Pumps

Question 1

All positive displacement pumps have pumping chambers. True or false?

Answer 1

True, the volume of the pump body itself fixes the amount of fluid displaced.

Question 2

Positive displacement pumps cannot handle entrained air. True or false?

Answer 2

False, some positive displacement pumps cannot handle air as well as liquid and can run dry.

Question 3

Double acting piston pumps discharge an equal amount of liquid on all strokes. True or false?

Answer 3

False, because of the space that the piston rod occupies, the volume on the return stroke is less.

Question 4

Which reciprocating pumps can be allowed to run dry?

Answer 4

Diaphragm Pump

Question 5

Rotary pumps produce a smoother flow than reciprocating pumps. True or false?

Answer 5

True, all rotary pumps deliver a much smoother flow than reciprocating pumps.

Question 6

Which type of pump is not dynamic?

Answer 6

Reciprocating

Question 7

What is the definition of absolute pressure?

Answer 7

Gauge pressure plus atmospheric pressure.

Question 8

As pressure is reduced, the boiling point of a liquid decreases. True or false?

Answer 8

True, a temperature increase in the liquid or too little pressure at the pump suction can cause liquid to begin to vaporize.

Question 9

What occurs in a pump when a liquid vaporizes in a closed system?

Answer 9

Cavitation occurs.

Question 10

What could cause cavitation to occur?

Answer 10

A decrease in liquid pressure.

Question 11

When the pump inlet is above the level of liquid in the supply reservoir, the pump has a suction head. True of false?

Answer 11

False, suction head describes the condition where the level of the supply liquid is ABOVE the centreline of the pump.

Question 12

What source of energy is available to allow liquid to enter a pump with suction lift?

Answer 12

Atmospheric pressure.

Question 13

Which pump component converts mechanical energy into kinetic energy?

Answer 13

Impeller

Question 14

What value must the NPSH-R be for proper pump operation?

Answer 14

Less than NPSH-A.

Question 15

Diffusers are?

Answer 15

Stationary

Question 16

Unless otherwise stated, pump performance curves are based on handling of what type of fluid?

Answer 16

Cold water.

Question 17

Pump curves are provided by the pump manufacturer. True or false?

Answer 17

True, there are many manufacturers and they ALL have pump curves.

Question 18

What does not contribute to friction loss through pipes?

Answer 18

Increase in atmospheric pressure.

Question 19

What could be a possible cause for an increase in differential pressure across a strainer?

Answer 19

The strainer needs to be cleaned.

Question 20

When you have a safe work permit to service a pump, what is the first thing you must do before commencing work?

Answer 20

Isolate the pumps prime mover.