EPA 608 Universal Practice Test: 100 Free Questions

Answer: B. Strong ultraviolet light breaks them apart, releasing chlorine atoms that destroy ozone.
Why: That stability is the problem. CFCs survive long enough to reach the stratosphere, where strong UV light splits them and frees chlorine. Chlorine is what depletes ozone.
Why not the others: CFCs don't wash out as acid rain; staying intact down low is exactly why they get so high. Fluorine isn't the ozone destroyer and doesn't act as a shield. Trapping heat is a global-warming effect, a separate issue from ozone depletion.
Source: EPA Test Topics, Core → Environmental Impacts (CFC definition)
Review topic: Environmental impacts

Answer: D. CFC, HCFC, HFC.
Why: R-12 is a CFC (chlorine, fluorine, carbon). R-22 is an HCFC (adds hydrogen, still has chlorine). R-134a is an HFC (no chlorine at all). EPA's topic list uses nearly the same example set (R-12, R-22, R-134).
Why not the others: The other orders swap at least one family. R-12 is never an HCFC, and R-134a is never an HCFC, because it contains no chlorine.
Source: EPA Test Topics, Core → Environmental Impacts
Review topic: Environmental impacts

Answer: A. CFCs, then HCFCs, then HFCs (which have zero ODP).
Why: ODP compares a chemical's ozone damage to CFC-11, which is set at 1.0. CFCs carry the most chlorine and the highest ODP. HCFCs are lower because hydrogen helps them break down sooner. HFCs contain no chlorine, so their ODP is zero.
Why not the others: Putting HCFCs above CFCs reverses the chlorine logic. HFCs can't be highest; they're zero. CFCs and HCFCs aren't equal. EPA gives HCFC ODPs of roughly 0.01 to 0.1, far below CFC-11's 1.0.
Source: EPA Test Topics, Core → Environmental Impacts (ODP definition) · EPA, Phaseout of Class II ODS
Review topic: Environmental impacts

Answer: C. Yes. The 2020 phaseout ended new U.S. production and import of R-22; it didn't ban servicing existing equipment.
Why: EPA's Class II schedule ended U.S. production and import of HCFC-22 in 2020. The phaseout targets making and importing the chemical; EPA notes that servicing existing refrigeration and air-conditioning equipment is one of the HCFC uses that continues.
Why not the others: The 2020 date stopped making and importing R-22, not using it. No federal rule forces a retrofit or retirement just because a system uses R-22. The 2010 date limited new R-22 production to servicing equipment built before 2010; it didn't retire anything.
Source: EPA, Phaseout of Class II ODS (schedule table)
Review topic: Clean Air Act and Montreal Protocol

Answer: D. January 1, 1996.
Why: Under Clean Air Act Section 604, production and import of Class I substances other than methyl bromide, including CFCs, ended January 1, 1996.
Why not the others: 1994 was the halon ban. 2010 and 2020 are HCFC-22 milestones, not CFC dates.
Source: EPA, Phaseout of Class I ODS
Review topic: Clean Air Act and Montreal Protocol

Answer: B. No. Knowingly releasing refrigerant after it has been recovered still violates the venting prohibition.
Why: §82.154(a)(3) says it plainly: knowingly releasing a Class I, Class II, or non-exempt substitute refrigerant after recovery is a violation.
Why not the others: The rule doesn't stop at the appliance. HFCs are non-exempt substitutes, so zero ODP doesn't make venting legal. There's no 50-pound venting allowance.
Source: 40 CFR 82.154(a)(3)
Review topic: Clean Air Act and Montreal Protocol

Answer: A. The statute sets the penalty per day for each violation, and EPA's current inflation-adjusted maximum is $124,426.
Why: 42 U.S.C. 7413(b) authorizes civil penalties 'per day for each violation.' EPA adjusts the dollar cap for inflation. For penalties assessed on or after January 8, 2025, 40 CFR 19.4 lists $124,426. Older study manuals print older figures, so learn the concept: per day, per violation, adjusted over time.
Why not the others: There's no flat single fine. $44,539 is an older figure that some manuals still print; the amount isn't frozen. The law reaches any 'person,' including individual technicians.
Source: 42 U.S.C. 7413(b) · 40 CFR 19.4, Table 1
Review topic: Clean Air Act and Montreal Protocol

Answer: B. Low-pressure: its refrigerant's liquid saturation pressure is below 45 psia at 104°F.
Why: EPA sorts appliances by the refrigerant's liquid saturation pressure at 104°F. Below 45 psia is low-pressure, and §82.152 names R-123 as an example, along with R-11, R-113, and R-245fa.
Why not the others: The medium, high, and very-high ranges are real, but they describe refrigerants such as R-134a, R-410A, and R-23. R-123 falls below 45 psia.
Source: 40 CFR 82.152, definitions of low-, medium-, high-, and very high-pressure appliance
Review topic: Section 608 regulations

Answer: C. It can remove refrigerant without help from any components inside the appliance.
Why: Self-contained equipment has its own means of drawing refrigerant out, such as its own compressor.
Why not the others: Leaning on the appliance's compressor is the definition of system-dependent equipment. The 15-pound limit applies to system-dependent equipment, not self-contained. Permanent pump-out units are a system-dependent exception.
Source: 40 CFR 82.152, definitions · 40 CFR 82.156(e)
Review topic: Section 608 regulations

Answer: A. A Section 608-certified technician, or an employer that shows the seller proof it employs one.
Why: The sales restriction covers non-exempt substitutes like R-410A. The buyer must hold Type I, II, III, or Universal certification, or employ someone who does and prove it to the seller.
Why not the others: A state contractor license isn't a Section 608 certification. A 609 certification qualifies a buyer only for refrigerant acceptable for MVAC use. There's no quantity exemption for stationary refrigerant.
Source: 40 CFR 82.154(c)(1)
Review topic: Section 608 regulations

Answer: D. Carbon dioxide.
Why: §82.154(a)(1) lists exempt substitutes. Carbon dioxide is exempt in any application.
Why not the others: R-410A and R-134a are non-exempt substitutes, so venting them is prohibited. R-32 doesn't appear on the exempt list either.
Source: 40 CFR 82.154(a)(1)(i)
Review topic: Section 608 regulations

