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EPA 608 Core Answer Explanations

Core is the foundation for the equipment-specific EPA Section 608 sections. These answer explanations are for learners building their first study plan, technicians refreshing the vocabulary behind the rules, and anyone preparing for Universal certification. The questions connect refrigerant properties, environmental effects, the refrigeration cycle, recovery terminology, and safe handling. Understanding those connections makes it easier to reason through a question whose wording differs from the example you memorized.

Start by separating terms that sound similar. Recovering, recycling, and reclaiming describe different processes, and an answer about one process may be wrong for another. Environmental questions also ask you to distinguish ozone depletion from global warming. For cycle questions, follow the refrigerant through the compressor and condenser and identify which change each component produces.

Use this page after a Core practice session. Read the explanation for a missed answer, then describe the idea in your own words before trying another question. The related links lead to background reading when a definition or rule still feels unclear. Return to the Core study guide for an organized overview, or use the practice test to check whether you can apply the concept without seeing the answer.

Most-missed topics

Use these review prompts to catch common mix-ups in this question set; they are not a ranking based on learner scores.

Recovery vocabulary: Recovery removes refrigerant and stores it externally; it does not necessarily clean or test it.
Recycling versus reclamation: Recycling cleans recovered refrigerant for reuse; reclamation meets specified purity requirements verified by analysis.
Ozone versus climate: HFCs do not contain chlorine and do not deplete stratospheric ozone, but many have high global warming potential.
Cycle components: The compressor raises vapor pressure; the condenser rejects heat and changes vapor to liquid.

Sources: EPA Section 608 definitions and 40 CFR § 82.156 recovery requirements. See each answer for related study material.

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Core

Which listed refrigerant has a very low 100-year GWP compared with R-22, R-134a, and R-410A?

Correct answer: D. R-1233zd(E)

R-1233zd(E) has a very low GWP, close to 1 on commonly used 100-year assessments. It is a chlorine-containing unsaturated HCFO, not an HFC. GWP values depend on the assessment used; R-22, R-134a, and R-410A have much higher values.

The condenser

Correct answer: A. changes a high-pressure vapor to a high-pressure liquid.

The condenser rejects heat from the refrigerant. In a normal refrigeration cycle, it changes high-pressure vapor from the compressor into high-pressure liquid.

📖 Related rule: Core Study Guide

Recover any remaining refrigerant and then render the cylinder useless, then recycle the metal is the proper disposal method for;

Correct answer: C. Disposable cylinders

Disposable cylinders are not reusable recovery cylinders. After any remaining refrigerant is recovered, they should be rendered unusable and the metal recycled.

Why can CFC refrigerants carry chlorine into the stratosphere?

Correct answer: B. They are relatively stable and poorly soluble in water.

CFC molecules can persist long enough for atmospheric circulation to carry them to the stratosphere, where UV radiation releases chlorine. This concerns chlorine bound in a refrigerant molecule, not the solubility of elemental chlorine.

Why should a technician check current EPA civil-penalty limits rather than memorize an old dollar amount?

Correct answer: D. Maximum civil penalties are adjusted for inflation.

EPA adjusts civil monetary penalty limits for inflation. Applicable amounts depend on the violation and relevant dates; old study-guide dollar figures are not reliable current limits. Source: 40 CFR 19.4.

📖 Related rule: § 82.154 — Prohibitions

Crop loss, eye disease, and skin cancer have been attributed to;

Correct answer: C. Depletion of Stratospheric ozone

Stratospheric ozone absorbs harmful ultraviolet radiation. Ozone depletion allows more UV to reach the surface, which is linked to crop damage, eye disease, and skin cancer.

What is the Significant New Alternatives Policy (SNAP) Program?

Correct answer: A. EPA's program for identifying safer refrigerant alternatives.

SNAP is an EPA program used to evaluate and list safer substitutes. It is not limited to one appliance category such as residential, commercial, or industrial refrigeration.

📖 Related rule: § 82.154 — Prohibitions

For a DOT 4BA/4BW recovery cylinder subject to the standard five-year requalification interval, how often is requalification required?

Correct answer: C. 5 years

The standard interval for these cylinders is five years. The applicable specification, markings, permitted test method, and any exception or special permit control; this is not a universal hydrostatic-test rule for every refrigerant container. Source: 49 CFR 180.209.

HFCs

Correct answer: A. will not damage stratospheric ozone, but have a high GWP.

HFCs do not contain chlorine, so they do not deplete stratospheric ozone. Many HFCs still have high global warming potential.

The compressor ________

Correct answer: B. changes a low-pressure vapor to a high-pressure vapor.

The compressor raises refrigerant pressure. It takes low-pressure vapor from the evaporator side and compresses it into high-pressure vapor.

📖 Related rule: Core Study Guide

Before shipping any used refrigerant cylinders, check that the cylinder meets what standards:

Correct answer: A. Department of Transportation

Used refrigerant cylinders are regulated for transport. Before shipping, the cylinder must meet Department of Transportation requirements.

📖 Related rule: § 82.154 — Prohibitions

Under AHRI Guideline K, a recovery cylinder for nonflammable fluorocarbon refrigerant conventionally has which colors?

Correct answer: B. grey body and yellow top.

AHRI Guideline K recommends a gray body and yellow top/collar for these recovery cylinders. Color is not proof of DOT approval or refrigerant identity; check labels, markings, ratings, and requalification. Flammable-refrigerant cylinder markings differ.

Which international agreement (Treaty) regulated the production and use of CFCs, HCFCs, halons, methyl chloroform and carbon tetrachloride?

Correct answer: B. Montreal Protocol

The Montreal Protocol is the international agreement that phased down or phased out many ozone-depleting substances, including CFCs and HCFCs.

The low-side test-pressure data-plate value should be used by a technician to determine a safe pressure for:

Correct answer: B. leak testing.

The low-side test-pressure value identifies a safe pressure limit for leak testing. It is not used to decide recovery, charging, or retrofit procedures.

HCFCs contain

Correct answer: B. Hydrogen, Chlorine, Fluorine, and Carbon

HCFC stands for hydrochlorofluorocarbon. The name identifies hydrogen, chlorine, fluorine, and carbon in the molecule.

Which of the following has the highest Ozone Depletion Potential?

Correct answer: D. CFCs

CFCs have the highest ozone depletion potential among the listed refrigerant groups because they contain chlorine and are very stable in the lower atmosphere.

Which listed ASHRAE safety group denotes lower toxicity and lower flammability with a low burning velocity?

Correct answer: B. A2L

A2L combines toxicity class A with flammability subclass 2L. It does not mean nonflammable or harmless. Source: ASHRAE Standard 34 safety classifications.

To process refrigerant to a level equal to new (virgin) product specifications as determined by chemical analysis defines

Correct answer: B. Reclaiming

Reclaiming means processing used refrigerant until it meets new-product specifications, verified by chemical analysis. Recovery and recycling do not necessarily reach that purity level.

📖 Related rule: § 82.154 — Prohibitions

Which element in CFCs and HCFCs contributes to stratospheric ozone depletion?

Correct answer: D. Chlorine

Chlorine released from CFCs and HCFCs can react with ozone in the stratosphere. That is why chlorine-containing refrigerants are tied to ozone depletion.

