🔍 Key Concepts

• How a purifier/centrifuge separates substances based on difference in density • Which contaminants in fuel oil are heavier or lighter than the fuel itself • What contaminants (like sulphur) are chemically bound in the fuel vs. physically mixed in

💭 Think About

• Think about which of the listed contaminants can be separated simply by spinning the mixture very fast so that heavier parts move outward • Ask yourself: in a settling tank, which contaminant would naturally settle to the bottom or rise to the top over time compared to the fuel? • Consider which option represents something that is dissolved or chemically combined with the fuel and therefore cannot be removed by a mechanical separator

✅ Before You Answer

• Identify which contaminant has a significantly different density from fuel oil and is present as a separate phase, not dissolved • Eliminate any options that would require a chemical process (not just mechanical separation) to remove • Recall that marine fuel oil centrifuges are primarily designed to remove this specific type of contaminant to protect engines and fuel systems