RETA CERTIFIED INDUSTRIAL REFRIGERATION OPERATOR (CIRO) MOCK EXAM
NEWEST EVALUATED EXAM PRACTICE 120 QUESTIONS 2026-2027|ORIGINAL
QUESTIONS & ANSWERS |DETAILED RATIONALES |HINTED COMPLETE EXAM
PREP GRADED A+*INSTANT DOWNLOAD PDF*
1. During operation of a low-temperature industrial refrigeration system, an
operator notices that suction pressure has gradually decreased while
compressor discharge temperature and discharge pressure have increased.
The evaporator load has not changed significantly, and the condenser
appears to be operating normally. Which condition is the MOST likely
explanation?
A. Excessive liquid refrigerant entering the compressor
B. Insufficient refrigerant flow through the evaporator
C. Excessive condenser flooding
D. Overfeeding of the expansion device
Answer: B
A starved evaporator reduces refrigerant mass flow and heat absorption,
causing suction pressure to fall. As the compressor continues operating against
a lower suction pressure, the compression ratio increases, which commonly
raises discharge temperature. The combination of low suction pressure and
elevated discharge temperature is therefore consistent with an evaporator
that is not receiving adequate refrigerant flow.
2. A reciprocating refrigeration compressor is controlled by a low-pressure
switch operating in pump-down mode. The thermostat calls for cooling, the
liquid-line solenoid valve opens, suction pressure rises, and the low-pressure
control closes its contacts to start the compressor. When the thermostat is
satisfied, the liquid-line solenoid closes. The compressor continues running
until the suction pressure falls to the low-pressure cutout setting. What is the
primary purpose of this control arrangement?
,A. To maintain a constant discharge pressure
B. To prevent the evaporator from becoming flooded during shutdown
C. To remove refrigerant from the evaporator and suction line during the off
cycle
D. To prevent the condenser from becoming overfilled with liquid refrigerant
Answer: C
A pump-down control system uses a liquid-line solenoid valve to stop
refrigerant flow when the thermostat is satisfied. The compressor continues
operating until the suction pressure falls to the low-pressure cutout setting,
effectively pumping most of the refrigerant out of the evaporator and suction
side. This reduces refrigerant migration and helps prevent liquid refrigerant
from reaching the compressor during shutdown.
3. What is the primary safety concern with ammonia in industrial
refrigeration systems?
A. Flammability
B. Toxicity
C. Low pressure
D. High cost
Answer: B
Ammonia is toxic and requires proper handling and ventilation. While
ammonia does have flammable characteristics at certain concentrations, its
toxicity represents the primary safety concern in industrial refrigeration
applications.
,4. Before beginning maintenance on a refrigeration compressor, which action
provides the most fundamental protection against unexpected startup?
A. Close the compressor discharge valve
B. Reduce the compressor suction pressure
C. Isolate the equipment from energy sources and apply lockout/tagout
procedures
D. Open the oil separator drain valve
Answer: C
Lockout/tagout (LOTO) is intended to prevent unexpected energization,
startup, or release of hazardous energy while maintenance is being performed.
A refrigeration compressor may have electrical energy, stored pressure,
rotating components, hot surfaces, and other hazards. Simply closing a
refrigeration valve does not necessarily eliminate electrical or mechanical
energy.
5. A technician is preparing to work on a refrigeration system that contains
ammonia. The technician has isolated the electrical supply but has not
isolated the ammonia circuit. Why is electrical isolation alone inadequate?
A. Ammonia systems cannot be electrically isolated
B. Refrigerant pressure and trapped chemical energy may remain even when
electrical power is disconnected
C. Disconnecting electricity automatically increases ammonia pressure
D. Ammonia becomes flammable whenever electrical power is removed
Answer: B
Refrigeration systems can contain significant stored energy in the form of
pressurized refrigerant. Disconnecting electrical power prevents many
electrically driven components from operating, but it does not remove
, pressure or refrigerant from isolated sections of piping. A trapped liquid
refrigerant section can also develop extremely high pressure as temperature
rises.
6. An ammonia refrigeration system is operating with a normal condensing
pressure, but the suction pressure at a particular evaporator is substantially
lower than expected. The evaporator has a liquid feed valve upstream, and
the evaporator outlet superheat is considerably higher than normal. Which
condition is the MOST likely explanation?
A. Excessive liquid refrigerant entering the evaporator
B. Restricted refrigerant flow into the evaporator
C. Excessive condenser flooding
D. Excessively low discharge superheat
Answer: B
A restriction in the liquid feed path reduces the amount of refrigerant entering
the evaporator. With insufficient refrigerant available to boil, a larger portion
of the evaporator becomes starved, increasing outlet superheat and lowering
the evaporator suction pressure. Possible causes include a partially closed
hand valve, plugged strainer, malfunctioning control valve, excessive pressure
drop, or an obstructed liquid line.
7. What is the primary refrigerant used in most industrial refrigeration
systems?