Clean refrigerant for reuse by separating the oil from the refrigerant and removing moisture from the refrigerant by passing it through one or more filter driers, is the definition of

Correct answer: D. Recycle

Recycling cleans recovered refrigerant for reuse by separating oil and removing moisture through filter-driers. Reclaiming is a higher standard that returns refrigerant to new-product specifications.

An ozone molecule contains

Correct answer: C. Three oxygen atoms

Ozone is O3, meaning each ozone molecule contains three oxygen atoms. Regular oxygen gas is O2, with two oxygen atoms.

A single chlorine atom can destroy how many ozone molecules?

Correct answer: D. 100,000

One chlorine atom can repeatedly break apart ozone molecules before it is removed from the cycle. The common EPA 608 test figure is up to 100,000 ozone molecules.

Which of the following refrigerants is an HFO?

Correct answer: D. R-1234ze

R-1234ze is an HFO refrigerant. R-22 is an HCFC, while R-134a and R-410A are HFC refrigerants.

Which type of refrigerant contains no chlorine?

Correct answer: C. HFCs

HFCs contain hydrogen, fluorine, and carbon but no chlorine. CFCs and HCFCs contain chlorine, which is why they can deplete ozone.

As of what date did it become unlawful to release Class I and Class II refrigerants to the atmosphere?

Correct answer: B. July 1, 1992

Section 608's venting prohibition for Class I (CFCs) and Class II (HCFCs) refrigerants took effect July 1, 1992 — that's the date intentional release became a federal violation under the Clean Air Act. The 1990 date is when the CAA Amendments were signed; later dates pertain to other phaseout milestones. Knowing 'venting became illegal in July 1992' is a recurring exam fact.

📖 Related rule: § 82.154 — Prohibitions

What is the ozone layer and why is it important to us on Earth?

Correct answer: B. A stratospheric shield that absorbs much of the sun's harmful ultraviolet radiation.

The ozone layer is a region of the stratosphere (about 10–30 miles up) rich in O3 molecules that absorb the sun's high-energy UV-B and UV-C radiation before it reaches the surface. Without it, UV exposure would dramatically increase skin cancer, cataracts, and ecosystem damage. The other options confuse the ozone layer with refrigerants or with the troposphere.

The atom found in CFC and HCFC refrigerants that destroys ozone in the stratosphere is?

Correct answer: D. Chlorine

Chlorine is the ozone-destroying atom: UV radiation in the stratosphere breaks the C-Cl bond in CFCs/HCFCs, freeing chlorine atoms that catalytically split O3 molecules. One chlorine atom can destroy thousands of ozone molecules before being deactivated. Fluorine and carbon are bystanders; hydrogen makes HCFCs less stable in the troposphere (which is why HCFCs have lower ODP than CFCs).

What is an ozone molecule made of?

Correct answer: C. Three oxygen atoms, written as O3.

Ozone is O3 — three oxygen atoms bound together. Normal atmospheric oxygen is O2; ozone forms in the stratosphere when UV radiation splits O2 and one of the freed atoms bonds with another O2. This third oxygen atom is what makes ozone an effective UV absorber.

Which refrigerant is a CFC?

Correct answer: D. R-12

R-12 is a CFC containing carbon, chlorine, and fluorine. R-22 and R-123 are HCFCs; R-134a is an HFC with no chlorine. CFC atmospheric persistence allows chlorine to reach the stratosphere and contribute to ozone depletion.

What is the name of the atom that attacks ozone molecules?

Correct answer: C. Chlorine and bromine atoms released into the atmosphere.

Free chlorine and bromine atoms — released when UV radiation breaks down CFCs, HCFCs, and halons in the stratosphere — are what attack ozone. The atom rips an oxygen off O3 (forming ClO + O2), then regenerates so it can destroy thousands more ozone molecules. CFC or HCFC molecules themselves don't react with ozone; they have to break apart first.

Which refrigerant is an HFC?

Correct answer: A. R-134A

R-134a is an HFC (hydrofluorocarbon) — no chlorine, so its ODP is zero. R-12 is a CFC, R-22 and R-123 are HCFCs (still contain chlorine, just less stable). HFCs replaced CFCs/HCFCs because they don't deplete ozone, though many still have high GWP.

Describe how one Chlorine atom can destroy 100,000 ozone molecules.

Correct answer: A. Chlorine breaks ozone apart and is freed again, so the same atom can repeat the reaction.

Chlorine destroys ozone catalytically: Cl + O3 → ClO + O2, then ClO + O → Cl + O2. The chlorine atom comes back out of the reaction unchanged, free to attack another ozone molecule. That regeneration is why a single chlorine atom can destroy tens of thousands of ozone molecules before being deactivated by other chemistry.

Which refrigerant contains no chlorine?

Correct answer: A. R-134A

R-134a is an HFC (hydrofluorocarbon) — it has hydrogen, fluorine, and carbon, but no chlorine. R-12, R-22, and R-123 all contain chlorine, which is what damages stratospheric ozone. HFCs were developed specifically to replace chlorinated refrigerants for that reason.

Which of the following correctly identifies refrigerants in the CFC, HCFC, and HFC categories?

Correct answer: A. CFCs: R-11/R-12/R-500; HCFCs: R-22/R-123; HFCs: R-134a.

R-11 and R-12 are CFCs; R-500 is a CFC-containing blend of R-12 and R-152a. R-22 and R-123 are HCFCs, and R-134a is an HFC. HFCs contain no chlorine; a refrigerant blend may contain components from more than one chemical family.

The rule of thumb for refilling approved cylinders is a maximum of ________ percent liquid?

Correct answer: C. 80%

Refillable refrigerant cylinders must never be filled beyond 80% of their rated capacity by liquid volume. The remaining 20% headspace allows for liquid expansion as temperature rises; without it, hydraulic pressure can rupture the cylinder.

What do the letters in “HCFC” stand for?

Correct answer: B. Hydrochlorofluorocarbons

HCFC stands for HydroChloroFluoroCarbon. The added hydrogen makes the molecule less stable, so most break down in the troposphere before reaching the stratosphere — that's why HCFCs (R-22, R-123) have lower ODP than CFCs (R-11, R-12). HFCs drop the chlorine entirely; HFOs are HFCs with a double bond that further reduces atmospheric lifetime.

To recover refrigerant is to?

Correct answer: A. Remove refrigerant from a system and store it externally without testing or processing it.

Recovery means simply removing refrigerant from a system into an external container — no cleaning, no testing, no processing. Recycling cleans the refrigerant on site (oil separation, filter-drier passes). Reclamation reprocesses it to AHRI 700 new-product purity, normally off site. Knowing the three definitions is a recurring exam topic.

What is ODP?

Correct answer: B. Ozone Depletion Potential

ODP (Ozone Depletion Potential) measures how much a chemical destroys stratospheric ozone compared to R-11, which is set at 1.0. The other options are made-up phrases with similar initials. ODP is paired with GWP (Global Warming Potential) when classifying refrigerants for regulation.

R-134A is a “drop in” refrigerant for?

Correct answer: D. None; R-134a is not a drop-in refrigerant.

