Question 139Steam Plants - QMED

The correct answer is C) no oil is overflowing from the gravity tank. In a gravity type lube oil service system, the presence of oil in the sight glass of the return drop line indicates that oil is overflowing from the gravity tank and circulating through the system. If no oil appears in the sight glass, it means that no oil is overflowing from the gravity tank, suggesting a potential issue with the system, such as a clogged line or a failure in the oil supply. The other options are incorrect because: A) a failure of all lube oil pumps would not necessarily prevent oil from overflowing the gravity tank, B) the lack of oil in the sight glass does not directly indicate that no oil is flowing to the bearings, and D) the gravity tanks being empty is not the only possible reason for the lack of oil in the sight glass.