TRADE & TECHNICAL LICENSES HVAC EPA 608
Leak Detection & Recovery Mastery Practice
Exam | Complete Study Guide with Verified
Questions & Detailed Rationales | Updated 2026
| Leak Detection Methods, Vacuum & Recovery
Techniques, Recovery Machines, Environmental
Compliance, High-Yield Troubleshooting & Test-
Taking Strategies ❤️ | HVAC EPA 608 Mastery
Series – Part 3 of 6
Question 1: Which method is considered the most effective for locating small leaks
in a high-pressure refrigeration system?
A. Soap bubble solution
B. Ultrasonic detector
C. Electronic leak detector
D. Visual inspection
CORRECT ANSWER: C. Electronic leak detector
RATIONALE: Electronic leak detectors are highly sensitive and capable of identifying
very small leaks that other methods might miss in high-pressure systems.
Question 2: What color code is designated for refrigerant recovery cylinders?
A. Blue top with grey body
B. Yellow top with grey body
C. Grey body with yellow top
D. White body with green top
CORRECT ANSWER: C. Grey body with yellow top
RATIONALE: EPA regulations specify that recovery cylinders must be grey with a yellow
top to distinguish them from disposable cylinders.
Question 3: When performing a leak check on a low-pressure chiller, what is the
maximum pressure that should be used to avoid rupturing the rupture disk?
A. 5 psig
B. 10 psig
C. 15 psig
D. 25 psig
CORRECT ANSWER: B. 10 psig
RATIONALE: Low-pressure chillers have rupture disks set to open at 15 psig; therefore,
leak testing should not exceed 10 psig to prevent accidental activation.
Question 4: Which gas should exclusively be used for pressurizing a system for leak
detection?
,A. Oxygen
B. Compressed air
C. Nitrogen
D. Hydrogen
CORRECT ANSWER: C. Nitrogen
RATIONALE: Dry nitrogen is inert and does not react with system components or oil,
making it the safe standard for pressure testing.
Question 5: What is the primary purpose of a recovery machine?
A. To recharge the system with new refrigerant
B. To remove refrigerant from a system for storage
C. To clean the internal components of the compressor
D. To increase the pressure of the refrigerant
CORRECT ANSWER: B. To remove refrigerant from a system for storage
RATIONALE: Recovery machines are designed specifically to extract refrigerant from
appliances and store it in external cylinders.
Question 6: Under EPA regulations, venting of HFC refrigerants is:
A. Permitted during maintenance
B. Permitted if the amount is small
C. Prohibited
D. Permitted only in emergencies
CORRECT ANSWER: C. Prohibited
RATIONALE: Venting of ozone-depleting substances and their substitutes (including
HFCs) is prohibited under Section 608 regulations.
Question 7: Which leak detection method relies on hearing the sound of gas
escaping?
A. Fluorescent dye
B. Ultrasonic detector
C. Electronic sensor
D. Soap bubbles
CORRECT ANSWER: B. Ultrasonic detector
RATIONALE: Ultrasonic detectors identify the high-frequency sound waves generated
by turbulent gas flow at a leak site.
Question 8: What must be done to a recovery cylinder before each use?
A. Paint it grey
B. Weigh it to ensure it is not overfilled
,C. Heat it to expand the metal
D. Fill it with nitrogen
CORRECT ANSWER: B. Weigh it to ensure it is not overfilled
RATIONALE: Cylinders must be weighed to ensure they do not exceed the safe fill limit,
typically 80% of capacity by weight.
Question 9: When recovering refrigerant from a system with an operating
compressor, which method is fastest?
A. Vapor recovery
B. Liquid recovery
C. Push-pull method
D. Passive recovery
CORRECT ANSWER: B. Liquid recovery
RATIONALE: Removing refrigerant in the liquid phase is significantly faster than
removing it in the vapor phase.
Question 10: What is the required vacuum level for recovering refrigerant from a
high-pressure appliance manufactured after November 15, 1993?
A. 0 inches Hg
B. 4 inches Hg
C. 10 inches Hg
D. 15 inches Hg
CORRECT ANSWER: B. 4 inches Hg
RATIONALE: EPA regulations require high-pressure appliances to be evacuated to 4
inches of Hg vacuum during recovery.
