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Answer Explanations

Every practice question with its correct answer, a plain-language explanation, and a link to the EPA Section 608 rule it comes from. When you miss a question in the app, the "See this answer explained in full" link brings you straight here, to that exact question.

Core

Which of the following refrigerant has a GWP closest to "1"?

Correct answer: D. R-1233zd

R-1233zd is an HFO refrigerant with a very low global warming potential, close to 1. The other listed refrigerants have much higher GWP 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.

The chlorine in CFCs and HCFCs

Correct answer: B. will not dissolve in water.

CFCs and HCFCs are stable enough that their chlorine does not dissolve out in rainwater before reaching the stratosphere. That stability lets chlorine contribute to ozone depletion.

How much can a person be fined per day per violation for knowingly releasing a regulated substance that violates the Clean Air Act?

Correct answer: D. $44,539

The Clean Air Act allows large daily penalties for knowing violations. For this question bank, the tested penalty amount is $44,539 per day per violation.

📖 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

Reusable refrigerant containers under high-pressure must be hydrostatically tested how often?

Correct answer: C. 5 years

Reusable high-pressure refrigerant containers must be periodically hydrostatically tested. The standard interval tested here is every 5 years.

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

A refrigerant cylinder designed to hold recovered refrigerant has a:

Correct answer: B. grey body and yellow top.

Recovery cylinders use a gray body with a yellow top for identification. This helps distinguish them from disposable refrigerant containers.

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 ASHRAE classification means slightly flammable?

Correct answer: B. A2L

ASHRAE safety classifications use 2L for lower burning velocity, or slightly flammable, refrigerants. A1 is no flame propagation, while A3 is higher flammability.

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

The molecule found in CFCs and HCFCs that depletes ozone is

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 (chlorofluorocarbon) — only chlorine, fluorine, and carbon, no hydrogen. R-22 and R-123 are HCFCs (the 'H' adds a hydrogen, making them break down faster in the lower atmosphere). R-134a is an HFC, with no chlorine at all. CFCs have the highest ODP because all that chlorine reaches the stratosphere intact.

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.

CFCs (chlorofluorocarbon — only Cl, F, C) include R-11, R-12, R-500. HCFCs add an H atom that makes them break down faster in the lower atmosphere — R-22, R-123. HFCs have no chlorine at all (zero ODP) — R-134a, R-410A, R-32. The 'H' tells you whether chlorine is present in stable form, which controls ODP.

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 uses ester (POE) lubricant, while R-12 systems use mineral oil — and the two oils don't mix. R-134a also has different pressure/temperature characteristics, often requiring TXV, drier, and seal changes. "Drop-in" implies no oil or component changes, which is never true for an R-134a retrofit.

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

Correct answer: A. Higher Earth temperatures, more skin cancer, and more cataract cases.

A thinner ozone layer lets more UV-B reach the surface, which raises rates of skin cancer and cataracts and damages crops, plankton, and immune systems. Many ozone-depleters are also greenhouse gases, so they contribute to warming as well. The wrong options describe the opposite of the actual effects.

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

Correct answer: A. Subcooled liquid

Refrigerant leaving a receiver is subcooled liquid: it is below its saturation temperature for the existing pressure. Subcooling ensures the metering device sees pure liquid rather than flash gas, which is essential for stable system performance.

📖 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; R-134a is more expensive than R-12 was. 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.

Knowing violations of Section 608 can carry penalties up to $44,539 per day per violation, revocation of technician certification, and criminal referral to federal court. There's no warning-only tier (B), the loss isn't limited to a business license (C), and there's no first-offense exemption (D).

📖 Related rule: § 82.154 — Prohibitions

What incentive do others have to turn you in for violating the CAA?

Correct answer: A. An award of up to $10,000 is offered by the EPA

EPA may pay rewards up to $10,000 for information leading to a Section 608 conviction. The reward exists because most violations happen in the field where EPA inspectors won't see them — coworkers, customers, and competitors are the eyes and ears of enforcement.

📖 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 their employers. 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.

When was the CFC phase out date?

Correct answer: D. January 1, 1996

U.S. production and import of new CFCs ended on January 1, 1996, under the Montreal Protocol and Title VI of the Clean Air Act. Existing CFC stocks could still be used to service older equipment, but no new product could be made. The 1992 date is when the venting prohibition began — different rule, similar timeframe.

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

Correct answer: C. Recovery and recycling

Once new CFC production stopped in 1996, the only legal sources for servicing older equipment are recovered and recycled/reclaimed refrigerant from existing systems. There is no government stockpile, no licensed import for service use, and DuPont stopped making CFCs along with the rest of industry. That's why proper recovery is so important — it preserves the supply for legacy systems.

What must be done before scrapping a refrigerant container?

Correct answer: B. Recover it to 0 psig or lower and render it useless.

Before scrapping a refrigerant container, all refrigerant must be recovered until the cylinder reaches 0 psig or lower, and the cylinder must then be rendered useless (typically by puncturing it) so it cannot be reused or accidentally pressurized. This prevents intentional or accidental venting of any residual refrigerant.

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.

Who is responsible for removing refrigerants from a system that is being disposed of?

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

Section 608 puts recovery responsibility on the last person in the appliance disposal chain — typically the scrap yard or recycler — unless they receive a signed statement that refrigerant was already recovered. The original installer (A) and EPA (B) aren't responsible, and the original owner's responsibility ends at transfer (C).

📖 Related rule: § 82.154 — Prohibitions

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

Correct answer: A. No true drop-in exists because newer refrigerants require different oils.

A true drop-in would require no equipment or oil changes. R-12 uses mineral oil; alternatives like R-134a need POE oil, which won't mix with mineral oil left in the system, so the system has to be flushed. R-22 and R-410A operate at very different pressures and aren't substitutes for R-12 either.

What type of oil is used in R-134a, and how does it mix with other oils?

Correct answer: A. Ester-based oil, which does not mix with other types of oils.

R-134a uses polyolester (POE) oil because mineral oil isn't soluble with R-134a and won't return through the system. POE doesn't mix with mineral or alkylbenzene oils, which is why R-12-to-R-134a retrofits require flushing or multiple oil changes to get the residual mineral oil out.

Will the gases in a ternary blend leak at the same rate, and why or why not?

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

A ternary (3-component) blend like R-407C contains gases with different boiling points and vapor pressures. The lighter, more volatile component preferentially escapes through a leak, changing the remaining mixture's composition — this is called fractionation. That's why blends are charged as liquid and never topped off as vapor.

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

Explain how cooling of a space occurs in a refrigeration cycle

Correct answer: B. Heat is removed indoors and deposited outside the building.

A refrigeration cycle doesn't create cold; it moves heat. The evaporator absorbs heat from indoor air (the room feels cool); the condenser rejects that heat outdoors. Cold refrigerant is never added to the room directly (A), and liquid alone can't cool without changing phase to absorb heat (D).

📖 Related rule: Core Study Guide

Will refrigerant migrate to the crank case in a compressor?

Correct answer: A. Refrigerant seeks the lowest point in the system, the compressor crankcase.

Yes, refrigerant migrates to the crankcase during off-cycles, especially in cold weather, because it seeks the coldest, lowest-pressure point in the system and dissolves into the oil. A crankcase heater is used to keep the oil warm and drive the refrigerant back out before startup.

📖 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.

The red gauge connects to the discharge (high) side and reads only positive pressure — typically 0–500 psi. Blue is low-side, yellow is the center hose. The high-side gauge doesn't read vacuum because the high side never operates below atmospheric in normal service.

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.

Best practice (and EPA rule) is to use certified recovery equipment, leak-test regularly, repair leaks promptly, and keep service fittings/valves tight. The wrong answers — yearly top-offs (B), routine venting (C), and skipping leak checks (D) — are all explicitly prohibited and are the main causes of needless emissions.

What is the most effective method for checking for small leaks?

Correct answer: D. Halide torch

A halide torch is highly sensitive to chlorinated refrigerants — the flame turns bright green at very low concentrations, making it effective for tiny leaks of CFCs/HCFCs. Soap bubbles miss small leaks, dye marks larger ones, and nitrogen pressurization pinpoints leaks but only with another detection method. Note: a halide torch only works on chlorine-containing refrigerants.

📖 Related rule: § 82.154 — Prohibitions

How can you test a system for leaks?

Correct answer: A. Evacuate the system and pull a vacuum on it.

Pulling a deep vacuum and watching whether it holds (a "standing vacuum" or rise test) reveals leaks because outside air will leak inward. Hydrostatic water tests aren't done on refrigerant systems. Oxygen pressurization is dangerous — it can detonate when mixed with refrigerant oils. Building water pressure isn't usable on a sealed refrigerant circuit.

What should you look for if a compressor burns out?

Correct answer: C. Strong smell in refrigerant

A burned-out compressor produces a sharp, acrid smell in the recovered refrigerant from the breakdown of oil and refrigerant into acids. Recovery from a burnout requires using suction-line filter-driers, recovering into a dedicated tank if possible, and treating the recovered refrigerant as contaminated.

📖 Related rule: Core Study Guide

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

Correct answer: A. Triple-evacuate, install a permanent filter-drier, and pull a deep vacuum.

Compressor burnouts release acid and moisture into the oil. The repair: install a suction-line filter-drier, evacuate to deep vacuum, and triple-evacuate (with nitrogen breaks) to dilute and remove contaminants. Reusing oil, diluting with fresh refrigerant, or "burning off" contamination just spreads acid through the new compressor.

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.

How is recycling different from reclaiming?

Correct answer: C. Reclaiming processes refrigerant to new-product specifications.

Recycling is a basic on-site cleanup — oil separation and filter-drier passes — that reduces contaminants but does not certify purity. Reclamation is a full reprocessing to AHRI Standard 700 (the same purity spec as new product) and is normally done at a dedicated off-site facility with chemical testing. Reclaimed refrigerant can be sold to anyone; recycled refrigerant generally must stay with the same owner.

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 standards must refrigerant recovery equipment meet?

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

Recovery equipment manufactured after Nov 15, 1993 must be certified to ARI/AHRI Standard 740 by an EPA-approved third-party lab (UL, ETL, etc.) and labeled accordingly. Self-certification, manufacturer claims, and DOT shipping rules don't qualify — the labeling proves the machine meets specific evacuation levels for each appliance type. Always check the certification label before using a recovery unit on a job.

📖 Related rule: § 82.154 — Prohibitions

What two main types of recovery equipment are used?

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

Recovery equipment is divided into self-contained (active) and system-dependent (passive) types. Active units have their own compressor and condenser and can recover from any appliance, while passive units rely on the appliance's compressor or system pressure to push refrigerant into a non-pressurized container, and are limited to small appliances containing 15 lb or less.

What should you tell a consumer who complains about the added cost and time of recovering refrigerant?

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

Recovery isn't optional — Section 608 of the Clean Air Act makes intentional venting illegal and carries civil penalties up to tens of thousands of dollars per day. It also protects the ozone layer and limits greenhouse gases. Telling a customer it's optional, manufacturer-recommended, or limited to large systems would all be wrong and could get the technician in legal trouble.

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

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

Mixed refrigerant can't be reclaimed or reused, so it has to be recovered into a dedicated tank labeled as mixed/contaminated and sent for destruction (not reclamation). Never combine it with virgin or recovered refrigerant of any single type — that ruins the cylinder it's added to. Venting is never an option, and EPA does not require pre-call notification for normal recovery.

