BIT Unit 6 and 7

Which of the following statements about centrifugal pumps is correct?

• Centrifugal pumps are designed for handling high-pressure gases 

• Centrifugal pumps can only handle clean liquids 

• The impeller in a centrifugal pump imparts pressure in pulses 

• Centrifugal pumps provide a steady flow without pressure pulsation

In a centrifugal pump, the rotating wheel that imparts energy to the liquid is called the

• Rotor

• Impeller

• Vanes

• Casing

Reciprocating pumps are commonly used for reaching

• Pulses

• Steady flow

• Constant pressure

• Pulsating flow

The two basic classes of valves are:

• On/off and throttling

• Gate and globe

• Diaphragm and ball

• Swing and check

Globe valves cause energy wastage due to:

• Swirls and eddies in the liquid stream

• Straight-through flow pattern

• Increased pressure drop in the pipeline

• None of the above

What happens when the Reynolds number is less than 2,100 in a fluid flow inside a pipe?

• The flow is turbulent 

• The fluid will evaporate 

• The fluid will freeze 

• The flow is laminar

How is countercurrent flow different from cocurrent flow in a heat exchanger?

• Countercurrent flow involves fluids moving in opposite directions

• Cocurrent flow involves fluids moving at the same speed

• Cocurrent flow is more efficient in heat transfer

• Countercurrent flow occurs in vertical heat exchangers

Which handy rule is known to most chemical engineers regarding temperature and reaction rates?

• A 5 degree Fahrenheit increase will approximately double the rate of reactions

• A 10 degree Celsius increase will approximately double the rate of reactions

• A 5 degree Celsius increase will double the rate of reactions  

• A 20 degree Fahrenheit increase will double the rate of reactions

Throttling valves are used to:

• Change the rate of flow of liquids

• Completely stop the flow of liquids

• Control the pressure of the liquid

• None of the above

If a material is to be cooled, what is commonly used as the cooling medium in a shell-and-tube heat exchanger?

• Liquid nitrogen

• Cold brine

• Steam

• Dowterm E