Explain the difference between a centrifugal pump and a positive-displacement pump in terms of flow characteristics and typical applications aboard ship.

Study for the Machinery Repairman Test. Enhance skills with comprehensive questions, detailed hints, and insightful explanations. Dominate your exam!

The main idea is how flow changes as system head changes and what each pump type tends to deliver per rotation. Centrifugal pumps move fluid by an impeller that adds velocity; the discharge flow is strongly influenced by the system head. At higher head (more resistance), the flow rate falls, and at lower head it rises. The flow from a centrifugal pump is continuous and non-pulsating, making it well suited for moving large volumes where head varies.

Positive-displacement pumps, on the other hand, trap a fixed amount of fluid with each cycle and push it out at a nearly constant volume per revolution. Because the volume moved per revolution is fixed, they can build higher pressures even when the flow is small, and the flow remains steady as long as the speed is constant. This makes them ideal for high-pressure, precise or dosing applications aboard a vessel.

So the correct description matches centrifugal pumps as delivering flow that varies with head and speed and provides continuous, non-pulsating flow, while positive-displacement pumps deliver a fixed volume per revolution and produce high pressure with steady flow.