🔍 Key Concepts

• Trace the piping downstream of valve 1 to see which consumers (main engine vs SSDGs/boiler) it actually feeds. • Look at how many lines join at valve 1 and whether it functions as a 3‑way changeover (selecting one fuel or the other) or as a mixing point (combining flows). • Compare the position of valve 1 with other labeled valves (like 2, 3, 4, 5, 6, 7) to see which ones clearly belong to the main engine supply vs the auxiliary/boiler branch.

💭 Think About

• From valve 1, follow the line: does it go directly toward the main engine booster/heater train, or toward the branch labeled "To SSDGs and Boiler"? • Ask yourself: is valve 1 located where return fuel and supply fuel would be blended (a mixing tank line), or where only one of two different fuels is selected before going to the users? • Compare how heavy fuel oil (HFO) gets from the HFO day tank into the system versus how distillate oil (DO) enters; where in that path could a smooth changeover between fuels logically occur?

✅ Before You Answer

• Verify which equipment is immediately downstream of valve 1 (e.g., mixing tank, heaters, booster pumps, or SSDG/boiler branch). • Check whether valve 1 has two inlets of different fuel types coming to it (HFO and DO) or if it is only on the line from one day tank. • Confirm whether the main engine has its own separate arrangement (look near the viscosimeter, final heaters, and valve 7) that might already handle HFO/DO changeover for the main engine.