Question 317Motor Plants - Assistant Engineer

The correct answer is C) 110 mm. The size of the regulating ring required for the proper operation of the fuel oil centrifuge is determined by the fuel oil specific gravity and the separating temperature. The graph in the illustration shows the relationship between the regulating ring size, fuel oil specific gravity, and separating temperature. Based on the given information, with a fuel oil specific gravity of 0.9 kg/dm3 at 68°F and a separating temperature of 158°F, the correct regulating ring size is 110 mm. The other options are incorrect because they do not match the specific gravity and separating temperature values provided in the question. A regulating ring size of 110 mm is the appropriate choice for the given conditions.