🔍 Key Concepts

• Operation of a plate type heat exchanger (jacket water on one side, another fluid on the other) • How an internal leak in a heat exchanger affects levels and chemistry of each circuit • Typical symptoms of fluid cross-contamination vs. normal losses or scaling

💭 Think About

• If two closed cooling circuits start mixing, what happens to the fluid levels on each side over time? Which side would tend to gain fluid and which would lose? • Would an internal leak more directly cause a chemical-concentration change, a physical level change, or scale build‑up first? Think about what you would notice earliest in normal engine room watchkeeping. • Which option describes a symptom that would be both repeated/continuous and clearly tied to one circuit losing fluid into the other?

✅ Before You Answer

• Compare signs of gradual loss vs. overflow in the jacket water expansion tank. • Decide whether scale build‑up is a primary, immediate sign of a leak, or more of a long‑term water quality issue. • Ask yourself which sign would most directly point to mixing between two circuits, not just poor treatment or normal evaporation.