Question 416General Subjects - Assistant Engineer

The correct answer is D) the pump is not primed. For a centrifugal pump to work properly, it must be primed, meaning the pump casing and suction line must be filled with liquid before the pump is started. If the pump is not primed, the pump will not be able to draw in and deliver water, as the impeller needs to be submerged in liquid to create the necessary suction. The other answer choices, such as an improperly located seal ring or a plugged water seal pipe, may cause issues with the pump's operation, but they do not directly prevent the pump from being able to draw in and deliver water when first started, as an unprimed pump would.