🔍 Key Concepts

• Closed freshwater cooling system versus raw water cooling • Function of a thermostatic control device in engine cooling systems • Role of the heat exchanger in transferring heat from freshwater to seawater

💭 Think About

• In a closed freshwater system, what component actually changes position or flow path in response to engine temperature? • Which choice is a device that can actively regulate how much coolant is allowed to pass through the heat exchanger versus being routed elsewhere? • Do seawater conditions or tank levels usually control coolant flow, or do they just affect overall system performance?

✅ Before You Answer

• Identify which option is an active flow‑controlling valve rather than a condition (like temperature) or a passive level • Ask: which item commonly routes coolant either through the heat exchanger or around it depending on coolant temperature? • Verify in your engineering notes which component is normally used to bypass the heat exchanger during warm‑up and regulate flow when at operating temperature