🔍 Key Concepts

• Trace the fuel flow from the final heaters, through the viscosimeter, to the injection pumps on the schematic. • Notice what component the signal line from the viscosimeter (V) goes to and what that component actually controls. • Think about how ships normally keep heavy fuel at the correct viscosity, and what is usually adjusted: temperature (steam to heaters), mixing ratio, or pump speed.

💭 Think About

• On the diagram, after the fuel passes through the final heaters and filters, what is the very last control/measurement device before the injection pumps, and what does its feedback logically need to change to correct viscosity? • If the fuel becomes too thick or too thin, which of the four options describes a control action that would directly and quickly change viscosity without disturbing the rest of the system? • Compare a simple indicating instrument versus a control element: which answer choices describe mere indication, and which describe a closed-loop control to hold viscosity constant?

✅ Before You Answer

• Verify on the drawing that the viscosimeter (V) has a control line going to only one specific component – identify what that component adjusts. • Confirm which variable most directly affects fuel viscosity at the engine in a heavy fuel system: temperature via heater steam, three‑way mixing valve position, or booster pump speed. • Eliminate any option that describes a function already clearly assigned to another labeled component (such as the three‑way mixing valve or the booster pump) elsewhere in the schematic.