Nate Industry Competency Exam: Commercial
Refrigeration with All Correct & 100% Verified Answers
|Updated to Pass
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. ✔Correct Answer-D
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. ✔Correct Answer-D
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. ✔Correct Answer-A
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. ✔Correct Answer-B
The BTUs rejected at the condenser are always greater than the heat absorbed 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. ✔Correct Answer-D
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. ✔Correct Answer-A
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. ✔Correct Answer-A
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. ✔Correct Answer-B
What is true of systems with multiple evaporators at different temperatures?
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. ✔Correct Answer-A
If charging a system by subcooling, what metering devices is installed?
a. Capillary tube.
b. Restrictor.
c. Thermostatic expansion valve.
d. Fixed orifice. ✔Correct Answer-C
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. ✔Correct Answer-C
In a liquid line, excess pressure drop can cause:
a. Sweating suction lines.
b. Flash gas.
c. Compressor overload.
d. Liquid subcooling. ✔Correct Answer-B
What are the two factors making up the safety classification for refrigerants?
a. Toxicity and time weighted average.
, b. Toxicity and flammability.
c. Emergency exposure limit and time weighted average.
d. Flammability and TEWI. ✔Correct Answer-B
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. ✔Correct Answer-B
On an electrical diagram, the below symbol represents a control that:
a. Closes on pressure rise.
b. Opens on pressure rise.
c. Closes on temperature fall.
d. Opens on temperature rise. ✔Correct Answer-B
During the pulldown periods of single compressor condensing units, compressor overloading can
best be prevented by using a(n):
a. Thermostatic expansion valve.
b. Evaporator pressure regulating valve.
c. Crankcase pressure regulating valve.
d. Head pressure valve. ✔Correct Answer-C
The purpose of a crankcase heater is to:
a. Reduce refrigerant migration into the oil during the off cycle.
b. Minimize refrigerant flooding into the compressor.
c. Remove any oil that may have migrated into the refrigerant.
d. Warm the oil to allow compressors to start easier. ✔Correct Answer-A
An electrical motor is designed to operate 120/240 volts. In using 120 volts, the current draw is 10
amperes. What would the current draw in using 240 volts?
a. 10 A.
b. 5 A.
c. 2.5 A.
d. 20 A. ✔Correct Answer-B
If the cut-out setting is raised 10°F and the differential doses not change, what is the effect on the
cut-in setting?
a. No effect on the cut-in.
b. The cut-in is lowered 10°F.
c. The cut-in is raised 10°F.
d. The cut-in is raised 20°F. ✔Correct Answer-C
What occurs on a multi-fan condenser with ambient temperature control as the outside temperature
drops?
Refrigeration with All Correct & 100% Verified Answers
|Updated to Pass
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. ✔Correct Answer-D
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. ✔Correct Answer-D
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. ✔Correct Answer-A
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. ✔Correct Answer-B
The BTUs rejected at the condenser are always greater than the heat absorbed 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. ✔Correct Answer-D
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. ✔Correct Answer-A
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. ✔Correct Answer-A
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. ✔Correct Answer-B
What is true of systems with multiple evaporators at different temperatures?
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. ✔Correct Answer-A
If charging a system by subcooling, what metering devices is installed?
a. Capillary tube.
b. Restrictor.
c. Thermostatic expansion valve.
d. Fixed orifice. ✔Correct Answer-C
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. ✔Correct Answer-C
In a liquid line, excess pressure drop can cause:
a. Sweating suction lines.
b. Flash gas.
c. Compressor overload.
d. Liquid subcooling. ✔Correct Answer-B
What are the two factors making up the safety classification for refrigerants?
a. Toxicity and time weighted average.
, b. Toxicity and flammability.
c. Emergency exposure limit and time weighted average.
d. Flammability and TEWI. ✔Correct Answer-B
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. ✔Correct Answer-B
On an electrical diagram, the below symbol represents a control that:
a. Closes on pressure rise.
b. Opens on pressure rise.
c. Closes on temperature fall.
d. Opens on temperature rise. ✔Correct Answer-B
During the pulldown periods of single compressor condensing units, compressor overloading can
best be prevented by using a(n):
a. Thermostatic expansion valve.
b. Evaporator pressure regulating valve.
c. Crankcase pressure regulating valve.
d. Head pressure valve. ✔Correct Answer-C
The purpose of a crankcase heater is to:
a. Reduce refrigerant migration into the oil during the off cycle.
b. Minimize refrigerant flooding into the compressor.
c. Remove any oil that may have migrated into the refrigerant.
d. Warm the oil to allow compressors to start easier. ✔Correct Answer-A
An electrical motor is designed to operate 120/240 volts. In using 120 volts, the current draw is 10
amperes. What would the current draw in using 240 volts?
a. 10 A.
b. 5 A.
c. 2.5 A.
d. 20 A. ✔Correct Answer-B
If the cut-out setting is raised 10°F and the differential doses not change, what is the effect on the
cut-in setting?
a. No effect on the cut-in.
b. The cut-in is lowered 10°F.
c. The cut-in is raised 10°F.
d. The cut-in is raised 20°F. ✔Correct Answer-C
What occurs on a multi-fan condenser with ambient temperature control as the outside temperature
drops?