Question 11: Which component in a recovery machine prevents refrigerant from
flowing back into the system?
A. Filter drier
B. Check valve
C. Pressure relief valve
D. Sight glass
CORRECT ANSWER: B. Check valve
RATIONALE: Check valves ensure unidirectional flow, preventing recovered refrigerant
from returning to the appliance.
Question 12: What is the leak repair threshold for commercial refrigeration
systems containing more than 50 pounds of refrigerant?
A. 10%
B. 20%
, C. 30%
D. 40%
CORRECT ANSWER: B. 20%
RATIONALE: Commercial refrigeration systems must be repaired if the leak rate
exceeds 20% of the charge per year.
Question 13: Why is it important to change the oil in a recovery machine after
recovering a burnout?
A. To improve the color of the oil
B. To remove acid and contaminants
C. To increase the machine's weight
D. To reduce noise levels
CORRECT ANSWER: B. To remove acid and contaminants
RATIONALE: Burnouts produce acid and debris that contaminate the oil, potentially
damaging the recovery machine if not changed.
Question 14: Which safety equipment is mandatory when connecting a recovery
machine?
A. Hearing protection
B. Safety glasses and gloves
C. Steel-toed boots
D. Face shield only
CORRECT ANSWER: B. Safety glasses and gloves
RATIONALE: PPE including eye protection and gloves is required to protect against
frostbite and flying debris during connection.
Question 15: What happens if a recovery cylinder is overfilled?
A. The refrigerant becomes unstable
B. The pressure may rise dangerously due to hydrostatic pressure
C. The cylinder changes color
D. The recovery machine stops automatically
CORRECT ANSWER: B. The pressure may rise dangerously due to hydrostatic
pressure
RATIONALE: Liquid expands with heat; an overfilled cylinder has no vapor space,
leading to potentially explosive pressure increases.
Question 16: Which method is best for detecting leaks in a system that cannot be
pressurized?
A. Soap bubbles
B. Electronic leak detector
Leak Detection & Recovery Mastery Practice
Exam | Complete Study Guide with Verified
Questions & Detailed Rationales | Updated 2026
| Leak Detection Methods, Vacuum & Recovery
Techniques, Recovery Machines, Environmental
Compliance, High-Yield Troubleshooting & Test-
Taking Strategies ❤️ | HVAC EPA 608 Mastery
Series – Part 3 of 6
Question 1: Which method is considered the most effective for locating small leaks
in a high-pressure refrigeration system?
A. Soap bubble solution
B. Ultrasonic detector
C. Electronic leak detector
D. Visual inspection
CORRECT ANSWER: C. Electronic leak detector
RATIONALE: Electronic leak detectors are highly sensitive and capable of identifying
very small leaks that other methods might miss in high-pressure systems.
Question 2: What color code is designated for refrigerant recovery cylinders?
A. Blue top with grey body
B. Yellow top with grey body
C. Grey body with yellow top
D. White body with green top
CORRECT ANSWER: C. Grey body with yellow top
RATIONALE: EPA regulations specify that recovery cylinders must be grey with a yellow
top to distinguish them from disposable cylinders.
Question 3: When performing a leak check on a low-pressure chiller, what is the
maximum pressure that should be used to avoid rupturing the rupture disk?
A. 5 psig
B. 10 psig
C. 15 psig
D. 25 psig
CORRECT ANSWER: B. 10 psig
RATIONALE: Low-pressure chillers have rupture disks set to open at 15 psig; therefore,
leak testing should not exceed 10 psig to prevent accidental activation.
Question 4: Which gas should exclusively be used for pressurizing a system for leak
detection?
,A. Oxygen
B. Compressed air
C. Nitrogen
D. Hydrogen
CORRECT ANSWER: C. Nitrogen
RATIONALE: Dry nitrogen is inert and does not react with system components or oil,
making it the safe standard for pressure testing.
Question 5: What is the primary purpose of a recovery machine?
