Tag: DEF

“What is AdBlue?” “Is AdBlue the same as DEF?” These are two of the first questions new diesel fleet vehicle owners and operators ask. If you’re confused about AdBlue and diesel exhaust fluid (DEF), you’re not alone.

This Q&A will help clear up confusion.

Q: What is AdBlue?

A: It’s a marketing term for diesel exhaust fluid. It’s a registered trademark of the German Association of the Automotive Industry, so you’ll see and hear the term more in Europe. In the U.S., you’ll see and hear DEF more.

Chemically and functionally, AdBlue and DEF are the same. Like prescription drugs whose patents expire and there is no legally protected exclusivity on the formula, DEF has a specific formula that can be manufactured and marketed by different companies. If we were to explain AdBlue and DEF using a drug store analogy, DEF is to acetaminophen (or paracetamol in some countries) as AdBlue is to the brand Tylenol. The difference is the name.

In this Q&A, we’ll stick to calling the fluid AdBlue for simplicity. (Calling it DEF or diesel exhaust fluid, however, would be equally correct.)

Q: What is AdBlue fluid?

A: The fluid is a clear, nontoxic fluid typically made of 32.5% synthetic, vehicle-grade urea (ammonia) and 67.5% deionized water. AdBlue must meet a purity standard set by the International Standards Organization (ISO).

“The ISO 22241 series provides the specifications for quality characteristics, for handling, transportation and storage and for the refilling interface as well as the test methods, needed by the manufacturers of motor vehicles and their engines, by converter manufacturers, by producers and distributors of the urea solution and by fleet operators,” the foreward on ISO 22241-1:2019 states.

“The urea solution (AUS 32) as specified in this document is commercially available and may exist under various trade names.”

AdBlue is one of those trade names.

Q: What does AdBlue do?

A: First, let’s clarify something: AdBlue is not a fuel, and it was not created to mix with fuel. It’s not a fuel additive. But it is transported, stored and dispensed like fuel. It requires its own separate, dedicated, clearly marked tanks in vehicles and for bulk storage. You can purchase it at gas station fuel dispensers near diesel. This wide availability of AdBlue at the pump and in volumes small enough to carry by hand provides convenience — and confusion.

Now that you know what AdBlue is not, you can make sense of how it works. AdBlue reduces harmful nitrogen oxide (NO_X) emissions from heavy-duty diesel vehicles. These emissions contribute to air pollution and smog, according to the Environmental Protection Agency (EPA).

To protect human health and the environment, the EPA requires most diesel engine heavy-duty trucks manufactured after 2010 to come equipped with a technology called selective catalytic reduction (CSR). AdBlue works with CSR systems to reduce NO_X emissions and meet EPA requirements. (Europe has its own regulations for diesel engine vehicles registered after 2015.)

When a CSR-equipped engine is running, the CSR system injects a small amount of AdBlue into the vehicle exhaust produced by normal diesel combustion. There, AdBlue mixes with the heated exhaust gases and breaks down into carbon dioxide and ammonia. Then, the NO_X in the SCR catalyst reacts with the ammonia and breaks down into safe nitrogen gas and water vapor.

Beyond contributing to cleaner air, AdBlue boosts engine performance and fuel economy. And because injection occurs outside the engine, diesel engine manufacturers have boosted power output and achieved a cleaner burn and more efficient combustion.

Q: Where to Buy AdBlue?

A: You may buy small amounts of AdBlue at gas stations, auto parts stores and big box stores. It’s widely available. You also may buy it in bulk. This is the better option for owners of diesel fleet vehicles and gas stations. Ask your reputable bulk fuel supplier about the best bulk options for your needs.

Q: Is AdBlue more of a consumer product?

A: It’s for any diesel vehicle with CSR technology. Joe Farmer can buy it for use in his one heavy-duty diesel farm vehicle. Large trucking companies can use AdBlue across their entire national fleets. The common requirement among all vehicles that use AdBlue is they have a tank for diesel fuel and another tank for AdBlue. (Never mix diesel fuel and AdBlue. Remember, injection of happens outside the engine after diesel combustion.) Two-tank systems ensure the proper diesel-to-AdBlue ratio, which is about 50-to-1 for most diesel vehicle manufacturers.

