433A Pumps and Compressors 2

Question 1

What is the purpose of priming a centrifugal pump?

Accepted Answer

To fill the pump casing and suction line with liquid to displace air, since centrifugal pumps cannot pump air

Answer

To lubricate the pump bearings

Answer

To test the pump motor

Answer

To adjust the impeller clearance

Question 2

What are the signs of cavitation in a centrifugal pump?

Accepted Answer

Noise like pumping gravel, reduced flow and pressure, and erosion damage to the impeller

Answer

Smooth, quiet operation

Answer

Increased flow rate above design

Answer

Lower bearing temperatures

Question 3

What is a gear pump and what type of fluid transfer is it used for?

Accepted Answer

A positive displacement pump using meshing gears to move fluid, used for viscous liquids and hydraulic systems

Answer

A pump driven by a gear motor

Answer

A centrifugal pump with gear-shaped impeller

Answer

A pump used only for gear oil

Question 4

What is the function of a packing gland on a pump?

Accepted Answer

To compress packing rings around the shaft to control leakage while allowing slight dripping for cooling and lubrication

Answer

To pack the pump for shipping

Answer

To increase pump pressure

Answer

To protect the pump from overheating

Question 5

What is a diaphragm pump and what is its main advantage?

Accepted Answer

A positive displacement pump using a flexible diaphragm, capable of handling abrasive, viscous, and chemically aggressive fluids without contamination

Answer

A pump that uses sound waves

Answer

A high-speed centrifugal pump

Answer

A pump used only for water treatment

Question 6

What is the best efficiency point (BEP) of a centrifugal pump?

Accepted Answer

The flow rate and head at which the pump operates at its highest efficiency, with minimum vibration and longest life

Answer

The maximum pressure the pump can generate

Answer

The point at which the pump shuts off

Answer

The minimum speed the pump can operate at