R-134a cannot simply replace another refrigerant without evaluating the equipment and lubricant. Follow a manufacturer-approved retrofit procedure, including lubricant, seals, metering, and labeling requirements.

Name some of the health and environmental effects of ozone depletion.

Correct answer: A. Increased UV exposure, skin cancer, cataracts, and damage to crops and ecosystems.

Stratospheric ozone absorbs much of the sun's harmful UV radiation. Depletion increases UV-B exposure and its health and ecological effects. Greenhouse warming and ozone depletion are different mechanisms.

The condition and state of the refrigerant leaving a receiver is?

Correct answer: A. Liquid refrigerant.

The receiver's liquid outlet supplies liquid to the liquid line. Whether that liquid is saturated or subcooled depends on operating conditions; subcooling is not guaranteed merely by being in a receiver.

📖 Related rule: Core Study Guide

What evidence do we have that CFCs and HCFCs are depleting the ozone?

Correct answer: A. Stratospheric chlorine trends match CFC emissions, while volcanoes contribute little chlorine.

Direct atmospheric measurements show stratospheric chlorine concentrations rose in lockstep with CFC/HCFC production, then began to decline after the Montreal Protocol cut emissions. Volcanic chlorine is mostly water-soluble HCl that rains out of the lower atmosphere — it doesn't reach the stratosphere in significant amounts. The data, not just modeling, drives the link between CFCs and ozone loss.

The component of an air conditioning system that changes a low pressure vapor to a high pressure vapor is the?

Correct answer: D. Compressor

The compressor takes in low-pressure, low-temperature vapor from the evaporator and compresses it into high-pressure, high-temperature vapor headed for the condenser. The condenser then rejects heat and condenses the vapor; it does not raise pressure.

📖 Related rule: Core Study Guide

What characteristics make it easy for CFCs to reach the stratosphere and how do they get there?

Correct answer: B. CFCs do not dissolve or break down easily, so winds carry them to the stratosphere.

CFCs are chemically very stable — they don't dissolve in water (so rain doesn't wash them out) and don't react in the lower atmosphere. That long lifetime gives normal atmospheric mixing decades to carry them up to the stratosphere, where intense UV finally breaks them apart and frees the chlorine. Density doesn't matter much because gases mix; what matters is how long the molecule survives intact.

Why do we now use R-134a refrigerant?

Correct answer: B. HFCs do not contain any chlorine

HFCs like R-134a contain no chlorine, so they have zero ozone depletion potential — that's the regulatory reason for the switch from R-12 (a CFC). Cost wasn't the driver. It's not a drop-in for R-22 or R-11, which run at very different pressures.

What is the purpose of the CAA?

Correct answer: C. Limit how much of a pollutant can be in U.S. air.

The Clean Air Act sets nationwide limits on how much of a given pollutant may be released into U.S. air. It applies federally, not just to California (A), and it does set enforceable pollutant limits (B is wrong). It regulates air quality, not aircraft (D is a play on the abbreviation).

📖 Related rule: § 82.154 — Prohibitions

What three things is the CAA doing to control chlorofluorocarbon emissions?

Correct answer: A. Setting phase-out dates, prohibiting venting, and requiring recovery before disposal.

Title VI of the CAA phases out ozone-depleting substances on a published schedule, prohibits the knowing release (venting) of refrigerant during service, and requires recovery before equipment disposal. Tax credits for CFC use, state opt-outs, and voluntary-only guidelines all run opposite to how the CAA actually works.

📖 Related rule: § 82.154 — Prohibitions

What can states do in addition to the CAA?

Correct answer: A. Enforce stricter standards than the CAA and create refrigerant laws.

The CAA sets a federal floor, not a ceiling — states are free to pass stricter refrigerant rules (California's CARB regulations are the classic example). States cannot override federal law (C) or veto EPA enforcement (D), and inaction (B) is not required.

📖 Related rule: § 82.154 — Prohibitions

What three things can happen if you violate the CAA?

Correct answer: A. Daily fines, loss of certification, and possible federal court charges.

Violations can lead to civil penalties and, where applicable, criminal enforcement and certification-related consequences. Penalty amounts are adjusted over time and depend on the legal provision and relevant dates; do not rely on an old fixed dollar figure.

📖 Related rule: § 82.154 — Prohibitions

How can suspected unlawful refrigerant venting be reported?

Correct answer: A. Through EPA's environmental-violation reporting channels.

EPA accepts reports of suspected environmental violations. Provide factual information through official channels; do not assume a report guarantees a reward or attempt unsafe evidence collection.

📖 Related rule: § 82.154 — Prohibitions

Which of the following is true about refrigerant purchasing under EPA rules?

Correct answer: A. Sales are restricted to certified technicians, including HCFC purchases in larger cylinders.

Section 608 sales restrictions limit purchases of regulated refrigerants (CFC, HCFC, and most HFCs) to EPA-certified technicians or employers of certified technicians, with narrow exceptions such as purchases for resale and appliance manufacturers. There's no under-20-pound exemption for the general public (B), manufacturers aren't the only allowed buyers (C), and there's no one-pound retail rule (D).

📖 Related rule: § 82.154 — Prohibitions

What is the Montreal Protocol?

Correct answer: B. A treaty among nations to protect the stratospheric ozone layer.

The Montreal Protocol (1987) is an international treaty that phases out production and consumption of ozone-depleting substances — CFCs, halons, carbon tetrachloride, methyl chloroform, and HCFCs. It is widely credited as the most successful global environmental treaty: stratospheric chlorine peaked in the late 1990s and is now declining. The Kigali Amendment (2016) added HFCs to the protocol's scope.

What chemicals does the Montreal Protocol control?

Correct answer: A. CFCs, halons, carbon tetrachloride, and methyl chloroform.

The Montreal Protocol targets ozone-depleting substances: CFCs, HCFCs, halons (firefighting agents), carbon tetrachloride, and methyl chloroform. HFCs were added later via the 2016 Kigali Amendment because they are potent greenhouse gases, but the original protocol's focus was strictly stratospheric ozone.

On what date did the U.S. phaseout of most CFC production and import for ordinary use take effect?

Correct answer: D. January 1, 1996

The main U.S. CFC phaseout took effect January 1, 1996, subject to specified exemptions. It did not prohibit all continued use of previously produced CFCs in existing equipment. Follow recovery, sales, and other applicable requirements.

Where do CFC refrigerants come from for equipment servicing of older systems?

Correct answer: C. Previously produced stock and properly recovered, recycled, or reclaimed supplies.

Existing CFC equipment can be serviced using lawful existing stocks and properly handled recovered refrigerant. Transfers for use by a new owner generally require reclamation; phaseout of new production does not mean every existing cylinder must be discarded.

What must be done before scrapping a refrigerant container?

Correct answer: B. Recover remaining refrigerant and follow the container manufacturer's disposal procedure.

Do not vent, puncture, or cut a cylinder that still contains refrigerant. A 0 psig reading alone does not prove it is empty. Qualified handling and the manufacturer's disposal instructions determine when it can be rendered unusable and recycled.

What must be done before disposing of an appliance containing CFCs or HCFCs?