Q: Can I Store AdBlue in Bulk?

A: Yes. Small, medium and large businesses store AdBlue in bulk for use in their commercial diesel vehicles. The benefits of bulk storage include:

• Price breaks for purchasing in bulk.
• Convenience and immediate availability at specific, known locations.
• Reduced risk of running out during critical operations.
• Reduced contamination risk with AdBlue quality control and testing oversight.
• Storage capacity flexibility.
• Faster transfers.

Whether you call it AdBlue, DEF or diesel exhaust fluid, now you know what it means, how it works and why it’s required.

More Resources

• DEF Storage Regulations
• Diesel Bugs
• What is Diesel Exhaust Fluid? Top 7 Questions About DEF.

Need Help? Ask the Experts

For help in choosing the right AdBlue storage tank or transfer tank, it makes sense to ask the experts. Unity Fuel Solutions is North America’s leader in double walled storage tanks. For advice on the tank and system that’s right for you, call the Unity team at 800-234-1689.

Water in diesel exhaust fluid (DEF) tanks is bad news — whether the tanks store DEF in bulk or in smaller amounts within diesel engine vehicles.

Because of the harmful effects, you might consider water in DEF a type of fuel contamination despite DEF’s not meeting the definition of a fuel. Water in DEF tanks doesn’t get as much attention as diesel bugs, but the effects include lost product and vehicles that won’t run. It makes good business sense to keep water out of DEF and diesel storage tanks, alike.

Below are the causes, effects and solutions for water in DEF tanks so you can keep your equipment and vehicles operating at peak performance.

Can You Put Water in DEF Tank?

No, never put water in a DEF tank. Confusion and bad internet advice about water in DEF tanks likely exists because diesel exhaust fluid is mostly water. The composition leads people to assume that topping off their DEF tanks with a little more water won’t hurt anything. But this is wrong. When water makes its way into DEF storage tanks or DEF tanks on vehicles, things can go awry quickly.

Diesel exhaust fluid is a clear liquid like water, but DEF (also called AdBlue) doesn’t contain regular tap water, which contains minerals and ions. DEF is 32.5% synthetic vehicle-grade urea (ammonia) and 67.5% deionized water.

For a diesel vehicle’s selective catalytic reduction (SCR) system to bring about catalytic conversion and reduce nitrogen oxide (NO_X) emissions, the proper concentration of deionized water must be used.

Causes: How Water Gets Into DEF Tanks

Water can make its way into DEF storage tanks two ways:

1. When DEF is stored in bulk.
2. When DEF is stored in vehicle tanks.

Water in DEF Bulk Storage Tanks

Water in DEF bulk storage tanks and DEF transfer tanks can occur when owners overlook regularly scheduled inspections, maintenance and repairs and when they use the same tanks for different products.

Without performing regularly scheduled tank inspections, owners risk going about business as usual and missing easily resolvable problems that otherwise can turn into disasters. One problem owners tend to overlook without consistent tank inspections is water condensation that might have formed within tanks’ air voids during fluctuating temperatures. Other problems that inspections flag include faulty fittings and seals and simple human errors, such as leaving a lid off a tank.

Water in DEF Vehicle Tanks

Water contamination of vehicle DEF storage tanks at the vehicle is preventable. The simplest way? Never put any kind of water in your vehicle’s DEF tank. As with any fuel cap on a vehicle, ensure the DEF cap is sealed tight after every fill. This will keep rain and water from car washes out of the DEF tank.

Effects: Symptoms of Bad DEF Fluid

Symptoms of bad DEF fluid include a DEF color of anything besides clear, including cloudiness. In addition, bad DEF fluid contaminated with water can lead to equipment failure and can void manufacturer warranties. Other effects and symptoms to watch for include:

• Check engine light. Something’s not right. Don’t ignore this.
• Crystallization: Evidence shows that when people have topped off their vehicles’ DEF tanks with hard water, deposits can form in the SCR systems’ exhaust or injector nozzles.
• Diluted DEF: Water in excess of 67.5% reduces the effectiveness of DEF NO_X neutralization.
• Increased DEF consumption.
• Vehicle slows or stops.

