Open-Loop Scrubber (EGCS)
Exhaust gas cleaning system that uses seawater as the alkali source to remove SOx, then discharges treated wash water overboard.
In practice
Operated as default in open ocean. The chief engineer monitors washwater pH (>6.5 after dilution) and the discharge log. Many port states ban open-loop discharge in their territorial waters; ships switch to closed-loop or compliant fuel before crossing the line.
Regulatory detail & full definition
Compliant under MARPOL Annex VI Reg. 14 as an equivalent to low-sulphur fuel. Effluent must meet IMO MEPC.259(68) limits (pH > 6.5 at the discharge point, 4 m from discharge; PAH and turbidity limits). Banned in Singapore, China, German waters, several Baltic and US states; charters often spell out where open-loop is permitted.
Authoritative source: IMO Resolutions Index ↗
Related
Source: MEPC.259(68) — 2015 Guidelines for EGCS
High confidence
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