Power Engineering - 4B9 Practice
Questions and Answers
A compression refrigeration system can be divided into two sections: a high pressure
section containing the head pressure and a low pressure section carrying the _____
pressure:
a. Discharge
b. Saturation
c. Absolute
d. Suction - ANSWER-d. Suction
A compression refrigeration system may be pumped down for which of the following
reasons?
a. To perform maintenance on the low-pressure side of the system.
b. To perform maintenance at the discharge of the compressor.
c. To perform maintenance on the high-pressure side of the system.
d. To perform maintenance on the condenser. - ANSWER-a. To perform maintenance
on the low-pressure side of the system.
A direct expansion type evaporator that has more than one refrigerant circuit requires
__________ to provide even refrigerant flow in each circuit.
a. An expansion valve
b. A distributor
c. A purge valve
d. A backpressure regulator - ANSWER-b. A distributor
A liquid trap located in the suction line before a refrigeration compressor, which
evaporates liquid refrigerant and returns it to the compressor as a gas, is called:
a. An oil separator
b. A strainer-drier
c. A distributor
d. An accumulator - ANSWER-d. An accumulator
A pressure relief device on a refrigeration system shall have sufficient capacity to
prevent the pressure in the pressure vessel from rising more than _____ above the
setting of the pressure relief device.
a. 10%
b. 150%
c. 103 kPa
,d. 25% - ANSWER-a. 10%
A safety control designed to protect the chiller from freezing is the:
a. Vane closed switch
b. Low oil pressure shut down switch
c. Motor demand limiter
d. Chilled water flow switch - ANSWER-d. Chilled water flow switch
A sulfur candle is used to test for
a. R-744 leaks
b. R-717 leaks
c. R-290 leaks
d. CFC leaks - ANSWER-b. R-717 leaks
Absorption refrigeration systems may use waste heat in order to
a. pressurize the system
b. evaporate water from the weak lithium bromide
c. decrease the evaporation point of the refrigerant
d. maintain a minimum load on the system, during periods of low cooling demand
e. increase the lithium boiling point. - ANSWER-b. evaporate water from the weak
lithium bromide
Absorption refrigeration systems may use waste in order to
a. pressurize the system
b. evaporate water from the weak lithium bromide
c. decrease the evaporation point of the refrigerant
d. maintain a minimum load on the system, during periods of low cooling demand
e. increase the lithium boiling point. - ANSWER-b. evaporate water from the weak
lithium bromide
All refrigeration evaporators:
a. Require regular defrosting
b. Are part of the high side of the system
c. Are located between the expansion valve and the king valve.
d. Are flooded with refrigerant
e. Boil liquid refrigerant at low pressure and low temperature - ANSWER-e. Boil liquid
refrigerant at low pressure and low temperature
Ammonia piping (according to IIAR), should be labelled in:
a. Yellow background with black letters
, b. Orange background with black letters
c. Red background with white letters
d. Orange background with white letters - ANSWER-b. Orange background with black
letters
Ammonia systems are seldom used for air conditioning purposes in large building
mainly because ammonia:
a. Systems require more power than most building systems can provide.
b. Is too toxic.
c. Does not provide sufficient cooling capacity for large installations.
d. Systems require too much maintenance. - ANSWER-b. Is too toxic.
Ammonia, as well as being toxic, is also:
a. Miscible with oil
b. Odourless
c. Flammable
d. A low pressure refrigerant - ANSWER-c. Flammable
An evaporator that can easily be cleaned and defrosted manually without interrupting
the cooling process is which type of evaporator?
a. Liquid recirculating evaporator
b. Finned evaporator
c. Plate surface evaporator
d. Shell and tube evaporator - ANSWER-c. Plate surface evaporator
An example of a high leak probability system is a:
a. A direct expansion system
b. An indirect closed system
c. A double indirect system
d. A Class T system - ANSWER-a. A direct expansion system
Before operating a new refrigeration plant, or one in which piping alterations have been
made, the system must be tested for:
a. High pressure
b. Moisture content
c. Excessive oil consumption
d. Leaks - ANSWER-d. Leaks
compressor. Which is NOT a factor in determining the degree of hazard of a refrigerant?
a. Type of compressor used
Questions and Answers
A compression refrigeration system can be divided into two sections: a high pressure
section containing the head pressure and a low pressure section carrying the _____
pressure:
a. Discharge
b. Saturation
c. Absolute
d. Suction - ANSWER-d. Suction
A compression refrigeration system may be pumped down for which of the following
reasons?
a. To perform maintenance on the low-pressure side of the system.
b. To perform maintenance at the discharge of the compressor.
c. To perform maintenance on the high-pressure side of the system.
d. To perform maintenance on the condenser. - ANSWER-a. To perform maintenance
on the low-pressure side of the system.
