RETA CARO Practice exam QUESTIONS
AND ANSWERS 100% CORRECT
What is the volume of a cold storage room that is 150' long, 80' wide and 35' high?
A.219,000 cubic feet
B.420,000 cubic feet
C.12,000 cubic feet
D.392,000 cubic feet - CORRECT ANSWERS B.420,000 cubic feet
150x80x35
How much heat must be removed to convert 5 pounds of water that is at 32°F to ice at 20°F when the
specific heat of ice is 0.5?
A.750 BTUs
B.970 BTUs
C.144 BTUs
D.726 BTUs - CORRECT ANSWERS A.750 BTUs
5 x 0.5 x (32-20) = 30
5 x 144 = 720
30 + 720 = 750
What does temperature indicate?
A.The pressure of a vapor
B.Latent heat energy of an object
C.The quantity of heat energy in an object
D.Intensity of heat energy in an object - CORRECT ANSWERS Intensity of heat energy in an
object
What is required to move heat from one object to another?
A.Temperature difference
B.Heat of fusion
,C.Change of state
D.Latent heat - CORRECT ANSWERS Temperature difference
Which of these is required to obtain a valid reading from a pressure/temperature chart?
A.The refrigerant must be in a superheated condition.
B.The refrigerant must be in a saturated condition.
C.The refrigerant must be at a constant temperature.
D.The refrigerant must be in a sub-cooled condition. - CORRECT ANSWERS B.The refrigerant
must be in a saturated condition.
Which of these is equivalent to 150 PSIA?
A.164.7 PSIG
B.185.0 PSIG
C.121.7 PSIG
D.135.3 PSIG - CORRECT ANSWERS D. 135.3 PSIG
(look on saturation chart)
What is a function of the compressor in a mechanical refrigeration system?
A.To remove liquid from the evaporator
B.To accept vapor from the evaporator and compress it to increase its pressure and temperature
C.To pump liquid to the expansion device
D.To remove vapor from the condenser and send it to the receiver - CORRECT ANSWERS To
accept vapor from the evaporator and compress it to increase its pressure and temperature
What does the term "compression ratio" refer to?
A.The ratio of discharge pressure to suction pressure in PSIG
B.The ratio of suction gas volume to discharge gas volume
C.The ratio of discharge pressure to suction pressure in PSIA
D.The ratio of piston length to piston diameter - CORRECT ANSWERS C. The ratio of
discharge pressure to suction pressure in PSIA
The compression ratio is the ratio of the absolute discharge pressure (psia) to absolute suction pressure
(psia), found using the formula Discharge Pressure Absolute ÷ Suction Pressure Absolute.
,Which of these is an essential component of a mechanical refrigeration system?
A.Receiver
B.Expansion device
C.Thermostat
D.Accumulator - CORRECT ANSWERS Expansion device
Which of these accurately describes sub-cooled liquid?
A.Liquid returning from the condenser
B.Liquid at -20°F
C.Liquid at 95°F
D.Liquid cooled below its saturation pressure - CORRECT ANSWERS D. Liquid cooled below
its saturation pressure
What will liquid refrigerant trapped in a pipe do when heated?
A.Expand
B.Freeze
C.Condense
D.Evaporate - CORRECT ANSWERS A. Expand
Which refrigerant is more forgiving to moisture in a refrigeration system?
A.R-717
B.R-507
C.R-134a
D.HCFC-22 - CORRECT ANSWERS A. R-717
Which of these conditions is indicated in an ammonia condenser operating with 180 PSIG pressure at
the drain outlets and 90°F liquid temperature leaving the condenser?
A. Non-condensables in the condenser
B. 5°F superheat on the condenser
C. System is operating normally
D. 10°F subcooled liquid on the condenser - CORRECT ANSWERS A. Non-condensables in the
condenser
, 95F - 180psig
90F - 165.54 psig
(on saturation chart)
Which of these is most likely to occur when air leaks into a refrigeration system?
A.A rapid increase of evaporator pressure
B.A reduction of compressor power consumption
C.An increase in compressor discharge pressure
D.A reduction of condensing or head pressure - CORRECT ANSWERS An increase in
compressor discharge pressure
Which of these is the greatest risk from closing valves on each end of a liquid line between a liquid pump
and an evaporator during maintenance of an ammonia refrigeration system?
A.Excessive discharge temperature when the line is reopened
B.Inadequate pressure in the line when the line is reopened
C.Collapse of the line if the liquid cools more than a few degrees
D.Rupture of the line if the liquid warms - CORRECT ANSWERS Rupture of the line if the
liquid warms
Under what conditions do halocarbon refrigerants become most hazardous?
A.When they come in contact with an open flame
B.When they are cooled
C.When oil is present at condensing temperatures
D.When they are compressed - CORRECT ANSWERS A.When they come in contact with an
open flame
Why is the discharge temperature of a screw compressor lower than the discharge temperature of a
reciprocating compressor?
A. There really is not any difference between these two types of compressors.
B. Significant quantities of oil flow into the rotor section of a screw compressor.
C. Oil coolers are larger for times when the compressor is running overloaded.
D. Screw compressors are more efficient than reciprocating compressors. - CORRECT ANSWERS
Significant quantities of oil flow into the rotor section of a screw compressor.
