Question 97Motor Plants - 1st Asst/Chief

The correct answer is D) at the main engine fuel oil header. Heavy fuel oil used in the system shown in the illustration will have the lowest viscosity at the main engine fuel oil header. This is because as the fuel oil flows through the system, it is heated and its viscosity is reduced. The lowest viscosity point will be at the final stage, which is the main engine fuel oil header, just before the fuel is injected into the engine. The other options are incorrect because the fuel oil will have a higher viscosity at the transfer pump discharge, in the settling tank, and in the three-way valve, as it has not yet been fully heated and processed through the system.