Question 420Motor Plants - Assistant Engineer

The correct answer is A) The temperature of the fuel from the preheater should be gradually reduced after switching over the three-way valve. This is the correct answer because when switching from heavy fuel oil to diesel oil, the temperature of the fuel needs to be gradually reduced to prevent thermal shock and damage to the engine components. Heavy fuel oil requires higher temperatures to maintain its viscosity, while diesel oil can operate at lower temperatures. Reducing the temperature gradually allows the engine systems to adapt to the change in fuel properties. The other options are incorrect because B) mixing heavy fuel and diesel oil is not recommended, C) increasing the heating steam would be counterproductive, and D) securing the heating steam before the switch would result in the fuel cooling too quickly, which could also damage the engine.