KEVOS® MAKEOS · Maintenance
Filter Beta Ratio and Capture Efficiency
What beta ratio and capture efficiency does this filter achieve, and what will pass downstream?
Filtration (beta) ratio of a filter element from upstream and downstream particle counts at a given size, the capture efficiency, and the downstream count expected from a known beta ratio and upstream contamination.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Calculation | choice | Calculate beta from counts, or the downstream count from a rated beta. |
| Upstream particles at the size | per mL | Particle count upstream of the filter at the stated size. |
| Downstream particles at the size | per mL | Particle count downstream at the same size. |
| Beta ratio (rating mode) | Rated beta ratio at the size of interest (from the filter maker’s ISO 16889 / ISO 4572 multipass test). |
Method and formulas
- β_x = upstream count ÷ downstream count at particle size x.
- Efficiency = (1 − 1 ÷ β) × 100%.
- Downstream count = upstream ÷ β.
- Example: 5000 upstream and 25 downstream particles per mL is β = 200 (99.5% efficient).
Limitations
- Beta ratios apply at one particle size and test condition; flow surges and cold starts reduce real efficiency.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Compare filter elements by their tested beta ratio
- Estimate downstream cleanliness from a filter rating
- Check a filter’s performance from before-and-after counts
Who it is for
- Reliability engineers
- Lubrication technicians
- Maintenance engineers
What you get
- Beta ratio
- Capture efficiency
- Particles passing
Interpreting the result
- β 200 captures 99.5%; going from β 75 to β 200 cuts particles passing by more than half.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2441–2442. Topic reference; no source tables or recommended settings are reproduced.
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Open the Filter Beta Ratio and Capture Efficiency calculator
