duty cycle, geography, load ratings, etc.

What is the number of miles a truck can expect to travel on one gallon of DEF?
DEF consumption is directly related to fuel consumption. A truck averaging 6 MPG can expect to go approximately 300 miles on one gallon of DEF.

Is any maintenance required on the DEF Dosing Unit Filter?
The DEF Dosing Unit Filter will need to be replaced about every 200k miles as part of routine maintenance.

How can an operator determine how much DEF they will need/use?
The average consumption rate of DEF is between 2-3% of the diesel fuel consumption. For example, for every 100 gallons of diesel fuel consumed, between 2 and 3 gallons of Diesel Exhaust Fluid will be automatically injected into the exhaust system. A typical diesel truck should go about 300 miles on one gallon of Diesel Exhaust Fluid. The refueling interval will depend on the size of tank you have.

Is the DEF dose rate the same for all engine manufacturers?
The DEF dose rate will vary slightly amongst engine manufacturers. While most engines will have a dose rate of 2% to 3% of diesel fuel consumed, the dose rate will range from 1% to 3%.

What happens if the vehicle runs out of DEF?
Vehicles using DEF will have indicators on the dash that will alert the driver of the DEF quantity on board. A gauge similar to a fuel gauge will indicate the DEF level. There will be a DEF low level warning lamp illuminated when DEF is low. If a vehicle is operated to the degree of running out of DEF, vehicle power will be reduced enough to encourage the operator to refill the DEF tank. Once the tank has been refilled the engine will resume normal power levels.

Frequently Asked Questions

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 have a fleet, Halron Lubricants Inc can provide DEF in a variety of package and dispensing solutions that meet your needs. Contact a Halron Sales Representative at 1-800-236-5845 or click here to learn more

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.

To learn more about Halron's brand of DEF, click here

Green Bay, WI
1618 State Street
Green Bay, WI 54304

Toll-Free: 800-236-5845
Phone: 920-436-4000
Fax: 920-436-4004

Wisconsin Rapids
611 25th Ave North
Wisconsin Rapids, WI 54495

Toll-Free: 800-842-5766
Phone: 715-423-8767
Fax: 715-424-1032


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