Pumping Systems, Operations. Test 9 – Online Maritime Tests

During operation: What is one of the most important differences between a centrifugal pump and a piston pump?

A centrifugal pump does not need lubrication.
A centrifugal pump can not go as low as a piston pump in the vacuum area.
A piston pump is always driven by steam.
It is easier to damage a centrifugal pump than a piston pump if they run dry.

Centrifugal pumps and displacement pumps differ in several characteristics. Which of the following statements regarding a centrifugal pump is correct?

The inlet is in the outer diameter of the impeller and the pressure discharge is in the center of the impeller.
A centrifugal pump is designed to take suction from 30 - 35 meters heigth (suction height).
A centrifugal pump is always fitted in a vertical possition.
It is important that the rotation direction is correct to avoid dry running.

Worm and worm wheel distinguish between what pump components?

The driving and driven shaft gears.
The tangential gear and the straight shaft gear.
The rounded and the bellow gear.
The long shaft gear and the stub shaft gear.

On a ship installation it is preferable on vertical pumps to have shaft sealing at the pump upper only. For what reason?

Containment of liquid in the pump over long idle periods.
Observance of conditions (i.e. leakage) if mechanically sealed.
Adjustment of the seal if possible.
All of the mentioned alternatives.

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