What Is Diesel Exhaust Fluid?


Diesel exhaust fluid or DEF is a vital ingredient in vehicle emission control. Diesel engines produce dangerous nitrogen oxides or NOx that pollute the air. To lower NOx levels, DEF is mixed with diesel exhaust particles in a process known as Selective Catalytic Reduction. This breaks things down into plain nitrogen and water which poses no threat to the environment.

DEF is a precise solution with 32.5% high-grade urea and 67.5% de-ionized water. This is not an additive for the fuel. Despite the name, it never actually touches the diesel itself. It has its own isolated tank from which the system gets small amounts for spraying onto the exhaust stream.

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What Is Diesel Exhaust Fluid?

In this article, we discuss what you need to know about diesel exhaust fluid, including the benefits that you will receive by using DEF.

Why Is Selective Catalytic Reduction Being Used?

SCR technology has been around since the late 1950s. It has been used in lowering the harmful emissions in coal-fired plants for decades. Since 2004, it has been included in diesel vehicles in Japan. SCR was widely adopted in response to the US Environmental Protection Agency’s stricter emissions standard in 2010. It is considered as the best way to reduce pollutants without compromising vehicle performance or fuel-efficiency. That’s because it only acts on the exhaust stream after the engine has done its job. Manufacturers still have the freedom to tweak the engine in any way they want. In short, SCR does not impede progress.

How Much DEF Is Needed In Trucks?

DEF consumption depends on factors such as dosing rate and fuel efficiency. The dosing rate is the ratio of DEF to diesel. Meanwhile, fuel efficiency is the number of miles per gallon. For example, a medium truck can travel 8 miles per gallon with a dosing rate of 2%. It will take 400 miles for this vehicle to consume 50 gallons of fuel and 1 gallon of DEF. Trucks that travel about 50,000 miles or so each year will have an annual DEF requirement that is substantial.


What Will Happen If A Truck Runs Out Of DEF?

Keeping the DEF tank filled with fluid is a serious matter for the environment. Trucks that use SCR technology are designed to slow down as the DEF level gets dangerously low. Drivers won’t be able to reach their destination in time unless they remedy the situation.

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Is Diesel Exhaust Fluid Harmful?

commercial diesel truck driver after using diesel exhaust fuel

DEF is not harmful. You do not need to wear protective clothing when handling DEF. Just be careful so as not to stain your clothes. If it gets on your skin, then wash it off with water. Do the same thing if it spills on the floor. If you inhale it, then go outside and get some fresh air until you feel better. If you ingest it, then consult a doctor right away. Note that the fluid can corrode metals like aluminum, zinc, copper, and carbon steel. Check with your supplier about appropriate storage materials.

What Is The Shelf Life Of DEF?

DEF should be used within two years of manufacture. Check the label to see the actual expiry date and adhere to it. Make sure that the container is shielded from direct sunlight and other heat sources. Shelf life can shorten is exposed to high temperatures for prolonged periods. On the bright side, expired DEF can be recycled as lawn fertilizer when diluted with water thanks to its urea content.

How Does Temperature Affect DEF?

commercial fleet fueling

Since DEF is 67.5% water, high temperature can lead to its evaporation. Prevent this by keeping the lid closed on the containers. As for low temperatures, DEF can crystallize into a slushy consistency at 12 degrees Fahrenheit. This is not a cause for concern as vehicles are designed to thaw frozen tanks in various ways. Just start the engine and trust the system.

What Happens If Diesel Gets Into The DEF Tank?

Diesel and DEF should never mix. Several measures are in place to prevent this including blue filling caps for DEF with clear labeling. Diesel nozzles are also bigger than those for DEF so that they won’t fit in the wrong tank. If a mix up happens by mistake, then stop the vehicle and drain the DEF tank. Do not make the truck move until the issue has been resolved to prevent damage to the catalyst.

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How Can I Buy Diesel Exhaust Fluid?

It is possible to purchase DEF in small amounts at truck stops and pumping stations but these tend to be expensive. They are also unreliable as they could run out of supply without warning. Since trucks travel tens of thousands of miles a year, they are likely to consume over a hundred gallons of DEF annually. A large fleet will require a large supply at the point of origin. DEF suppliers like Tevis Energy can deliver DEF to fill storage tanks or to top up trucks directly. The entire fleet can be scanned to see how much each truck needs. Tevis Energy also delivers jugs or drums of DEF to customers.


Call Tevis Energy To Learn More About Our DEF Deliveries

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Tevis Energy proudly offers commercial fueling services, including DEF deliveries, in our service area of central Maryland and southern Pennsylvania. Our DEF delivery trucks can either deliver to a storage tank or fleet fuel directly to a fleet of trucks. We can also deliver to deliver jugs or drums of DEF to customers.

Our goal is to give you the best DEF prices and delivery service to meet your specific business requirements.

Explore Our Commercial Fuel Deliveries Call Now: (410) 876-6800

Call Tevis Energy to learn more about one of our many services.  You can click here to contact us now or call us at (410) 876-6800 to find out more!