EPA 608 study sheet

Every practice question with its correct answer and the reason, grouped by section. Print it, read it on the job, then test yourself on the practice test.

Written from EPA's Section 608 regulations (40 CFR Part 82, Subpart F) and the AIM Act leak rules (40 CFR Part 84) where noted. These are not the official exam questions.

Core (27 questions)

Ozone, regulations, the 3 Rs, recovery, cylinders, safety and shipping. Required for every certification.

Which element in CFC and HCFC refrigerants destroys stratospheric ozone?
Chlorine
Chlorine released from CFCs and HCFCs in the stratosphere breaks ozone molecules apart. One chlorine atom can destroy thousands of ozone molecules.
Which refrigerant group has the highest ozone depletion potential?
CFCs (like R-12)
CFCs contain the most chlorine and are the most stable, so they reach the stratosphere intact. HCFCs deplete ozone less; HFCs and HFOs contain no chlorine.
HFC refrigerants such as R-410A and R-134a:
Don't deplete ozone but are greenhouse gases
HFCs contain no chlorine, so their ozone depletion potential is zero, but many have high global warming potential (GWP). That's why the AIM Act phases them down.
Where is the ozone layer that shields the earth from ultraviolet radiation?
Stratosphere
Protective ozone is in the stratosphere, roughly 6 to 30 miles up. Ground-level (tropospheric) ozone is a pollutant.
Which international agreement set the phaseout of ozone-depleting substances?
Montreal Protocol
The 1987 Montreal Protocol set the schedule for phasing out CFCs and HCFCs. The Clean Air Act Section 608 carries it out in the US for stationary equipment.
Under Section 608, intentionally venting refrigerant while servicing equipment is:
Prohibited, except for de minimis releases during good-faith recovery
The venting prohibition covers CFC, HCFC, HFC and substitute refrigerants. Only small de minimis releases that happen while properly recovering or connecting/disconnecting hoses are not violations.
Which of these is a de minimis release?
Refrigerant released when disconnecting hoses after proper recovery
De minimis means the small, unavoidable release that happens while doing the job correctly, such as at hose connections. Anything deliberate is illegal venting.
Which gas may be released to the atmosphere?
Nitrogen used as a holding charge or leak test gas
Pure nitrogen can be vented. Refrigerant left in a system, or refrigerant mixed with air or nitrogen, must be recovered.
Removing refrigerant from a system and storing it in an external container without necessarily testing or processing it is:
Recovery
Recovery is just removing and storing. Recycling cleans it on site (oil separation, filter-driers). Reclaiming processes it to new-product purity (AHRI 700) and requires lab analysis.
Reclaimed refrigerant must meet which purity standard before it can be sold?
AHRI 700
Reclaimed refrigerant is processed by an EPA-certified reclaimer and tested to the AHRI 700 purity standard before resale.
Recovered refrigerant may be put back into:
The same system, or another system owned by the same owner
Recovered or recycled refrigerant can go back into equipment owned by the same owner. To sell it to a different owner, it must be reclaimed first.
Before you can buy refrigerant for stationary equipment you must:
Hold EPA Section 608 certification (or Section 609 for MVAC refrigerant)
Sales of refrigerant are restricted to certified technicians. Section 608 covers stationary equipment; Section 609 covers motor vehicle AC.
Recovery equipment used on the job must be:
