Question 360Steam Plants - 1st Asst/Chief

The correct answer is C) specific gravity of the oil being purified. The size of the discharge ring used for the efficient operation of a disk-type purifier is dependent on the specific gravity of the oil being purified. This is because the specific gravity of the oil affects the buoyancy and flow of the oil through the purifier, which in turn determines the optimal size of the discharge ring to maintain efficient separation and removal of contaminants. The other options are incorrect because the maximum design speed and rated capacity of the purifier, as well as the viscosity of the oil, do not directly determine the size of the discharge ring. These factors may influence the overall design and performance of the purifier, but the specific gravity of the oil is the primary factor that dictates the appropriate discharge ring size for efficient operation.