🔍 Key Concepts

• Hydraulic symbols for hand-operated pumps versus motor-driven pumps in schematics • How many directions (open/close) each pump at points M, F, and E can control in this circuit • SOLAS/USCG requirement that remote emergency control of watertight doors must at least be able to close the door

💭 Think About

• Compare the symbol and labeling at Item E with the symbol and labeling at Item M. Which one clearly shows a motor, and which looks like a simple manual pump? • Look at the piping connected to E. Does it connect to both the "open" and "close" lines, or only one? What does that tell you about its function? • Think about where an emergency manual control for a watertight door is usually located on a ship: near the door, in a common passageway, or on the bridge?

✅ Before You Answer

• Confirm whether E is connected only to the close hydraulic line or to both open and close lines. • Identify which station in the drawing already provides both open and close manual operation (compare with the hand pumps at F). • Verify which option describes a manual pump with an emergency closing function rather than normal powered operation.