Answer: B. Ester (POE) oil with R-134a; alkylbenzene oil with HCFC refrigerants.
Why: EPA's Core list names esters with R-134 refrigerants and alkylbenzenes with HCFCs. HFCs don't mix well with the mineral oils used in older systems, so ester oils such as POE are the usual match.
Why not the others: Mineral oil isn't miscible with HFCs like R-134a. HCFCs can run on mineral or alkylbenzene oil. 'Any oil works' ignores the compatibility problem EPA specifically lists.
Source: EPA Test Topics, Core → Substitute Refrigerants and Oils · Mainstream manual, pp. 32–33
Review topic: Substitute refrigerants and oils

Answer: D. R-407C is a zeotropic blend; removing vapor from the cylinder can change the mixture's component ratio.
Why: EPA's Core list identifies fractionation as a blend-refrigerant issue. Chemours' R-407C guidance says to remove R-407C from the cylinder as liquid for optimum performance. The same guidance says R-407C can be topped off after a leak, so the reason to learn liquid charging is preserving the blend ratio—not a blanket rule that every leaked R-407C charge must be discarded.
Why not the others: R-407C vapor can enter a pressurized system when conditions allow. Liquid charging does not eliminate temperature glide. EPA's public topic list teaches the blend behavior; it does not create a regulation requiring every blend to be charged as liquid.
Source: EPA Test Topics, Core → Substitute Refrigerants and Oils · Chemours, Freon R-407C Frequently Asked Questions
Review topic: Substitute refrigerants and oils

Answer: A. High-pressure liquid, usually a few degrees subcooled.
Why: The condenser rejects heat and turns high-pressure vapor into high-pressure liquid. That liquid flows through the filter drier to the metering device.
Why not the others: Low-pressure vapor is what leaves the evaporator. Superheated high-pressure vapor is what enters the condenser. The low-pressure liquid-vapor mix appears after the metering device.
Source: EPA Test Topics, Core → Refrigeration · Mainstream manual, pp. 34–36
Review topic: Refrigeration

Answer: C. It's a compound gauge that reads pressure above atmosphere in psig and vacuum in inches of mercury.
Why: The low-side gauge is typically blue and has a compound scale: psig above zero, inches of mercury (in. Hg) below it.
Why not the others: The high-side gauge is the red one. Micron readings come from a separate electronic vacuum gauge. The center hose (usually yellow) has no gauge of its own.
Source: EPA Test Topics, Core → Refrigeration (gauges) · Mainstream manual, pp. 38–44
Review topic: Refrigeration

Answer: B. Clean it, for example with oil separation and filter-driers, for reuse in equipment of the same owner, without meeting full reclaim specifications.
Why: Recycling cleans refrigerant enough to reuse in the same owner's equipment. It doesn't require a lab test.
Why not the others: Reprocessing to AHRI 700 with lab verification is reclaiming. Removing and storing without processing is recovering. Destruction isn't one of the three Rs.
Source: 40 CFR 82.152, definitions of recover, recycle, reclaim
Review topic: Three R definitions

Answer: A. It must be reclaimed to the required purity standard by a certified reclaimer.
Why: Recovered refrigerant can go back into the same appliance, or another appliance owned by the same person, without processing. A different owner is different. Used refrigerant sold or transferred for use must first be reclaimed.
Why not the others: Matching refrigerant type doesn't change ownership. Recycling doesn't meet the reclaim standard. Who did the recovery doesn't matter.
Source: 40 CFR 82.156(h) · 40 CFR 82.154(d) · 40 CFR 82.152, reclaim
Review topic: Three R definitions

Answer: B. Into a separate, dedicated recovery cylinder, not into a cylinder holding clean R-22.
Why: EPA's Core list stresses avoiding mixed refrigerants. A mix can't be reclaimed as either refrigerant, so it goes in its own cylinder and is typically sent for destruction.
Why not the others: Adding it to the R-22 cylinder contaminates that whole cylinder. Venting is illegal no matter what the mix is. Filtering doesn't separate two refrigerants.
Source: EPA Test Topics, Core → Recovery Techniques · Mainstream manual, p. 49
Review topic: Recovery techniques

Answer: C. Short hoses with a large inside diameter.
Why: EPA lists hose length and diameter, equipment size, and ambient temperature as factors in recovery speed. Shorter, wider hoses restrict flow less.
Why not the others: Long, narrow hoses add restriction and slow recovery. A smaller machine moves less refrigerant. Cold temperatures lower refrigerant pressure, which slows recovery.
Source: EPA Test Topics, Core → Recovery Techniques
Review topic: Recovery techniques

Answer: C. To remove air and moisture from the system.
Why: EPA's Core list is direct: evacuate at the end of service to get air and moisture out.
Why not the others: Recovery comes before opening the system, not at the end of service. A vacuum pump does the evacuation, not the system's compressor. Evacuation isn't limited to HFC systems.
Source: EPA Test Topics, Core → Dehydration Evacuation
Review topic: Dehydration evacuation

Answer: D. Dry nitrogen, fed through a pressure regulator with a relief valve.
Why: EPA's topic list says to use nitrogen rather than oxygen or compressed air, with a regulator and relief valve. A full nitrogen cylinder holds far more pressure than a refrigeration system can safely take.
Why not the others: Oxygen and air can make refrigerant and oil mixtures combustible under pressure. An R-22 manufacturer's SDS warns against mixing it with oxygen or air above atmospheric pressure. Skipping the regulator risks over-pressurizing the system.
Source: EPA Test Topics, Core → Safety · Mainstream manual, p. 45 · Hudson R-22 SDS, §§5, 7, 10
Review topic: Safety

Answer: C. Liquid refrigerant expands as it warms; without vapor space, the pressure can rupture the cylinder.
Why: EPA lists the risk of filling cylinders more than 80% full. Leaving at least 20% vapor space gives expanding liquid room.
Why not the others: The limit is about safety, not shipping fees, machine capability, or reclaimer paperwork.
Source: EPA Test Topics, Core → Safety · Mainstream manual, p. 41
Review topic: Safety

