What is a Micron?

The unwanted particles found in today’s DEF are measured in microns (μ). A micron is a unit of linear measure in the metric system used to measure distance from one point to another. A micron rating for DEF filtration is a generalized way of quantifying the ability of a filter’s media to remove contaminants of a particular size.

For example, a filter with a micron rating of “7” will filter out contaminants of 7 microns or larger and a filter with a micron rating of “3” will filter out contaminants of 3 microns or larger. Filter efficiency refers to a measurement of the filter’s retention efficiency. The measurement is typically the number of particles retained by a filter compared to the number of particles present in the DEF that will pass through the filter. A 7 micron filter with 98.7% efficiency rating removes 98.7% of the particles at or above the 7 micron size.

Proper Storage and Filtration of DEF is Critical

As the graphic below illustrates, the wide variance in filtration throughout the manufacturing and delivery process of DEF makes awareness of proper storage and filtration an essential part of your Selective Catalytic Reduction (SCR) aftertreatment system’s reliability and performance.

def process illustration

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