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 sweeps moisture and debris out of the system, while a new filter-drier traps anything the nitrogen flush loosens. This combination is especially important after a burnout or open-system repair. Nitrogen is used because it's inert, dry, and won't react with refrigerant or oil — never use compressed air (moisture, and explosion risk with refrigerant oils) or oxygen.

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 emissions, saves energy, and helps remove oil more effectively.

Faster recovery means less time on the job, lower energy use by the recovery machine, and less chance for fugitive emissions during a long pull. It also keeps the refrigerant moving with the oil rather than letting oil settle and trap refrigerant. Speed never replaces required steps — leak check and evacuation still must happen after recovery.

If you smell a strong odor during recovery, what is most likely the problem?

Correct answer: A. Compressor has burned out

A strong burnt or acrid smell during recovery almost always indicates a compressor burnout — overheated motor windings break down the oil and refrigerant into acidic byproducts. Treat the system as contaminated: install suction-line and liquid-line filter-driers, change them after running, and use acid-test kits. Don't reuse the recovered refrigerant in another system.

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 from a refrigeration system. Moisture combined with refrigerant and oil produces corrosive acids, sludges, and ice in the metering device, all of which damage compressors and shorten service life. A deep vacuum (typically below 500 microns) boils any remaining water out of the system.

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

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

Moisture left in an operating system reacts with refrigerant and lubricant under heat to form highly corrosive and toxic acids (such as hydrochloric and hydrofluoric acids in halocarbon systems). These acids attack motor windings, copper, and metal surfaces, leading to compressor burnout and contaminated oil.

What must be done before starting evacuation?

Correct answer: C. Recover all refrigerant

A vacuum pump is not a recovery device, so under EPA Section 608 all refrigerant must first be removed with certified recovery equipment before evacuation begins; otherwise the pump would discharge refrigerant to atmosphere, which is a violation. Installing a dryer, sight glass, or nitrogen comes later in the service sequence, after recovery and (often) after evacuation.

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; it decreases evacuation time by increasing pressure.

Warming the system raises the vapor pressure of any moisture and trapped refrigerant so it boils out faster, which shortens evacuation time. There is no explosion risk from gentle heating during evacuation, and the claim that it lengthens evacuation time has the physics backwards.

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.

At deep vacuum, the pumping speed is limited by conductance through the connecting line, and conductance falls sharply with length and rises with the fourth power of diameter. So the connection should be as short and as large in diameter as practical; the fixed 3-foot, 3/8-inch options would severely throttle the pump and lengthen evacuation.

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.

A gauge mounted right at the pump reads the pump's own inlet, not the system pressure, because the pressure drop along hoses and fittings can be large at deep vacuum. Placing the micron gauge at the system (as far from the pump as practical) gives the true equipment pressure, which is what matters for dehydration and EPA recovery verification.

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

Correct answer: C. System isolated, pump off; complete when required vacuum holds for one minute.

Vacuum is verified by isolating the system and shutting the pump off so the gauge reads the system itself, not the running pump. If the required level holds for at least one minute the system is dry and tight; if pressure rises, moisture is still boiling off or there is a leak, so the read-while-running and first-reached options would mask both problems.

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

What is the leading cause of refrigeration accidents leading to death?

Correct answer: B. Oxygen deprivation

Most refrigeration fatalities are oxygen-deprivation (asphyxiation) events in confined mechanical rooms — refrigerant gas isn't poisonous in normal concentrations, but it's heavier than air and pushes breathable air out. Phosgene exposure is real but rare. Freezing and electrocution are far less common as refrigeration-specific causes of death.

📖 Related rule: § 82.154 — Prohibitions

What personal protective equipment should you wear when handling refrigerants?

Correct answer: A. Safety glasses, butyl-lined protective gloves, and safety shoes.

Liquid refrigerant causes instant frostbite, so eye protection and refrigerant-rated (butyl-lined) gloves are required to keep skin and eyes safe. Safety shoes protect against dropped cylinders and tools. Sandals/T-shirts, dust-mask only, or no PPE leave you exposed to common refrigerant hazards.

What are the requirements under ASHRAE standard 15-1994?

Correct answer: A. A refrigerant sensor must alarm and start ventilation where leaked refrigerant can concentrate.

ASHRAE 15 requires a refrigerant sensor that alarms and triggers emergency ventilation in any space where a leak could build up to dangerous concentrations — not just rooms with one specific refrigerant. The rule applies regardless of refrigerant type, sized to the refrigerant's safety class. Limiting it to R-11, R-12, or R-123 only would miss the broader safety intent.

Under what conditions will alarm and ventilation sound under ASHRAE standard 15-1994?

Correct answer: A. Before the TLV-TWA or oxygen-deprivation level is exceeded.

The sensor must alarm and start ventilation BEFORE the TLV-TWA (threshold limit value, time-weighted average) or the oxygen-deprivation concentration is reached — that's the whole point of the sensor. Waiting until limits are exceeded would defeat the safety system. ASHRAE 15 sets the trigger conservatively to give occupants time to evacuate.

What is the safest rating of a refrigerant according to the ASHRAE scale?

Correct answer: A. A-1 is considered the safest refrigerant while B-3 is the least safe

ASHRAE 34 ranks refrigerants by toxicity (A = lower, B = higher) and flammability (1 = none, 2L = mild, 2 = lower, 3 = higher). A1 means low toxicity AND no flame propagation — the safest combination. B3 would be high toxicity AND high flammability — the worst combination. R-134a, R-22, R-410A are A1; R-123 is B1; ammonia is B2L.

📖 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 mixed with refrigerant or refrigerant oil can form an explosive mixture under pressure. The combination has caused fatal explosions during leak checking, which is why only dry nitrogen (inert and oxygen-free) is acceptable for pressurizing a system.

When using nitrogen to charge a system, what piece of equipment should it be charged through and where should a relief valve be located?

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

Nitrogen cylinders contain pressures over 2,000 psig, far above any system's design pressure, so a pressure-reducing regulator must be used. A pressure-relief valve installed downstream of the regulator protects the system from over-pressurization if the regulator fails.

📖 Related rule: § 82.154 — Prohibitions

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

Correct answer: B. The data plate on the low-side pressure valve.

The system data plate (nameplate) shows the design test pressures the manufacturer certified the appliance for. ARI directories list general refrigerant data, not appliance-specific test pressures. Always use the listed test pressure to avoid over-pressurizing components like the low-side or evaporator.

📖 Related rule: § 82.154 — Prohibitions

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

Correct answer: A. They must not be installed in series, and corroded valves should be replaced.

Relief valves are installed in parallel so each can independently relieve pressure — in series, blockage of one defeats the redundancy. Corroded valves must be replaced because rust can prevent them from opening at the set pressure or cause them to leak continuously. Treating corrosion as "expected" or skipping inspection violates safety code.

📖 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.

Heat decomposes refrigerants into toxic compounds — chlorinated refrigerants can yield phosgene gas (used as a chemical weapon in WWI). Sealed cylinders can also rupture explosively because liquid refrigerant expands rapidly when heated, generating extreme hydrostatic pressure. Refrigerants don't become inert or safer when heated.

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

Correct answer: B. Evacuate all refrigerant and purge with nitrogen

Brazing on a system that still contains refrigerant decomposes the refrigerant into toxic acids and phosgene. A nitrogen purge during brazing also prevents oxygen from forming copper-oxide scale inside the lines that would later contaminate the system. Reading an MSDS is good practice but it doesn't actually protect the work — only recovery + nitrogen purge does.

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

Correct answer: D. Vacate and ventilate the area or use self-contained breathing apparatus.

A large refrigerant leak can quickly displace breathable oxygen in a mechanical room — you can collapse before you smell anything because refrigerants have weak odor at low concentrations. Get out, ventilate, and only re-enter wearing self-contained breathing apparatus (SCBA). Continuing to work, waiting for odor to clear, or relying on a paper mask can be fatal.

What types of cylinders can be used for recovery and how can you visually identify them?

Correct answer: D. Yellow tops and gray bodies

DOT-approved refillable recovery cylinders are gray with a yellow top — a uniform marking required regardless of which refrigerant is inside, since recovery cylinders may be reused for many different refrigerants. Service cylinders for new refrigerant use color-codes by chemical (e.g., light blue for R-134a). 'Marked RECOVERY' or refrigerant-color-matched cylinders aren't the DOT recovery standard.

How often should refillable cylinders be hydrostatically tested?

Correct answer: A. Every 5 years

DOT regulations require refillable refrigerant cylinders to be hydrostatically tested every 5 years. The retest date is stamped on the cylinder; once it expires, the cylinder cannot legally be transported in commerce until it is retested.

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

Correct answer: B. Completely evacuated of all refrigerants and have a pressure of 0 psig or lower

Before scrapping any cylinder, it must be fully evacuated of refrigerant to 0 psig or lower and rendered useless. This guarantees no residual refrigerant is vented and prevents the cylinder from being repressurized or reused once it leaves the technician's control.

Why shouldn’t you fill cylinders above 80% of their capacity by weight?

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

Liquid refrigerant expands sharply with temperature. A cylinder filled past 80% has too little vapor space, so a small temperature rise leaves no room for the liquid to expand and pressure rises hydraulically until the cylinder ruptures or explodes.

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.

Heating a refrigerant cylinder dangerously increases internal pressure and can also break refrigerant down into toxic decomposition products such as phosgene, hydrogen fluoride, and hydrogen chloride. The cylinder may explode, leak, or vent corrosive gases. Cylinders should never be heated above 125°F.

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.

Fill level can be controlled with a mechanical float, an electronic float, or by weighing the cylinder on a scale during charging. Weighing is the most accurate because it measures the actual mass of refrigerant against the cylinder's rated capacity, ensuring the 80% liquid limit is not exceeded.

In what position should cylinders be shipped?

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

DOT requires refrigerant cylinders to be shipped upright, either secured in a cradle or vertically bundled and strapped to a pallet. Upright shipping keeps the relief device in the vapor space; a cylinder transported on its side could vent liquid through the relief valve, which would cause uncontrolled, rapid release.

What type of DOT tag is required for shipping refrigerant cylinders?

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

DOT requires a hazard-class label identifying the refrigerant as Class 2.2, non-flammable compressed gas. The label tells handlers and emergency responders what is in the cylinder and how to handle it during transport, storage, and accidents.

In the stratosphere, ozone is destroyed primarily by:

Correct answer: B. Free chlorine atoms

Free chlorine atoms are the principal ozone-destroyers in the stratosphere. UV breaks the C-Cl bond in CFCs/HCFCs/halons, releasing the atom; one chlorine catalytically destroys thousands of ozone molecules before being deactivated. CO2 and water vapor are greenhouse gases but don't deplete ozone; nitrogen is essentially inert.

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 (R-11, R-12) have the highest ODP because they are 100% chlorinated halocarbons with no hydrogen — extremely stable, so they reach the stratosphere intact. HCFCs add an H atom and break down faster (lower ODP). HFCs and hydrocarbons contain no chlorine, so their ODP is zero. R-11 has ODP = 1.0 (the reference); R-22's ODP is about 0.05.

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.

Direct measurements — by satellites, balloons, and ground stations — detect chlorine compounds that can only have come from CFCs/HCFCs in the stratosphere, and the amounts track CFC production trends. The science is based on actual atmospheric chemistry data, not models alone or industry self-reporting. That measured evidence is what drove the Montreal Protocol.

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

Correct answer: B. January 1, 1996

U.S. CFC production and import for new use ended on January 1, 1996, under Title VI of the Clean Air Act and the Montreal Protocol. Service of older equipment can continue using recovered, recycled, or reclaimed CFC stock. Don't confuse this date with the 1990 Clean Air Act Amendments or the 1992 venting prohibition.

