8. NATE Industry Competency Exam
Commercial Refrigeration Questions &
Answers
1.With the condensing pressure and compressor speed remaining constant,
a decrease in suction pressure will cause a(n):
a. Decrease in compressor capacity and decrease in current.
b. Increase in compressor capacity and decrease in current.
c. Increase in compressor capacity and increase in current.
d. Decrease in compressor capacity and increase in current
ANS D
2.An indication of non-condensable gas in a refrigeration system is
significantly:
a. Lower-than-normal suction pressures.
b. higher-than-normal suction pressures.
c. Lower-than-normal head pressures.
d. higher-than-normal head pressures
ANS D
3.An automatic expansion valve controls refrigerant flow to an evaporator
by maintaining a constant:
a. Suction pressure.
b. Pressure differential across the valve port.
c. Liquid line pressure.
d. Superheat
ANS A
4.What is the approximate compression ratio of a compressor operating at
,35 psig suction pressure and 135 psig discharge pressure?
a. 1:03.
b. 3:01.
c. 1:04.
d. 4:01
ANS B
5.The BTUs rejected at the condenser are always greater than the heat
ab- sorbed in the evaporator because:
a. The condenser is mounted outside with restricted airflow.
b. Of the high temperature of the discharge vapor and length of the
discharge line.
c. Of the inefficiency of the condenser and pressure drop in the
discharge line.
d. Of the heat of compression in the compressor
ANS D
6.A unit cooler is inspected and found to be completely iced up. The
heaters and defrost timer are found to be working properly. A technician
should:
a. Adjust the defrost termination switch to a higher temperature setting.
b. Adjust the thermostatic expansion valve to a higher superheat setting.
c. Clear all of the ice from the coil and find out why the coil is frosted.
d. Increase the frequency of the defrost cycle
ANS A
7.what is the correct gauge pressure corresponding to an absolute
pressure of 24.7 psia at sea level?
a. 10 psig.
b. 12.6 psig.
,c. 39.4 psig.
d. 39.7 psig
ANS A
8.For a lineup of medium temperature case, an evaporator temperature 0f
23°F is needed. The following conditions exist:
· The suction line pressure drop is equivalent to approximately 2°F.
· The liquid line pressure drop is equivalent to 1°F.
The compressor capacity should be selected based on a saturated suction
temperature of:
a. 20°F.
b. 21°F.
c. 23°F.
d. 25°F
ANS B
9.What is true of systems with multiple evaporators at different
tempera- tures?
a. It is required to install evaporator pressure regulator(s).
b.The compressor discharge pressure will be a function of the coldest space
c. It is required to install a head pressure control valve.
d. It is required to install a crankcase pressure regulator
ANS A
10.If charging a system by subcooling, what metering devices is installed?
a. Capillary tube.
b. Restrictor.
c. Thermostatic expansion valve.
d. Fixed orifice
ANS C
, 11.The most critical refrigerant line with respect to sizing for
compressor performance is the:
a. Liquid line.
b. Discharge line.
c. Suction line.
d. Bypass line
ANS C
12.In a liquid line, excess pressure drop can cause:
a. Sweating suction lines.
b. Flash gas.
c. Compressor overload.
d. Liquid subcooling
ANS B
13.What are the two factors making up the safety classification for
refriger- ants?
a. Toxicity and time weighted average.
b. Toxicity and flammability.
c. Emergency exposure limit and time weighted average.
d. Flammability and TEWI
ANS B
14.What would be most affected by the use of an oversized suction line?
a. Discharge temperature.
b. Oil return.
c. Return gas temperature.
d. Refrigerant migration
ANS B
Commercial Refrigeration Questions &
Answers
1.With the condensing pressure and compressor speed remaining constant,
a decrease in suction pressure will cause a(n):
a. Decrease in compressor capacity and decrease in current.
b. Increase in compressor capacity and decrease in current.
c. Increase in compressor capacity and increase in current.
d. Decrease in compressor capacity and increase in current
ANS D
2.An indication of non-condensable gas in a refrigeration system is
significantly:
a. Lower-than-normal suction pressures.
b. higher-than-normal suction pressures.
c. Lower-than-normal head pressures.
d. higher-than-normal head pressures
ANS D
3.An automatic expansion valve controls refrigerant flow to an evaporator
by maintaining a constant:
a. Suction pressure.
b. Pressure differential across the valve port.
c. Liquid line pressure.
d. Superheat
ANS A
4.What is the approximate compression ratio of a compressor operating at
,35 psig suction pressure and 135 psig discharge pressure?
a. 1:03.
b. 3:01.
c. 1:04.
d. 4:01
ANS B
5.The BTUs rejected at the condenser are always greater than the heat
ab- sorbed in the evaporator because:
a. The condenser is mounted outside with restricted airflow.
b. Of the high temperature of the discharge vapor and length of the
discharge line.
c. Of the inefficiency of the condenser and pressure drop in the
discharge line.
d. Of the heat of compression in the compressor
ANS D
6.A unit cooler is inspected and found to be completely iced up. The
heaters and defrost timer are found to be working properly. A technician
should:
a. Adjust the defrost termination switch to a higher temperature setting.
b. Adjust the thermostatic expansion valve to a higher superheat setting.
c. Clear all of the ice from the coil and find out why the coil is frosted.
d. Increase the frequency of the defrost cycle
ANS A
7.what is the correct gauge pressure corresponding to an absolute
pressure of 24.7 psia at sea level?
a. 10 psig.
b. 12.6 psig.
,c. 39.4 psig.
d. 39.7 psig
ANS A
8.For a lineup of medium temperature case, an evaporator temperature 0f
23°F is needed. The following conditions exist:
· The suction line pressure drop is equivalent to approximately 2°F.
· The liquid line pressure drop is equivalent to 1°F.
The compressor capacity should be selected based on a saturated suction
temperature of:
a. 20°F.
b. 21°F.
c. 23°F.
d. 25°F
ANS B
9.What is true of systems with multiple evaporators at different
tempera- tures?
a. It is required to install evaporator pressure regulator(s).
b.The compressor discharge pressure will be a function of the coldest space
c. It is required to install a head pressure control valve.
d. It is required to install a crankcase pressure regulator
ANS A
10.If charging a system by subcooling, what metering devices is installed?
a. Capillary tube.
b. Restrictor.
c. Thermostatic expansion valve.
d. Fixed orifice
ANS C
, 11.The most critical refrigerant line with respect to sizing for
compressor performance is the:
a. Liquid line.
b. Discharge line.
c. Suction line.
d. Bypass line
ANS C
12.In a liquid line, excess pressure drop can cause:
a. Sweating suction lines.
b. Flash gas.
c. Compressor overload.
d. Liquid subcooling
ANS B
13.What are the two factors making up the safety classification for
refriger- ants?
a. Toxicity and time weighted average.
b. Toxicity and flammability.
c. Emergency exposure limit and time weighted average.
d. Flammability and TEWI
ANS B
14.What would be most affected by the use of an oversized suction line?
a. Discharge temperature.
b. Oil return.
c. Return gas temperature.
d. Refrigerant migration
ANS B
