🔍 Key Concepts

• Mechanical seal construction – stationary vs rotating faces, springs, secondary seals • How mechanical seals are cooled and lubricated in typical pump applications • Difference between mechanical seals vs packing glands (adjustable vs non‑adjustable in service)

💭 Think About

• For a typical centrifugal pump with a mechanical seal, what is usually in direct contact with the seal faces during operation? • Is a mechanical seal something that you normally ‘tighten up’ periodically like packing, or is it designed to run with a controlled amount of leakage and minimal adjustment? • Would a properly selected mechanical seal be commonly used on fuel oil pumps aboard ships, or is that application generally avoided?

✅ Before You Answer

• Identify which option correctly describes how mechanical seals are normally cooled and lubricated. • Eliminate any choice that treats a mechanical seal like adjustable packing that you routinely tighten to stop leaks. • Consider whether the statement about fuel oil transfer pumps matches common marine practice and manufacturer guidance.