RETA CIRO INDUSTRIAL REFRIGERATION
LUBRICATION PRACTICE EXAM WITH
ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. In a reciprocating ammonia compressor, what is the primary
purpose of refrigeration compressor oil?
A. To increase the ammonia concentration in the evaporator
B. To lubricate moving components, reduce friction and wear, and assist
with sealing
C. To increase condenser pressure
D. To prevent liquid ammonia from entering the receiver
Answer: B. To lubricate moving components, reduce friction and
wear, and assist with sealing
Rationale: Compressor oil forms a lubricating film between moving
surfaces such as bearings, crankshaft components, piston assemblies,
and other mechanically loaded surfaces. In many reciprocating
compressors, oil also contributes to sealing between piston rings and
cylinder walls. Proper oil management therefore protects equipment
reliability while minimizing friction, heat generation, and mechanical
wear.
2. Why is selecting the correct oil viscosity particularly important
for a screw compressor operating at low evaporating temperatures?
1
,A. Viscosity has no relationship to compressor operation
B. Higher viscosity always increases compressor efficiency
C. Oil viscosity affects lubrication-film strength, internal leakage, oil
circulation, and bearing protection
D. Low-temperature operation automatically eliminates the need for oil
Answer: C. Oil viscosity affects lubrication-film strength, internal
leakage, oil circulation, and bearing protection
Rationale: Refrigeration compressor oil must maintain appropriate
viscosity under the temperatures and pressures encountered in the
compressor. If viscosity becomes too low, the lubricating film can
become inadequate and internal leakage may increase. If it becomes
excessively high, oil circulation and injection can be impaired. The
correct viscosity is therefore a balance between lubrication, heat
transfer, sealing, and circulation requirements.
3. An industrial refrigeration compressor suddenly develops
abnormally low oil pressure. Which condition should be investigated
FIRST?
A. Loss of oil supply, restricted oil passage, or inadequate oil level
B. Excessive condenser subcooling
C. Excessive evaporator surface area
D. High receiver liquid level alone
Answer: A. Loss of oil supply, restricted oil passage, or inadequate
oil level
Rationale: Low oil pressure can rapidly threaten bearings and other
lubricated components. The operator should investigate the oil level,
oil pump operation where applicable, suction or pickup restrictions, oil
filters, oil lines, and differential pressure across the lubrication system.
2
,Continuing to operate a compressor with inadequate lubrication can
result in severe mechanical damage.
4. What is the primary function of an oil separator installed in an
industrial refrigeration system?
A. To remove water from cooling-tower water
B. To separate lubricating oil from the refrigerant discharge gas and
facilitate oil return
C. To raise evaporator pressure
D. To eliminate all refrigerant vapor from the condenser
Answer: B. To separate lubricating oil from the refrigerant
discharge gas and facilitate oil return
Rationale: Refrigerant compressors can discharge oil along with
refrigerant vapor. An oil separator reduces the amount of oil carried
into downstream refrigeration components and provides a controlled
means of returning recovered oil to the compressor or oil-management
system. Effective separation helps maintain compressor oil inventory
and reduces excessive oil accumulation in condensers, receivers,
evaporators, and piping.
5. What is one major danger of allowing excessive oil to accumulate
in an ammonia evaporator?
A. It can reduce effective heat-transfer performance
B. It always increases evaporator capacity
C. It eliminates refrigerant pressure drop
D. It increases the ammonia boiling point to atmospheric pressure
Answer: A. It can reduce effective heat-transfer performance
3
, Rationale: Oil can accumulate on heat-transfer surfaces and interfere
with the transfer of heat between the refrigerated product or process
fluid and the refrigerant. Excessive oil accumulation can therefore
reduce evaporator performance, increase approach temperatures, and
contribute to poor system efficiency. Oil return and appropriate oil
draining are important parts of industrial refrigeration operation.
6. A screw compressor's oil injection system is primarily important
because the oil performs several functions. Which combination is
most accurate?
A. Only refrigerant purification
B. Only bearing lubrication
C. Lubrication, sealing, and heat removal
D. Increasing evaporator pressure and decreasing condenser temperature
Answer: C. Lubrication, sealing, and heat removal
Rationale: In many oil-injected screw compressors, oil has multiple
critical duties. It lubricates bearings and other moving components,
seals internal clearances between the rotors, and absorbs substantial
heat generated during compression. The oil must subsequently be
cooled adequately before being returned to the compressor.
7. Why should an operator avoid assuming that any petroleum-
based lubricant is suitable for an ammonia refrigeration
compressor?
A. Ammonia reacts identically with every lubricant
B. Refrigeration oils have specific requirements for chemical
compatibility, viscosity, stability, and operating temperature
C. Petroleum products cannot be stored in metal containers
D. Petroleum oil always freezes in ammonia systems
4
LUBRICATION PRACTICE EXAM WITH
ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. In a reciprocating ammonia compressor, what is the primary
purpose of refrigeration compressor oil?