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

Correct answer: C. January 1, 2020

R-22 production and import for use in new equipment ended in 2010; the full phaseout (no new R-22 production or import for any use) took effect January 1, 2020. After 2020, only recovered, recycled, or reclaimed R-22 can be used to service existing equipment. R-410A and other HFC blends replaced R-22 in new residential and commercial AC.

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 refrigerant, a technician must:

Correct answer: B. Recover the refrigerant

Section 608 requires refrigerant to be recovered before any appliance is disposed of, scrapped, or recycled. Venting outdoors (A) violates the venting prohibition. Cutting refrigerant lines (C) before recovery is exactly what the rule is designed to prevent. Burying intact equipment (D) doesn't address either the legal duty or the environmental harm.

The venting prohibition under Section 608 applies to:

Correct answer: C. CFCs, HCFCs, and their substitutes, including HFCs.

Section 608's venting prohibition originally covered Class I (CFCs) and Class II (HCFCs) refrigerants and was extended to substitutes — including HFCs and HFC blends — under the 2016 EPA rule. Knowing or careless venting of any of these is illegal during service, maintenance, and disposal. Limiting the rule to one class would miss the post-2016 expansion.

📖 Related rule: § 82.154 — Prohibitions

The maximum civil penalty under the Clean Air Act for knowingly venting refrigerant is up to:

Correct answer: C. $37,500 per day per violation

The Clean Air Act sets a maximum civil penalty of up to $37,500 per day per violation for knowing refrigerant violations (this number is adjusted for inflation periodically and now exceeds $40,000). EPA also offers up to $10,000 to people who provide information leading to convictions. The other amounts are too low to match the actual statutory maximum.

📖 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 (passive) equipment has no compressor of its own. It relies on the appliance's compressor or on the appliance's own internal pressure to push refrigerant into a non-pressurized recovery container. Because of this it is only allowed on small appliances containing 15 lb of refrigerant or less.

Section 608 covers all air-conditioning and refrigeration equipment containing CFCs or HCFCs EXCEPT:

Correct answer: C. Motor vehicle air conditioners

Motor vehicle air conditioners (MVAC) are regulated under Section 609 of the Clean Air Act, with their own technician certification — Section 608 doesn't apply to them. Supermarket refrigeration, residential central AC, and centrifugal chillers are all stationary equipment covered by 608. Knowing the 608/609 split is a common exam question.

📖 Related rule: § 82.154 — Prohibitions

Recovery and recycling equipment must be certified by:

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

All recovery and recycling equipment must be tested and certified by an EPA-approved third-party laboratory (such as UL or AHRI), not by the manufacturer itself. The laboratory tests the unit against AHRI 740 to verify it meets the required recovery efficiencies and final vacuums before it can be sold for use under Section 608.

📖 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.

Under the Section 608 sales restriction, refrigerant in containers larger than two pounds may only be sold to:

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

Under the Section 608 sales restriction, refrigerant in containers larger than two pounds may be sold only to Section 608 certified technicians or their employers (who must employ certified technicians). The rule keeps regulated refrigerants out of the hands of anyone not trained or authorized to recover them.

📖 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.

Section 608 prohibits any 'knowing release' of refrigerant during service, maintenance, repair, or disposal — regardless of equipment size or refrigerant type (CFC, HCFC, HFC, or other substitute). 'De minimis' releases that occur during good-faith use of recovery equipment are not violations, but intentional venting always is. Charge size and chemical class don't get you out of the rule.

📖 Related rule: § 82.154 — Prohibitions

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

Correct answer: B. Do not exist; retrofits require lubricant and component changes.

True 'drop-in' substitutes don't really exist — every refrigerant change requires evaluating compatibility of the lubricant (mineral vs. POE vs. PAG), elastomers, expansion device, and capacity match. Often you change oil, filter-drier, and possibly the metering device. Calling something a 'drop-in' is marketing shorthand; EPA and AHRI both warn against assuming no work is needed.

📖 Related rule: Core Study Guide

R-134a is most commonly used with which type of lubricant?

Correct answer: C. Polyolester (POE)

R-134a doesn't return mineral or alkylbenzene oil through the system, so it requires polyolester (POE) — a synthetic ester that is miscible with R-134a. POE is hygroscopic (absorbs moisture aggressively from the air), which is why R-134a/POE systems require strict moisture control and proper evacuation.

HCFC refrigerants are typically compatible with which lubricant?

Correct answer: A. Mineral oil or alkylbenzene.

HCFCs (R-22, R-123) work with mineral oil or alkylbenzene because chlorine in the molecule helps oil return through the system. HFCs (R-134a, R-410A) need synthetic POE (polyolester) oil; PAG oil is used in automotive R-134a systems. Mixing the wrong oil family ruins compatibility — POE in mineral oil systems and vice versa cause oil-return and lubrication failures.

Fractionation in a refrigerant blend refers to:

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

Refrigerant blends (like R-410A or R-407C) contain components with different boiling points and vapor pressures. When the blend leaks (especially from the vapor side) the lighter, more volatile components escape first, leaving the remaining mixture at a different composition than nameplate. That's fractionation — and it's why blends are charged as liquid, not topped off as vapor.

In the refrigeration cycle, cooling occurs when refrigerant:

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

Cooling actually happens at the evaporator, where liquid refrigerant absorbs heat from indoor air and changes phase to vapor — the heat absorbed is the latent heat of vaporization. Condensing rejects that heat outdoors (the opposite end of the cycle). The metering device drops pressure but doesn't directly cool, and compression adds 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 — oil, moisture, particulates — through oil separation and one or more passes through filter-driers, usually right at the job site with the recovery/recycle machine. It does NOT meet AHRI 700 purity (that's reclamation) and is not destruction or venting. Recycled refrigerant can be reused only by the same owner; cross-owner reuse requires reclamation.

"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. Makes the refrigerant unusable and unable to be reclaimed.

Different refrigerants can't be separated economically once mixed, so a cylinder of mixed refrigerant can't be reclaimed and usually has to be sent for destruction at the owner's expense. Always use dedicated cylinders per refrigerant. Labeling alone doesn't fix mixed contents — the chemistry can't be undone.

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. Refrigerants are not safe in any quantity (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. Safety goggles and gloves; SCBA in heavy concentrations.

Goggles protect eyes against frostbite from a liquid splash; gloves protect skin from contact and cold burns. In heavy concentrations (mechanical-room leaks) only self-contained breathing apparatus (SCBA) supplies safe air — paper masks and dust masks don't filter refrigerant or supply oxygen, and going in without PPE is fatal.

DOT-approved refillable refrigerant recovery cylinders are color coded:

Correct answer: B. Yellow body with a gray top.

DOT-approved refillable refrigerant recovery cylinders have a gray body with a yellow top — a standardized marking so any technician can recognize a recovery cylinder regardless of refrigerant type inside. Service cylinders for new product use chemical-specific colors (e.g., light blue for R-134a). The other color combinations would represent other gases (green = nitrogen, etc.).

Refillable recovery cylinders should never be filled to more than what percentage of their capacity?

Correct answer: C. 80%

DOT rules and refrigerant industry practice limit recovery cylinder fill to 80% of capacity — leaving room for liquid refrigerant to expand as ambient temperature rises. Overfilling can rupture the cylinder if it warms up. Always weigh recovered refrigerant; never fill by pressure alone.

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.

Type I

Silicone elastomers, for use in seals and gaskets, are not compatible with which refrigerants?

Correct answer: C. HFOs

Some seal and gasket materials are not compatible with newer HFO refrigerants. The compatibility of elastomers should always match the refrigerant and equipment design.

After the refrigerant has been recovered, which of the following can be used to flush the system?

Correct answer: C. Nitrogen

After refrigerant recovery, dry nitrogen can be used for flushing. Oxygen or compressed air should not be used because they can create safety and contamination hazards.

If a strong odor is detected while performing a refrigerant recovery process,

Correct answer: B. A compressor burnout has likely occurred.

A strong odor during recovery often points to a compressor burnout. Burnouts can create acidic, contaminated oil and decomposition products.

Which of the following is true regarding refrigerant leaks on small appliances?

Correct answer: A. EPA does not require repair, but leaks should be repaired whenever possible.

EPA leak repair requirements for small appliances are less strict than for larger appliances. Even when repair is not mandatory, fixing leaks is still the best practice.

When pressurizing a system with nitrogen you should;

Correct answer: C. Use a pressure regulator and downstream relief valve in the line.

Nitrogen cylinders are high-pressure cylinders. A regulator and downstream relief valve protect the system from being over-pressurized during leak testing.

📖 Related rule: § 82.154 — Prohibitions

A small appliance is defined by EPA as;

Correct answer: D. Factory-charged, hermetically sealed appliances with 5 lbs or less of refrigerant.

EPA defines a small appliance as factory-made, factory-charged, hermetically sealed, and containing 5 pounds or less of refrigerant.

📖 Related rule: § 82.154 — Prohibitions

Which of the following is an example of a non-condensable?

Correct answer: B. Air

Air is a non-condensable because it does not condense under normal refrigeration system operating conditions. Non-condensables can raise system pressure and reduce efficiency.

If regulations change after the technician becomes certified;

Correct answer: C. The technician is responsible for complying with regulatory changes.

Certification does not freeze the rules in place. Technicians are responsible for learning and following later regulatory changes.

📖 Related rule: § 82.154 — Prohibitions

When a system is in deep vacuum;

Correct answer: C. Never energize the compressor.

A compressor motor should not be energized in a deep vacuum because the reduced dielectric strength can damage motor windings.

Which HC refrigerant is allowed for use in NEW Domestic Small Appliances ?

Correct answer: C. R-600a

R-600a is isobutane, a hydrocarbon refrigerant approved for certain new domestic small appliances. It is not a general retrofit refrigerant for existing systems.

Self-contained or active recovery equipment

Correct answer: B. Has its own means to recover refrigerant.

Self-contained, or active, recovery equipment has its own compressor or recovery mechanism. System-dependent equipment relies on the appliance or system pressure.

When filling a charging cylinder with a regulated refrigerant;

Correct answer: A. The refrigerant vapor that is vented off the top of the cylinder must be recovered.

Venting regulated refrigerant from a charging cylinder is not allowed as a normal practice. Vapor removed from the cylinder must be recovered.

📖 Related rule: § 82.154 — Prohibitions

Type I Certification is required for

Correct answer: A. Persons handling refrigerant during service or repair of small appliances.

Type I certification applies to technicians handling refrigerant during maintenance, service, repair, or disposal of small appliances.

📖 Related rule: § 82.154 — Prohibitions

Technicians who perform sealed-system service on small appliances must have;

Correct answer: B. Type I or Universal certification.

Small appliance sealed-system work requires Type I certification. Universal certification also qualifies because it includes Type I.

📖 Related rule: § 82.154 — Prohibitions

Recovery equipment must be

Correct answer: B. Certified by an EPA-approved testing laboratory.

Recovery equipment must be certified by an EPA-approved testing organization. This certification shows the equipment meets required recovery standards.

📖 Related rule: § 82.154 — Prohibitions

When using a system-dependent recovery system on an appliance that has an operating compressor, the technician should

Correct answer: C. Run the compressor and recover from the high side of the system only.

With an operating compressor and system-dependent recovery, the appliance compressor can help move refrigerant to the high side for recovery.

Small appliances in recreational vehicles may use refrigerants such as Ammonia, Hydrogen, and water. These refrigerants

Correct answer: B. Should not be recovered.

