🔍 Key Concepts

• Bearing lubrication requirements in large main propulsion steam turbines • Effect of high oil temperature on viscosity, film strength, and bearing life • Typical operating range for lube oil in turbine bearings vs. purifier discharge temperature

💭 Think About

• Which option talks about a fixed maximum temperature that would protect the oil’s viscosity and the bearing metal under heavy load? • Does the temperature of oil leaving the centrifugal purifier necessarily match what the bearings actually need for safe operation? • If outlet oil is allowed to be much hotter than inlet oil, what does that say about heat removal and potential damage to the bearing surfaces?

✅ Before You Answer

• Compare each choice to what you know about the safe temperature range for mineral lube oils in high‑speed machinery • Decide whether relative temperature rise (difference between inlet and outlet) or an absolute temperature limit is more important for bearing protection • Ask whether the centrifugal purifier’s outlet temperature is a control point for bearing safety, or just part of the conditioning system