🔍 Key Concepts

• Main lube oil system suction side and what causes increasing vacuum • How duplex strainers are cleaned or switched over safely while underway • Risks of introducing air or losing suction on the main lube oil pump

💭 Think About

• Is an increasing suction vacuum usually a sign of a blockage/restriction or a leak on the suction side? • Which actions can safely clear a suspected restriction without opening the system to atmosphere while the main engine is running? • Which option best reflects standard, conservative engineering practice for protecting the main engine from lube oil starvation?

✅ Before You Answer

• Verify which actions would maintain pump suction and avoid air ingestion into the lube oil system while underway • Check which option involves opening the system (covers, drains, vents) with the engine still running and why that may be unsafe • Consider how a duplex strainer is normally cleaned or restored to proper flow when differential or suction vacuum rises