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2020 / 2021 Edition

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Avoiding common AdBlue issues

AdBlue tank

Volvo CE’s technical support team offers some useful advice on preventing common problems with AdBlue

ADBLUE is a solution made for emissions control, by reducing the nitrogen oxide (NOx) emitted from diesel engines. It is a liquid, similar in appearance to water, that is sprayed into the engine’s exhaust before it leaves the machine, and according to the technical support team at Volvo Construction Equipment, it is one of the most common engine-related issues in terms of the number calls they receive each day.

Improper handling, accidentally putting AdBlue into the diesel tank, and contamination are among the common occurrences they hear about. These incidents can cause severe damage to construction equipment, incurring high costs of repair in the process, so with prevention being far better than cure, Volvo CE’s experts offer the following advice to help avoid such issues.

Proper handling, they say, is essential to avoid any AdBlue-related problems, and it is always advisable to follow the manufacturer’s instructions prior to handling. AdBlue should be stored in a cool, dry location out of direct sunlight, and preferably indoors in stainless steel or plastic containers. It is important to note that AdBlue will freeze below –10ºC, turning it slushy, although this does not impede its performance or quality. If it has be kept in cold conditions, it should be in an expandable container, as its volume increases by 7% when it freezes. And although AdBlue naturally degrades over time, it can last up to one year.

AdBlue should never be mixed with diesel. If an operator starts a machine with AdBlue in the fuel lines, the machine can be severely damaged, incurring large repair bills. This confusion can easily occur as fuel and AdBlue tanks are often near to one another. It is vital to remember that AdBlue has its own filling port. The cap for the AdBlue tank is blue and the size of the fill hole tends to be of smaller diameter than the fuel hole.

If in any doubt whether the correct filling port was used, the tank should be drained and flushed with de-ionized water or clean AdBlue fluid to avoid potential damage. Also, operators should immediately contact their Volvo dealer if they accidentally add AdBlue to the fuel tank, as they will be able to provide advice on preventing further damage and remedying the issue.

Absolute purity is essential for AdBlue to do its job effectively, making it vulnerable to contamination. Contaminants can easily get into the fluid through the tank cap area, which can lead to damage and, as a consequence, long, unplanned downtime for the machine. Dirt and dust can easily get washed down into the tank from the fill cap area if it is not cleaned thoroughly before fluid is added.

Operators and maintenance staff should be made aware that is it extremely important to avoid contamination and that cleaning around the filler cap before use is vital, as is storing AdBlue in a dedicated container. Containers that have been used for other materials or fluids – even if they have undergone a thorough cleaning – should not be used; AdBlue really is that sensitive to contamination.

An indicator that AdBlue may be contaminated is an increase in consumption, a selective catalytic reduction (SCR) system malfunction, or, quite simply, engine shutdown. The ideal concentration of urea-based AdBlue is 32.5–37%, and problems may occur if this ratio is out of spec, indicating contamination. A digital refractometer should be used to test and monitor the purity of AdBlue.

The above points are the biggest concerns, but there are a number of other issues to bear in mind. Once the AdBlue tank is empty, a dashboard indicator light will appear and, after some time, the engine will de-rate. Also, AdBlue filters should be changed regularly in accordance with service intervals, and operators should bear in mind that AdBlue tanks can prone to a build-up of condensation, which may lead to contamination. Topping off the AdBlue tank at the end of the day will help avoid this.

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