TERM-BETA-RATIO
Beta Ratio
Filtration Performance
Also: ß ratio · filtration ratio · Beta-x · beta_x(c)
Abbrev: β_x(c) · β₁₀(c)
Canonical Definition
The ratio of the number of particles of a given size (x µm) upstream of a filter to the number of the same-sized particles downstream, as measured by the multi-pass test per ISO 16889. Expressed as β_x(c), where x is the particle size in micrometres and c denotes the counting method. A Beta ratio of 200 at 10 µm (β₁₀(c) = 200) means 200 upstream particles for every 1 downstream particle, corresponding to 99.5% single-pass efficiency.
Engineering Context
Beta ratio is the primary standardised efficiency metric for hydraulic and lubrication filters. It enables direct performance comparison across manufacturers because all measurements follow the same multi-pass test conditions defined in ISO 16889. Specifying β₁₀(c) ≥ 200 is a minimum requirement for proportional valve protection in mobile hydraulics.
Applicable Standards
Related Technologies
Protection Systems
Knowledge Center Articles
KC-00 Governance Metadata
| Permanent ID | TERM-BETA-RATIO |
| Category | Filtration Performance |
| Status | Published |
| Version | 1.0 |
| Last Reviewed | 2026-07-05 |
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