A. To increase the ammonia concentration in the evaporator
B. To lubricate moving components, reduce friction and wear, and assist
with sealing
C. To increase condenser pressure
D. To prevent liquid ammonia from entering the receiver
Answer: B. To lubricate moving components, reduce friction and
wear, and assist with sealing
Rationale: Compressor oil forms a lubricating film between moving
surfaces such as bearings, crankshaft components, piston assemblies,
and other mechanically loaded surfaces. In many reciprocating
compressors, oil also contributes to sealing between piston rings and
cylinder walls. Proper oil management therefore protects equipment
reliability while minimizing friction, heat generation, and mechanical
wear.
2. Why is selecting the correct oil viscosity particularly important
for a screw compressor operating at low evaporating temperatures?
1
,A. Viscosity has no relationship to compressor operation
B. Higher viscosity always increases compressor efficiency
C. Oil viscosity affects lubrication-film strength, internal leakage, oil
circulation, and bearing protection
D. Low-temperature operation automatically eliminates the need for oil
Answer: C. Oil viscosity affects lubrication-film strength, internal
leakage, oil circulation, and bearing protection
Rationale: Refrigeration compressor oil must maintain appropriate
viscosity under the temperatures and pressures encountered in the
compressor. If viscosity becomes too low, the lubricating film can
become inadequate and internal leakage may increase. If it becomes
excessively high, oil circulation and injection can be impaired. The
correct viscosity is therefore a balance between lubrication, heat
transfer, sealing, and circulation requirements.
3. An industrial refrigeration compressor suddenly develops
abnormally low oil pressure. Which condition should be investigated
FIRST?
A. Loss of oil supply, restricted oil passage, or inadequate oil level
B. Excessive condenser subcooling
C. Excessive evaporator surface area
D. High receiver liquid level alone
Answer: A. Loss of oil supply, restricted oil passage, or inadequate
oil level
Rationale: Low oil pressure can rapidly threaten bearings and other
lubricated components. The operator should investigate the oil level,
oil pump operation where applicable, suction or pickup restrictions, oil
filters, oil lines, and differential pressure across the lubrication system.
2
,Continuing to operate a compressor with inadequate lubrication can
result in severe mechanical damage.
4. What is the primary function of an oil separator installed in an
industrial refrigeration system?
A. To remove water from cooling-tower water
B. To separate lubricating oil from the refrigerant discharge gas and
facilitate oil return
C. To raise evaporator pressure
D. To eliminate all refrigerant vapor from the condenser
Answer: B. To separate lubricating oil from the refrigerant
discharge gas and facilitate oil return
Rationale: Refrigerant compressors can discharge oil along with
refrigerant vapor. An oil separator reduces the amount of oil carried
into downstream refrigeration components and provides a controlled
means of returning recovered oil to the compressor or oil-management
system. Effective separation helps maintain compressor oil inventory
and reduces excessive oil accumulation in condensers, receivers,
evaporators, and piping.
5. What is one major danger of allowing excessive oil to accumulate
in an ammonia evaporator?
A. It can reduce effective heat-transfer performance
B. It always increases evaporator capacity
C. It eliminates refrigerant pressure drop
D. It increases the ammonia boiling point to atmospheric pressure
Answer: A. It can reduce effective heat-transfer performance
3
, Rationale: Oil can accumulate on heat-transfer surfaces and interfere
with the transfer of heat between the refrigerated product or process
fluid and the refrigerant. Excessive oil accumulation can therefore
reduce evaporator performance, increase approach temperatures, and
contribute to poor system efficiency. Oil return and appropriate oil
draining are important parts of industrial refrigeration operation.
6. A screw compressor's oil injection system is primarily important
because the oil performs several functions. Which combination is
most accurate?
A. Only refrigerant purification
B. Only bearing lubrication
C. Lubrication, sealing, and heat removal
D. Increasing evaporator pressure and decreasing condenser temperature
Answer: C. Lubrication, sealing, and heat removal
Rationale: In many oil-injected screw compressors, oil has multiple
critical duties. It lubricates bearings and other moving components,
seals internal clearances between the rotors, and absorbs substantial
heat generated during compression. The oil must subsequently be
cooled adequately before being returned to the compressor.
7. Why should an operator avoid assuming that any petroleum-
based lubricant is suitable for an ammonia refrigeration
compressor?
A. Ammonia reacts identically with every lubricant
B. Refrigeration oils have specific requirements for chemical
compatibility, viscosity, stability, and operating temperature
C. Petroleum products cannot be stored in metal containers
D. Petroleum oil always freezes in ammonia systems
4