Answer: A. A DOT-approved refillable recovery cylinder with a gray body and yellow top.
Why: EPA's topic list calls for DOT-approved recovery cylinders, marked with the yellow-and-gray color code, and says never to refill disposable cylinders.
Why not the others: Disposable cylinders are never refilled. 'Any cylinder' ignores the DOT approval requirement. The green-and-gray combination isn't EPA's recovery-cylinder code.
Source: EPA Test Topics, Core → Safety · Mainstream manual, pp. 26, 46–47
Review topic: Safety

Answer: D. The vapor is heavier than air and displaces oxygen, risking suffocation; high concentrations can also cause heart irregularities.
Why: EPA lists oxygen deprivation and cardiac effects among exposure risks. An R-22 safety data sheet puts its vapor density at about 3 times air and warns of rapid suffocation in confined spaces.
Why not the others: Low toxicity doesn't make a confined space safe. Heavier-than-air vapor pools low instead of rising. R-22 is non-flammable, so fire isn't the main risk here.
Source: EPA Test Topics, Core → Safety · Hudson R-22 SDS, §§2, 9
Review topic: Safety

Answer: A. Refrigerant identification plus a DOT classification tag; for R-22, Class 2.2 non-flammable gas.
Why: EPA's Core list names the required labels: refrigerant identification and a DOT classification tag. The R-22 SDS lists it as DOT hazard class 2.2, non-flammable gas, UN1018.
Why not the others: Your certification number isn't a shipping label. A handwritten note doesn't identify the DOT hazard class. There's no weight exemption.
Source: EPA Test Topics, Core → Shipping · Hudson R-22 SDS, §14
Review topic: Shipping

Answer: A. Type II, because it isn't a small appliance; small appliances are fully manufactured, charged, and hermetically sealed at the factory.
Why: A small appliance must be fully manufactured, charged, and hermetically sealed in a factory with 5 pounds or less. A system finished and connected in the field isn't hermetically sealed at the factory, so the charge size alone doesn't make it Type I.
Why not the others: Five pounds or less is only half the definition. Small charges still need certification. Section 609 covers motor vehicle A/C, not stationary equipment.
Source: 40 CFR 82.152, small appliance
Review topic: Recovery requirements (small appliance definition)

Answer: A. A factory-sealed packaged terminal heat pump holding 3 pounds.
Why: §82.152 lists packaged terminal air heat pumps among small appliances, as long as they're fully manufactured, charged, and hermetically sealed at the factory with 5 pounds or less.
Why not the others: Walk-ins with remote condensing units and rooftop units are field-connected or too large; they're Type II equipment. Centrifugal chillers using low-pressure refrigerant are Type III.
Source: 40 CFR 82.152, small appliance
Review topic: Recovery requirements (small appliance definition)

Answer: C. Recover 90% of the refrigerant, or evacuate to 4 inches of mercury vacuum.
Why: For post-1993 equipment, §82.156(b) requires 90% recovery when the appliance's compressor works, or evacuation to 4 in. Hg vacuum.
Why not the others: 80% is the figure for a non-working compressor, or for pre-1993 equipment. 0 psig and 10 in. Hg come from the Type II/III table, which excludes small appliances.
Source: 40 CFR 82.156(b)
Review topic: Recovery requirements

Answer: A. Recover 80% of the refrigerant, or evacuate to 4 inches of mercury vacuum.
Why: With a non-working compressor, §82.156(b)(2) drops the target to 80%. The 4 in. Hg option still applies.
Why not the others: 90% applies when the compressor works. No rule requires 100%. 25 mm Hg absolute is the low-pressure appliance level.
Source: 40 CFR 82.156(b)
Review topic: Recovery requirements

Answer: C. Recover 80% of the refrigerant, or evacuate to 4 inches of mercury vacuum, whether or not the compressor works.
Why: For pre-November 15, 1993 recovery equipment, the small-appliance requirement is 80%, with no split by compressor condition. The 4 in. Hg option applies too.
Why not the others: The 90%/80% split applies only to post-1993 equipment. 95% and 70% don't appear in the rule.
Source: 40 CFR 82.156(b)(1), (b)(3)
Review topic: Recovery requirements

Answer: D. When a certified technician closely and continually supervises the work.
Why: EPA exempts apprentices from certification only while they are closely and continually supervised by a certified technician. The federal definition also limits apprentice status to two years from first registration.
Why not the others: Apprentices can do the work under supervision. The two-year window doesn't remove the supervision requirement. There's no charge-size exception.
Source: EPA, Section 608 Technician Certification Requirements · 40 CFR 82.152, apprentice
Review topic: Technician requirements

Answer: D. Yes. System-dependent equipment is barred only on appliances with a full charge over 15 pounds, unless it's a permanent pump-out unit.
Why: §82.156(e) limits system-dependent equipment to appliances holding 15 pounds or less (unless permanently attached as a pump-out unit). A 3-pound water cooler is well under that.
Why not the others: Passive recovery is common on small appliances. The limit is based on charge, not refrigerant type. It works with working or dead compressors, using different techniques.
Source: 40 CFR 82.156(e)
Review topic: Recovery techniques

Answer: B. Recover any remaining refrigerant itself, or get a signed statement or contract showing who recovered it, their address, and the date.
Why: The final processor in the disposal chain must either recover what's left or obtain a signed statement (name and address of who recovered it, and the date) or a qualifying contract.
Why not the others: The final processor carries a specific duty. Verbal confirmation isn't enough. The rule applies to all Class I, Class II, and non-exempt substitute refrigerants, not just R-12.
Source: 40 CFR 82.155(b)
Review topic: Disposal

Answer: B. "Leaked out" covers system failures and accidents, not deliberate acts like cutting lines, and accepting a statement you know is false is a violation.
Why: §82.155 defines 'leaked out' as escape through system failures, accidents, or other unavoidable events, not deliberate acts such as cutting refrigerant lines. It also makes it a violation to accept a statement you know, or have reason to know, is false.
Why not the others: Not every signed statement qualifies. Notarizing a false statement doesn't fix it. There's no age exception.
Source: 40 CFR 82.155(b)(2)(i), (iii)
Review topic: Disposal

Answer: C. 3 years.
Why: §82.155(c) requires the final processor to keep copies on site, on paper or electronically, for three years.
Why not the others: One year is too short. Five years and 'indefinitely' aren't the rule. (Certifying programs, not scrap yards, keep test records indefinitely.)
Source: 40 CFR 82.155(c)
Review topic: Disposal