Solutions

Water in DEF Bulk Storage Tanks

• Inspect DEF bulk storage tanks as part of your regularly scheduled maintenance routine.
• Ensure DEF tanks remain watertight so rain and snowmelt cannot enter the tanks.
• If anything on a tank does not pass inspection, repair or replace the tank.
• Verify DEF quality when DEF is delivered or when it’s in bulk storage. To do this, request the Certificate of Analysis from your DEF supplier. As an alternative, you may submit a sample for testing according to ISO 22241-1.
• Test DEF for minerals such as calcium and deposit composition using ICP Spectrometry or XRF Spectrometry.
• You can use a handheld DEF refractometer to measure fluid concentration specifications. An acceptable measurement of urea concentration reads between 32.5% and 37%.

How to Clean DEF Tank

If you suspect anything besides pure DEF has been inside your DEF tank:

• Drain the tank and flush it with deionized water or new diesel exhaust fluid.
• When your DEF tank is empty, rinse it with warm water.
• Clean, dry and reassemble the tank.
• Fill the tank with fresh diesel exhaust fluid.

Water in DEF Vehicle Tanks

• Check for crystallization on exhaust piping and DEF injectors.
• You can use some of the sampling and testing procedures for bulk storage tanks.

More Resources

• Diesel Exhaust Fluid? What is DEF, and why do we use it?
• DEF Storage Regulations
• DEF Tank
• DEF Transfer tank

Need Help? Ask the Experts

For help in choosing the right DEF storage tank or DEF transfer tank, it makes sense to ask the experts. Unity Fuel Solutions is North America’s leader in double walled storage tanks. For advice on the tank and system that’s right for you, call the Unity team at 800-234-1689.

Small, medium and large businesses considering diesel exhaust fluid (DEF) for their commercial diesel vehicles generally have the same seven questions about DEF (also called AdBlue).

Here are answers to help you make informed decisions. And there’s more good news: You don’t need an advanced degree in chemistry to comply with federal emissions regulations.

1. What is Diesel Exhaust Fluid (DEF)?

Diesel exhaust fluid isn’t a fuel, although it’s transported and stored like fuel in separate, dedicated tanks.

The nontoxic, nonflammable and biodegradable fluid, when injected into vehicle exhaust produced by normal diesel combustion, works with a technology called selective catalytic reduction (CSR) to reduce poisonous, highly reactive nitrogen oxide (NOX) emissions.

Because NOX contributes to air pollution and smog, the Environmental Protection Agency (EPA) requires most diesel engine heavy-duty trucks manufactured after 2010 to include CSR.

DEF helps vehicles with CSR technology meet EPA requirements for diesel exhaust emissions.

2. What is Diesel Exhaust Fluid Made Of?

Diesel exhaust fluid ingredients are typically 32.5% synthetic, vehicle-grade urea (ammonia) and 67.5% deionized water.

DEF must meet a purity standard set by the International Standards Organization (ISO).

The ISO defines technically pure urea as an “industrially produced grade of urea (CAS Number 57-13-6) with traces of biuret, ammonia and water only, free of aldehydes or other substances such as anticaking agent, and free of contaminants such as sulphur (sic) and its compounds, chloride, nitrate or other compounds.”

The ISO defines pure water as “water very low in inorganic, organic or colloidal contaminants, produced, for example, by single distillation, by deionization, by ultra-filtration or by reverse osmosis.”

3. What Does Diesel Exhaust Fluid Do?

DEF converts NOX emissions produced during diesel engine combustion into harmless gases — nitrogen and water vapor — through a chemical change.

