A 99.9% log reduction sounds impressive. But what does it really mean for discharge compliance? Two systems with identical certified log reductions can have vastly different practical performance—and the difference lies in measurement uncertainty.
The Problem with Log Reduction Numbers
Log reduction is a statistical measure. When laboratories test BWMS performance, they report results with uncertainty ranges. A system might be certified at:
- 99.9% reduction (± 0.1%)
- 99.99% reduction (± 0.5%)
The uncertainty isn’t just academic—it propagates through to actual discharge concentrations.
Introducing Log-Reduction Uncertainty Propagation
The new tool in the BWM Suite takes the measurement uncertainty from type-approval test reports and propagates it through to expected discharge concentration.
What It Calculates:
- Probability of Exceedance – What’s the chance discharge exceeds D-2 limits?
- Risk Classification – Is the system:- Robust: Wide safety margins- Marginal: Small margins, careful monitoring needed- High Risk: Significant probability of exceedance
Who Benefits from This Tool?
For BWMS Manufacturers
- Validate that production units match type-approval performance
- Support technical documentation for flag state approvals
- Identify whether design changes affect uncertainty margins
For Technical Reviewers
- Evaluate competing BWMS with objective, quantitative criteria
- Move beyond “which has the higher log reduction”
- Provide regulators with probability-based compliance assessment
For Shipowners
- Make informed decisions when selecting BWMS
- Understand real-world performance expectations
- Plan maintenance schedules that maintain compliance margins
Why Standard Log Reduction Comparisons Fall Short
Comparing two systems by their certified log reduction alone is like comparing cars by top speed without considering fuel efficiency, safety ratings, or maintenance requirements.
Log-reduction uncertainty propagation adds the scientific rigor that compliance decisions actually need.
Explore the Log-Reduction Uncertainty Propagation tool at https://bwms.ingeniat.eu
Demo account (frontend login):
[email protected]/admin123— admin role