Correct answer: D. Refrigerant must be recovered

Section 608 requires that refrigerant be recovered from any appliance before it is disposed of, regardless of charge size. The person who actually disposes of the appliance is responsible for ensuring recovery happened, and a signed statement may be needed in the chain of custody. The 'tag' options are made-up — there is no DOE/CAA/EPA tag for refrigerant identification at disposal.

For a small appliance entering the waste stream, who must ensure refrigerant has been recovered before final disposal?

Correct answer: D. The final person in the appliance disposal chain.

The final disposer must recover the refrigerant or obtain the required verification that it was previously recovered, as applicable. This duty does not authorize venting earlier in the disposal chain or erase other persons' obligations. Source: 40 CFR 82.155.

📖 Related rule: § 82.154 — Prohibitions

Are there "drop-in" replacements for R-12 systems and if not, why?

Correct answer: A. No universal drop-in exists; follow a refrigerant- and equipment-specific retrofit procedure.

A replacement refrigerant must be approved for the application and compatible with the equipment and lubricant. Required oil or component changes depend on the specific retrofit; do not claim every replacement requires the same changes.

For stationary R-134a equipment designed for POE lubricant, how should replacement oil be selected?

Correct answer: A. Use the manufacturer's approved POE grade and compatibility requirements.

Lubricant choice depends on the compressor and application. POE/mineral-oil mixing is not the same issue as refrigerant/oil miscibility and oil return. Follow manufacturer limits on residual oil and approved lubricant combinations.

Why can a zeotropic blend's composition change during a vapor leak?

Correct answer: A. They leak at different rates because each component has its own vapor pressure.

Liquid and vapor phases of a zeotropic blend can have different compositions. Loss of vapor can change the remaining composition; the effect depends on the blend and leak conditions. Withdraw blend charge from the supply cylinder as liquid and follow the manufacturer's charging procedure.

What does a compressor compress?

Correct answer: D. Low-pressure, low-temperature vapor.

A compressor compresses low-pressure, low-temperature vapor returning from the evaporator. It must never see liquid refrigerant, which is incompressible and will cause slugging damage to valves and pistons.

📖 Related rule: Core Study Guide

How does a vapor-compression air conditioner remove heat from an indoor space?

Correct answer: B. It absorbs heat at the evaporator and rejects it at the condenser.

Refrigerant absorbs heat in the evaporator and releases heat in the condenser. The condenser also rejects the energy supplied to the compressor. Sensible heat transfer can occur as well as the phase-change heat transfer.

📖 Related rule: Core Study Guide

Why can refrigerant migrate into a compressor crankcase during an off cycle?

Correct answer: A. A cooler crankcase and refrigerant's affinity for oil can draw vapor into the compressor.

Off-cycle migration depends on temperature and refrigerant/oil behavior, not simply elevation. Manufacturer-specified crankcase heaters and other controls can limit refrigerant accumulation and oil dilution.

📖 Related rule: Core Study Guide

What color is the compound gauge and what does the compound gauge measure?

Correct answer: A. Blue; it measures low pressure and vacuum.

The blue compound gauge connects to the suction (low) side and reads both positive pressure and vacuum (in. Hg) — it's called "compound" because it spans both ranges. Red is the high-side gauge, yellow is the center service hose. Green isn't a standard manifold color.

What color is the high pressure gauge?

Correct answer: B. Red; it measures the high-side discharge pressure.

Red conventionally identifies the high-side gauge on a service manifold. Check the instrument's range, refrigerant compatibility, and pressure rating; color alone does not establish suitability.

What are three things the center hose is used for and what color is it usually?

Correct answer: B. Yellow hose connected to recovery, evacuation, or charging devices.

The yellow center hose on a manifold gauge set is the service port — it connects to whatever auxiliary device the job requires: a recovery machine, vacuum pump, or charging cylinder/scale. Blue is low-side, red is high-side, both connecting directly to the system.

What things should you look for in equipment and systems to help limit refrigerant emissions?

Correct answer: A. Use EPA-approved equipment, check for leaks, repair leaks, and keep service fittings tight.

Use suitable certified recovery equipment, control service losses, and inspect and repair leaks as required. Scheduled topping-off is not a substitute for diagnosing leaks or meeting the applicable Section 608 or AIM Act requirements.

Which tool can detect small leaks of a refrigerant for which it is specifically rated?

Correct answer: D. A compatible electronic refrigerant leak detector.

Use an electronic leak detector compatible with the specific refrigerant and follow its instructions. Pressure monitors, vacuum gauges, and thermometers do not directly pinpoint gas leaks.

📖 Related rule: § 82.154 — Prohibitions

Which method can locate an accessible leak in a properly prepared refrigerant circuit?

Correct answer: A. An approved regulated dry-nitrogen pressure test with bubble solution.

Use the manufacturer's pressure-test procedure and limits. A standing-vacuum test can reveal a problem but pressure rise can also result from moisture or outgassing, and it does not locate the leak.

After a suspected compressor burnout, what should be checked before returning the system to service?

Correct answer: C. Oil/refrigerant contamination using the manufacturer's prescribed tests.

Use suitable acid/contamination testing and the manufacturer's cleanup procedure. Do not rely on touching lines or subjective checks as proof of a specific failure.

📖 Related rule: Core Study Guide

What will need to happen if the oil has been contaminated by a burnout?

Correct answer: A. Follow the manufacturer's burnout cleanup, lubricant, filter-drier, and evacuation procedure.

Burnout cleanup depends on the system and contamination. Replace or treat contaminated components and lubricant as specified, then verify cleanup. A permanent suction filter-drier and one fixed evacuation sequence are not universal requirements.

How is recovery different from recycling?

Correct answer: A. Recovery stores removed refrigerant; recycling cleans recovered refrigerant for reuse.

Recovery just removes the refrigerant from the appliance and puts it into a container — no purity work. Recycling adds basic on-site cleanup (oil separation, filter-drier passes) so the refrigerant can be reused, but not to new-product purity. Reclamation goes further: lab-tested to AHRI 700 specs, normally off site.

What distinguishes reclamation from routine field recycling?

Correct answer: C. Reclamation processes and verifies refrigerant to the required purity specification.

Recycling reduces contaminants; reclamation requires processing and analytical verification to the specified purity. EPA-certified reclaimers perform reclamation for resale. Reclaimed refrigerant remains subject to applicable sales restrictions.

Name reasons recovery is important?

Correct answer: A. To preserve refrigerant supply, prevent venting, and reduce ozone-depletion risk.

Recovery matters because it (1) keeps ozone-depleters and high-GWP gases out of the atmosphere, (2) preserves the limited supply of phased-out refrigerants like R-12 and R-22 for service use, and (3) is required by Section 608 of the Clean Air Act. The other options invert the rationale — recovery is not about price-gouging or skipping required processes.

What certification applies to Section 608 recovery equipment manufactured or imported on or after November 15, 1993?

Correct answer: A. Certified and labeled by an EPA-approved testing laboratory.

Applicable recovery/recycling equipment must be certified by an EPA-approved organization. Older equipment has different conditions. EPA's Section 608 program lists AHRI and UL; do not confuse it with Section 609 equipment certification. Source: 40 CFR 82.158.

📖 Related rule: § 82.154 — Prohibitions

What two main types of recovery equipment are used?

Correct answer: A. System-dependent/passive and self-contained/active.

