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NOx emission control: What you need to know about AdBlue

auto motor und sport
Exhaust gas cleaning with SCR and AdBlue against NOx
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What is AdBlue?

A dBlue is an aqueous urea solution that consists of 32.5 percent urea and 67.5 percent demineralized water. The ultra-pure urea is produced synthetically through the chemical reaction of ammonia and carbon dioxide. Approximately one kilogram of natural gas is used for one liter of AdBlue. The production is therefore not CO2-neutral. Technical urea is used in fertilizers, shampoos and cosmetics, among other things, but AdBlue has yet another quality standard.

What does Adblue do in the exhaust gas?
Schematic representation of how AdBlue works.

AdBlue is carried in an extra tank in the vehicle and injected into the exhaust gas flow. When exposed to heat, ammonia is produced, which in turn reacts with the nitrogen oxides, which are converted into harmless nitrogen and water vapor in an SCR catalytic converter (SCR=selective catalytic reduction). The reduction in nitrogen emissions should be up to 90 percent. So far, BMW is the only manufacturer to combine an NOx storage catalytic converter, which also removes nitrogen oxides from the exhaust gas. This also reduces the amount of AdBlue required. The new BMW 520d promptly performed best with this exhaust gas cleaning system in our latest emissions test. Click here for our test results .

What makes the AdBlue system from Twintec different?

The current SCR systems only work from a certain exhaust gas temperature, accordinglythe urea cannot initially be converted into ammonia during a cold start. The BNOX system from Twintec heats AdBlue in a separate component and converts it directly into ammonia, which is then fed directly into the SCR catalytic converter. Here is more information and test results with the Twin-Tec retrofit

What to do when the AdBlue light comes on?

Der The level of the AdBlue tank is monitored electronically. If the urea is running low, the on-board computer reports and displays a corresponding message in the cockpit. A first notice is usually given at 2,400 kilometers remaining range, and another message at around 1,600 kilometers. If the range falls below 1,000 kilometers or if the AdBlue tank is completely empty, the engine can no longer be started. For many vehicles such as the V-Class from Mercedes the fill level can also be read off manually in the on-board computer.

How do I fill up Adblue?

AdBlue does NOT belong in the fuel tank. Depending on the car model, the filler neck is located directly next to the filler neck or in the trunk or in the engine compartment.

There are different positions depending on the manufacturer and model for the AdBlue filler neck. In many cars, it is now conveniently located next to the fuel filler neck. But beware! Adblue must NOT be filled into the fuel tank. If you accidentally poured Adblue into the tank, do not start the engine! Contact a workshop!

Otherwise, you can simply fill AdBlue into the AdBlue tank using a funnel or a spout supplied with the canister. You should then wait a few minutes until the on-board electronics recognize the new level. The warning light is no longer allowedappear.

In Germany there are still very few AdBlue dispensing systems at petrol stations. Here, too, you have to pay attention! There are dispensing systems for trucks with an AdBlue tank of up to 100 liters. This system pumps 20 liters of AdBlue per minute into the tank, which is designed for 40 liters per minute. The nozzle therefore does not fit into the filler neck of a car. If in doubt, have a look in your logbook, there are instructions there.

Where is the filler neck for AdBlue?

As I said: There are big differences depending on the brand and model. Filler necks right next to the filler neck behind the fuel filler flap are practical, but they are also available in the engine compartment or in the trunk, for example in the spare wheel well or even under the trunk floor. Then there is a hole with a rubber stopper in it. In our photo show we show you examples of where to find the filler neck.

Is AdBlue toxic or dangerous for people and nature?

No, AdBlue is non-toxic and largely odorless or can smell faintly of ammonia. Drops should be wiped up and rinsed with water. Contact with steel, iron, nickel and non-ferrous metals can corrode. House contact is to be avoided. AdBlue belongs to the lowest water hazard class 1.

How do I store AdBlue?

At 20 degrees Celsius, AdBlue can be kept for at least two years, at temperatures below It crystallizes at 11 degrees Celsius and expands by around 7 percent. Containers can then burst. Crystallized AdBlue can be thawed by warming it up, the temperature should not exceed 30 degrees Celsius.

Where can I get AdBlue?

AdBlue is available at filling stations , in hardware stores or in online trading in various container sizes. It starts with a 1.89 liter bottle up to a 20 liter canister, and even 200 liter drums are available. Make sure that you have a funnel or a filling aid on board, if necessary, or that the bottles you have bought have such a filling aid. Here is an overview of the sales outlets.

What does AdBlue cost?

The prices vary widely. At Amazon you get different quantities and containers at prices between 0.78 euros and 4.97 euros per liter. At filling stations, prices can be significantly higher, and car manufacturers are also paying more for AdBlue. Our recommendation: Put a 5 or 10 liter canister in the trunk.

How big is an AdBlue tank?

In our table we will show you the AdBlue tank size

How high is the AdBlue consumption inCar?

There is no realistic, general indication of AdBlue consumption. This depends on the driving style. The Mercedes-V-Class long-term test car from the auto motor und sport editorial team consumes between one and a good two liters per 1000 kilometers.

Who owns the rights to AdBlue?

AdBlue is a registered trademark of the Association of the Automotive Industry in 161 countries. The VDA owns the trademark rights for 161 countries worldwide and monitors compliance with the AdBlue standards according to ISO 22241/1 and DIN 70070, but does not regulate sales and marketing. This is done by numerous licensees.


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