Scrubber SO₂/CO₂ Ratio Check
MEPC.340(77) equivalence: SO₂/CO₂ ratio must be ≤ 4.3 for 0.50 % global cap (or ≤ 21.7 for 3.5 % cap) when using an EGCS scrubber instead of compliant fuel.
SO₂ / CO₂ ratio
0.001 -
Limit for target
4.30 -
Compliance
Compliant (≤ 4.3)
Formula, assumptions, and limits
$$\frac{\text{SO}_2 [\text{ppm}] / 10^4}{\text{CO}_2 [\%]} \leq \{4.3 \, (0.50\%), \; 0.86 \, (0.10\%)\}$$
The SO₂/CO₂ ratio proxy lets CEMS-style continuous monitoring prove compliance without measuring sulphur in the fuel directly. MEPC.340(77) introduced in 2020 replacing the older MEPC.184(59) method.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $SO₂$ | Sulphur dioxide in dry exhaust | ppm | CEMS / portable analyser |
| $CO₂$ | Carbon dioxide | % v/v | CEMS / portable analyser |
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