The freshwater cooling systems serving the main engines on your general-purpose supply vessel are arranged as shown in the illustration. If coolant drain valves are inadvertently opened during engine operation, what combination set of symptoms would most likely result? Illustration MO-0138
• Effect of opening drain valves on a closed freshwater cooling loop (loss of coolant, presence of air) • Relationship between system pressure, coolant flow, and engine outlet temperature • Role of the jacket water expansion tank and gravity head line in maintaining pump suction
• If coolant is continuously draining while the engine is running, what happens first at the expansion tank, and how does that affect pump suction and discharge pressure? • With reduced or interrupted coolant flow through the engine, would you expect the outlet temperature from the engine to go up or down? Why? • Compare what you’d see on the pressure gauge and temperature indicator if the system were over‑cooled versus if it were losing water and possibly drawing air.
• Verify what direction the fresh water pumps move coolant and where they take suction relative to the expansion tank and drain valves. • Check how a falling level in the jacket water expansion tank would affect the available NPSH (suction head) to the pumps and thus their discharge pressure. • Decide whether reduced coolant circulation around the liners and heads would most likely produce high or low engine outlet temperature before choosing the symptom set.
No comments yet
Be the first to share your thoughts!