A direct expansion type evaporator that has more than one refrigerant circuit requires
__________ to provide even refrigerant flow in each circuit.
a. An expansion valve
b. A distributor
c. A purge valve
d. A backpressure regulator - ANSWER-b. A distributor
A liquid trap located in the suction line before a refrigeration compressor, which
evaporates liquid refrigerant and returns it to the compressor as a gas, is called:
a. An oil separator
b. A strainer-drier
c. A distributor
d. An accumulator - ANSWER-d. An accumulator
A pressure relief device on a refrigeration system shall have sufficient capacity to
prevent the pressure in the pressure vessel from rising more than _____ above the
setting of the pressure relief device.
a. 10%
b. 150%
c. 103 kPa
,d. 25% - ANSWER-a. 10%
A safety control designed to protect the chiller from freezing is the:
a. Vane closed switch
b. Low oil pressure shut down switch
c. Motor demand limiter
d. Chilled water flow switch - ANSWER-d. Chilled water flow switch
A sulfur candle is used to test for
a. R-744 leaks
b. R-717 leaks
c. R-290 leaks
d. CFC leaks - ANSWER-b. R-717 leaks
Absorption refrigeration systems may use waste heat in order to
a. pressurize the system
b. evaporate water from the weak lithium bromide
c. decrease the evaporation point of the refrigerant
d. maintain a minimum load on the system, during periods of low cooling demand
e. increase the lithium boiling point. - ANSWER-b. evaporate water from the weak
lithium bromide
Absorption refrigeration systems may use waste in order to
a. pressurize the system
b. evaporate water from the weak lithium bromide
c. decrease the evaporation point of the refrigerant
d. maintain a minimum load on the system, during periods of low cooling demand
e. increase the lithium boiling point. - ANSWER-b. evaporate water from the weak
lithium bromide
All refrigeration evaporators:
a. Require regular defrosting
b. Are part of the high side of the system
c. Are located between the expansion valve and the king valve.
d. Are flooded with refrigerant
e. Boil liquid refrigerant at low pressure and low temperature - ANSWER-e. Boil liquid
refrigerant at low pressure and low temperature
Ammonia piping (according to IIAR), should be labelled in:
a. Yellow background with black letters
, b. Orange background with black letters
c. Red background with white letters
d. Orange background with white letters - ANSWER-b. Orange background with black
letters
Ammonia systems are seldom used for air conditioning purposes in large building
mainly because ammonia:
a. Systems require more power than most building systems can provide.
b. Is too toxic.
c. Does not provide sufficient cooling capacity for large installations.
d. Systems require too much maintenance. - ANSWER-b. Is too toxic.
Ammonia, as well as being toxic, is also:
a. Miscible with oil
b. Odourless
c. Flammable
d. A low pressure refrigerant - ANSWER-c. Flammable
An evaporator that can easily be cleaned and defrosted manually without interrupting
the cooling process is which type of evaporator?
a. Liquid recirculating evaporator
b. Finned evaporator
c. Plate surface evaporator
d. Shell and tube evaporator - ANSWER-c. Plate surface evaporator
An example of a high leak probability system is a:
a. A direct expansion system
b. An indirect closed system
c. A double indirect system
d. A Class T system - ANSWER-a. A direct expansion system
Before operating a new refrigeration plant, or one in which piping alterations have been
made, the system must be tested for:
a. High pressure
b. Moisture content
c. Excessive oil consumption
d. Leaks - ANSWER-d. Leaks
compressor. Which is NOT a factor in determining the degree of hazard of a refrigerant?
a. Type of compressor used