Some RV absorption appliances use ammonia, hydrogen, and water rather than regulated fluorocarbon refrigerants. Those mixtures should not be recovered with refrigerant recovery equipment.

Small appliances are equipped with a straight piece of tubing (process stub) that is used;

Correct answer: A. As the installation location for a piercing-type access valve.

The process stub is a straight piece of tubing used to access the sealed system. A piercing-type access valve can be installed there for recovery or service.

Applying heat, with a heat gun, to the compressor

Correct answer: B. can help vaporize any trapped liquid refrigerant during recovery.

Gentle heat can help trapped liquid refrigerant boil off so it can be recovered. A heat gun should be used carefully, not an open flame.

System-dependent recovery methods may only be used on appliances containing;

Correct answer: C. 15 pounds of refrigerant or less.

System-dependent recovery is limited to smaller charges. For this question, the tested cutoff is appliances containing 15 pounds of refrigerant or less.

System-dependent or passive recovery equipment;

Correct answer: A. Captures refrigerant into a non-pressurized container.

System-dependent, or passive, recovery relies on the appliance compressor or system pressure and can collect refrigerant in a non-pressurized container.

When using a system-dependent recovery system on an appliance that has a non-operating compressor, the technician should

Correct answer: A. Place access fittings on both the low and high side.

When the compressor will not run, refrigerant can remain trapped on both sides of the system. Access to both the high and low sides improves recovery.

With a non-operating system compressor, recovery equipment must be capable of recovering

Correct answer: D. 80 percent of the refrigerant or achieving 4 inches of vacuum.

For a non-operating compressor in this Type I context, the recovery target is 80 percent of the refrigerant or 4 inches of vacuum.

Recovering multiple types of refrigerants in the same cylinder

Correct answer: B. will make the reclaimed refrigerants unreclaimable.

Mixing refrigerants contaminates the recovery cylinder. Mixed refrigerants are difficult or impossible to reclaim as usable refrigerant.

If, after installing a fitting for the purpose of recovering the appliance's refrigerant, you find that the system pressure is 0 psig

Correct answer: C. Refrigerant recovery is not required.

If the small appliance is already at 0 psig after access is installed, there is no remaining positive-pressure refrigerant charge to recover.

A cylinder label must contain what type of information about the refrigerant?

Correct answer: B. Type and amount of refrigerant

A cylinder label must clearly identify the type of refrigerant and the amount (net weight) inside. Knowing the exact contents prevents cross-contamination during charging or recovery and is required for accurate recordkeeping under Section 608.

What is the EPA definition of a small appliance?

Correct answer: C. Manufactured, charged and hermetically sealed in a factory and contains five pounds or less of refrigerant

EPA defines a small appliance under §82.152 as one fully manufactured, charged, and hermetically sealed in a factory containing 5 pounds or less of refrigerant — household refrigerators, window ACs, water coolers, dehumidifiers, vending machines. The 5-pound threshold determines which Type I rules and recovery requirements apply.

Which best describes the definition of Type I “Small Appliance”, as defined by EPA?

Correct answer: A. Factory-made, charged, sealed systems with 5 pounds or less of refrigerant.

EPA defines a Type I 'small appliance' specifically as a system manufactured, charged, and hermetically sealed at the factory with 5 lb or less of refrigerant — examples include household refrigerators, freezers, window AC units, water coolers, and dehumidifiers. Just being small or sealed isn't enough; it must be all three (factory-made, factory-charged, factory-sealed). Central AC and field-charged units don't qualify.

📖 Related rule: § 82.154 — Prohibitions

Which of the following is true about PTACs and MVACs as small appliances?

Correct answer: A. A PTAC qualifies as a small appliance, but an MVAC does not.

A Packaged Terminal AC (PTAC, the hotel/motel through-wall unit) qualifies as a small appliance under §82.152 — factory-sealed and ≤5 lb. Motor Vehicle ACs (MVAC) are regulated separately under Section 609, not as small appliances, and require Section 609 certification rather than Type I.

For small appliance use, the recovery equipment manufactured after November 15, 1993 must be capable of recovering:

Correct answer: A. 80% with the compressor off or 90% with it operating, both at 4 inches of vacuum.

Small-appliance recovery equipment manufactured after November 15, 1993 must recover 90% of the refrigerant when the appliance compressor runs, or 80% when it does not, or pull a 4-inch Hg vacuum, whichever is achieved first. These performance levels are tested under ARI/AHRI 740 conditions before EPA approval.

What is the maximum amount of refrigerant a small appliance can have by definition?

Correct answer: B. 5 pounds or less

5 pounds is the EPA size cutoff for small appliances under Section 608. Above 5 lb, equipment falls under Type II/III rules (high or low pressure systems) with stricter leak repair, evacuation, and recordkeeping requirements.

The sale of Class I and Class II refrigerants will be restricted to technicians certified by an EPA approved program after:

Correct answer: D. November 14, 1994

Section 608 restricted the sale of Class I (CFC) and Class II (HCFC) refrigerants to certified technicians beginning November 14, 1994. Anyone purchasing these refrigerants after that date must hold a valid EPA Section 608 certification card, with employer-purchase exceptions limited to the technicians employed there.

📖 Related rule: § 82.154 — Prohibitions

Who is responsible for complying with the laws if the EPA changes the laws after technician certification?

Correct answer: B. It is the responsibility of the technician to comply with any future changes in the law

Once certified, the technician personally remains responsible for following current EPA rules — certification is permanent, but it does not freeze the regulations. When EPA updates Section 608 or adds related requirements under laws such as the AIM Act, the technician must learn which rule applies. The company and equipment owner have separate responsibilities, but personal compliance is on the technician.

📖 Related rule: § 82.154 — Prohibitions

The release of vapor from the top of a graduated charging cylinder when filling may:

Correct answer: C. Not be vented and must be recovered.

Vapor released from the top of a graduated charging cylinder is refrigerant and must be recovered, not vented. Section 608 prohibits intentional venting of refrigerant during service, including the small amounts released to set a charging cylinder's level.

Should regulations of the Clean Air Act (CAA) change after a technician is certified:

Correct answer: C. The technician must learn and comply with future law changes.

Certification is permanent and does not require retesting when EPA changes the rules — but the technician is personally responsible for staying current with the law. Grandfathering (ignoring changes) is not a valid defense for a violation. Higher-score retests aren't part of how Section 608 works.

📖 Related rule: § 82.154 — Prohibitions

Recovery equipment manufactured before November 15, 1993 must meet what standards?

Correct answer: B. Capable of recovering 80% of the refrigerant whether or not the compressor is operating or achieve a 4 inch vacuum under conditions of ARI 740.

Recovery equipment built BEFORE Nov 15, 1993 is grandfathered to a less strict standard: it must recover 80% of the refrigerant regardless of compressor operation, OR pull a 4-inch Hg vacuum under ARI 740 conditions. Equipment built after Nov 15, 1993 is held to a tougher 90% / 4-inch vacuum standard with the compressor operating. The 'before/after Nov 15, 1993' date is the key dividing line.

System-dependent (passive) refrigerant recovery of small appliances:

Correct answer: C. Recovers refrigerant in a non-pressurized container.

System-dependent (passive) recovery uses the small appliance's own compressor or its system pressure to push refrigerant into a non-pressurized container, often a plastic-lined drum. It cannot be used on appliances with more than 15 lb of refrigerant; for those, active (self-contained) equipment is required.

Recovery equipment manufactured after November 15, 1993 must meet what standards if using a compressor?

Correct answer: D. Be capable of recovering 90% of the refrigerant with the compressor operating or achieve a 4 inch vacuum under conditions of ARI 740.

Recovery equipment built AFTER Nov 15, 1993 must meet ARI/AHRI 740: 90% recovery with the compressor operating, or pull a 4-inch Hg vacuum if the compressor is not running. Pre-1993 equipment was only required to hit 80%. Memorize the 'Nov 15, 1993 / 90% / 4-inch Hg' combination — it's a frequent exam fact.

Recovery equipment with no compressor must?

Correct answer: B. Be capable of recovering 80% of the refrigerant without the compressor operating or achieve a 4 inch vacuum under conditions of ARI 740

Recovery equipment without its own compressor must, under ARI/AHRI 740 test conditions, recover at least 80% of the refrigerant from a small appliance whose compressor cannot operate, or pull a 4-inch Hg vacuum. These limits ensure passive units still capture most of the charge before the appliance is opened.

Before disposing of a small appliance containing R-12, it is necessary to:

Correct answer: B. Recover the refrigerant

Section 608 prohibits disposal of any appliance with refrigerant left inside — recovery is required regardless of equipment size. Pressurizing with nitrogen, inverting the unit, or leak checking aren't disposal-prep steps; they don't remove the refrigerant. The recovery requirement applies even to small one-pound systems.

What is a low-loss fitting and why is it needed?

Correct answer: B. A manual or automatic closing fitting that limits refrigerant loss at disconnect.

Low-loss fittings have a check or shutoff that closes when hoses are disconnected, capturing the small slug of refrigerant trapped in the hose instead of venting it to atmosphere. EPA requires them on recovery and service hoses. Capped fittings, plain quick-connects, or hose-storage caps don't satisfy the rule.

A system has been operating with a complete restriction at the capillary tube inlet, what access is required for recovery?

Correct answer: B. Two access valves, on the high and low sides of the system

A complete restriction at the cap-tube inlet isolates the high side from the low side, so refrigerant on each side can't equalize through the metering device. To recover both sides, you must install two access valves — one each on the high and low side. A single valve would only get the side it's on, leaving refrigerant trapped in the other half.

What does the service aperture on a small appliance typically look like?

Correct answer: B. A straight tube entered with a piercing access valve.

Most small sealed appliances have no factory service port — just a stubbed-off straight process tube the manufacturer used to charge the system. Technicians attach a piercing (saddle/Schrader-type) access valve to enter the system. Hook-shaped tubes aren't standard, and permanent factory-installed valves are typical only on larger equipment.

CFCs will not be manufactured in the United States after:

Correct answer: D. 1996

U.S. CFC production ended on January 1, 1996, under the Montreal Protocol and Title VI of the Clean Air Act. Existing CFC stocks could still be used to service older systems, but no new CFCs could be manufactured or imported. The earlier dates are other phaseout milestones (1990 CAA Amendments, 1992 venting prohibition, 1994 mandatory technician certification).

What should be done with leaks in small appliances?

Correct answer: A. Leak repair is not mandatory, but it should be done whenever possible.

EPA leak-repair rules apply only to appliances containing 50 lb or more of refrigerant. Small appliances (≤5 lb) have no mandatory repair threshold — but you must still recover before service or disposal, and venting is always prohibited. There is no 1–5 lb mandatory repair bracket.

To work on small appliances after November 14, 1994, a technician must be certified as:

Correct answer: D. A or C above

Type I certification is required to work on small appliances; Universal (which covers Types I, II, and III) also qualifies. Type II is for high-pressure equipment and doesn't cover small appliances. So both 'Type I' and 'Universal' are correct, making 'A or C above' the right answer.

📖 Related rule: § 82.154 — Prohibitions

How can you tell what type of refrigerant is in a system?

Correct answer: A. Check the unit label, manufacturer's data sheet, and a pressure-temperature chart.

Identify refrigerant by the unit label first, cross-reference with manufacturer documentation, then verify with a pressure-temperature (P/T) chart that the operating pressure matches the saturation pressure for that refrigerant at the measured temperature. Tasting refrigerant is dangerous and useless. Cylinder weight alone or assuming the gas can't be identified both fail field practice.

When using a pressure-temperature chart for a pure refrigerant, what does the chart let you determine?