Answer: D. At the same temperature, their saturation pressures are too close to tell apart.
Why: At 75°F, R-12 sits near 77 psig and R-134a near 78 psig. That's closer than normal gauge and thermometer error. The pressure-temperature method only separates refrigerants that are far apart, and noncondensables or a fractionated blend make it worse.
Why not the others: Every refrigerant has a pressure-temperature relationship. A unit that has stabilized at room temperature is exactly when the method works. R-12 is well above atmospheric pressure at 75°F.
Source: Mainstream manual, pp. 49–52 (Table C-5 and method limits) · EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques (identifying refrigerant)

Answer: C. Noncondensable gases, such as air, are in the system.
Why: When liquid and vapor sit together at a stable temperature, pressure should match the saturation pressure for that temperature. Extra pressure beyond that points to noncondensables such as air.
Why not the others: An undercharge doesn't push pressure above saturation. A high reading isn't normal. Azeotropes still follow a single pressure-temperature curve.
Source: EPA Test Topics, Type 1 → Recovery Techniques · Mainstream manual, p. 52
Review topic: Recovery techniques (noncondensables)

Answer: B. On both the high side and the low side.
Why: EPA's Type I list calls for both high- and low-side access valves when the compressor is inoperative. With no compressor moving refrigerant, you need access to both sides to get it out.
Why not the others: Accessing one side traps refrigerant on the other side of the metering device.
Source: EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques

Answer: C. Heat the compressor and sharply strike it.
Why: EPA lists heating and sharply striking the compressor as a way to free refrigerant from the oil when using a system-dependent device on an inoperative compressor.
Why not the others: Nitrogen mixes with the refrigerant you're trying to recover. Repeatedly trying to start a seized compressor doesn't release the charge. Venting leftover refrigerant is not a de minimis release.
Source: EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques

Answer: B. Use a vacuum pump to pull refrigerant into a non-pressurized recovery container.
Why: EPA names using a vacuum pump with a non-pressurized recovery container as a system-dependent option when the compressor won't run.
Why not the others: Discharging outdoors is venting. Disposable cylinders are never refilled. A pressurized cylinder won't accept refrigerant from a dead system on its own.
Source: EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques

Answer: A. Run the appliance's compressor to help move refrigerant into the recovery device.
Why: EPA's Type I list says to operate an operative compressor during system-dependent recovery. The compressor does the pumping a passive device can't.
Why not the others: Leaving the compressor off, or disconnecting it, throws away your best recovery tool. Heating the condenser alone won't drive the recovery.
Source: EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques

Answer: D. Remove it; these fittings tend to leak over time.
Why: EPA's Type I list says solderless access fittings should be removed at the end of service. They aren't meant as permanent fittings.
Why not the others: Leaving it for next time, or trusting one bubble test or a tape cap, keeps a known leak path on the system.
Source: EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques

Answer: D. R-134a.
Why: EPA's Type I list names HFC-134a as the likely substitute for CFC-12.
Why not the others: R-22 is an HCFC that's being phased out itself. R-11 and R-123 are low-pressure chiller refrigerants.
Source: EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Recovery techniques

Answer: B. A process stub.
Why: §82.154(e)(2) bars selling small appliances unless they have a process stub, a length of tubing that gives access to the refrigerant and can be resealed.
Why not the others: Larger appliances need a servicing aperture; small appliances need a process stub. Sight glasses and pump-out units aren't required.
Source: 40 CFR 82.154(e)(2) · 40 CFR 82.152, process stub
Review topic: Equipment

Answer: B. Refrigerant flow cools a hermetic compressor's motor; running in a deep vacuum can overheat and burn it out.
Why: Hermetic motors are cooled by the refrigerant passing through. In a deep vacuum there's almost no flow, so windings heat quickly. A burnout ruins the compressor and contaminates what's left.
Why not the others: A deeper vacuum doesn't help once the requirement is met. The small-appliance standard is 80% or 90% recovery, or 4 in. Hg. EPA actually says to operate a working compressor during passive recovery; the issue is not running it into a deep vacuum.
Source: Mainstream manual, pp. 37–38 · EPA Test Topics, Type 1 → Recovery Techniques
Review topic: Safety

Answer: A. Recovery equipment certified under §82.158, either self-contained or system-dependent.
Why: §82.156(b) requires a recovery and/or recycling machine certified under §82.158. Both self-contained and system-dependent equipment can be certified for small appliances.
Why not the others: Exhausting to the outdoors is venting. Certification applies to the equipment, not just the tech. Passive devices are allowed on small appliances.
Source: 40 CFR 82.156(b)
Review topic: Recovery requirements

Answer: A. R-600a in household refrigerators is an exempt substitute, so the venting prohibition doesn't apply, but it's flammable, so the manufacturer's service procedures matter.
Why: §82.154(a)(1)(ix) exempts isobutane in household refrigerators and freezers from the venting prohibition and the rest of Subpart F. Exempt doesn't mean harmless. Hydrocarbons are highly flammable.
Why not the others: The exemption covers the Subpart F requirements, including recovery levels. R-600a is specifically allowed in this end use. Household refrigerators are small appliances, not Type II equipment.
Source: 40 CFR 82.154(a)(1)(ix)
Review topic: Venting prohibition (exempt substitutes)

Answer: B. No federal leak-repair requirement applies at that size, but refrigerant must still be properly recovered before the system is opened.
Why: Section 608 leak repair (§82.157) applies to appliances with 50 or more pounds of ozone-depleting refrigerant. The newer HFC leak-repair rule (§84.106) starts at 15 pounds. A 2-pound R-134a water cooler falls under neither. Evacuation rules still apply before opening it.
Why not the others: The 30-day timeline and 10% threshold belong to the larger-appliance rules. Recovery is still required under §82.156(b).
Source: 40 CFR 82.157(a) · 40 CFR 84.106(a) · 40 CFR 82.156(b)
Review topic: Leak repair scope

Answer: C. High heat can decompose it into toxic, corrosive products such as hydrochloric and hydrofluoric acids.
Why: EPA's Type I list flags decomposition products at high temperatures. An R-22 safety data sheet warns that flames, hot spots, or welding can create hydrochloric acid, hydrofluoric acid, and carbonyl halides.
Why not the others: Heat makes refrigerant more dangerous, not inert. The products are toxic acids, not harmless smoke or CO2.
Source: EPA Test Topics, Type 1 → Safety · Hudson R-22 SDS, §§2, 10
Review topic: Safety