Self-contained equipment provides its own recovery capability; system-dependent equipment relies on appliance components or pressure. Both must be suitable for the refrigerant and application. System-dependent equipment has a 15-pound full-charge limit except for permanently attached pump-out units. Source: 40 CFR 82.156(e).

What should you explain to a customer concerned about the cost of required recovery of a non-exempt refrigerant?

Correct answer: A. Recovery is legally required and protects health and the environment.

Applicable recovery requirements cannot be waived because a customer wants a cheaper repair. Recovery limits refrigerant emissions and preserves supplies. Consult current EPA requirements rather than quoting an outdated penalty amount.

How should you handle recovery of a system that has mixed refrigerants?

Correct answer: A. Recover the mixture into a separate tank.

Recover mixed refrigerant into a separate, compatible, properly labeled container and consult a certified reclaimer. Depending on the mixture and facility, separation/reclamation may be possible or destruction may be necessary. Never vent it or contaminate a cylinder of known refrigerant.

After recovery, what are nitrogen and a filter drier used for?

Correct answer: A. They dry the system, flush debris, and trap loosened debris.

Dry nitrogen can be part of an approved purge or cleaning procedure after refrigerant recovery, while an appropriate filter-drier removes moisture and captures contaminants. Follow the manufacturer's cleanup method; nitrogen purging does not replace proper dehydration and does not clean every type of contamination.

What are the variables that affect the recovery rate?

Correct answer: A. System size, recovery equipment, suction hose size, and ambient temperature.

Recovery speed depends on real physics: how much refrigerant is in the system, how much pumping capacity the recovery machine has, hose diameter and length (bigger and shorter = faster), and ambient/cylinder temperatures. Cylinder color, hose age, and brand of gauges have no effect on recovery rate — those answers are distractors.

Why is it important to have faster recovery?

Correct answer: A. It reduces service time while still meeting recovery and safety requirements.

Efficient recovery reduces job time, but speed does not replace the required recovery level, safe cylinder fill limits, or equipment instructions. Oil removal is not the general purpose of speeding refrigerant recovery.

What is the appropriate response to an unexpected strong odor during recovery?

Correct answer: A. Stop and assess exposure and contamination safely; do not diagnose by smell alone.

Unexpected odor may indicate a leak or contamination. Follow the refrigerant SDS, exposure controls, and equipment procedures. A burnout is one possible cause, not a diagnosis established by odor.

Why is it necessary to dehydrate a refrigeration system?

Correct answer: D. Remove water and water vapor from the system.

Dehydration removes water and water vapor that can contribute to corrosion, chemical degradation, and ice blockages. Follow the manufacturer's vacuum and standing-test requirements; a low reading alone does not prove that all moisture has been removed.

What happens if moisture is left in an operating refrigeration system?

Correct answer: B. It can create highly corrosive and toxic acids.

Moisture can contribute to acid formation, corrosion, lubricant degradation, and ice blockages. The reactions depend on the refrigerant and lubricant; not every system forms the same acids.

Before dehydrating a refrigerant circuit with an ordinary vacuum pump, what must be done?

Correct answer: C. Recover refrigerant using suitable recovery equipment to the applicable required level.

Recovery captures refrigerant; subsequent dehydration removes moisture and noncondensables. Do not use an ordinary vacuum pump to discharge refrigerant to atmosphere. Follow 40 CFR 82.156 and equipment instructions.

What are the four factors that affect the evacuation time?

Correct answer: A. Equipment size, ambient temperature, moisture amount, and vacuum-pump/suction-line capacity.

Evacuation time is driven by physical factors: the internal volume of the equipment, the ambient temperature (which sets how easily water boils off), the amount of moisture present, and the capacity of the pump and suction line that has to move the vapor. The other choices list cosmetic or unrelated items (cylinder color, day of week) that have no effect on how long pump-down takes.

Can you increase the temperature of a refrigeration system for evacuation and if so, what purpose does it have?

Correct answer: A. Yes; approved controlled warming can help moisture vaporize.

After recovery, manufacturer-approved controlled warming can assist dehydration by helping moisture vaporize. Use compatible equipment and monitor limits; no open flame or unapproved ignition source is appropriate.

How long and what diameter should the piping connection to the vacuum pump be?

Correct answer: D. As short as possible and as wide in diameter as possible.

Short, suitably large vacuum-rated hoses reduce flow restriction and speed evacuation. Hose and fitting compatibility, valve cores, pump capacity, and system moisture also affect evacuation time.

How big should the vacuum hoses be in relation to the pump intake connection?

Correct answer: B. Equal to or larger than the pump intake connection

Hoses should match or exceed the pump intake diameter so they don't become the restriction that limits pumping speed. Standard 1/4-inch service hoses choke a large vacuum pump, while equal-or-larger evacuation hoses preserve the conductance the pump was designed for.

For accurate vacuum readings, where should the vacuum gauge be located?

Correct answer: C. As far as possible from the vacuum pump.

Place the micron gauge on the system, away from the pump where practical, to measure system pressure rather than just pump-inlet pressure. Isolate the pump for the manufacturer's standing-vacuum test. Deep-vacuum dehydration and EPA recovery limits serve different purposes.

When should the measurement of vacuum for a system be done and how do we know when dehydration is complete?

Correct answer: C. Isolate the system from the pump and meet the manufacturer's vacuum and hold-time criteria.

A brief low reading at the pump does not establish that the system is dry and tight. Use the manufacturer's target, isolation procedure, hold time, and allowed pressure rise. One minute is not a universal dehydration acceptance test.

What are the risks of inhaling (breathing in) refrigerants?

Correct answer: A. Refrigerants can be deadly if inhaled or heated.

Refrigerants displace oxygen and can cause asphyxiation; some also cause cardiac sensitization (fatal arrhythmia) at high concentrations. When heated by flame or hot surfaces they decompose into toxic byproducts like phosgene and hydrogen chloride. They are not inert (B) and don't become safer with heat (C, D).

📖 Related rule: § 82.154 — Prohibitions

How can a large refrigerant release cause asphyxiation?

Correct answer: B. By displacing oxygen in the breathing atmosphere.

Refrigerants can displace oxygen in the breathing atmosphere, especially in enclosed spaces, leading to asphyxiation.

📖 Related rule: § 82.154 — Prohibitions

What personal protective equipment should you wear when handling refrigerants?

Correct answer: A. Eye protection and gloves/clothing selected using the refrigerant SDS and task hazards.

Use appropriate eye protection and cold/chemical-resistant gloves and clothing. The SDS and job risk assessment determine materials and additional protection; one glove material is not suitable for every refrigerant.

What is a purpose of machinery-room refrigerant detection under applicable safety requirements?

Correct answer: A. Warn of unsafe refrigerant concentrations and initiate required protective actions.

Machinery-room detection and ventilation depend on the refrigerant, system, adopted code, and applicable ASHRAE Standard 15 edition. An ordinary oxygen sensor is not a universal replacement for refrigerant-specific detection.

How should machinery-room refrigerant alarm setpoints be selected?

Correct answer: A. Using the refrigerant-specific limits and applicable code/standard.