Correct answer: A. Expected saturation pressure for that refrigerant at a given temperature.

A pressure-temperature chart correlates a refrigerant's saturation temperature to its saturation pressure. Knowing one tells you the other for that pure refrigerant — useful for confirming the gas matches the label and for checking subcooling/superheat in the field. P/T charts say nothing about wattage, line size, or fill weight.

What might happen if a cylinder containing mixed refrigerants is given to a reclamation center?

Correct answer: A. The center may refuse it, return it at the owner's expense, or charge to destroy it.

Mixed refrigerant can't be reclaimed because separating different refrigerants is impractical and contaminates equipment. A reclamation center will typically refuse a mixed cylinder, return it at the owner's expense, or charge a fee to send it for destruction. That cost is why dedicated, properly purged hoses and recovery machines per refrigerant matter so much.

What is the difference between a self-contained recovery tank and a system-dependent recovery tank?

Correct answer: A. Self-contained equipment has its own compressor; system-dependent relies on the appliance.

A self-contained recovery unit has its own compressor and condenser, so it can recover refrigerant from any appliance and into a pressurized DOT-approved tank. System-dependent equipment has no compressor and depends on the appliance's compressor or pressure to push refrigerant into a non-pressurized container; it is limited to small appliances.

What are things that can cause high recovery discharge pressures?

Correct answer: A. Closed tank inlet valve or excess air in the system.

High discharge pressure during recovery usually means refrigerant has nowhere to go — a closed cylinder valve, a kinked hose, or non-condensable air mixed in with the refrigerant raising pressure above the saturation curve. Hot ambient or undersized cylinders can also drive pressure up. Cold ambient and oversized cylinders generally lower discharge pressure, so those answers are wrong.

How can you check if there is excess air / non-condensables in a tank?

Correct answer: B. Compare recovery-tank pressure to the refrigerant pressure-temperature chart.

Let the recovery tank stabilize at room temperature, then compare its pressure to the refrigerant's pressure-temperature chart for that temperature. If the measured pressure is higher than the P-T chart predicts, non-condensables (air) are present and must be carefully bled off the top of the tank or the refrigerant rejected.

What temperature must a cylinder be at to check for excess air?

Correct answer: B. Room temperature before taking a pressure reading.

A cylinder must be at a known stable temperature, ideally room temperature (around 70°F to 75°F), before reading its pressure. Without thermal equilibrium the gauge reading will not match the pressure-temperature chart, making it impossible to tell whether non-condensables are present.

What type of system can a vacuum pump be used on for recovery?

Correct answer: A. System-dependent (passive) recovery

A vacuum pump is permitted only in system-dependent (passive) recovery, where the appliance's own compressor or refrigerant pressure pushes refrigerant into a non-pressurized container and the pump just helps pull the last vapor. On an active recovery job the EPA requires a self-contained, certified recovery unit, because a vacuum pump alone is not designed or approved to capture pressurized refrigerant.

When using a system-dependent recovery system with an operating compressor, where should the refrigerant be recovered from?

Correct answer: A. High side of the system

When the appliance compressor is operating, system-dependent recovery is performed from the high side because the compressor is actively pumping refrigerant to that side. Drawing from the high side captures the charge most efficiently while the compressor still runs.

When using a system-dependent recovery system with a non-operating compressor, where should the refrigerant be recovered from?

Correct answer: C. Both high and low side

If the appliance compressor will not run, system-dependent recovery must pull from both the high and low sides at once because there is no internal pressure differential to move refrigerant. Connecting both sides equalizes the system through the recovery container and reaches the required vacuum more reliably.

How can you release trapped refrigerants in the oil during recovery?

Correct answer: A. Heat and gently tap the compressor, and activate the defrost heater.

Refrigerant dissolved in the compressor oil comes out as the oil warms — gentle heat (heat lamp, hot water bag) and light tapping help drive it out, and on a refrigerator/freezer running the defrost heater warms the system from inside. Adding water or venting are both wrong (dangerous and illegal). Pushing more refrigerant in just dilutes the recovery.

A "small appliance" under Section 608 is one that is fully manufactured, charged, and hermetically sealed in a factory with how much refrigerant?

Correct answer: B. 5 pounds or less

Section 608 §82.152 defines a small appliance as one fully manufactured, charged, and hermetically sealed in a factory with 5 pounds or less of refrigerant. This 5-pound threshold determines which sales restrictions, evacuation levels, and Type I rules apply. The 2-, 10-, and 50-pound numbers are distractors from other parts of the regulation.

📖 Related rule: § 82.154 — Prohibitions

Recovery equipment manufactured BEFORE November 15, 1993 used on small appliances must achieve a vacuum of at least:

Correct answer: B. 4 inches of mercury vacuum

Under EPA Section 608, recovery equipment built before Nov 15, 1993 only had to reach 4 in. Hg vacuum on a small appliance, because older machines could not reliably pull deeper. Equipment built on or after that date must meet a stricter target, and 0 psig or 25 in. Hg are values for other appliance categories.

Recovery equipment manufactured AFTER November 15, 1993 used on a small appliance with a working compressor must recover at least:

Correct answer: C. 90% of the refrigerant

For a small appliance with a working compressor, recovery equipment manufactured after November 15, 1993 must recover at least 90% of the refrigerant (or pull a 4-inch Hg vacuum, whichever comes first). When the appliance compressor will not run, the requirement drops to 80% because removal is harder without the appliance's own pumping action.

In a small appliance, an unusually high pressure for a known refrigerant at a measured temperature suggests:

Correct answer: B. The presence of non-condensables such as air.

A pure refrigerant at a known temperature has a single saturation pressure (per its pressure-temperature chart). If actual head pressure is higher than the chart predicts at that temperature, something else (typically air leaked in during service) is adding partial pressure on top of the refrigerant. That's the textbook diagnostic for non-condensables in a system.

📖 Related rule: Core Study Guide

To recover refrigerant from a small appliance with an inoperative compressor using a system-dependent (passive) device, a technician may:

Correct answer: B. Heat or sharply rap the compressor while drawing vacuum on a recovery container.

When a small-appliance compressor will not run, a passive recovery device drives refrigerant out by pulling a vacuum on a non-pressurized recovery container while gently heating or sharply rapping the compressor to drive trapped refrigerant out of the oil. This combination is needed to reach the required 80% recovery level.

When recovering from a small appliance with an inoperative compressor, access valves should be installed:

Correct answer: C. On both the high and low sides

With an inoperative compressor, the high and low sides can't equalize through the compressor pumping action, so a single access valve would only get the side it's on. Installing access valves on both the high and low sides ensures all the refrigerant can be recovered. If the compressor still ran, one access point would be enough because the compressor would equalize the system.

When using a system-dependent (passive) recovery device on a small appliance with an OPERATIVE compressor:

Correct answer: A. Operate the appliance's compressor during recovery.

If the small-appliance compressor still works, a passive recovery device should operate the appliance's compressor during recovery so it pumps refrigerant out into the recovery container. The appliance's own pumping action is what allows the unit to reach the higher 90% recovery level required for working compressors.

After completing service on a small appliance, solderless (saddle/piercing) access fittings should be:

Correct answer: B. Removed at the conclusion of service.

Saddle/piercing fittings rely on a rubber gasket against a punctured tube — they leak over time, and EPA discourages leaving them on the appliance permanently. Standard practice is to remove the piercing fitting at the end of service and seal the tube. Painting over or filling with sealant doesn't fix the long-term leak risk.

The most common HFC substitute for CFC-12 (R-12) in small appliances is:

Correct answer: B. R-134a

R-134a (HFC) is the most common substitute for R-12 (CFC) in small appliances and automotive AC because both run at similar pressures. It is not a true drop-in: R-134a requires POE lubricant in stationary equipment, or PAG in MVAC, instead of R-12 mineral oil. R-22, R-410A, and R-123 are wrong pressure/application matches for small R-12 appliances.

When refrigerants are exposed to an open flame or very hot surface, they can decompose into:

Correct answer: B. Hazardous byproducts including phosgene and hydrogen chloride.

When refrigerants contact open flame or hot surfaces, the chemical bonds break down. Chlorinated refrigerants form phosgene (highly toxic, used as a WWI chemical weapon) and hydrogen chloride (a corrosive acid gas). Refrigerants don't decompose into pure oxygen or harmless water vapor, and CO2 is far from the primary danger.

Type II

All HVAC/R systems must be protected by a

Correct answer: D. Pressure relief valve

HVAC/R systems need pressure relief protection to prevent unsafe overpressure. A relief valve protects the system if pressure rises beyond safe limits.

📖 Related rule: Core Study Guide

Proper recovery techniques begin with the use of appropriate recovery equipment that has been certified by

Correct answer: C. an EPA approved laboratory

Under Section 608, recovery and recycling equipment must be tested and certified by an EPA-approved laboratory (such as UL or AHRI) against the AHRI 740 performance standards. Manufacturer self-certification is not sufficient; the lab certification confirms the unit meets the required recovery efficiencies and final vacuum levels.

📖 Related rule: § 82.154 — Prohibitions

When using a recovery unit on a system containing 100 lbs. of R-410A it must be evacuated to

Correct answer: A. 0 inches of Mercury

R-410A is a high-pressure refrigerant, and EPA Section 608 recovery tables require evacuation only to 0 in. Hg (atmospheric) for high-pressure appliances containing less than 200 lbs of charge when using equipment built on or after Nov 15, 1993. The deeper vacuums (4, 10, 15 in. Hg) listed here apply to other appliance categories, not a 100 lb R-410A system.

Unless plans are made to replace a system with a leak rate that exceeds the maximum leak rate, repairs must be made within;

Correct answer: D. 90 days.

When an appliance exceeds its allowable leak rate and the owner is not retrofitting or replacing it, repairs must be completed within 30 days, and that window can extend to 90 days for parts or scheduling reasons. After repair, follow-up leak verification is required. The shorter answers (30/45/60 days) describe the standard repair clock or interim deadlines, not the maximum extension.

A high-pressure appliance containing 210 lbs. of R-407C refrigerant must be evacuated (recovered) to a level of

Correct answer: D. 0 inches of vacuum

R-407C is a high-pressure HFC blend. Under EPA Section 608, high-pressure appliances containing 200 lbs or more of refrigerant must be evacuated to 0 in. Hg (atmospheric) when using equipment manufactured before Nov 15, 1993, and only modestly deeper with newer equipment. The deeper vacuum levels listed (4, 10, 15 in. Hg) correspond to other charge-size or equipment-age combinations, not this one.

EPA regulations state that removal of which component constitutes a "major repair"?

Correct answer: B. Compressor

Removal of the compressor is classified as a major repair under Section 608, along with the condenser, evaporator, and auxiliary heat exchanger. Major repairs trigger stricter evacuation requirements (deep vacuum) and follow-up leak verification. Smaller jobs like changing a filter-drier or service valve are non-major repairs.

📖 Related rule: § 82.154 — Prohibitions

A refrigerant sensor which will sound an alarm and automatically start a ventilation system in occupied equipment rooms falls under ASHRAE Standard;

Correct answer: A. 15

ASHRAE Standard 15 governs the safety of refrigeration systems, including machinery-room sensors, alarms, and emergency ventilation requirements. ASHRAE 34 covers refrigerant safety classifications (A1, B2, etc.) and 90.1 covers building energy efficiency, so they are related but address different topics. Don't confuse Standard 15 (safety) with Standard 34 (refrigerant naming/classification).

What must the equipment owners/operators include in recovered refrigerant records for equipment with refrigerant charges that range from 5 to 50 pounds?

