🔍 Key Concepts

• Lube oil properties and how temperature affects viscosity and bearing protection • Typical operating temperature range for main turbine lube oil systems • Why overheating lube oil is dangerous for bearings and oil life

💭 Think About

• Think about what temperature range keeps the oil thin enough to flow easily, but still thick enough to protect the bearings in a high‑speed turbine. • Ask yourself: at what approximate temperature does most mineral lube oil begin to oxidize rapidly or lose film strength? • Consider whether the outlet temperature should be a fixed safe limit, a temperature difference, or something that varies with sea water temperature.

✅ Before You Answer

• Compare the choices to a realistic safe upper limit for continuous lube oil operation in main turbines. • Eliminate any answer that would clearly risk oil breakdown or bearing damage over time. • Decide whether a well‑designed cooler system would be controlled by oil requirements or by external factors like sea water temperature.