Certified by an EPA-approved testing organization
Recovery and recycling equipment must be certified (tested by an EPA-approved lab such as AHRI or UL) to meet EPA's evacuation standards.
Why does a system pulled into a deep vacuum get dehydrated?
Lower pressure lowers water's boiling point, so moisture boils off and is removed
In a deep vacuum, water boils at room temperature or below, turns to vapor, and the pump removes it. A micron gauge proves it's dry.
Where should the micron gauge be connected to measure the vacuum accurately?
At the system, as far from the pump as practical
A gauge at the pump reads the pump, not the system. Connect it at the system, often on a core removal tool.
A disposable (single-use) refrigerant cylinder must never be:
Refilled
Disposable cylinders are for one-time use. Refilling them is illegal and dangerous. Empty them, render them useless and recycle the metal.
Recovery cylinders are commonly identified by:
A gray body and yellow top
Recovery cylinders are gray with yellow shoulders. They must be DOT-approved and are refillable.
A recovery cylinder should be filled to no more than:
80% of its capacity (by liquid volume)
Leave room for liquid to expand with temperature. A full cylinder can rupture hydrostatically. Weigh it or use the float switch.
Breathing refrigerant vapor in an enclosed space is dangerous mainly because:
It displaces oxygen and can cause suffocation and heart irregularities
Refrigerant vapor is heavier than air and pushes oxygen out of low, closed spaces. High concentrations can also cause cardiac arrhythmia. Ventilate and use detectors.
When refrigerant contacts an open flame or very hot surface, it can form:
Toxic gases such as phosgene and acids
Heated CFCs and HCFCs can decompose into toxic phosgene and hydrochloric/hydrofluoric acids. Never braze on a pressurized or refrigerant-filled system.
What should you use to pressurize a system for a leak test?
Dry nitrogen with a pressure regulator and relief valve
Oxygen or air with oil can explode. Use dry nitrogen through a regulator, never above the system's test pressure.
Refrigerant safety class A2L means:
Lower toxicity, lower flammability (mildly flammable)
In ASHRAE 34, A = lower toxicity; 2L = lower flammability with a low burning velocity. R-32 and R-454B are A2L.
Compared with A2L refrigerants, A3 refrigerants such as R-290 (propane) are:
Highly flammable
A3 means lower toxicity and higher flammability. These need strict charge limits, ignition-source control and proper tools.
Before shipping a used refrigerant cylinder, it must be labeled with:
The refrigerant type and amount, and meet DOT requirements
Cylinders shipped for reclaim must be DOT-approved and labeled with refrigerant type and quantity, plus required DOT hazard labels.
Since January 1, 2026, the AIM Act leak repair rules apply to appliances holding at least how much HFC (or substitute with GWP above 53) refrigerant?
15 lb
The ozone-depleting refrigerant rule under Section 608 applies at 50 lb or more. The AIM Act rule (40 CFR Part 84) brings appliances with 15 lb or more of HFCs under leak repair starting in 2026.
Leak rate thresholds that trigger repair are:
10% comfort cooling, 20% commercial refrigeration, 30% industrial process refrigeration
These are annual leak rates as a percent of full charge. Exceed the threshold and the leak generally must be repaired within 30 days.
Section 608 technician certification:
Does not expire
Section 608 certification is good for life. Keep your card or a copy; employers and wholesalers will ask for it.