A. R-22
B. Ammonia (NH₃)
NEWEST EVALUATED EXAM PRACTICE 120 QUESTIONS 2026-2027|ORIGINAL
QUESTIONS & ANSWERS |DETAILED RATIONALES |HINTED COMPLETE EXAM
PREP GRADED A+*INSTANT DOWNLOAD PDF*
1. During operation of a low-temperature industrial refrigeration system, an
operator notices that suction pressure has gradually decreased while
compressor discharge temperature and discharge pressure have increased.
The evaporator load has not changed significantly, and the condenser
appears to be operating normally. Which condition is the MOST likely
explanation?
A. Excessive liquid refrigerant entering the compressor
B. Insufficient refrigerant flow through the evaporator
C. Excessive condenser flooding
D. Overfeeding of the expansion device
Answer: B
A starved evaporator reduces refrigerant mass flow and heat absorption,
causing suction pressure to fall. As the compressor continues operating against
a lower suction pressure, the compression ratio increases, which commonly
raises discharge temperature. The combination of low suction pressure and
elevated discharge temperature is therefore consistent with an evaporator
that is not receiving adequate refrigerant flow.
2. A reciprocating refrigeration compressor is controlled by a low-pressure
switch operating in pump-down mode. The thermostat calls for cooling, the
liquid-line solenoid valve opens, suction pressure rises, and the low-pressure
control closes its contacts to start the compressor. When the thermostat is
satisfied, the liquid-line solenoid closes. The compressor continues running
until the suction pressure falls to the low-pressure cutout setting. What is the
primary purpose of this control arrangement?
,A. To maintain a constant discharge pressure
B. To prevent the evaporator from becoming flooded during shutdown
C. To remove refrigerant from the evaporator and suction line during the off
cycle
D. To prevent the condenser from becoming overfilled with liquid refrigerant
Answer: C
A pump-down control system uses a liquid-line solenoid valve to stop
refrigerant flow when the thermostat is satisfied. The compressor continues
operating until the suction pressure falls to the low-pressure cutout setting,
effectively pumping most of the refrigerant out of the evaporator and suction
side. This reduces refrigerant migration and helps prevent liquid refrigerant
from reaching the compressor during shutdown.
3. What is the primary safety concern with ammonia in industrial
refrigeration systems?
A. Flammability
B. Toxicity
C. Low pressure
D. High cost
Answer: B
Ammonia is toxic and requires proper handling and ventilation. While
ammonia does have flammable characteristics at certain concentrations, its
toxicity represents the primary safety concern in industrial refrigeration
applications.
,4. Before beginning maintenance on a refrigeration compressor, which action
provides the most fundamental protection against unexpected startup?
A. Close the compressor discharge valve
B. Reduce the compressor suction pressure
C. Isolate the equipment from energy sources and apply lockout/tagout
procedures
D. Open the oil separator drain valve
Answer: C
Lockout/tagout (LOTO) is intended to prevent unexpected energization,
startup, or release of hazardous energy while maintenance is being performed.
A refrigeration compressor may have electrical energy, stored pressure,
rotating components, hot surfaces, and other hazards. Simply closing a
refrigeration valve does not necessarily eliminate electrical or mechanical
energy.
5. A technician is preparing to work on a refrigeration system that contains
ammonia. The technician has isolated the electrical supply but has not
isolated the ammonia circuit. Why is electrical isolation alone inadequate?
A. Ammonia systems cannot be electrically isolated
B. Refrigerant pressure and trapped chemical energy may remain even when
electrical power is disconnected
C. Disconnecting electricity automatically increases ammonia pressure
D. Ammonia becomes flammable whenever electrical power is removed
Answer: B
Refrigeration systems can contain significant stored energy in the form of
pressurized refrigerant. Disconnecting electrical power prevents many
electrically driven components from operating, but it does not remove
, pressure or refrigerant from isolated sections of piping. A trapped liquid
refrigerant section can also develop extremely high pressure as temperature
rises.
6. An ammonia refrigeration system is operating with a normal condensing
pressure, but the suction pressure at a particular evaporator is substantially
lower than expected. The evaporator has a liquid feed valve upstream, and
the evaporator outlet superheat is considerably higher than normal. Which
condition is the MOST likely explanation?
A. Excessive liquid refrigerant entering the evaporator
B. Restricted refrigerant flow into the evaporator
C. Excessive condenser flooding
D. Excessively low discharge superheat
Answer: B
A restriction in the liquid feed path reduces the amount of refrigerant entering
the evaporator. With insufficient refrigerant available to boil, a larger portion
of the evaporator becomes starved, increasing outlet superheat and lowering
the evaporator suction pressure. Possible causes include a partially closed
hand valve, plugged strainer, malfunctioning control valve, excessive pressure
drop, or an obstructed liquid line.
7. What is the primary refrigerant used in most industrial refrigeration
systems?
A. R-22
B. Ammonia (NH₃)
