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DEF filters - Keeping your catalyst and the environment clean
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Diesel Exhaust Fluid (DEF) filters are often overlooked during routine maintenance. They form part of the Selective Catalytic Reduction (SCR) system used in diesel-powered vehicles such as tractors and forklifts. Driven by global emissions legislation, SCR technology has become increasingly common. Understanding how it works — and why regular DEF filter replacement is essential — is more important than ever.
Why do diesel engines use Diesel Exhaust Fluid?
Selective Catalytic Reduction (SCR) technology has made a significant difference in improving the air that we breathe today. This technology uses Diesel Exhaust Fluid (DEF), also known as AdBlue®, to reduce harmful emissions and to comply with current emission standards.
A small pump injects DEF fluid into the untreated exhaust of your diesel engine. Mixing these two components ignites a chemical reaction that converts highly polluting Nitrogen oxides (Nox) into harmless Nitrogen (N2) and water (H2O). SCR catalysts are currently the preferred method for meeting diesel emission standards and reduce as much as 95% of Nitrogen oxide emissions.
What is DEF and why does it need filtering?
Diesel Exhaust Fluid is a liquid mixture of 32,5% urea and 67,5% deionised water. Unfortunately, the urea —an organic compound— has a tendency to crystallise. These crystals often lead to issues with the injection pump and the SCR catalyst, which ultimately leads to a machine standstill.
DEF filters offer the right protection against these crystal formations and other contaminants. They ensure optimal functionality of the DEF injection pump and keep the diesel SCR system working at peak performance.
How often should a DEF filter be replaced?
It’s important to note that DEF or AdBlue® filters don’t outlast the lifespan of your vehicle. Exhaust fluid contamination and injection pump defects can lead to SCR malfunction, putting your machine at a standstill.
For non-road vehicles, recommendations may vary per manufacturer. Changing the filter every 3 years or 3,000 hours, whichever comes first, is a good starting point.