Type I (25 questions)

Small appliances made, charged and hermetically sealed at the factory with 5 lb or less of refrigerant.

A Type I "small appliance" is one that is manufactured, charged and hermetically sealed at the factory with:
5 lb or less of refrigerant
Examples: household refrigerators and freezers, window AC units, dehumidifiers, water coolers and vending machines with 5 lb or less.
With recovery equipment made after November 15, 1993, and the small appliance's compressor working, you must recover:
90% of the refrigerant, or pull a 4 in. Hg vacuum
Compressor working: 90% (or 4 in. Hg vacuum). Compressor not working: 80% (or 4 in. Hg vacuum).
With recovery equipment made after November 15, 1993, and the compressor NOT working, you must recover:
80% of the refrigerant, or pull a 4 in. Hg vacuum
With a dead compressor, refrigerant is trapped in the oil and system. Help it out by heating, tapping the compressor, or using a vacuum and both access points.
Self-contained (active) recovery equipment:
Has its own compressor to pull refrigerant out
Self-contained equipment stores refrigerant in a pressurized recovery tank. System-dependent (passive) equipment relies on the appliance's compressor or pressure.
System-dependent (passive) recovery equipment captures refrigerant into:
A non-pressurized container or bag
Passive recovery uses the appliance's own pressure or compressor to push refrigerant into a non-pressurized container. EPA limits it to appliances with a full charge of 15 lb or less, unless it's a pump-out unit permanently attached to the appliance (40 CFR 82.156(e)).
When using system-dependent recovery on a unit with an inoperative compressor, you should:
Access both the high and low sides
Installing access on both sides improves recovery speed and percentage when the compressor can't help.
Piercing access valves (line taps) on a small appliance:
Should be leak-checked and are best removed after service
Piercing valves tend to leak over time. Leak test them and remove or replace them with proper fittings when the job is done.
If a small appliance's refrigerant may have been contaminated by a compressor burnout, you should check for:
A strong odor and acid in the oil
Burnouts produce acids. Use protective gear, recover the refrigerant, and clean the system before recharging.
Before recovering from a small appliance, why should you know what refrigerant is inside?
To avoid mixing refrigerants in the recovery cylinder
Mixed refrigerants can't be reclaimed easily and may be refused or charged a disposal fee. Read the nameplate and use a dedicated cylinder.
Some older appliances may contain sulfur dioxide, methyl formate or ammonia. If you suspect these, you should:
Not use standard recovery equipment and follow safety procedures
These refrigerants are toxic and corrosive. They are not recovered with standard equipment; follow safety procedures and local rules.
Before a small appliance is disposed of, the person taking the final step in the disposal chain must:
Make sure refrigerant was recovered and keep a signed statement or record
Scrap recyclers and landfills must verify that refrigerant was recovered before the appliance is disposed of, often with a signed statement.
Which of these helps recover refrigerant from a small appliance with a failed compressor?
Heating the compressor and tapping it while recovering
Warming the compressor and tapping it helps release refrigerant dissolved in the oil.
Using recovery equipment made BEFORE November 15, 1993, how much refrigerant must you recover from a small appliance?
80%, or evacuate to 4 in. Hg vacuum
Older recovery equipment must recover 80% whether or not the compressor works. Newer equipment: 90% with a working compressor, 80% without. Any of these can instead be met by pulling the appliance to 4 in. Hg vacuum (40 CFR 82.156(b)).
Instead of measuring the percentage recovered, a technician can meet the small appliance recovery requirement by:
Evacuating the appliance to 4 in. Hg vacuum
40 CFR 82.156(b) lets you satisfy the requirement by evacuating the small appliance to four inches of mercury vacuum.
System-dependent (passive) recovery equipment may not be used on appliances with a full charge of more than:
15 lb, unless it is permanently attached as a pump-out unit
40 CFR 82.156(e) limits system-dependent equipment to appliances with 15 lb or less, except a pump-out unit permanently attached to the appliance. Small appliances (5 lb or less) are within the limit.
When must refrigerant be recovered from a small appliance?
Before opening it for service, and before disposing of it
40 CFR 82.156(b) requires recovery before opening a small appliance or when disposing of it, using certified recovery equipment.
Recovery equipment used on small appliances must be:
Certified under EPA's equipment certification rules (40 CFR 82.158)
Small appliance recovery must use a recovery or recycling machine certified under 82.158. A vacuum pump alone is not recovery equipment.
Under EPA's safe disposal rules, who is the "final processor" of a small appliance?
The person who takes the final step in the disposal process, such as a scrap recycler or landfill
40 CFR 82.155 puts the responsibility on whoever takes the final disposal step. They must recover remaining refrigerant or verify it was recovered.
A signed statement given to a final processor to show refrigerant was recovered must include:
The name and address of the person who recovered it and the date it was recovered
40 CFR 82.155 requires the recoverer's name and address and the recovery date.
How long must a final processor keep the signed statements or contracts that show refrigerant was recovered?
3 years
40 CFR 82.155 requires copies to be kept on site, in hard copy or electronically, for three years.
If all the refrigerant in a small appliance leaked out before it reached the scrap yard, the final processor must get:
A signed statement that all refrigerant leaked out before delivery
40 CFR 82.155 allows a signed statement that all refrigerant had leaked out before delivery and recovery isn't possible.
A scrap recycler accepts a signed statement it knows is probably false. Under EPA rules this is:
A violation
40 CFR 82.155 makes it a violation to accept a statement or contract the final processor knows or has reason to believe is false.
Final processors must tell their suppliers that:
Refrigerant must be recovered before the appliance is delivered
40 CFR 82.155 requires final processors to notify suppliers that refrigerant must be recovered before delivery.
Which of these is a Type I small appliance?
A window AC unit factory-sealed with 2 lb of refrigerant
Small appliances are manufactured, charged and hermetically sealed at the factory with 5 lb or less. A field-charged split system with 8 lb is a Type II appliance.
A technician with only Type I certification may service:
Factory-sealed appliances holding 5 lb or less
Type I covers small appliances only. Residential split systems need Type II; low-pressure chillers need Type III. Universal covers all three.