Answer: D. The same appliance, or another appliance owned by the same person.
Why: §82.156(h) allows returning recovered refrigerant to the appliance it came from, or to another appliance owned by the same person, without recycling or reclaiming.
Why not the others: Other owners' appliances require reclaimed refrigerant. Consent doesn't change the ownership rule. Reclaiming isn't always required.
Source: 40 CFR 82.156(h)
Review topic: Recovery requirements

Answer: B. Excessive superheat, or oily residue at joints on a hermetic system.
Why: EPA's Type II list names excessive superheat and traces of oil as signs of leakage. A short charge starves the evaporator, which raises superheat, and escaping refrigerant carries oil with it.
Why not the others: Low superheat and high subcooling point toward overfeeding or overcharge, not a leak. Higher head pressure on a hot day is normal.
Source: EPA Test Topics, Type 2 → Leak Detection
Review topic: Leak detection

Answer: D. Nitrogen alone is best; nitrogen with a trace of R-22 is next; pure refrigerant is least preferred.
Why: EPA's list is explicit: nitrogen alone is best, and nitrogen with a trace amount of HCFC-22 beats pure refrigerant.
Why not the others: The first and last options reverse EPA's order. Compressed air isn't on the list and shouldn't be used to pressurize systems.
Source: EPA Test Topics, Type 2 → Leak Detection
Review topic: Leak detection

Answer: B. Recover the charge to the required level first; after repairs, a small amount of refrigerant can be added with nitrogen as a trace gas.
Why: The system must be evacuated to the required level before it's opened. A trace-gas mix is allowed only when a small amount of refrigerant is added to nitrogen for leak detection. Adding nitrogen to a full charge to avoid recovery is venting that charge.
Why not the others: Mixing nitrogen into a charged system doesn't exempt the refrigerant already there. Neither charge size nor refrigerant type changes that.
Source: 40 CFR 82.156(a) · Mainstream manual, pp. 23–24
Review topic: Leak detection

Answer: D. It exceeds the 10% comfort-cooling threshold, so the owner must repair it (or elect to retrofit or retire it).
Why: §82.157 covers appliances with 50 or more pounds of ozone-depleting refrigerant such as R-22. Comfort cooling triggers at 10%, and 12% is over.
Why not the others: 15% is the old pre-2019 comfort-cooling figure. The size trigger is 50 pounds, not 100. The phaseout doesn't exempt R-22 systems from leak repair.
Source: 40 CFR 82.157(a), (c)
Review topic: Leak repair requirements

Answer: C. 40 CFR 84.106, under the AIM Act.
Why: Since April 10, 2020, §82.157 covers only appliances with 50 or more pounds of ozone-depleting refrigerant. Starting January 1, 2026, §84.106 covers appliances with 15 or more pounds of HFCs (or other substitutes with GWP above 53), with a 20% threshold for commercial refrigeration. Its exclusions are ODS-only appliances and residential and light-commercial air conditioning and heat pumps, not supermarket racks.
Why not the others: §82.157 doesn't reach HFC-only equipment, and 35% is an old threshold. HFCs are covered now. §84.106 includes commercial refrigeration.
Source: 40 CFR 82.157(a) · 40 CFR 84.106(a), (c)(2)
Review topic: Leak repair requirements (2026 rule change)

Answer: C. 30 days, or 120 days if an industrial process shutdown is needed.
Why: Both §82.157(d) and §84.106(d) set 30 days from when refrigerant is added, or 120 days when repair requires an industrial process shutdown.
Why not the others: Ten days is the window for the follow-up verification test. Ninety days isn't in the rule. One year is the retrofit or retirement plan timeline.
Source: 40 CFR 82.157(d) · 40 CFR 84.106(d)
Review topic: Leak repair requirements

Answer: B. Within 10 days, or within 10 days of reaching normal operating conditions if the system was evacuated for the repair.
Why: The follow-up test confirms the repair holds once the system is running normally. §82.157(e)(2) sets 10 days.
Why not the others: Thirty days is the repair window. Twelve months relates to when repairs are presumed successful. Both initial and follow-up tests are required.
Source: 40 CFR 82.157(e) · 40 CFR 84.106(e)
Review topic: Leak repair requirements

Answer: A. Yes: up to 30 days after the part arrives, capped at 180 days from when the leak rate was exceeded, with an extension request sent to EPA within the first 30 days.
Why: §82.157(f) allows extra time when needed components aren't available: up to 30 days after delivery, not beyond 180 days (270 with an industrial process shutdown). Repairs that don't need the part must still be done within 30 days, and the extension request goes to EPA within 30 days.
Why not the others: Extensions exist, but they're conditional, not automatic. Continuing to add refrigerant is not a compliance option.
Source: 40 CFR 82.157(f)
Review topic: Leak repair requirements (extensions)

Answer: A. Every three months, until four consecutive quarters show it hasn't leaked above the threshold.
Why: For commercial refrigeration and industrial process refrigeration with 500 or more pounds, §82.157(g) requires quarterly inspections until four quarters in a row are under the threshold.
Why not the others: Annual inspections apply to smaller commercial and industrial systems and to comfort cooling. Monthly isn't in the rule. Verification tests don't replace the inspection schedule.
Source: 40 CFR 82.157(g)(1)(i)
Review topic: Leak repair requirements (inspections)

Answer: D. The tech gives the owner service documentation, and the owner keeps leak-repair records for at least three years.
Why: §82.157(b) requires whoever adds or removes refrigerant to give the owner documentation. §82.157(l) requires records to be kept at least three years unless otherwise specified.
Why not the others: The owner carries the main recordkeeping duty. One year is too short. The size trigger for these records is 50 pounds, not 200.
Source: 40 CFR 82.157(b), (l)
Review topic: Leak repair requirements (recordkeeping)

Answer: A. Hydrocarbons aren't approved as retrofit refrigerants for this equipment.
Why: EPA's Type II topic list includes the idea that hydrocarbons are not approved for retrofits. Its Core list also says there are no true 'drop-in' replacements.
Why not the others: Labels, charge size, and oil changes don't turn an unapproved retrofit into an approved one.
Source: EPA Test Topics, Type 2 → Refrigeration; Core → Substitute Refrigerants
Review topic: Refrigeration (retrofits)