Correct answer: A. The quantity of refrigerant (by type) added or recovered from disposed appliances each year and quantity of refrigerant (by type) sent for reclamation or destruction.

For appliances with charges between 5 and 50 lb, owners must keep an annual record of refrigerant added, refrigerant recovered from disposed equipment, and refrigerant sent for reclamation or destruction. The monthly options are wrong — that level of detail is not the EPA requirement at this charge size. Records must be retained and made available to EPA on request.

📖 Related rule: § 82.154 — Prohibitions

When dehydrating a system, it should be evacuated to a minimum level of;

Correct answer: C. 500 Microns

Industry practice (per ASHRAE/HVAC service standards) is to dehydrate a system to 500 microns or lower so that any remaining water boils off at room temperature and is removed by the vacuum pump. 25,000 microns is far too shallow to boil off moisture, and 30 in. Hg is an inches-of-mercury reading that lacks the resolution needed to confirm dryness.

Which of the following refrigerants is classified as a very high-pressure refrigerant?

Correct answer: B. R-744

R-744 (carbon dioxide) is classified as a very high-pressure refrigerant; its critical temperature is around 88°F and operating pressures reach well over 1,000 psig. R-410A and R-22 are high-pressure refrigerants but operate at much lower pressures, while R-123 is a low-pressure refrigerant that runs in a vacuum on the low side.

A high-pressure appliance containing less than 200 lbs. of an HCFC or HFC refrigerant must be evacuated (recovered) to a level of

Correct answer: A. 15 inches of vacuum

Per Section 608 evacuation requirements, a high-pressure appliance with less than 200 lbs of HCFC or HFC refrigerant must be evacuated to 15 inches of vacuum (mercury). The threshold gets stricter for larger systems (200+ lbs) and for major repairs, where deeper vacuums are required. 0 or 4 inches wouldn't pull enough refrigerant to meet the recovery rule.

If a covered leaking appliance will not be repaired, what is the usual retrofit-or-retire requirement?

Correct answer: A. Plan within 30 days; complete within one year.

If the owner chooses retrofit or retirement instead of repair, the usual rule is to develop the plan within 30 days and complete it within one year. Limited extensions or relief can apply in defined circumstances. The 30-day deadline is for the plan, not universal completion of the entire retrofit.

📖 Related rule: § 82.154 — Prohibitions

For a 50-pound-or-larger appliance covered by Section 608 leak-repair requirements, which records must document whether a repair worked?

Correct answer: A. The dates, methods, locations, and results of the initial and follow-up verification tests.

For a covered 50+ lb ODS appliance that exceeds the trigger rate, the repair record must document the initial and follow-up verification tests, including when and how they were performed, the repaired leak locations tested, and the results. A separate chronic-leak report is triggered if the appliance leaks 125% or more of its full charge in a calendar year.

📖 Related rule: § 82.154 — Prohibitions

A crankcase heater is often used to prevent refrigerant from mixing with compressor oil during periods of

Correct answer: A. Low ambient temperature

A crankcase heater warms the compressor oil during off-cycles in cold weather to drive refrigerant out of the oil. At low ambient temperatures, refrigerant migrates to the coldest spot, which is often the compressor crankcase, where it dissolves into the oil and can cause foaming, slugging, and bearing damage on startup.

📖 Related rule: Core Study Guide

Under Section 608, leaks must be repaired on an industrial process refrigeration appliance with 50 pounds or more of ozone-depleting refrigerant when the annualized leak rate reaches ________ or more.

Correct answer: C. 30%

Industrial process refrigeration has a 30% annual leak threshold. Commercial refrigeration is 20%, while comfort cooling and other covered appliances use 10%. The appliance category, refrigerant, and charge size all matter.

Under Section 608, an Industrial Process Refrigeration (IPR) system containing 50 pounds or more of ozone-depleting refrigerant must be repaired when the annual leak rate exceeds:

Correct answer: C. 30%

IPR systems covered by Section 608 trigger leak repair at a 30% annual leak rate. Commercial refrigeration uses 20%, and comfort cooling and other appliances use 10%. For Section 608 leak repair, the appliance must contain 50 pounds or more of ozone-depleting refrigerant.

📖 Related rule: § 82.154 — Prohibitions

Refrigerants CFC-12, HCFC-22, and HFC-134a are all classified as Type ________ substances.

Correct answer: C. A-1

Under ASHRAE Standard 34, R-12, R-22, and R-134a are all Class A1: 'A' means low toxicity, '1' means no flame propagation. B-class refrigerants (B1, B2) are higher toxicity (e.g., R-123 is B1, ammonia is B2L). Knowing the safety class drives machinery-room and ventilation requirements.

Under the 2026 AIM Act program, what annual leak-rate threshold applies to a covered HFC appliance categorized as comfort cooling?

Correct answer: B. 10%

A covered HFC appliance categorized as comfort cooling uses a 10% annual leak-rate threshold under 40 CFR 84.106. The AIM Act program generally begins at 15 pounds of HFC or certain substitutes with GWP above 53, but residential and light-commercial AC and heat-pump appliances are excluded.

What happens to a refrigerant that is heated above the saturation temperature?

Correct answer: A. It remains in the vapor state.

A refrigerant heated above its saturation temperature for the given pressure becomes superheated vapor and remains in the vapor state. Saturation temperature is the boiling/condensing point at a given pressure; below it the refrigerant is subcooled liquid, at it the refrigerant is a liquid-vapor mix, and above it the refrigerant is fully vaporized.

When recovering refrigerant from a medium-pressure system with more than 200 lbs. of refrigerant, recover to a level of

Correct answer: B. 4" Hg

For medium/high-pressure systems with more than 200 lb of refrigerant, EPA-required recovery levels reach into vacuum (typically 4 inches Hg), versus 0 in. Hg for systems under 200 lb. Pulling deeper helps draw more refrigerant out before disposal or major service. The lower-vacuum and atmospheric answers correspond to smaller systems or older standards.

Non-condensables will cause;

Correct answer: D. High discharge pressure

Non-condensables (mainly air) collect in the top of the condenser and take up space that should be holding refrigerant vapor that is condensing, which raises head pressure and discharge pressure. The result is reduced capacity, higher amp draw, and elevated compressor discharge temperature that can break down oil.

📖 Related rule: Core Study Guide

Refrigerant should be recovered from the condenser outlet if the condenser is;

Correct answer: A. Below the receiver

When the condenser sits below the receiver, refrigerant can pool in the condenser instead of draining to the receiver, so you recover from the condenser outlet to capture all the trapped liquid. If the condenser is above the receiver, gravity drains the liquid into the receiver, so you recover from the receiver instead. Always recover from the lowest point holding liquid.

What can be done with a refrigerant trace gas and nitrogen mixture after a system leak is found?

Correct answer: D. Release to the atmosphere.

A nitrogen and trace-refrigerant mixture used for pressure leak testing may be released to the atmosphere. EPA allows venting of de minimis quantities of refrigerant released during good-faith leak testing with nitrogen, since the volume of HCFC/HFC trace gas is very small. Pure refrigerant or recovered refrigerant must still be recovered, not vented.

A new split system should be checked for leaks by

Correct answer: D. pressurizing the system with a few ounces of system refrigerant and an inert gas.

A trace charge of the system refrigerant lets a leak detector spot the leak, while nitrogen (an inert gas) safely raises pressure to make leaks visible. Compressed air introduces moisture and oxygen — mixed with refrigerant oil under pressure that can form a combustible mixture. Releasing the factory charge wastes refrigerant and tells you nothing about leaks.

What conditions allow for a system to be opened and repaired without recovering the refrigerant to the required vacuum level?

Correct answer: A. A system with a large leak and internal pressure of 0 psig

EPA Section 608 allows the required vacuum level to be waived only when leaks are so large that recovery to that level is not reasonably achievable; in that case the system must still be evacuated to atmospheric pressure (0 psig) before opening. Major component replacement, CFC use, or a dead compressor are not by themselves grounds to skip the required recovery level.

When should piercing-type valves be used, and what is a common problem with them?

Correct answer: A. Use only when no other access is available; they tend to leak if left installed.

Piercing/saddle valves are intended for one-time emergency access — their seal is just a rubber gasket against a punctured tube and the seal degrades over time. Use them only when no factory service port exists, and remove them after service. They should never be relied on for permanent installation.

Before charging a new system with refrigerant, what should be done?

Correct answer: B. Pressurize with nitrogen, an inert gas, and leak check.

Nitrogen is dry and inert, so it pressurizes new lines for leak testing without reacting with system materials, introducing moisture, or combusting. Compressed air contains moisture and oxygen — bad for the system long-term and dangerously combustible when mixed with refrigerant oils. Oxygen with refrigerant oil under pressure is explosive.

Which refrigerant can be used for leak detection as a trace gas and pressurized with nitrogen?

Correct answer: D. R-115

R-22 (or, in the older study material, the trace HCFC R-115 from R-502) may be mixed with nitrogen as a trace gas for leak detection. The nitrogen does the pressurizing, and the small amount of refrigerant trips an electronic leak detector. EPA permits this practice and the released mix can be vented as de minimis.

What tools can you use to find the general area of leaks and pinpoint leaks?

Correct answer: C. Electronic or ultrasonic detectors can help locate the general area of a leak.

Electronic and ultrasonic leak detectors sweep an area to find roughly where a leak is — they alarm on rising concentration but can't tell you the exact joint. Soap bubbles, oil traces, or fluorescent dye then pinpoint the exact spot. The standard two-step approach is area first, pinpoint second.

Traces of oil around a sight glass inlet fitting of a refrigeration system might be the indication of:

Correct answer: A. A leak

Refrigerant oil is carried with the refrigerant through the system, so wherever refrigerant escapes, oil traces remain behind. An oily film around a sight glass or fitting is almost always a leak indicator. Overcharge, restrictions, or excess oil don't typically leave oil residue at fittings.

Describe ways you can visually look for leaks.

Correct answer: A. Soap bubbles at fittings, oil traces, and excessive superheat from low charge.

Visual indicators of a leak include soap bubbles at fittings, oil traces around joints, and high superheat at the evaporator from a low charge. The wrong answers describe non-leak indicators (compressor cycling, thermostat setting, suction-pressure-only readings) that don't isolate refrigerant loss.

📖 Related rule: Core Study Guide

Type II classification, as identified by EPA, applies to what equipment?

Correct answer: D. High-pressure equipment with more than five pounds of refrigerant.

Type II certification covers high- and very-high-pressure equipment with more than 5 lb of refrigerant — supermarket racks, residential and commercial split systems, heat pumps, condensing units, etc. Type I is small appliances (≤5 lb factory-sealed), Type III is low-pressure chillers. Universal covers all three categories.

📖 Related rule: § 82.154 — Prohibitions

Under Section 608, what are the current leak-rate thresholds for comfort-cooling and industrial-process-refrigeration appliances containing 50 pounds or more of ozone-depleting refrigerant?

Correct answer: A. Comfort cooling: 10%; industrial process refrigeration: 30%.

For Section 608 appliances containing 50 pounds or more of ozone-depleting refrigerant, comfort cooling uses a 10% annual threshold and industrial process refrigeration uses 30%. Commercial refrigeration is a separate category at 20%.

What type of refrigerant was the most common before outlawing CFCs and HCFCs?

Correct answer: B. R-22

R-22 (HCFC-22) was the most common refrigerant in residential and commercial AC for decades before its phaseout. R-12 was common in autos and small appliances; R-500 was a blend used in some commercial equipment; R-134a is the HFC successor to R-12. New R-22 production and import ended January 1, 2020 in the U.S.