Type II (25 questions)

High-pressure and very high-pressure appliances: residential and commercial AC, heat pumps and most refrigeration.

Using recovery equipment made after November 15, 1993, an R-22 appliance with less than 200 lb of charge must be evacuated to:
0 in. Hg
R-22 (HCFC-22) appliances: under 200 lb to 0 in. Hg, 200 lb or more to 10 in. Hg.
Using recovery equipment made after November 15, 1993, an R-22 appliance with 200 lb or more of charge must be evacuated to:
10 in. Hg
R-22 at 200 lb or more: 10 in. Hg. Other high-pressure refrigerants: under 200 lb to 10 in. Hg, 200 lb or more to 15 in. Hg.
A very high-pressure appliance (like one using R-13 or R-503) must be evacuated to:
0 in. Hg
Very high-pressure appliances are evacuated to 0 in. Hg regardless of charge size.
You may skip the required evacuation level if:
Leaks make reaching it impossible or would contaminate the refrigerant, and you isolate leaking parts where possible
When leaks make the level unreachable, isolate leaking components, evacuate the rest to the required level, and evacuate the leaking part to the lowest level practical.
When an appliance's leak rate exceeds the threshold, repairs must generally be made within:
30 days
Owners generally have 30 days to repair once the annualized leak rate exceeds the threshold, followed by verification tests.
The leak rate threshold for comfort cooling appliances is:
10% per year
Comfort cooling 10%, commercial refrigeration 20%, industrial process refrigeration 30% (annual rate, percent of full charge).
A common first sign of a leak in a high-pressure system is:
Oil residue at a joint or fitting
Refrigerant carries oil. An oily spot at a flare, braze joint or Schrader valve is a classic leak indicator. Confirm with a detector or bubbles.
To leak test a system that has no refrigerant in it, pressurize it with:
Dry nitrogen
Nitrogen is the standard. Never use oxygen or air. Check the system's maximum test pressure on the nameplate.
Recovering refrigerant in the liquid phase first:
Speeds up recovery
Moving liquid first (often by push-pull) recovers most of the charge quickly. Then recover the remaining vapor.
The push-pull method should NOT be used when:
The system has less than about 15 lb of refrigerant, or a liquid column can't be maintained
Push-pull moves liquid with vapor pressure. It needs enough liquid to form a continuous column, so it's not effective on small charges or heat pumps with reversing valves in some setups.
Chilling the recovery cylinder during recovery:
Lowers its pressure and speeds up recovery
A colder cylinder has lower saturation pressure, so refrigerant moves into it faster.
After recovery, if the system pressure rises again, it usually means:
Refrigerant is still boiling out of the oil or trapped liquid
Wait a few minutes after reaching the required level. A rise means refrigerant is still coming out; recover again.
Before recovery, the system's refrigerant should be identified because:
Mixed refrigerants can't be reclaimed and contaminate the cylinder
Use a dedicated recovery cylinder per refrigerant. Mixed refrigerant is expensive to dispose of.
A receiver in a high-pressure system stores:
Liquid refrigerant
The receiver holds liquid refrigerant leaving the condenser. During recovery or pump-down, refrigerant can be stored there.
When servicing, the best place to recover liquid refrigerant in many systems is from:
The liquid line or receiver outlet
Liquid is at the liquid line and receiver. Vapor recovery happens on the suction and discharge sides.
When charging a system that's in a vacuum, start with:
Vapor, to raise the pressure above freezing before charging liquid
Charging liquid into a deep vacuum can freeze moisture and tubes in the evaporator. Break the vacuum with vapor first, then charge liquid into the liquid line.
Zeotropic blends such as R-407C (and blends with glide like R-454B) should be charged:
As liquid, to keep the blend's composition correct
Blends can fractionate. Charge liquid from the cylinder, metered through a restriction into the suction side if needed.
Before opening a system that contains A2L refrigerant, you should:
Recover the refrigerant, purge with nitrogen, and keep ignition sources away
A2Ls are mildly flammable. Follow manufacturer procedures: recover, evacuate, purge with nitrogen, use A2L-rated tools and control ignition sources.
Recovery equipment's own oil and refrigerant must be:
Cleared before switching to a different refrigerant
Purge the recovery unit and use a separate cylinder when changing refrigerants to prevent cross-contamination.
Before disposing of a high-pressure appliance, the refrigerant must be:
Recovered to the required evacuation level
Disposal still requires recovery to the applicable evacuation level, plus recordkeeping where required.
Which leak detection method finds the general area of a leak fastest on a large system?
An electronic leak detector
Electronic detectors scan quickly for the general area. Pinpoint with bubbles. Pressure or vacuum tests confirm a leak exists but don't locate it.
Which type of system uses a reversing valve?
Heat pump
The reversing (4-way) valve switches the direction of refrigerant flow so a heat pump can heat or cool.
Recovering from a system with a working compressor, you can recover from the high side first because:
The compressor pushes refrigerant toward the condenser and receiver
With the compressor running, much of the charge collects on the high side. With a dead compressor, recover from both sides.
Using recovery equipment made after November 15, 1993, a medium-pressure appliance (like an R-134a chiller) with 200 lb or more of charge must be evacuated to:
15 in. Hg vacuum
EPA's evacuation table: medium-pressure with less than 200 lb, 10 in. Hg; medium-pressure with 200 lb or more, 15 in. Hg (with post-1993 equipment).
System-dependent recovery equipment can't be used on an appliance with a full charge of more than:
15 lb, unless permanently attached as a pump-out unit
40 CFR 82.156(e). Most Type II jobs above 15 lb need self-contained recovery equipment.