AND ANSWERS 100% CORRECT
What is the volume of a cold storage room that is 150' long, 80' wide and 35' high?
A.219,000 cubic feet
B.420,000 cubic feet
C.12,000 cubic feet
D.392,000 cubic feet - CORRECT ANSWERS B.420,000 cubic feet
150x80x35
How much heat must be removed to convert 5 pounds of water that is at 32°F to ice at 20°F when the
specific heat of ice is 0.5?
A.750 BTUs
B.970 BTUs
C.144 BTUs
D.726 BTUs - CORRECT ANSWERS A.750 BTUs
5 x 0.5 x (32-20) = 30
5 x 144 = 720
30 + 720 = 750
What does temperature indicate?
A.The pressure of a vapor
B.Latent heat energy of an object
C.The quantity of heat energy in an object
D.Intensity of heat energy in an object - CORRECT ANSWERS Intensity of heat energy in an
object
What is required to move heat from one object to another?
A.Temperature difference
B.Heat of fusion
,C.Change of state
D.Latent heat - CORRECT ANSWERS Temperature difference
Which of these is required to obtain a valid reading from a pressure/temperature chart?
A.The refrigerant must be in a superheated condition.
B.The refrigerant must be in a saturated condition.
C.The refrigerant must be at a constant temperature.
D.The refrigerant must be in a sub-cooled condition. - CORRECT ANSWERS B.The refrigerant
must be in a saturated condition.
Which of these is equivalent to 150 PSIA?
A.164.7 PSIG
B.185.0 PSIG
C.121.7 PSIG
D.135.3 PSIG - CORRECT ANSWERS D. 135.3 PSIG
(look on saturation chart)
What is a function of the compressor in a mechanical refrigeration system?
A.To remove liquid from the evaporator
B.To accept vapor from the evaporator and compress it to increase its pressure and temperature
C.To pump liquid to the expansion device
D.To remove vapor from the condenser and send it to the receiver - CORRECT ANSWERS To
accept vapor from the evaporator and compress it to increase its pressure and temperature
What does the term "compression ratio" refer to?
A.The ratio of discharge pressure to suction pressure in PSIG
B.The ratio of suction gas volume to discharge gas volume
C.The ratio of discharge pressure to suction pressure in PSIA
D.The ratio of piston length to piston diameter - CORRECT ANSWERS C. The ratio of
discharge pressure to suction pressure in PSIA
The compression ratio is the ratio of the absolute discharge pressure (psia) to absolute suction pressure
(psia), found using the formula Discharge Pressure Absolute ÷ Suction Pressure Absolute.
,Which of these is an essential component of a mechanical refrigeration system?
A.Receiver
B.Expansion device
C.Thermostat
D.Accumulator - CORRECT ANSWERS Expansion device
Which of these accurately describes sub-cooled liquid?
A.Liquid returning from the condenser
B.Liquid at -20°F
C.Liquid at 95°F
D.Liquid cooled below its saturation pressure - CORRECT ANSWERS D. Liquid cooled below
its saturation pressure
What will liquid refrigerant trapped in a pipe do when heated?
A.Expand
B.Freeze
C.Condense
D.Evaporate - CORRECT ANSWERS A. Expand
Which refrigerant is more forgiving to moisture in a refrigeration system?
A.R-717
B.R-507
C.R-134a
D.HCFC-22 - CORRECT ANSWERS A. R-717
Which of these conditions is indicated in an ammonia condenser operating with 180 PSIG pressure at
the drain outlets and 90°F liquid temperature leaving the condenser?
A. Non-condensables in the condenser
B. 5°F superheat on the condenser
C. System is operating normally
D. 10°F subcooled liquid on the condenser - CORRECT ANSWERS A. Non-condensables in the
condenser
, 95F - 180psig
90F - 165.54 psig
(on saturation chart)
Which of these is most likely to occur when air leaks into a refrigeration system?
A.A rapid increase of evaporator pressure
B.A reduction of compressor power consumption
C.An increase in compressor discharge pressure
D.A reduction of condensing or head pressure - CORRECT ANSWERS An increase in
compressor discharge pressure
Which of these is the greatest risk from closing valves on each end of a liquid line between a liquid pump
and an evaporator during maintenance of an ammonia refrigeration system?
A.Excessive discharge temperature when the line is reopened
B.Inadequate pressure in the line when the line is reopened
C.Collapse of the line if the liquid cools more than a few degrees
D.Rupture of the line if the liquid warms - CORRECT ANSWERS Rupture of the line if the
liquid warms
Under what conditions do halocarbon refrigerants become most hazardous?
A.When they come in contact with an open flame
B.When they are cooled
C.When oil is present at condensing temperatures
D.When they are compressed - CORRECT ANSWERS A.When they come in contact with an
open flame
Why is the discharge temperature of a screw compressor lower than the discharge temperature of a
reciprocating compressor?
A. There really is not any difference between these two types of compressors.
B. Significant quantities of oil flow into the rotor section of a screw compressor.
C. Oil coolers are larger for times when the compressor is running overloaded.
D. Screw compressors are more efficient than reciprocating compressors. - CORRECT ANSWERS
Significant quantities of oil flow into the rotor section of a screw compressor.