The required level of evacuation for recovery equipment manufactured after November 15, 1993, on a system containing less than 200 pounds of R-12 refrigerant is:

Correct answer: C. 10 inches Hg

R-12 is a high-pressure refrigerant. Under EPA Section 608 recovery tables, equipment manufactured on or after Nov 15, 1993 working on a high-pressure appliance with less than 200 lbs of charge must reach 10 in. Hg vacuum. The 4 in. Hg level applies to older (pre-1993) equipment, and 0 in. Hg applies to small appliances or larger charges of high-pressure refrigerant.

What is the purpose of the filter drier and when should it be changed?

Correct answer: B. It removes moisture and should be replaced routinely or when the system is opened.

A filter-drier removes moisture, acid, and small particles from the refrigerant circuit. It should be replaced any time the system is opened for service and routinely as part of maintenance, because once the desiccant is saturated it stops protecting the system and can release contaminants back into the refrigerant stream.

📖 Related rule: Core Study Guide

Industrial process refrigeration equipment containing 50 pounds or more of ozone-depleting refrigerant requires repair when the annual leak rate exceeds ________ %.

Correct answer: B. 30

Industrial process refrigeration uses a 30% annual leak threshold. Commercial refrigeration is 20%, while comfort cooling and other covered Section 608 appliances use 10%.

📖 Related rule: § 82.154 — Prohibitions

How can you tell through a sight glass if there is excess moisture in the system?

Correct answer: B. The moisture indicator on the sight glass changes color.

A moisture-indicating sight glass changes color when the refrigerant is wet (typically green for dry, yellow for wet). The technician can spot moisture in the system at a glance without opening the circuit; a color change calls for replacing the filter-drier and dehydrating the system.

Comfort-cooling and other appliances containing 50 pounds or more of ozone-depleting refrigerant require repair when the annual leak rate exceeds ________ %:

Correct answer: A. 10

Comfort cooling and 'all other' appliances covered by Section 608 use a 10% annual leak threshold. Commercial refrigeration is 20%, and industrial process refrigeration is 30%.

📖 Related rule: § 82.154 — Prohibitions

Using large vacuum pumps can lead to freezing of water in the system what are ways the technician can help prevent the freezing?

Correct answer: A. Increase pressure by introducing nitrogen to counteract freezing

Pulling a fast, deep vacuum lowers the boiling point of trapped water enough that the evaporating water self-cools and freezes inside tubes, blocking further evacuation. Adding dry nitrogen raises the system pressure so the ice melts and can be drawn off as vapor on the next pull; charging refrigerant vapor risks contaminating the recovery cylinder.

The majority of the liquid to be recovered from a system will be found in the:

Correct answer: B. Receiver (when applied)

On systems equipped with a receiver, most of the liquid refrigerant pools there during off-cycles — that's the receiver's job. Recovering from the receiver outlet captures the bulk of the charge as liquid, which is faster than vapor recovery. The condenser holds liquid only when it's below the receiver; the evaporator and low side carry mostly vapor.

Foaming at start-up may be found in what component? What does this mean?

Correct answer: B. Refrigerant in compressor oil causes foaming; a crankcase heater helps prevent migration.

When a system sits idle, refrigerant migrates and condenses into the cooler compressor crankcase oil. At startup, pressure drops and the dissolved refrigerant flashes off, foaming the oil and risking liquid slugging or oil pump-out. A crankcase heater keeps the oil warmer than the rest of the system so refrigerant migrates elsewhere instead.

What are preferred ways to measure a deep vacuum?

Correct answer: B. Measure in microns, preferably to 500 microns, or inches Hg.

Compound gauges and ordinary analog gauges lose all useful resolution in the last inch of mercury, so a deep vacuum (typically 500 microns for dehydration) is read with a thermistor or thermocouple micron gauge. Skipping the measurement entirely or relying on the manifold's compound gauge will let moisture and non-condensables stay in the system.

📖 Related rule: § 82.154 — Prohibitions

If it becomes the owners responsibility to maintain records of all refrigerant added to units that contain more than ________ pounds of refrigerant charge.

Correct answer: D. 50 pounds

Section 608 leak-repair and recordkeeping rules begin at the 50-pound charge threshold. Owners of 50+ lb systems must log every refrigerant addition, calculate annualized leak rate, and conduct verification tests when the leak rate exceeds the trigger. Below 50 lb, federal rules don't require addition records.

📖 Related rule: § 82.154 — Prohibitions

What do inches HG stand for?

Correct answer: C. Inches of mercury

"Hg" is the chemical symbol for mercury, so inches Hg means inches of mercury — the unit used to measure vacuum on a compound gauge. 29.92 in. Hg is one atmosphere; deeper vacuums show smaller atmospheric pressures. Inches of water (D) is a different, much smaller pressure unit used for airflow, not refrigerant vacuum.

Exceptions to the required evacuation levels for recovery equipment that require an appliance be evacuated to only 0 psig apply to appliances that”\:

Correct answer: B. Are filled with water or substances that would damage recovery equipment.

EPA Section 608 lets a technician stop at 0 psig (atmospheric) when pulling a deeper vacuum would draw water or other contaminants into the recovery machine and damage it. Salvage timing, fan-motor problems, and condenser type are not listed as exceptions to the required evacuation level.

When evacuating a vapor compression system how many microns does the vacuum need to achieve?

Correct answer: C. 500

Standard service practice is to dehydrate a vapor-compression system to 500 microns so any remaining water boils off at room temperature and is removed by the pump. 50 or 250 microns is typically below what a service pump can hold against outgassing, while 1000 microns leaves enough moisture in the system to cause acid formation and component damage.

Why should you never start a hermetic compressor when under deep vacuum?

Correct answer: A. Motor winding could be damaged

Refrigerant gas insulates the windings of a hermetic motor; under deep vacuum the dielectric strength of the surrounding atmosphere falls sharply, so energizing the motor can arc across the windings and burn them out. Mechanical concerns like valve or shaft damage are not the primary risk, and refrigerant moisture is irrelevant when the system has been pulled to vacuum.

The condition and state of refrigerant entering the receiver is:

Correct answer: C. Subcooled high pressure liquid

Refrigerant entering the receiver has just left the condenser, so it is high-pressure subcooled liquid. The receiver stores this liquid and ensures only solid liquid (no flash gas) is fed to the metering device, regardless of system load.

📖 Related rule: Core Study Guide

What is a receiver, where is it located and what is the state of the refrigerant after leaving the receiver?

Correct answer: A. After the condenser; subcooled high pressure liquid

A receiver is a storage vessel for liquid refrigerant located after the condenser and before the metering device. Refrigerant leaves the receiver as subcooled high-pressure liquid, ready to be metered into the evaporator without any vapor bubbles disrupting flow.

📖 Related rule: Core Study Guide

What is the liquid line?

Correct answer: C. Line between the condenser and the metering device

After the condenser, refrigerant is high-pressure liquid traveling to the metering device (TXV/cap tube) — that segment is the "liquid line." Compressor-to-condenser is the discharge line; evaporator-to-compressor is the suction line. Naming each line by its location helps you reason about its expected pressure and state.

📖 Related rule: Core Study Guide

What criteria must recovery equipment meet if manufactured after November 15, 1993?

Correct answer: A. EPA-approved lab certification, low-loss fittings, and the stricter vacuum standards.

Recovery equipment manufactured after November 15, 1993 must be certified by an EPA-approved lab to ARI/AHRI 740, use low-loss fittings on its hoses, and meet the post-1993 stricter recovery levels and final vacuums. Pre-1993 equipment can stay in service but only meets the older, less stringent vacuum levels.

📖 Related rule: § 82.154 — Prohibitions

How many inches of Mercury vacuum is required for HCFC-22, for appliances containing more than 200 lbs refrigerant, using equipment manufactured after 11/15/1993?

Correct answer: C. 10

HCFC-22 is a high-pressure refrigerant. Under EPA Section 608, recovery equipment manufactured on or after Nov 15, 1993 working on a high-pressure appliance with 200 lbs or more of charge must reach 10 in. Hg vacuum. The 4 in. Hg level is for older (pre-1993) equipment, and 0 or 15 in. Hg are the wrong direction for this appliance class.

What are considered “major” repairs according to the EPA?

Correct answer: B. Removal of the compressor, condenser, evaporator, or auxiliary heat exchanger.

Section 608 defines a major repair as removing the compressor, condenser, evaporator, or auxiliary heat exchanger coil. These components require the entire refrigerant charge to be recovered to the post-1993 deep-vacuum levels and the system to be evacuated and leak-checked before recharging.

📖 Related rule: Core Study Guide

What can you do if you can’t reach the required evacuation levels on leaky equipment?

Correct answer: B. Evacuate to atmospheric pressure if leaks make the required level unattainable.

EPA Section 608 allows the required vacuum level to be waived on equipment so leaky that the deeper level is not reasonably attainable, but the system must still be evacuated to at least atmospheric pressure (0 psig) before opening. Stopping at any positive psig (4, 10, 15) would still vent refrigerant when the system is opened, which is prohibited.

What are steps taken before using recovery equipment?

Correct answer: A. Check service valves, check recovery-unit oil, and clear refrigerant from the unit receiver.

Before using recovery equipment, verify the appliance service valves are positioned correctly, check the oil level in the recovery unit's compressor, and clear any refrigerant left over from the previous job out of the recovery unit's internal receiver. Skipping these steps causes contamination, undercharged recovery, and equipment damage.

What types of hoses and couplings should be used during the recovery process?

Correct answer: A. Quick couplers, self-sealing hoses, and hand valves to minimize release.

Use low-loss fittings: quick-disconnect couplers, self-sealing hoses, and hand valves at the connections. These minimize the small refrigerant release that happens every time a hose is connected or disconnected. Garden hoses, plain rubber tubing, and open copper lines aren't rated for refrigerant pressure and would dump refrigerant or pull air into the system.

What common contaminants can be found in the oils?

Correct answer: A. Particulates, acids, and moisture.

Compressor oil typically becomes contaminated with metal particulates from wear, acids from refrigerant breakdown (especially after burnouts), and moisture from inadequate evacuation or leaks. Filter-driers and acid test kits target exactly these three. Helium and sand aren't realistic system contaminants.

Why might recovery equipment using hermetic compressors overheat?

Correct answer: B. The unit depends on refrigerant flow through the compressor for cooling.

Hermetic compressors used in recovery equipment are cooled by refrigerant flowing through the motor windings. Near the end of recovery the flow drops sharply, so the motor loses its cooling and can overheat. Letting the unit cool down between cycles, or using oil-cooled designs, prevents thermal damage.

If switching from recovering one refrigerant to another, what steps must be taken before recovering the new refrigerant?

Correct answer: A. Purge the old refrigerant, change the filter, and evacuate the recovery equipment.

Switching refrigerants on a recovery machine requires purging the leftover gas, changing the filter-drier, and evacuating the unit per the manufacturer's procedure — otherwise you contaminate the next refrigerant and ruin its reclaim value. Mixed refrigerant cannot be reclaimed and has to be sent for destruction. Dedicated equipment for each refrigerant is the safest option.

Describe ways to speed up the recovery.

Correct answer: A. Cool the recovery cylinder, warm the appliance, and recover liquid through the liquid line.

Recovery moves refrigerant from high pressure (the appliance) to low pressure (the cylinder), so widening that gap speeds things up: warm the appliance to raise its pressure, cool the cylinder to lower its pressure, and recover liquid through the liquid line because liquid moves much faster than vapor. Reversing any of those slows recovery and may cause a no-flow condition.

