Question 1

Name two methods commonly used to unload a reciprocating compressor.

Accepted Answer

The two methods are ...

Question 2

Since there are no "valves" in a scroll compressor, what must be done to prevent refrigerant from flowing backward when the compressor cycles off?

Accepted Answer

Install check valves.

Question 3

A centrifugal compressor uses ____ for capacity control.

Accepted Answer

A)   guide vanes
B)   block vanes
C)   guide blocks
D)   control vanesE) B) and C)
F) A) and D) A

Question 4

The ends of a chiller evaporator are closed off by standard or marine boxes. What is the difference?

Accepted Answer

Supply and return piping is co...

Question 5

Electronic starters are much smaller than conventional starters.

Accepted Answer

A) True 
 B)False

Question 6

A purge unit ____.

Accepted Answer

A)   helps to provide subcooling in the condenser
B)   helps to provide superheat in the suction line
C)   relieves non-condensable gases from the system to the atmosphere
D)   provides capacity controlE) A) and D)
F) C) and D)

Question 7

Why are open-drive compressors often started up for a short time in the off season?

Accepted Answer

The shaft seal on the compressor is kept...

Question 8

How is the capacity of a screw compressor controlled?

Accepted Answer

The capacity is cont...

Question 9

What is accomplished by having a compressor that is equipped with unloaders?

Accepted Answer

The compressor is able to oper...

Question 10

The evaporator of a chiller can be used to absorb heat from ____.

Accepted Answer

A)   water
B)   a solution of water and polyethylene glycol
C)   the refrigerant
D)   both a and bE) B) and D)
F) B) and C)

Question 11

Lithium bromide is ideal for use in absorption systems because it is non-corrosive.

Accepted Answer

A) True 
 B)False

Question 12

The refrigerant in an absorption chiller whose source of energy is steam or hot water is ____________________.

Accepted Answer

The answer of The refrigerant in an absorption chiller whose...

Question 13

Why are multiple smaller compressors sometimes preferred over one large compressor?

Accepted Answer

If one of the cylinders of a l...

Question 14

Centrifugal compressors are designed with the lubrication isolated from the refrigerant vapor. Why?

Accepted Answer

Oil mixed with the l...

Question 15

The compressors used in low pressure chillers are the ____ type.

Accepted Answer

A)   reciprocating
B)   scroll
C)   screw
D)   centrifugalE) All of the above
F) A) and D)

Question 16

In centrifugal compressors, capacity control is accomplished by the use of ___________________________________ at the impeller inlet.

Accepted Answer

The answer of In centrifugal compressors, capacity control is accomplished...

Question 17

Speeds up to ____ rpm are used in centrifugal compressors.

Accepted Answer

A)   15,000
B)   20,000
C)   25,000
D)   30,000E) B) and C)
F) A) and D)

Question 18

To unload a reciprocating compressor, hot gas bypass across the cylinder is the best method.

Accepted Answer

A) True 
 B)False

Question 19

Two basic categories of chillers are the ____.

Accepted Answer

A)   compression cycle and absorption
B)   purge and absorption
C)   absorption and lithium bromide
D)   purge and lithium bromideE) A) and B)
F) A) and C)

Question 20

When a chiller using a low-pressure refrigerant is operating, the low pressure side of the system ____.

Accepted Answer

A)   always shows a positive pressure
B)   is always in a vacuum
C)   contains a mixture of oil and air
D)   rejects oxygen and moistureE) B) and D)
F) A) and D) B

Exam 47: High-Pressure, Low-Pressure, and Absorption Chilled-Water Systems

Name two methods commonly used to unload a reciprocating compressor.

Correct AnswerverifiedThe two methods are ...View AnswerShow Answer

Since there are no "valves" in a scroll compressor, what must be done to prevent refrigerant from flowing backward when the compressor cycles off?

Correct AnswerverifiedInstall check valves.

A centrifugal compressor uses ____ for capacity control.

Correct AnswerverifiedA

The ends of a chiller evaporator are closed off by standard or marine boxes. What is the difference?

Correct AnswerverifiedSupply and return piping is co...View AnswerShow Answer

Electronic starters are much smaller than conventional starters.

Correct AnswerverifiedShow Answer

A purge unit ____.

Correct AnswerverifiedShow Answer

Why are open-drive compressors often started up for a short time in the off season?

Correct AnswerverifiedThe shaft seal on the compressor is kept...View AnswerShow Answer

How is the capacity of a screw compressor controlled?

Correct AnswerverifiedThe capacity is cont...View AnswerShow Answer

What is accomplished by having a compressor that is equipped with unloaders?

Correct AnswerverifiedThe compressor is able to oper...View AnswerShow Answer

The evaporator of a chiller can be used to absorb heat from ____.

Correct AnswerverifiedShow Answer

Lithium bromide is ideal for use in absorption systems because it is non-corrosive.

Correct AnswerverifiedShow Answer

The refrigerant in an absorption chiller whose source of energy is steam or hot water is ____________________.

Correct AnswerverifiedShow Answer

Why are multiple smaller compressors sometimes preferred over one large compressor?

Correct AnswerverifiedIf one of the cylinders of a l...View AnswerShow Answer

Centrifugal compressors are designed with the lubrication isolated from the refrigerant vapor. Why?

Correct AnswerverifiedOil mixed with the l...View AnswerShow Answer

The compressors used in low pressure chillers are the ____ type.

Correct AnswerverifiedShow Answer

In centrifugal compressors, capacity control is accomplished by the use of ___________________________________ at the impeller inlet.

Correct AnswerverifiedShow Answer

Speeds up to ____ rpm are used in centrifugal compressors.

Correct AnswerverifiedShow Answer

To unload a reciprocating compressor, hot gas bypass across the cylinder is the best method.

Correct AnswerverifiedShow Answer

Two basic categories of chillers are the ____.

Correct AnswerverifiedShow Answer

When a chiller using a low-pressure refrigerant is operating, the low pressure side of the system ____.

Correct AnswerverifiedB

Correct Answer
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The two methods are ...
View Answer

Correct Answer
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Install check valves.

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A

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Supply and return piping is co...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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The shaft seal on the compressor is kept...
View Answer

Correct Answer
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The capacity is cont...
View Answer

Correct Answer
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The compressor is able to oper...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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If one of the cylinders of a l...
View Answer

Correct Answer
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Oil mixed with the l...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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B