Managing Diesel Exhaust Fluid (DEF)
Managing Diesel Exhaust Fluid (DEF)

Tips for Managing Diesel Exhaust Fluid: The Latest Addition to Fluid Management

Here’s a pretty startling statistic—in the next year, the off-highway engine market will consume about 20 million gallons of Diesel Exhaust Fluid (DEF). In the next five years that number is projected to rise to 260 million gallons.  That’s a lot of equipment running with DEF.  DEF does require special attention in its use and storage, so here’s a quick hit list to help you and your crew handle it effectively.

Use DEF that meets OEM Specifications.

You should always use DEF that meets OEM specifications for your equipment.

DEF used in Cat® SCR systems must meet the requirements outlined in the International Organization for Standardization (ISO) standard 22241-1. ISO 22241-1 requirements are met by many brands of DEF, including those that carry the AdBlue or API certifications.

Know when DEF needs to be added.

The DEF tank on Cat machines has a 1:1 fill rate with the fuel tank. If fuel is added, DEF needs to be added. The DEF fill cap is an industry standard blue and easily identifiable.

Check DEF storage conditions.

DEF will start to freeze at 12 degrees Fahrenheit (-11°C), so you’ll want to store it in a conditioned space if possible.

DEF will expand when frozen, just like water. Approved containers are designed to handle the expansion and contraction, just like the DEF tanks on your equipment. Freezing does not change the effectiveness of the fluid.

The ideal storage temperature for DEF is between 15ºF and 77ºF (-9ºC and 25ºC). It should not be exposed to direct sunlight for long periods of time as the urea will decompose.

Refer to ISO 22241-3 for further information regarding DEF handling, transportation and storage.

Avoid DEF Contamination.

Contamination could cause your system to use more DEF than it should, degrade components and even lead to emissions system failure. If contamination damages the catalyst in your SCR system, it could void the warranty. The catalysts in SCR systems use rare metals and replacing one can cost as much as $15,000. When refilling the DEF tank, clean thoroughly around the fill neck and the dispensing nozzle every time. Most DEF tanks have only sediment filters and lack the kind of high-efficiency filtration common to diesel fuel and air systems.

Transfer containers should be avoided. If a container must be used, use it ONLY for DEF.

Make sure your operators understand idle time impact on DEF.

If operators run machines according to manufacturer’s recommendations, there should be no problems with DEF. However, it is good practice to pay close attention to idle time. Too much idling of new emissions-compliant machines can build up soot in their diesel particulate filters, requiring more frequent regens. Excessive idling can also cause the DEF to crystalize in the injectors which can cause even more problems. Making sure that operators keep idle time to a minimum also saves fuel and reduces maintenance costs.


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