Question 261General Subjects - QMED

The correct answer is C) a liquid seal. A liquid seal is used to prevent air leakage between the shaft and stuffing box packing in a centrifugal pump. The liquid seal, typically water, is introduced into the stuffing box and creates a barrier that prevents air from being drawn into the pump casing. This helps maintain the pump's efficiency and prevents cavitation issues. The other options are incorrect because: A) lantern rings are used to distribute the packing compression evenly, not to create a seal; B) a compressed packing gland alone does not prevent air leakage; and D) the stuffing box gland is responsible for compressing the packing, not creating a liquid seal.