Type III (25 questions)

Low-pressure appliances, mainly centrifugal chillers using refrigerants like R-123 and R-1233zd.

Low-pressure appliances (like R-123 or R-1233zd centrifugal chillers) operate:
Below atmospheric pressure on the low side
Low-pressure chillers run in a vacuum on the evaporator side, so leaks let air and moisture in rather than refrigerant out.
Because a low-pressure chiller's low side is in a vacuum, the most common leak symptom is:
Air and moisture entering the system (non-condensables)
Leaks pull air in. A purge unit removes non-condensables; frequent purge running signals a leak.
The purge unit on a low-pressure chiller removes:
Air and moisture (non-condensables)
High-efficiency purge units remove non-condensables while releasing very little refrigerant. Track purge run time; rising run time means a leak.
Using recovery equipment made after November 15, 1993, a low-pressure appliance must be evacuated to:
25 mm Hg absolute (about 29 in. Hg vacuum)
Low-pressure systems are evacuated to 25 mm Hg absolute. That's a much deeper vacuum than high-pressure systems need.
When recovering from a low-pressure chiller, recover the liquid first and then:
Recover the vapor
Most refrigerant is liquid. After liquid recovery, a large amount of vapor remains and must be recovered too.
During refrigerant recovery from a chiller, water should be circulated through the tubes to:
Prevent the water in the tubes from freezing
As pressure drops, refrigerant temperature falls. Circulating water (or draining it) prevents freezing and tube rupture.
To leak test a low-pressure chiller, pressurize it by:
Using controlled hot water or a heating blanket, or nitrogen, to no more than 10 psig
The rupture disc on most low-pressure chillers is set at 15 psig. Keep test pressure to 10 psig or less.
The rupture disc on a low-pressure chiller's evaporator is typically set at:
15 psig
Keep any test or warming pressure below the 15 psig rupture disc setting, generally to 10 psig.
When charging a low-pressure chiller from a deep vacuum, start with vapor until the pressure reaches about:
The saturation pressure for 32°F (to avoid freezing the water in the tubes)
Charging liquid into a deep vacuum flashes it to very low temperatures and can freeze the tubes. Raise pressure with vapor first.
Where should liquid refrigerant be added to a low-pressure chiller?
Through the evaporator charging valve
Charge liquid through the evaporator charging valve after vapor has raised the pressure above freezing conditions.
Recovery equipment for low-pressure systems commonly uses:
A high-efficiency condenser and low-pressure-rated design, often with water-cooled condensers
Low-pressure recovery machines are built to pull deep vacuums and handle large volumes of vapor.
Why should recovery continue after the liquid is removed from a low-pressure system?
A large mass of refrigerant remains as vapor
Low-pressure refrigerants are dense vapors. Hundreds of pounds can remain as vapor in a large chiller.
A low-pressure comfort cooling chiller with more than 50 lb of ozone-depleting refrigerant leaking above 10% per year must be:
Repaired, generally within 30 days
Chillers used for comfort cooling fall under the 10% threshold. Repairs and verification tests follow the leak repair rules.
R-123 is classified as B1, which means:
Higher toxicity, no flame propagation
B = higher toxicity. Equipment rooms need refrigerant monitors, ventilation and alarms per ASHRAE 15.
