Micron Rating
Definition
The nominal particle size, in micrometers (µm), that a filter is designed to remove — stated as either an absolute or a nominal value.
One micron equals one thousandth of a millimeter. High-flow liquid elements are commonly offered from 1 µm up to 100 µm, letting engineers match the rating to the smallest particle that must be removed.
A micron rating alone is incomplete without stating whether it is absolute or nominal, because the two describe very different real-world efficiency. Always compare like-for-like when cross-referencing OEM parts.
Relevance for high-flow filtration
R+F publishes the OEM micron rating for every replacement element so the fit is matched on efficiency as well as dimensions.
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Related terms
A filtration rating stating that a defined percentage — typically 99.9 % (beta 1000) — of particles at or above the rated micron size is removed in a single pass.
Nominal FiltrationA filtration rating indicating an approximate particle-removal efficiency — commonly 50–90 % — at the stated micron size, without a guaranteed single-pass value.
Beta Ratio (β)A dimensionless number expressing filtration efficiency: the ratio of particles of a given size upstream to those downstream of the filter.
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