Use the applicable refrigerant concentration limits, code edition, and equipment design. Toxicity, asphyxiation, and flammability can require different detection criteria; do not generalize a historical threshold to every refrigerant.

What does ASHRAE safety group A1 mean?

Correct answer: A. Lower toxicity and no flame propagation under the standard's test conditions.

The letter and number describe toxicity and flammability classifications, not an overall guarantee of safety or operating pressure. Follow the refrigerant SDS and applicable equipment requirements.

📖 Related rule: § 82.154 — Prohibitions

Why should oxygen or compressed air never be used to leak test a system?

Correct answer: A. Oxygen or compressed air, when mixed with refrigerants, can cause an explosion

Oxygen or compressed air can create hazardous reactions with refrigerant or oil under pressure. Use the manufacturer's approved inert-gas procedure, commonly regulated dry nitrogen, with appropriate pressure limits and relief protection.

When pressurizing a system with dry nitrogen for an approved test, what pressure controls are needed?

Correct answer: B. Charge through a pressure regulator, with a relief valve installed downstream of the regulator.

Nitrogen cylinder pressure can greatly exceed the equipment's allowed test pressure. Use a suitable regulator and downstream relief protection, and follow the equipment's specified test limit.

📖 Related rule: § 82.154 — Prohibitions

Where can you find the appropriate test pressures for a system?

Correct answer: C. The manufacturer's certified test data.

Use the manufacturer's specified test pressures, equipment nameplate ratings, and limits of all affected components. A service-valve label or a generic refrigerant list is not sufficient to determine the allowable test pressure.

📖 Related rule: § 82.154 — Prohibitions

What are the two conditions to be aware of in observing relief valves?

Correct answer: A. Inspect for damage/corrosion and verify the approved installation arrangement.

Pressure-relief devices must be correctly rated, installed, and maintained under the applicable code and manufacturer's instructions. Do not alter discharge paths or assume every engineered series arrangement is prohibited.

📖 Related rule: § 82.154 — Prohibitions

What can happen to refrigerants if they are exposed to direct flame or other excessive heat?

Correct answer: A. They can form toxic materials such as phosgene, and cylinders may explode.

Excessive heat can cause dangerous pressure rise and hazardous refrigerant decomposition. Products depend on refrigerant chemistry; chlorinated refrigerants can form especially toxic decomposition gases. Follow the SDS and never heat a cylinder with a flame.

Before welding, cutting or brazing a refrigerant line, what should be done?

Correct answer: B. Recover refrigerant and follow the manufacturer's hot-work and inert-purge procedure.

Remove refrigerant using approved recovery procedures, isolate energy sources, and follow the refrigerant-specific hot-work procedure. Flammable refrigerants require additional ignition and atmosphere controls. Do not weld, braze, or cut a charged line.

In case of a major refrigerant leak, what actions should be taken?

Correct answer: D. Evacuate the area and follow the emergency-response plan; restrict re-entry to qualified responders.

Leave a suspected hazardous atmosphere and summon appropriate help. Ventilation and leak isolation must be performed safely. SCBA requires trained, qualified users and a respiratory-protection program; possessing it does not make untrained re-entry safe.

How do you verify a cylinder is suitable for refrigerant recovery?

Correct answer: D. Check approval markings, pressure/refrigerant suitability, condition, and requalification.

Use a refillable recovery cylinder suitable for the refrigerant and pressure. Color conventions can help recognition but do not establish approval or contents. Do not refill disposable refrigerant cylinders.

For a DOT 4BA/4BW recovery cylinder subject to the standard five-year interval, when is requalification due?

Correct answer: A. Every 5 years

The standard interval is five years. Verify the cylinder specification, markings, applicable test method, and any exception or special permit. Source: 49 CFR 180.209.

What must be done to a cylinder (disposable or refillable) before scrapping it?

Correct answer: B. Recover remaining refrigerant and follow the manufacturer's approved cylinder-disposal procedure.

Zero gauge pressure alone does not prove a container has no remaining refrigerant. Do not puncture, cut, or scrap it until properly emptied and prepared under applicable instructions and requirements.

Why must a recovery cylinder's permitted liquid fill limit, commonly 80% of internal volume, not be exceeded?

Correct answer: B. Heat can raise pressure in an overfilled cylinder and cause an explosion.

Liquid expands when warmed. Adequate vapor space helps avoid dangerous hydraulic pressure. The common 80% guideline concerns liquid volume, not 80% of gross cylinder weight; determine permitted refrigerant mass from cylinder data and the applicable refrigerant filling limit.

What can happen if cylinders are exposed to flames or excessive heat?

Correct answer: A. The cylinder can explode, leak from rising pressure, or form toxic decomposition products.

Flames or excessive heat can cause pressure rise, container failure, and hazardous decomposition. Follow the cylinder and refrigerant manufacturer's temperature and storage limits.

What are the ways you can control the fill level of a refillable cylinder?

Correct answer: A. Mechanical floats, electronic floats, and weighing the cylinder on a scale.

Use a scale and the correct cylinder/refrigerant filling limit. A compatible float or overfill cutoff can be supplementary protection, but pressure or temperature alone does not establish safe fill. Account for tare weight; 80% liquid volume is not 80% gross weight.

Which transport practice is appropriate for upright service cylinders whose manufacturer requires upright handling?

Correct answer: A. Upright, secured in a cradle, or vertically bundled and strapped on a pallet.

Secure the cylinders against movement and protect valves in the specified orientation. Follow the cylinder instructions and applicable DOT transport requirements; do not transport cylinders loose.

Which hazard label applies to a refrigerant shipped as a nonflammable, nontoxic Division 2.2 compressed gas?

Correct answer: A. DOT classification tag indicating it is a “2.2 non-flammable gas”

Division 2.2 applies to nonflammable, nontoxic gases meeting that classification. Other refrigerants can require different classifications, including flammable-gas labeling. Check the SDS and DOT hazardous-materials requirements for the actual contents.

Which released species from CFCs can catalytically destroy stratospheric ozone?

Correct answer: B. Free chlorine atoms

UV breakdown of CFCs releases chlorine that participates in ozone-destruction cycles. Bromine from some other ozone-depleting substances also contributes. This question concerns CFC-related depletion, not every atmospheric ozone reaction.

Which of the following refrigerants contain chlorine?

Correct answer: A. CFCs and HCFCs

The "C" in CFC and HCFC stands for chloro — both contain chlorine. HFCs (hydrofluorocarbons) contain only hydrogen, fluorine, and carbon — no chlorine, so zero ODP. Hydrocarbons (propane, isobutane) contain only hydrogen and carbon, also no chlorine.

R-12, R-22, and R-134a are classified, respectively, as:

Correct answer: C. CFC, HCFC, HFC

R-12 is a fully halogenated CFC (chlorine + fluorine + carbon, no hydrogen) — high ODP and now phased out. R-22 is HCFC; the H makes it less stable in the atmosphere, lowering ODP compared to CFCs but not to zero. R-134a is HFC — no chlorine, zero ODP.

Which group of refrigerants has the highest ozone-depletion potential (ODP)?

Correct answer: C. CFCs

CFCs generally have higher ODP than HCFCs because of their chlorine content and atmospheric persistence. HFCs and hydrocarbons have zero ODP. CFCs contain carbon, chlorine, and fluorine; they are not '100% chlorine.'