Vehicles with CSR technology have a tank for diesel fuel and another tank for DEF. (Diesel fuel and DEF are not meant to mix. Do not combine them. DEF injection happens outside the engine after diesel combustion.) Two-tank systems ensure the proper diesel-to-DEF ratio, which is about 50-to-1 for most diesel vehicle manufacturers.

When a CSR-equipped engine is running, the CSR system injects a small amount of DEF into the diesel exhaust stream. DEF mixes with the heated exhaust gases, and the DEF breaks down into carbon dioxide and ammonia. Then, the NOX in the SCR catalyst reacts with the ammonia and breaks down into safe nitrogen gas and water vapor.

DEF has several benefits. Beyond cleaner air, DEF contributes to better engine performance and fuel economy. Because injection occurs outside the engine, diesel engine manufacturers have boosted power output and achieved a cleaner burn and more efficient combustion.

4. Does DEF go bad?

Yes, DEF can go bad because it contains no preservatives.  It naturally degrades over time the longer it is stored and longevity very much depends on storage conditions.  DEF goes bad more quickly in temperatures higher than 65°F but when stored at lower temperatures, shelf life is extended.

Most DEF producers recommend use within one to two years of production dates. Many diesel engine manufacturers recommend using DEF certified by the American Petroleum Institute (API).

Water contamination is also a major contributor to causing DEF to go bad. Water in a DEF tank should be avoided at all costs because it will contaminate the product and potentially damage any vehicle run off that product.

5. Does Diesel Exhaust Fluid Freeze?

Yes, diesel exhaust fluid freezes at 11 F, and when it does, its volume expands up to 7%. For commercial vehicles with built in DEF tanks we recommend leaving enough room for thermal expansion to prevent cracked tanks.

If DEF freezes, its composition will not change. Do not add anything, including water, to DEF to help it melt. Frozen DEF in a vehicle tank will melt when the engine is running. Water in DEF tanks will contaminate the DEF fuel tank and can ruin a vehicle.

6. What Color is a Diesel Exhaust Fuel Cap?

Most diesel exhaust fuel caps are blue to differentiate from diesel fuel caps, which are green. The color coding helps prevent inadvertent contamination of both diesel and DEF in tanks. (The actual color of DEF, however, is clear.)

7. How Do You Store DEF?

Many businesses store DEF in bulk DEF tanks and DEF transfer tanks at their business premises to ensure their vehicles have access to DEF on demand. These are stainless steel storage tanks and fittings designed and constructed specifically to accommodate the corrosive characteristics of DEF. This corrosive nature demands the need for DEF products to be transported, stored and pumped with the appropriate equipment.

Some commercial and consumer vehicle manufacturers build small DEF tanks into their diesel vehicles during the assembly process. This ensures the DEF tank always travels with the vehicle and can be filled up at fuel stations for convenience.

When a DEF tank on a vehicle runs dry, the vehicle likely will go into “limp mode” with a noticeable decrease in performance and eventual shutdown.

Petroleum industry experts, market analysts and trade associations, including the Petroleum Equipment Institute (PEI), expect the demand for DEF will increase and require increasingly larger aboveground and underground storage tanks.

“Most people associated with the petroleum marketing and equipment industries know that aboveground tanks (ASTs) storing ‘oil’ are regulated by EPA under the Spill Prevention, Control and Countermeasure (SPCC) rule,” wrote Rick Long, former executive vice president of PEI, in a blog. “Since DEF is composed of aqueous urea which does not meet the SPCC definition of ‘oil,’ ASTs containing DEF (including drums, totes, IBCs and tanks) are not regulated by EPA.

“However, a word of caution is necessary here: Some states develop and enforce regulations that are more stringent than the federal rules.”

Long, who also is an attorney, recommends checking your state’s aboveground storage tank regulations to ensure DEF storage compliance.

More Resources

Recommended Practices for the Storage and Dispensing of Diesel Exhaust Fluid (DEF)

Need Help? Ask the Experts

For help in choosing the right DEF storage tank, it makes sense to ask the experts. Unity Fuel Solutions is North America’s leader in double walled storage tanks. For advice on the tank and system that’s right for you, call the Unity team at 800-234-1689.