Answer: C. Recover liquid first.
Why: EPA's Type II list notes that recovering liquid at the beginning speeds up the process. Liquid moves far more refrigerant per minute than vapor.
Why not the others: Vapor-first is slower. Oil comes out after the refrigerant. A vacuum pump isn't a recovery device.
Source: EPA Test Topics, Type 2 → Recovery Techniques
Review topic: Recovery techniques

Answer: B. Chilling the recovery vessel, or heating the appliance or vessel being recovered from.
Why: EPA lists chilling the recovery vessel and heating the source as speed methods. Both raise the pressure difference that drives refrigerant into the cylinder.
Why not the others: Heating the receiving cylinder and chilling the source shrinks that pressure difference. Longer hoses and smaller units slow things down. Vapor-only recovery is slower than starting with liquid.
Source: EPA Test Topics, Type 2 → Recovery Techniques
Review topic: Recovery techniques

Answer: D. Clear the machine of the previous refrigerant following the manufacturer's procedure, and recover into a separate cylinder.
Why: EPA's Type II list covers methods for reducing cross-contamination and emissions when a machine is used with a new refrigerant. §82.156(g) requires following the manufacturer's directions.
Why not the others: Leftover refrigerant in the machine contaminates the next job. Purging to the air is venting. 'Running backward' isn't a recognized procedure.
Source: EPA Test Topics, Type 2 → Recovery Techniques · 40 CFR 82.156(g)
Review topic: Recovery techniques

Answer: C. Liquid refrigerant, or refrigerant dissolved in the oil, is still in the system; keep recovering.
Why: EPA's list says to wait a few minutes after reaching the required vacuum and watch for a rise. A rise means refrigerant is still boiling off.
Why not the others: Opening now would release refrigerant. A rising reading points to refrigerant left in the system, not the machine. Charging comes after repairs and evacuation, not now.
Source: EPA Test Topics, Type 2 → Recovery Techniques
Review topic: Recovery techniques

Answer: A. 0 inches of mercury vacuum (0 psig).
Why: R-410A is a high-pressure refrigerant. For a high-pressure appliance under 200 pounds, Table 1 requires 0 in. Hg with either age of equipment.
Why not the others: 10 in. Hg is for high-pressure appliances of 200 pounds or more. 15 in. Hg is for large medium-pressure appliances. 25 mm Hg absolute is for low-pressure appliances.
Source: 40 CFR 82.156, Table 1 · 40 CFR 82.152, high-pressure appliance
Review topic: Recovery requirements

Answer: A. 10 inches of mercury vacuum.
Why: R-22 is high-pressure. For a high-pressure appliance with 200 or more pounds, Table 1 requires 10 in. Hg with post-1993 equipment.
Why not the others: 0 in. Hg is for high-pressure appliances under 200 pounds. 4 in. Hg is the pre-1993 figure for this size. 15 in. Hg is for large medium-pressure appliances.
Source: 40 CFR 82.156, Table 1
Review topic: Recovery requirements

Answer: C. 15 inches of mercury vacuum.
Why: R-134a is medium-pressure. For a medium-pressure appliance with 200 or more pounds, Table 1 requires 15 in. Hg with post-1993 equipment.
Why not the others: 10 in. Hg is for medium-pressure appliances under 200 pounds (and large high-pressure ones). 4 in. Hg is the pre-1993 figure. 0 in. Hg is for high-pressure appliances under 200 pounds.
Source: 40 CFR 82.156, Table 1 · 40 CFR 82.152, medium-pressure appliance
Review topic: Recovery requirements

Answer: D. Evacuate it to no higher than 0 psig.
Why: §82.156(a)(1)(i) sets 0 psig for medium-, high-, and very high-pressure appliances getting non-major repairs, when the appliance won't be evacuated to the atmosphere afterward.
Why not the others: 10 in. Hg and 25 mm Hg absolute come from the full Table 1 requirements. Non-major repairs still require a reduced level before opening.
Source: 40 CFR 82.156(a)(1)(i)
Review topic: Recovery requirements

Answer: B. Replacing the condenser coil.
Why: A major repair involves removing the compressor, condenser, evaporator, or an auxiliary heat exchange coil, or leaving an opening of more than 4 square inches of flow area for more than 15 minutes.
Why not the others: Fan motors and contactors aren't part of the refrigerant circuit. Tightening a nut doesn't remove a component or open the circuit.
Source: 40 CFR 82.152, major maintenance, service, or repair
Review topic: Recovery requirements

Answer: B. Isolate the leaking parts; evacuate non-leaking parts to the normal level; evacuate leaking parts as low as possible without contaminating the refrigerant, never above 0 psig.
Why: §82.156(a)(2) covers this exact case: isolate where possible, meet Table 1 on non-leaking components, and take leaking components to the lowest level achievable without substantially contaminating the refrigerant, and no higher than 0 psig.
Why not the others: The rule gives a reduced target; it doesn't waive evacuation or allow venting. Pulling air through a leak contaminates the recovered refrigerant.
Source: 40 CFR 82.156(a)(2)
Review topic: Recovery requirements

Answer: A. Not unless it's permanently attached to the appliance as a pump-out unit.
Why: §82.156(e) prohibits system-dependent equipment on appliances with a full charge over 15 pounds, unless it's a permanently attached pump-out unit.
Why not the others: A working compressor, refrigerant type, or certification level doesn't lift the 15-pound limit.
Source: 40 CFR 82.156(e)
Review topic: Recovery requirements

Answer: D. 136.1 psia.
Why: Absolute pressure equals gauge pressure plus atmospheric pressure: 121.4 + 14.7 = 136.1 psia. EPA's Type II list calls out adding 14.7 to convert psig to psia.
Why not the others: 106.7 subtracts 14.7 instead of adding it. 121.4 skips the conversion. 151.3 adds 29.9, which is atmospheric pressure in inches of mercury, not psi.
Source: EPA Test Topics, Type 2 → Refrigeration
Review topic: Refrigeration (pressure-temperature)

