NATE INDUSTRY COMPETENCY EXAM:
COMMERCIAL REFRIGERATION
QUESTIONS & ANSWERS 100% SOLVED
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. - ANSWERD
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. - ANSWERD
A transformer rated at 40 VA at 24 volts output has a maximum capacity of:
a. 0.625 A.
b. 0.960 A.
c. 1.240 A.
d. 1.667 A. - ANSWERD
Using the illustration below, what is the pressure drop across the refrigerant distributor
and distributor tubes?
a. 2.5 psi.
b. 35 psi.
c. 71 psi.
d. 120 psi. - ANSWERB
The current that opens the contacts in the current relay is the:
a. Start-winding current.
b. Run-winding current.
c. 24-volt applied voltage.
,d. Back EMF. - ANSWERD
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. - ANSWERA
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. - ANSWERA
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. - ANSWERB
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. - ANSWERA
If charging a system by subcooling, what metering devices is installed?
a. Capillary tube.
b. Restrictor.
c. Thermostatic expansion valve.
d. Fixed orifice. - ANSWERC
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. - ANSWERC
In a liquid line, excess pressure drop can cause:
a. Sweating suction lines.
b. Flash gas.
c. Compressor overload.
d. Liquid subcooling. - ANSWERB
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. - ANSWERB
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. - ANSWERB
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. - ANSWERB
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. - ANSWERC
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.
COMMERCIAL REFRIGERATION
QUESTIONS & ANSWERS 100% SOLVED
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. - ANSWERD
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. - ANSWERD
A transformer rated at 40 VA at 24 volts output has a maximum capacity of:
a. 0.625 A.
b. 0.960 A.
c. 1.240 A.
d. 1.667 A. - ANSWERD
Using the illustration below, what is the pressure drop across the refrigerant distributor
and distributor tubes?
a. 2.5 psi.
b. 35 psi.
c. 71 psi.
d. 120 psi. - ANSWERB
The current that opens the contacts in the current relay is the:
a. Start-winding current.
b. Run-winding current.
c. 24-volt applied voltage.
,d. Back EMF. - ANSWERD
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. - ANSWERA
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. - ANSWERA
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. - ANSWERB
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. - ANSWERA
If charging a system by subcooling, what metering devices is installed?
a. Capillary tube.
b. Restrictor.
c. Thermostatic expansion valve.
d. Fixed orifice. - ANSWERC
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. - ANSWERC
In a liquid line, excess pressure drop can cause:
a. Sweating suction lines.
b. Flash gas.
c. Compressor overload.
d. Liquid subcooling. - ANSWERB
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. - ANSWERB
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. - ANSWERB
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. - ANSWERB
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. - ANSWERC
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.
