Two filters can both be labelled “10 micron” and perform very differently. To compare elements fairly you need to understand what the rating actually promises.
Nominal rating
A nominal rating is an approximate, manufacturer-defined value — it indicates the particle size at which the element removes a certain (often unspecified or modest) percentage of particles. Nominal ratings are useful as a rough guide but are not directly comparable between brands.
Absolute rating
An absolute rating states the particle size at which the element removes a high, defined percentage — tied to a measured efficiency. Absolute-rated elements give repeatable, comparable performance, which matters in critical or regulated duties.
The beta ratio
The beta ratio (β) quantifies efficiency at a given particle size:
βₓ = (particles ≥ x upstream) ÷ (particles ≥ x downstream)
From beta you get efficiency directly:
| Beta ratio | Efficiency |
|---|---|
| β = 2 | 50% |
| β = 20 | 95% |
| β = 200 | 99.5% |
| β = 1000 | 99.9% |
So an element quoted as “10 µm at β₁₀ ≥ 1000” removes 99.9% of particles ≥10 µm — a far stronger claim than a bare “10 micron nominal”.
Why it matters for procurement
When you replace an element, match the rating basis, not just the number. Swapping an absolute-rated element for a nominal one at the “same” micron can quietly reduce protection downstream. When you request a replacement, state the original rating and beta target so the equivalent is matched correctly.
Apply it to your filters
Looking at a specific OEM element? Start from a part page such as HFU640UY100J, or use the filter finder to match by OEM number. For duty-specific advice, send an inquiry with your target efficiency and we recommend a suitable high-flow element.