Answer: C. Check the equipment nameplate.
Why: Each refrigerant has its own recovery requirements, so identify it before starting. The nameplate is the first check.
Why not the others: Sniffing refrigerant is unsafe and unreliable. Pressure-temperature readings can't reliably separate similar refrigerants or systems with air in them. Assuming is how refrigerants get mixed.
Source: EPA Test Topics, Type 2 → Refrigeration · Mainstream manual, p. 49
Review topic: Refrigeration (identifying refrigerant)

Answer: C. The motor relies on refrigerant flow for cooling; running it under vacuum can damage the windings.
Why: EPA's Type II list says not to energize hermetic compressors under vacuum. With no refrigerant flowing, the motor has no cooling.
Why not the others: The compressor doesn't help dehydration. A vacuum decay check uses a gauge, not the compressor. It can start, and that's the risk.
Source: EPA Test Topics, Type 2 → Safety · Mainstream manual, pp. 37–38
Review topic: Safety

Answer: A. Controlled hot water or a built-in heating/pressurization device (such as Prevac), with nitrogen as the second choice.
Why: EPA's Type III list gives the order: hot water or a built-in pressurization device first, nitrogen second.
Why not the others: Nitrogen-first reverses EPA's order. Compressed air brings in moisture and noncondensables. Adding refrigerant just to raise pressure isn't a listed method.
Source: EPA Test Topics, Type 3 → Leak Detection
Review topic: Leak detection

Answer: A. Excessive purge-unit operation.
Why: Leaks let air and moisture in, and the purge unit runs more to remove them. EPA's Type III list names excessive purging as a sign.
Why not the others: The other options can have many causes and aren't the signs EPA lists.
Source: EPA Test Topics, Type 3 → Leak Detection
Review topic: Leak detection

Answer: C. Once per calendar year, until the owner can show one year without leaking above the threshold.
Why: R-123 is an HCFC, so §82.157 applies. Comfort-cooling appliances get annual inspections until one year under the threshold.
Why not the others: Quarterly inspections apply to commercial and industrial process refrigeration of 500 pounds or more. Monthly isn't in the rule. Verification tests don't replace inspections.
Source: 40 CFR 82.157(g)(1)(iii)
Review topic: Leak detection (inspections)

Answer: C. Report it to EPA by March 1 of the following year.
Why: Appliances that leak 125% or more of their full charge in a calendar year are 'chronically leaking.' The owner must report to EPA by March 1 of the next year.
Why not the others: Repairs don't cancel the report. Ten days and 'at retirement' aren't the deadline.
Source: 40 CFR 82.157(j)
Review topic: Leak detection (reporting)

Answer: B. Those methods show whether a system leaks, not where; they must be combined with a method that locates leaks.
Why: EPA's leak inspection definition says methods that only show whether an appliance is leaking, such as standing pressure or vacuum decay tests and sight-glass checks, must be paired with methods that find the leak's location.
Why not the others: Detection alone isn't an inspection. Vacuum tests aren't prohibited. Sight glasses appear on many system types.
Source: 40 CFR 82.152, leak inspection
Review topic: Leak detection

Answer: D. 30%.
Why: §82.157(c)(2)(ii) sets 30% for industrial process refrigeration.
Why not the others: 10% is comfort cooling. 20% is commercial refrigeration. 35% is the old pre-2019 figure.
Source: 40 CFR 82.157(c)(2)
Review topic: Leak repair requirements

Answer: B. 25%, which is over the 10% comfort-cooling threshold.
Why: Annualizing method: (pounds added ÷ full charge) ÷ (days since last addition ÷ 365) × 100. So (20 ÷ 400) ÷ (73 ÷ 365) × 100 = 0.05 ÷ 0.2 × 100 = 25%. R-123 is an HCFC and the chiller holds more than 50 pounds, so the 10% comfort-cooling threshold applies.
Why not the others: 5% forgets to annualize the 73 days. 20% and 50% come from arithmetic slips. The correct result is 25%.
Source: 40 CFR 82.152, leak rate (annualizing method) · 40 CFR 82.157(c)(2)(iii)
Review topic: Leak repair requirements (calculation)

Answer: A. Retrofit or retire it under a retrofit or retirement plan.
Why: §82.157(c)(1) requires repair unless the owner elects to retrofit or retire the appliance under the rule's plan requirements.
Why not the others: Topping off doesn't satisfy the rule. Mothballing only pauses the clock in specific ways; it isn't a permanent way out. Repair isn't optional.
Source: 40 CFR 82.157(c)(1)
Review topic: Leak repair requirements

Answer: D. Remove the liquid refrigerant.
Why: EPA's Type III list says recovering liquid first speeds up the process.
Why not the others: Vapor comes after liquid. Oil comes out later. Nitrogen would contaminate the refrigerant you're recovering.
Source: EPA Test Topics, Type 3 → Recovery Techniques
Review topic: Recovery techniques

Answer: C. A significant amount of refrigerant is still in the chiller as vapor and must be recovered too.
Why: EPA's Type III list stresses recovering vapor in addition to liquid. Low-pressure chillers have large volumes that hold a lot of vapor.
Why not the others: Vapor isn't exempt, and in a big chiller it isn't trivial. The requirement doesn't depend on refrigerant type.
Source: EPA Test Topics, Type 3 → Recovery Techniques
Review topic: Recovery techniques

Answer: A. Heat the oil to 130°F.
Why: EPA's Type III list says to heat oil to 130°F before removing it, driving dissolved refrigerant out of the oil.
Why not the others: 90°F is too low. 212°F is far past what EPA lists. Chilling keeps more refrigerant dissolved in the oil.
Source: EPA Test Topics, Type 3 → Recovery Techniques
Review topic: Recovery techniques

Answer: C. Circulating the water through the tubes, or draining the water side.
Why: As refrigerant pressure drops, its temperature drops too, and it can freeze water in the tubes. EPA's Type III list calls for circulating or removing the water.
Why not the others: Trapped, still water freezes more easily. Antifreeze doesn't go in the refrigerant. Faster evacuation lowers temperature faster.
Source: EPA Test Topics, Type 3 → Recovery Techniques
Review topic: Recovery techniques