CFC and HCFC refrigerants released into the atmosphere primarily affect:

Correct answer: B. The stratospheric ozone layer.

CFCs and HCFCs are stable enough to drift up to the stratosphere, where UV breaks them apart and the freed chlorine destroys ozone. Ground-level smog, drinking water, and soil acidity are real environmental issues but driven by other pollutants (NOx, VOCs, sulfur compounds) — not by halocarbon refrigerants.

Increased ultraviolet radiation reaching the Earth's surface as a result of stratospheric ozone depletion can cause:

Correct answer: A. Increased skin cancer and cataracts.

Less ozone means more UV-B reaches the surface, which damages skin cells (raising skin cancer rates) and the lens of the eye (raising cataract rates). It also harms crops, marine plankton, and immune systems. The other options describe unrelated air-quality issues — fuel economy, acid rain, and CO poisoning aren't linked to ozone depletion.

Evidence that CFCs and HCFCs deplete stratospheric ozone is supported by:

Correct answer: B. Atmospheric measurements showing CFC byproducts in the stratosphere.

Measurements of ozone-depleting substances and reactive chlorine in the stratosphere, together with laboratory chemistry and atmospheric observations, support the link. The conclusion does not depend on computer models or industry reports alone.

Production of CFC refrigerants in the United States was phased out on:

Correct answer: B. January 1, 1996

The main U.S. CFC production/import phaseout took effect January 1, 1996, with specified exemptions. Existing equipment may still be serviced using lawful previously produced or appropriately recovered supplies.

Production and import of HCFC-22 (R-22) for use in new equipment was phased out on:

Correct answer: A. January 1, 2010

The restriction on production/import of R-22 for new equipment took effect in 2010. The broader phaseout of ordinary R-22 production/import took effect January 1, 2020. Lawful existing stock and reclaimed supplies can still service existing equipment. Source: EPA HCFC phaseout guidance.

Knowingly releasing refrigerant during the servicing of an appliance is:

Correct answer: C. Prohibited under the Clean Air Act

Section 608 of the Clean Air Act prohibits the knowing release of any class I (CFC), class II (HCFC), or non-exempt substitute refrigerant during service, maintenance, repair, or disposal. There is no "small amount" exemption (A), no HFC carve-out from the venting prohibition (B), and no annual allowance (D).

📖 Related rule: § 82.154 — Prohibitions

Before disposing of an appliance containing a non-exempt regulated refrigerant, what must be done?

Correct answer: B. Recover the refrigerant

Recover the refrigerant according to the requirements for the appliance and refrigerant. Do not cut charged lines or vent the contents. Some substitute refrigerants have application-specific exemptions; those do not eliminate safety or other disposal obligations. Source: 40 CFR 82.154-82.156.

The venting prohibition under Section 608 applies to:

Correct answer: C. CFCs, HCFCs, and non-exempt substitutes, including HFCs.

The prohibition covers ozone-depleting refrigerants and non-exempt substitutes during maintenance, service, repair, or disposal. The statutory substitute prohibition took effect in 1995; it was not first created by the 2016 equipment-management rule. Source: 40 CFR 82.154(a).

📖 Related rule: § 82.154 — Prohibitions

Which statement about Clean Air Act civil penalties is accurate?

Correct answer: C. Applicable maximum amounts are adjusted for inflation.

Consult the current penalty schedule and applicable dates rather than an old study-guide amount. Civil penalties are not the only possible enforcement consequence. Source: 40 CFR 19.4.

📖 Related rule: § 82.154 — Prohibitions

The Montreal Protocol is:

Correct answer: B. An international agreement to phase out ozone-depleting substances.

The Montreal Protocol (1987) is an international treaty under which countries agreed to phase out production and consumption of ozone-depleting substances — CFCs, HCFCs, halons, and others. It is widely cited as the most successful environmental treaty: stratospheric chlorine is now declining. The U.S. implements it via Title VI of the Clean Air Act (Section 608 is part of that).

Which refrigerant is classified as a low-pressure refrigerant?

Correct answer: C. R-123

R-123 is a low-pressure refrigerant; its low-side pressure is below atmospheric (a vacuum) at normal chiller temperatures. R-11 was the older low-pressure refrigerant that R-123 replaced. R-22 and R-410A are high-pressure refrigerants and run well above atmospheric.

System-dependent (passive) recovery equipment:

Correct answer: B. Relies on appliance compressor or pressure to push refrigerant out.

System-dependent equipment relies on the appliance's components or pressure. The general full-charge limit is 15 pounds, except for permanently attached pump-out units. A small appliance is a separate factory-sealed category limited to five pounds. Source: 40 CFR 82.152 and 82.156(e).

Which equipment uses Section 609 rather than Section 608 technician certification for refrigerant service?

Correct answer: C. Motor vehicle air conditioners

MVAC service uses Section 609 certification. Some Section 608 provisions, including the venting prohibition and safe disposal requirements, also apply to MVACs; it is incorrect to say Section 608 never applies to them.

📖 Related rule: § 82.154 — Prohibitions

Section 608 recovery/recycling equipment manufactured or imported on or after November 15, 1993 must be certified by:

Correct answer: C. An EPA-approved third-party laboratory

Use equipment certified by an EPA-approved organization under applicable Section 608 requirements. EPA lists AHRI and UL. Older equipment has separate conditions. Source: 40 CFR 82.158.

📖 Related rule: § 82.154 — Prohibitions

Reclaimed refrigerant must be processed to meet:

Correct answer: A. AHRI Standard 700-2016

Reclaimed refrigerant must meet AHRI Standard 700, the same chemical purity specification as new product — that's what makes reclamation different from simple recycling. ASHRAE 15 covers machine-room safety, DOT 4BA-300 is a cylinder spec, NFPA 70 is the National Electrical Code — none of those address refrigerant purity.

Which purchaser qualifies to buy restricted refrigerant for servicing stationary appliances under Section 608?

Correct answer: B. Section 608 certified technicians or their employers.

Appropriately certified technicians and employers of certified technicians are qualifying purchasers; other specified regulatory exceptions exist. The small-can exception is limited to certain MVAC substitutes in compliant containers of two pounds or less, not all small refrigerant containers. Source: 40 CFR 82.154(c).

📖 Related rule: § 82.154 — Prohibitions

Which statement about the Clean Air Act venting prohibition is correct?

Correct answer: B. Knowing releases during service, maintenance, or disposal are prohibited.

Knowing releases of ozone-depleting refrigerants and non-exempt substitutes during covered activities are prohibited. De minimis releases associated with good-faith recovery/recycling attempts and specified application-specific substitute exemptions are treated separately. Source: 40 CFR 82.154(a).

📖 Related rule: § 82.154 — Prohibitions

True "drop-in" substitutes for CFC and HCFC refrigerants:

Correct answer: B. Must not be assumed; a retrofit requires a compatibility assessment and approved procedure.

A refrigerant change requires checking application approval, lubricant, components, controls, and performance. The actual changes depend on the manufacturer's retrofit instructions, not a universal requirement to replace every component.

📖 Related rule: Core Study Guide

Which lubricant is commonly specified for stationary R-134a refrigeration equipment designed for it?