A. To recharge the system with new refrigerant
B. To remove refrigerant from a system for storage
C. To clean the internal components of the compressor
D. To increase the pressure of the refrigerant
CORRECT ANSWER: B. To remove refrigerant from a system for storage
RATIONALE: Recovery machines are designed specifically to extract refrigerant from
appliances and store it in external cylinders.
Question 6: Under EPA regulations, venting of HFC refrigerants is:
A. Permitted during maintenance
B. Permitted if the amount is small
C. Prohibited
D. Permitted only in emergencies
CORRECT ANSWER: C. Prohibited
RATIONALE: Venting of ozone-depleting substances and their substitutes (including
HFCs) is prohibited under Section 608 regulations.
Question 7: Which leak detection method relies on hearing the sound of gas
escaping?
A. Fluorescent dye
B. Ultrasonic detector
C. Electronic sensor
D. Soap bubbles
CORRECT ANSWER: B. Ultrasonic detector
RATIONALE: Ultrasonic detectors identify the high-frequency sound waves generated
by turbulent gas flow at a leak site.
Question 8: What must be done to a recovery cylinder before each use?
A. Paint it grey
B. Weigh it to ensure it is not overfilled
,C. Heat it to expand the metal
D. Fill it with nitrogen
CORRECT ANSWER: B. Weigh it to ensure it is not overfilled
RATIONALE: Cylinders must be weighed to ensure they do not exceed the safe fill limit,
typically 80% of capacity by weight.
Question 9: When recovering refrigerant from a system with an operating
compressor, which method is fastest?
A. Vapor recovery
B. Liquid recovery
C. Push-pull method
D. Passive recovery
CORRECT ANSWER: B. Liquid recovery
RATIONALE: Removing refrigerant in the liquid phase is significantly faster than
removing it in the vapor phase.
Question 10: What is the required vacuum level for recovering refrigerant from a
high-pressure appliance manufactured after November 15, 1993?
A. 0 inches Hg
B. 4 inches Hg
C. 10 inches Hg
D. 15 inches Hg
CORRECT ANSWER: B. 4 inches Hg
RATIONALE: EPA regulations require high-pressure appliances to be evacuated to 4
inches of Hg vacuum during recovery.
Question 11: Which component in a recovery machine prevents refrigerant from
flowing back into the system?
A. Filter drier
B. Check valve
C. Pressure relief valve
D. Sight glass
CORRECT ANSWER: B. Check valve
RATIONALE: Check valves ensure unidirectional flow, preventing recovered refrigerant
from returning to the appliance.
Question 12: What is the leak repair threshold for commercial refrigeration
systems containing more than 50 pounds of refrigerant?
A. 10%
B. 20%
, C. 30%
D. 40%
CORRECT ANSWER: B. 20%
RATIONALE: Commercial refrigeration systems must be repaired if the leak rate
exceeds 20% of the charge per year.
Question 13: Why is it important to change the oil in a recovery machine after
recovering a burnout?
A. To improve the color of the oil
B. To remove acid and contaminants
C. To increase the machine's weight
D. To reduce noise levels
CORRECT ANSWER: B. To remove acid and contaminants
RATIONALE: Burnouts produce acid and debris that contaminate the oil, potentially
damaging the recovery machine if not changed.
Question 14: Which safety equipment is mandatory when connecting a recovery
machine?
A. Hearing protection
B. Safety glasses and gloves
C. Steel-toed boots
D. Face shield only
CORRECT ANSWER: B. Safety glasses and gloves
RATIONALE: PPE including eye protection and gloves is required to protect against
frostbite and flying debris during connection.
Question 15: What happens if a recovery cylinder is overfilled?
A. The refrigerant becomes unstable
B. The pressure may rise dangerously due to hydrostatic pressure
C. The cylinder changes color
D. The recovery machine stops automatically
CORRECT ANSWER: B. The pressure may rise dangerously due to hydrostatic
pressure
RATIONALE: Liquid expands with heat; an overfilled cylinder has no vapor space,
leading to potentially explosive pressure increases.
Question 16: Which method is best for detecting leaks in a system that cannot be
pressurized?
A. Soap bubbles
B. Electronic leak detector