Answer: B. Refrigerant is still coming out of the system or the oil; continue recovery.
Why: EPA's Type III list repeats the Type II lesson: wait a few minutes after reaching the required vacuum and watch for a rise. A rise means refrigerant is still in the system or dissolved in oil.
Why not the others: Opening now releases refrigerant. Blaming the purge unit ignores the refrigerant left behind. Adding nitrogen before recovery is finished contaminates what's left.
Source: EPA Test Topics, Type 3 → Recovery Requirements
Review topic: Recovery requirements

Answer: B. Vapor first, to raise pressure so water in the tubes doesn't freeze when liquid is added.
Why: Liquid entering a deep vacuum flashes and gets very cold. EPA's Type III list says to introduce vapor before liquid to prevent freezing water in the tubes.
Why not the others: Liquid-first is the freeze risk EPA warns about. Mixing both doesn't solve it. Oil isn't part of the refrigerant charging sequence.
Source: EPA Test Topics, Type 3 → Recharging Techniques
Review topic: Recharging techniques

Answer: C. Through the evaporator charging valve.
Why: EPA's Type III list names the evaporator charging valve.
Why not the others: The other locations aren't the charging point EPA lists; the purge unit removes noncondensables and isn't a charging port.
Source: EPA Test Topics, Type 3 → Recharging Techniques
Review topic: Recharging techniques

Answer: D. 25 mm Hg absolute.
Why: Table 1 lists 25 mm Hg absolute for low-pressure appliances with both pre- and post-November 15, 1993 recovery equipment.
Why not the others: 0 psig, 10 in. Hg, and 4 in. Hg belong to other appliance classes or situations.
Source: 40 CFR 82.156, Table 1
Review topic: Recovery requirements

Answer: B. 25,000 microns.
Why: One micron equals 0.001 mm Hg, so there are 1,000 microns in 1 mm Hg. 25 × 1,000 = 25,000 microns.
Why not the others: The other answers are off by factors of ten, a common slip when converting units.
Source: Mainstream manual, p. 39
Review topic: Recovery requirements (units)

Answer: A. Use heat, such as controlled hot water or a system pressurization device, to raise it to no higher than 0 psig; don't use methods like nitrogen that need later purging.
Why: For non-major repairs, §82.156(a)(1)(ii) has low-pressure appliances brought up to no higher than 0 psig. For refrigerants boiling at or below 85°F, methods like nitrogen that need later purging aren't allowed. EPA's topic list names controlled hot water and pressurization devices.
Why not the others: 25 mm Hg absolute is the full recovery level, not the non-major repair rule. Nitrogen is excluded for these refrigerants. A non-major repair still has a pressure requirement.
Source: 40 CFR 82.156(a)(1)(ii) · EPA Test Topics, Type 3 → Recovery Requirements
Review topic: Recovery requirements

Answer: D. Evacuate or pressurize to no higher than 5 psig before opening, or drain the oil into a system receiver at no higher than 5 psig.
Why: §82.156(a)(1)(iii) sets 5 psig as the limit for oil changes.
Why not the others: 25 mm Hg absolute is the full recovery level. 15 psig exceeds the limit. Oil changes still have a pressure requirement.
Source: 40 CFR 82.156(a)(1)(iii)
Review topic: Recovery requirements

Answer: C. Yes. The opening is 6 square inches, more than 4, and it stays open for more than 15 minutes.
Why: EPA counts as major any work that uncovers more than 4 square inches of flow area for more than 15 minutes. 2 × 3 = 6 square inches, open for 45 minutes.
Why not the others: Component removal is only one path to 'major.' The size threshold is 4 square inches, not 10. Charge size isn't part of the definition.
Source: 40 CFR 82.152, major maintenance, service, or repair
Review topic: Recovery requirements (major repair)

Answer: D. Removes noncondensables such as air that leak into the system, returning refrigerant to the system.
Why: Low-pressure chillers pull air and moisture in through leaks. The purge unit separates those noncondensables and sends refrigerant back. EPA lists the purge unit's purpose as a Type III topic.
Why not the others: Charging goes through the evaporator charging valve. Oil separation and pressure relief are different components.
Source: EPA Test Topics, Type 3 → Refrigeration
Review topic: Refrigeration

Answer: D. Low-pressure, because 25 psig equals 39.7 psia, which is below 45 psia.
Why: EPA's boundaries are in psia at 104°F. Convert first: 25 + 14.7 = 39.7 psia. Anything below 45 psia is low-pressure.
Why not the others: The boundary is 45 psia, not psig. It's nowhere near the high-pressure range of 170 to 355 psia. The pressure alone is enough to classify it.
Source: 40 CFR 82.152, pressure class definitions · EPA Test Topics, Type 2 → Refrigeration (add 14.7)
Review topic: Refrigeration (pressure classes)

Answer: A. Parts of the system run below atmospheric pressure, so outside air is pushed in.
Why: Low-pressure refrigerants sit below 45 psia even at 104°F, and much of the system operates in a vacuum. That's why EPA's Type III list talks about leaks into the system and uses excessive purging as a warning sign.
Why not the others: Refrigerant vapor is heavier than air, not lighter. The purge unit removes air; it doesn't pull it in. Parts that run above atmospheric pressure can still leak refrigerant out.
Source: EPA Test Topics, Type 3 → Leak Detection · 40 CFR 82.152, low-pressure appliance
Review topic: Leak detection

Answer: D. A refrigerant sensor in the equipment room.
Why: EPA's Type III list says ASHRAE Standard 15 requires an equipment-room refrigerant sensor for R-123. It also lists oxygen-deprivation sensors with all refrigerants.
Why not the others: A CO2 sensor doesn't detect R-123. EPA's list has no size exemption. Ventilation doesn't replace a required sensor.
Source: EPA Test Topics, Type 3 → Safety · ASHRAE Standard 15-2022, Addendum o, §8.9.5
Review topic: Safety

Answer: B. R-123 has higher toxicity than A-class refrigerants.
Why: In ASHRAE safety groups, the letter is toxicity and the number is flammability. 'A' means lower toxicity, so 'B' means higher toxicity. Flammability rises with the number (2L, 2, 3), so the '1' puts R-123 in the same flammability class as R-22.
Why not the others: Flammability is the number, not the letter. R-123 is an HCFC, so its ODP isn't zero.
Source: Mainstream manual, pp. 11–15 (Table C-2 and safety classes)
Review topic: Safety