Correct answer: C. Polyolester (POE)

POE is common in stationary R-134a equipment. The manufacturer specifies the actual oil and grade; automotive and other applications can use different lubricants. Maintain appropriate moisture control.

HCFC refrigerants are typically compatible with which lubricant?

Correct answer: A. Mineral oil or alkylbenzene.

Many HCFC systems use mineral oil or alkylbenzene, but permitted lubricants depend on the compressor and refrigerant. Some approved HCFC applications also use POE. Do not infer compatibility or mixing limits from refrigerant family alone.

Fractionation in a refrigerant blend refers to:

Correct answer: A. Blend components separating because they leak at different rates.

Zeotropic blends can have different liquid and vapor compositions. Vapor leakage or vapor withdrawal can change composition; the amount depends on the blend and conditions. Follow the manufacturer's liquid-withdrawal and charging procedure.

In the refrigeration cycle, cooling occurs when refrigerant:

Correct answer: B. Evaporates in the evaporator and absorbs heat.

Refrigerant evaporation absorbs heat from the load. Condensation rejects heat, including compressor work. The metering device reduces pressure and can cause flashing, but it is not the main heat exchanger absorbing room heat.

📖 Related rule: Core Study Guide

On a manifold gauge set, the low-side gauge is typically:

Correct answer: B. Blue and reads pressure and vacuum as a compound gauge.

The low-side (suction) gauge is blue and "compound" — it reads vacuum below atmospheric pressure as well as positive psig. Compound is needed because the suction side can run into vacuum during pump-down or recovery. Red is high-side, yellow is the center charge/recovery hose.

An electronic leak detector is most useful for:

Correct answer: B. Pinpointing small refrigerant leaks.

Electronic leak detectors are tuned to react to very small concentrations of refrigerant gas, which makes them excellent at pinpointing the exact leak location once you've narrowed the area. They don't measure superheat (A), recover refrigerant (C), or charge by weight (D) — those are different tools.

"Recover" is defined as:

Correct answer: A. Removing refrigerant from a system and storing it without testing or processing.

'Recover' is the simplest of the three terms: just remove refrigerant from a system into a container. No cleaning, no testing, no processing. Recycling adds basic on-site cleanup; reclamation is full reprocessing to AHRI 700 new-product purity. Knowing recover/recycle/reclaim is a recurring exam topic.

📖 Related rule: § 82.154 — Prohibitions

"Recycle" refrigerant means to:

Correct answer: B. Reduce contaminants with oil separation and filter-drier passes.

Recycling reduces contaminants, for example by oil separation and filtration. It does not include the analytical purity verification required for reclamation. Same-owner reuse of stationary-appliance refrigerant is treated differently from sale for use by another owner.

"Reclaim" refrigerant means to:

Correct answer: C. Reprocess it to AHRI 700 new-product specifications, usually off site.

Reclaim means a full chemical reprocessing to AHRI 700 (the new-product purity spec), normally done at a dedicated off-site facility by an EPA-certified reclaimer. That's what allows reclaimed refrigerant to be sold to a different owner or used as new product. Recovery and recycling don't meet that bar — only reclamation does.

During recovery, mixing different refrigerants in one cylinder:

Correct answer: B. Contaminates the contents and can complicate or prevent reclamation.

Do not mix different refrigerants during recovery. Some reclaimers can separate certain mixtures; others cannot accept them or must arrange destruction. Label and segregate mixed contents, consult the reclaimer, and never vent them.

Which factor will speed up refrigerant recovery?

Correct answer: C. Short, large-diameter hoses and warm appliance

Short, large-diameter hoses reduce flow restriction so refrigerant moves faster, and a warm appliance has higher pressure (more driving force into the cooler cylinder). Cold ambient and full/high-pressure cylinders both slow recovery — the cylinder needs lower pressure than the appliance to keep flow going. Long, narrow hoses choke the recovery rate.

At the end of service, a system should be evacuated with a vacuum pump in order to:

Correct answer: A. Remove air and moisture/non-condensables before charging.

Evacuation at the end of service boils off any moisture and pulls non-condensable air out of the system before fresh refrigerant goes in; otherwise water turns to acid and air raises head pressure. The vacuum pump cannot meaningfully cool refrigerant for cylinder filling, test the compressor, or recover oil — those are unrelated tasks.

Risks of exposure to refrigerant include:

Correct answer: A. Frostbite, oxygen displacement/asphyxiation, and possible cardiac sensitization

Liquid refrigerant flashing to vapor at any leak chills surrounding skin to frostbite temperatures. Vapor displaces oxygen in confined spaces (asphyxiation). High concentrations can cause cardiac sensitization that triggers fatal arrhythmias under stress or epinephrine. The risks are real, not negligible (D), and the risks aren't limited to electrocution (C) or sunburn (B).

📖 Related rule: § 82.154 — Prohibitions

When working with refrigerants, appropriate personal protective equipment includes:

Correct answer: B. Appropriate eye and hand protection; evacuate hazardous atmospheres and use qualified emergency responders.

Select PPE using the refrigerant SDS and task assessment. Do not enter a suspected oxygen-deficient or heavily contaminated area without the training, respiratory-protection program, and equipment required for the hazard.

Under AHRI Guideline K, which colors are conventional for a nonflammable-fluorocarbon recovery cylinder?

Correct answer: B. Gray body with a yellow top/collar.

This is a recovery-cylinder color convention, not proof of DOT approval or contents. Flammable-refrigerant markings differ. Always read the labels and cylinder markings; new-product cylinder colors no longer uniquely identify refrigerant.

The common recovery-cylinder fill guideline limits liquid to what percentage of internal volume, subject to the applicable cylinder/refrigerant limits?

Correct answer: C. 80%

The common guideline is 80% liquid volume to leave expansion space. Use the correct cylinder/refrigerant mass limit and a scale, accounting for tare weight. It is not 80% of the cylinder's gross weight.

For pressurizing a system to check for leaks, which gas is preferred?

Correct answer: C. Nitrogen

Dry nitrogen is the preferred gas for pressurizing a system to check for leaks. It is inert, dry, inexpensive, and will not react with refrigerant or oil, while oxygen and compressed air can form an explosive mixture with refrigerant oils and must never be used.

📖 Related rule: § 82.154 — Prohibitions

When using nitrogen for leak testing, you must use:

Correct answer: B. A pressure regulator and a pressure-relief valve.

Nitrogen cylinders contain pressures over 2,000 psig, so a pressure regulator is required to drop the supply to a safe test pressure, and a pressure-relief valve must be installed downstream to protect the system if the regulator fails. Connecting a nitrogen cylinder to a system without both of these is a known cause of fatal explosions.

📖 Related rule: § 82.154 — Prohibitions

Cylinders containing recovered refrigerant being shipped must be labeled with:

Correct answer: B. Refrigerant identification and the appropriate DOT classification tag.

Recovery cylinders shipped for transport are regulated by DOT as compressed gas: they must show the refrigerant identification (e.g., R-22, R-134a) and the proper DOT hazard classification placard/label. Initials, bar codes, or no label at all all fail DOT requirements. Required labeling protects shippers, carriers, and emergency responders if a cylinder is involved in an accident.