HVAC: EPA 608 CERTIFICATION STUDY GUIDE
2026/2027 EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS
(VERIFIED ANSWERS)|ALREADY GRADED A+
What is difference between self-contained recovery tank and system-dependent
recovery tank? - CORRECT ANSWER ✔✔- A self-contained recovery tank uses its
own power to recover refrigerant from systems and is capable of reaching
required recovery rates with or without compressor operating. Stores in
pressurized tank.
A system-dependent recovery tank captures refrigerant into a non-pressurized
container. Uses system's compressor, an external heat source, or vacuum pump
to recover refrigerant.
What are two things that can cause high discharge pressures? - CORRECT
ANSWER ✔✔- Not opening tank inlet valve or having excess air will cause higher
discharge pressures
How can you check if a tank contains excess air or non-condensables? - CORRECT
ANSWER ✔✔- Check pressure inside recovery tank after allowing temp of cylinder
to stabilize to room temperature
What type of system can a vacuum pump be used on for recovery? - CORRECT
ANSWER ✔✔- A vacuum pump can only be used on a recovery device in
combination with a non-pressurized container and can not be used with self-
contained recovery equipment (pressurized container)
,When using a system-dependent recovery system with an operating compressor,
where should the refrigerant be recovered from? With a non-operating
compressor? - CORRECT ANSWER ✔✔- When using a system-dependent recovery
process with an operating compressor, run the compressor and recover from the
high side of the system.
When using a non-operating compressor, it may be necessary to access both low
and high side of system to achieve required recovery level and it will speed the
recovery
How can you release trapped refrigerants in the oil? - CORRECT ANSWER ✔✔-
Necessary to heat and tap compressor with mallet several times or use vacuum
pump
How will activating a defrost timer aid in recovery process? - CORRECT ANSWER
✔✔- Help vaporize any trapped liquid refrigerant
When should piercing type valves be used? What is a common problem with
these valves? - CORRECT ANSWER ✔✔- Copper or aluminum tubing only. Tend to
leak over time
What are some other small refrigeration systems that contain other types of
refrigerants? Should these refrigerants be recovered with standard EPA
equipment? - CORRECT ANSWER ✔✔- Ammonia, hydrogen or water and
therefore, should not be recovered using current EPA-approved recovery devices.
Similarly, systems built before 1950 may have methyl formate, methyl chloride, or
sulfur dioxide as refrigerants and require special recovery equipment
, What should be done before charging a new system with refrigerant? - CORRECT
ANSWER ✔✔- The unit should first be pressurized with NITROGEN (inert gas) and
leak checked
What are the leak repair requirements for comfort cooling appliances and
commercial appliances containing 50 pounds or more of refrigerant? - CORRECT
ANSWER ✔✔- The leak rate exceeds 15% in comfort cooling appliances
The leak rate exceeds 35% in all commercial and industrial process refrigeration
Using large vacuum pumps can lead to freezing of water in the system. What are
two ways the technician can help prevent freezing? - CORRECT ANSWER ✔✔-
Increase pressure by introducing nitrogen to counteract freezing. Liquid charging
of an R-12 refrigeration system should begin with vapor from a vacuum level to a
pressure of approximately 33 psig followed by a liquid charge through the liquid-
line service valve.
Foaming at start-up may be found in what component? What does this mean? -
CORRECT ANSWER ✔✔- Refrigerant in the oil will cause oil foaming in the
compressor at start-up
When evacuating a vapor compression system how many microns does the
vacuum need to achieve? - CORRECT ANSWER ✔✔- 500 microns (or 29.90" Hg)
Why should you never start a hermetic compressor when under deep vacuum? -
CORRECT ANSWER ✔✔- The motor winding could be damaged if energized
2026/2027 EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS
(VERIFIED ANSWERS)|ALREADY GRADED A+
What is difference between self-contained recovery tank and system-dependent
recovery tank? - CORRECT ANSWER ✔✔- A self-contained recovery tank uses its
own power to recover refrigerant from systems and is capable of reaching
required recovery rates with or without compressor operating. Stores in
pressurized tank.
A system-dependent recovery tank captures refrigerant into a non-pressurized
container. Uses system's compressor, an external heat source, or vacuum pump
to recover refrigerant.
What are two things that can cause high discharge pressures? - CORRECT
ANSWER ✔✔- Not opening tank inlet valve or having excess air will cause higher
discharge pressures
How can you check if a tank contains excess air or non-condensables? - CORRECT
ANSWER ✔✔- Check pressure inside recovery tank after allowing temp of cylinder
to stabilize to room temperature
What type of system can a vacuum pump be used on for recovery? - CORRECT
ANSWER ✔✔- A vacuum pump can only be used on a recovery device in
combination with a non-pressurized container and can not be used with self-
contained recovery equipment (pressurized container)
,When using a system-dependent recovery system with an operating compressor,
where should the refrigerant be recovered from? With a non-operating
compressor? - CORRECT ANSWER ✔✔- When using a system-dependent recovery
process with an operating compressor, run the compressor and recover from the
high side of the system.
When using a non-operating compressor, it may be necessary to access both low
and high side of system to achieve required recovery level and it will speed the
recovery
How can you release trapped refrigerants in the oil? - CORRECT ANSWER ✔✔-
Necessary to heat and tap compressor with mallet several times or use vacuum
pump
How will activating a defrost timer aid in recovery process? - CORRECT ANSWER
✔✔- Help vaporize any trapped liquid refrigerant
When should piercing type valves be used? What is a common problem with
these valves? - CORRECT ANSWER ✔✔- Copper or aluminum tubing only. Tend to
leak over time
What are some other small refrigeration systems that contain other types of
refrigerants? Should these refrigerants be recovered with standard EPA
equipment? - CORRECT ANSWER ✔✔- Ammonia, hydrogen or water and
therefore, should not be recovered using current EPA-approved recovery devices.
Similarly, systems built before 1950 may have methyl formate, methyl chloride, or
sulfur dioxide as refrigerants and require special recovery equipment
, What should be done before charging a new system with refrigerant? - CORRECT
ANSWER ✔✔- The unit should first be pressurized with NITROGEN (inert gas) and
leak checked
What are the leak repair requirements for comfort cooling appliances and
commercial appliances containing 50 pounds or more of refrigerant? - CORRECT
ANSWER ✔✔- The leak rate exceeds 15% in comfort cooling appliances
The leak rate exceeds 35% in all commercial and industrial process refrigeration
Using large vacuum pumps can lead to freezing of water in the system. What are
two ways the technician can help prevent freezing? - CORRECT ANSWER ✔✔-
Increase pressure by introducing nitrogen to counteract freezing. Liquid charging
of an R-12 refrigeration system should begin with vapor from a vacuum level to a
pressure of approximately 33 psig followed by a liquid charge through the liquid-
line service valve.
Foaming at start-up may be found in what component? What does this mean? -
CORRECT ANSWER ✔✔- Refrigerant in the oil will cause oil foaming in the
compressor at start-up
When evacuating a vapor compression system how many microns does the
vacuum need to achieve? - CORRECT ANSWER ✔✔- 500 microns (or 29.90" Hg)
Why should you never start a hermetic compressor when under deep vacuum? -
CORRECT ANSWER ✔✔- The motor winding could be damaged if energized
