🔍 Key Concepts

• Purpose of a sludge tank in an engine room fuel oil system • Difference between sludge (oily waste) and water drained from fuel/settling tanks • Typical discharge points from a fuel oil purifier/centrifuge

💭 Think About

• Think about what comes out of a fuel oil centrifuge: does it produce only clean fuel, or does it also produce waste? Where does that waste normally go? • Consider how water is usually removed from a settling tank: is it handled as sludge/oily waste, or is it drained somewhere else? • Ask yourself: is the sludge tank mainly for oily residues, for water, or for both together?

✅ Before You Answer

• Verify what is meant by “sludge” in the context of fuel oil treatment (oily solids/emulsions vs relatively clean water). • Check standard practice: where does water drained from settling tanks normally go on a ship—into a sludge tank, a drain tank, or another system? • Confirm whether the sludge tank is primarily designed for high-oil-content waste or for relatively clean separated water.