Before opening a low-pressure appliance for a repair that is NOT major, after recovery it must be:
Pressurized to no higher than 0 psig
For non-major repairs, 40 CFR 82.156(a)(1) requires a low-pressure appliance to be at a pressure no higher than 0 psig before it is opened, so air isn't drawn in and refrigerant isn't pushed out.
To raise a low-pressure appliance to 0 psig before a non-major repair, when its refrigerant boils above 85°F at atmospheric pressure (like R-11 or R-123), you must:
Use heat first, then nitrogen only to bring it from that level up to atmospheric
40 CFR 82.156(a)(1): use heat to raise the pressure as much as possible; nitrogen may make up the rest to atmospheric pressure.
For low-pressure appliances whose refrigerant boils at or below 85°F at atmospheric pressure, raising the pressure with nitrogen is:
Not allowed, because it would require purging later
40 CFR 82.156(a)(1) says these appliances must not be pressurized with methods like nitrogen that require subsequent purging, since purging releases refrigerant.
If leaks make it impossible to reach 25 mm Hg absolute on a low-pressure appliance, you must evacuate the leaking component to:
The lowest level reachable without substantially contaminating the refrigerant, never above 0 psig
40 CFR 82.156(a)(2) covers leaking appliances: evacuate to the lowest attainable level without substantial contamination, and that level may not exceed 0 psig.
In "25 mm Hg absolute," absolute means the pressure is measured from:
A perfect vacuum (zero pressure)
Absolute pressure starts at a perfect vacuum. 25 mm Hg absolute is a very deep vacuum, about 29 in. Hg on a compound gauge.
Which is the deeper (lower) pressure?
25 mm Hg absolute
25 in. Hg vacuum leaves about 4.9 in. Hg absolute, roughly 125 mm Hg absolute, five times higher than the 25 mm Hg absolute required for low-pressure appliances.
The required evacuation level for low-pressure appliances with recovery equipment made before November 15, 1993 is:
25 mm Hg absolute, the same as for newer equipment
EPA's evacuation table lists 25 mm Hg absolute for low-pressure appliances regardless of when the recovery equipment was made.
A pump-out unit permanently attached to a chiller with several hundred pounds of refrigerant is:
Allowed, because the 15 lb limit on system-dependent equipment excludes permanently attached pump-out units
40 CFR 82.156(e) bars system-dependent equipment on appliances over 15 lb unless it is permanently attached as a pump-out unit.
Which refrigerants are examples used in low-pressure appliances?
R-11 and R-123
EPA's evacuation table lists CFC-11 and HCFC-123 as low-pressure refrigerants. R-13 and R-503 are very high-pressure; R-410A, R-22 and R-404A are high-pressure.
During a non-major repair, if a section of a low-pressure appliance can't be isolated, the open piping should be:
Covered to limit air and moisture getting in
EPA's practice rule for non-major repairs calls for covering openings when isolation isn't possible.
Why does EPA prefer heat over nitrogen to bring a low-pressure appliance up to atmospheric pressure?
Nitrogen mixes with the refrigerant and later has to be purged, releasing refrigerant
Gas added to a low-pressure system collects as a non-condensable and has to be purged out, carrying refrigerant with it. Heat raises pressure without adding gas.

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