Question 619Steam Plants - Assistant Engineer

The correct answer is C) at the top through the regulating tube. In a disk-type centrifugal purifier, the contaminated oil enters the centrifuge at the top through the regulating tube. This allows the oil to be evenly distributed across the disks, facilitating the separation of contaminants from the oil. The other answer choices are incorrect because: A) the neck of the top disk is not where the oil enters the centrifuge, B) the funnel body is not the inlet for the contaminated oil, and D) the oil does not enter at the bottom through the oil inlet, which is the outlet for the cleaned oil.