🔍 Key Concepts

• Fuel oil day tanks purpose and location in a diesel fuel system • Common contaminants found in fuel tanks (think about water, biological growth, and solids) • How each contaminant can affect engine performance and safety

💭 Think About

• For each option (water, micro-organism growth, sludge), ask yourself: Is this something that realistically can accumulate in a fuel tank over time? • Consider what can enter fuel during storage, transfer, and from tank condensation. • Think about what the engineer’s goal is when "checking and cleaning" a fuel day tank—are they targeting just one type of contamination, or anything that could harm the engine or clog filters?

✅ Before You Answer

• Verify which problems water in fuel tanks can cause (e.g., corrosion, poor combustion, microbial growth). • Verify where micro-organisms (bacteria, fungi) live and grow in fuel systems—do they need water present? • Verify what sludge in fuel tanks is made of and how it forms (sediment, degraded fuel, biomass, rust).