Under what circumstances can recovered refrigerant be reused?

Correct answer: B. It may return to the same appliance or another appliance owned by the same person.

Recovered (or recovered-and-recycled) refrigerant can be reused in the same appliance or in another appliance owned by the same person — that's the 'same-owner' rule. To sell or use it across owners, the refrigerant must be reclaimed to AHRI 700 purity by an EPA-certified reclaimer. This rule prevents contaminated refrigerant from being passed around between unrelated systems.

Where should you remove the refrigerant in a system that has a condenser below the receiver?

Correct answer: A. From the condenser outlet

When the condenser sits below the receiver, refrigerant should be recovered from the condenser outlet because liquid pools at the lowest point. Drawing from there pulls liquid first, which is much faster than recovering vapor from a higher port.

📖 Related rule: Core Study Guide

In a hermetic high-pressure system, excessive superheat and oil traces around fittings are signs of:

Correct answer: B. A refrigerant leak

High superheat plus oil traces around fittings on a high-pressure system point to a refrigerant leak: the system is undercharged, raising superheat, while escaping refrigerant carries oil out through the leak. The right next step is to pressurize and leak-check the system before adding any refrigerant.

📖 Related rule: § 82.154 — Prohibitions

Before charging or recharging a high-pressure system, the technician should:

Correct answer: A. Pressurize and leak-check the system

Before charging or recharging a high-pressure system, the technician must pressurize and leak-check it first, typically using nitrogen with a small refrigerant trace. Charging a leaking system simply releases the new refrigerant and violates Section 608 venting rules.

For pressure-leak testing a high-pressure system, the most preferred gas is:

Correct answer: C. Nitrogen alone; a trace of HCFC-22 mixed with nitrogen is acceptable.

Dry nitrogen alone is the preferred gas for pressure leak-testing a high-pressure system, with a small trace of HCFC-22 acceptable when an electronic leak detector is used. Oxygen, compressed air, and pure refrigerant are never acceptable because of explosion risk and venting rules.

For industrial process refrigeration appliances containing 50 pounds or more of ozone-depleting refrigerant, the allowable annual leak rate is:

Correct answer: C. 30%

Industrial process refrigeration (IPR) over 50 lb has a 30% annual allowable leak rate — the most lenient threshold because IPR systems run harsh duty with very large charges. Comfort cooling is much stricter at 10%. Once exceeded, repair must be completed within the required timeframe and verified by leak test.

For comfort cooling and other appliances containing 50 pounds or more of ozone-depleting refrigerant, the allowable annual leak rate is:

Correct answer: B. 10%

Comfort cooling and 'all other' appliances over 50 lb have a 10% annual allowable leak rate under the post-2019 EPA rule — the strictest of the categories. The 20% number is the legacy threshold; 35% was the legacy IPR threshold. Comfort cooling always gets the tightest leak rule.

Records relating to leak repair on a >50 pound appliance must:

Correct answer: B. Be kept by the owner/operator and made available to EPA on request.

Section 608 makes the appliance owner/operator responsible for keeping leak repair records — refrigerant added, leak inspections, repair attempts, verification tests — and producing them for EPA on request. The records aren't sent to AHRI or posted publicly; they live with the owner. Discarding them after repair is not allowed.

📖 Related rule: § 82.154 — Prohibitions

Owners may receive an extension on the timeframe to repair a leak when:

Correct answer: B. Needed parts are unavailable or industry/safety codes prevent immediate repair.

EPA grants extensions when the repair is genuinely impossible within the standard window — typically because parts are on backorder, the system has to be shut down at a specific time, or industry/safety codes mandate special procedures. Owner inconvenience or low refrigerant cost are not valid reasons. Extensions must be documented in the leak repair records.

Recovery from a high-pressure system can be sped up by:

Correct answer: B. Recovering liquid at the beginning of the recovery process.

Liquid moves through hoses far faster than vapor, so recovering liquid first dramatically shortens the job — then you switch to vapor for what's left. Long, narrow hoses and cooling the appliance both slow things down (lower flow rate, lower system pressure). Always pull liquid from the lowest point holding it (receiver or condenser outlet).

Other ways to speed recovery include:

Correct answer: A. Heating the appliance and chilling the recovery cylinder.

Recovery is driven by the pressure difference between appliance and cylinder. Warming the appliance raises its pressure; chilling the cylinder lowers its pressure — together that widens the gap and speeds recovery. Reversing both, adding nitrogen, or using narrower hoses all slow recovery and may cause flow to stall.

To minimize cross-contamination when a recovery/recycling machine that previously held one refrigerant is used with a different refrigerant, you should:

Correct answer: B. Change filter-driers and evacuate or purge the machine per the manufacturer.

Switching refrigerants on a recovery/recycle machine requires changing the filter-driers and evacuating or purging the unit per the manufacturer — otherwise residue from the previous refrigerant contaminates the next batch and ruins its reclaim value. Mixed refrigerant can't be reclaimed and has to be destroyed. Dedicated machines per refrigerant avoid the issue entirely.

After reaching the required recovery vacuum, a technician should:

Correct answer: B. Wait a few minutes and watch for a pressure rise from remaining refrigerant.

After hitting the target vacuum the technician isolates the system and waits a few minutes; refrigerant trapped in the oil or as liquid will gas off and push the gauge back up, signalling that recovery has to be repeated. Disconnecting immediately, restarting the system, or venting vapor would each leave refrigerant behind or release it to atmosphere.

Using recovery equipment manufactured AFTER November 15, 1993, a high-pressure appliance containing 200 pounds or more of refrigerant being opened for a major repair must be evacuated to:

Correct answer: C. 15 inches of mercury vacuum

For a high-pressure appliance with 200 lb or more of refrigerant being opened for a major repair, post-1993 recovery equipment must evacuate the system to 15 in. Hg vacuum (about half of an atmosphere). Smaller charges and non-major repairs use less stringent levels (4 in. Hg or 0 psig).

A "major" repair on a high-pressure appliance is one that involves:

Correct answer: A. Replacing a compressor, condenser, evaporator, or auxiliary heat exchanger.

A major repair on a high-pressure appliance is one that requires removing or replacing the compressor, condenser, evaporator, or auxiliary heat exchanger coil. These jobs trigger the deepest recovery vacuum requirements, while replacing components like filter-driers or service valves does not.

📖 Related rule: Core Study Guide

System-dependent (passive) recovery equipment may NOT be used on appliances containing more than:

Correct answer: B. 15 pounds of refrigerant

System-dependent (passive) recovery equipment may only be used on appliances containing 15 lb of refrigerant or less. Above 15 lb, the appliance is not classified as a small appliance and active (self-contained) recovery equipment is required so that recovery is not dependent on the appliance's own compressor or pressure.

For disposal of a high-pressure appliance containing less than 200 pounds, recovery equipment manufactured after November 15, 1993 must achieve at least:

Correct answer: B. 10 inches of mercury vacuum

When disposing of a high-pressure appliance with less than 200 lb of charge, post-1993 recovery equipment must evacuate it to 10 in. Hg vacuum. The disposal/major-repair vacuum requirements scale with charge size: 0 psig under 200 lb for non-major repair, 10 in. Hg for disposal under 200 lb, 15 in. Hg for 200 lb or more.

For a leaky high-pressure appliance where the required evacuation level is not reasonably attainable, the appliance must:

Correct answer: B. Be evacuated to at least 0 psig

EPA Section 608 lets a leaky high-pressure appliance be exempted from the deeper recovery target, but it still must be drawn down to at least atmospheric pressure (0 psig) before it is opened so no refrigerant vents during repair. Venting to atmosphere is a violation, and leaving the system charged or scrapping it are not the prescribed responses.

To identify the refrigerant in an unknown high-pressure appliance, you can:

Correct answer: A. Check the nameplate or use a refrigerant identifier.

Identify an unknown refrigerant by reading the appliance nameplate or by sampling the charge with a refrigerant identifier. Mixing recovered refrigerants of different types contaminates both, so confirming the type before recovery is essential.

📖 Related rule: Core Study Guide

To convert a pressure reading from psig to psia, you must:

Correct answer: B. Add 14.7

psig is gauge pressure (relative to atmosphere) and psia is absolute pressure. Atmospheric pressure at sea level is about 14.7 psi, so psia = psig + 14.7. Subtracting goes the wrong direction; multiplying or skipping the conversion are wrong by definition.

In a high-pressure system, the receiver:

Correct answer: A. Stores high-pressure liquid refrigerant.

In a high-pressure system the receiver stores high-pressure subcooled liquid refrigerant downstream of the condenser. The receiver feeds liquid to the metering device on demand and is sized to hold the entire charge during pump-down service.

📖 Related rule: Core Study Guide

Hydrocarbon refrigerants (such as propane) are:

Correct answer: B. Not approved for retrofits in conventional systems

Hydrocarbon refrigerants (propane R-290, isobutane R-600a) are flammable. EPA SNAP approves them only for new equipment specifically designed and certified to handle flammable refrigerants — not as retrofits in existing CFC/HCFC systems where electrical components and seals weren't built for flammables. They are not interchangeable with HFCs.

Hermetic compressor motor windings should never be energized while the system is under a deep vacuum because:

Correct answer: B. Reduced dielectric strength can cause winding burnout.

In a hermetic compressor the refrigerant gas surrounding the motor is what gives the windings their dielectric (insulating) strength. Under deep vacuum that gas is gone, so applied voltage can arc between turns and burn the motor out. The other answers (running too fast, overcharging, neutral on time) are not real consequences of energizing the windings under vacuum.

ASHRAE Standard 15 requires that mechanical equipment rooms be equipped with:

Correct answer: A. A refrigerant/oxygen-deprivation sensor and adequate ventilation.

ASHRAE 15 requires equipment rooms to have a refrigerant sensor (or oxygen-deprivation sensor, depending on refrigerant) plus emergency ventilation that activates on alarm. The sensor must trip BEFORE TLV-TWA or oxygen-deprivation limits are reached. A telephone, normal lighting, or nothing extra wouldn't satisfy the safety standard.

Type III

When pressurizing a low-pressure system for leak-detection purposes, do not exceed

Correct answer: B. 10 psig

A low-pressure chiller normally operates in a vacuum and has a 15 psig rupture disc on the evaporator. EPA and industry practice cap leak-test pressure at 10 psig to stay safely below the disc's burst rating. Exceeding 10 psig risks rupturing the disc and venting refrigerant.

What can be used to pressurize a chiller system before opening the system for a non-major repair?

Correct answer: B. Nitrogen

Nitrogen is used to pressurize a chiller before opening it for a non-major repair. Dry nitrogen is inert, cheap, and dry, so it will not react with refrigerant or introduce moisture. Oxygen and compressed air can form an explosive mixture with refrigerant oil and must never be used.

Where is the purge unit located in a low-pressure system?

Correct answer: A. The top of the condenser.

The purge unit is mounted on top of the condenser, where non-condensable gases (air and moisture) collect because they will not condense and rise above the liquid refrigerant. The purge unit pulls those gases off the top, separates out any refrigerant vapor, and vents only the air and moisture.

📖 Related rule: Core Study Guide

In a low-pressure chiller, air and other non-condensables collect at the;

Correct answer: B. top section of the condenser.

Air and other non-condensables collect in the top of the condenser because they do not change phase at the temperatures and pressures present in the condenser. They float on top of the condensing refrigerant and reduce condensing surface area, which is why the purge unit takes its suction from this point.

📖 Related rule: Core Study Guide

If a strong odor is detected during the recovery process,

Correct answer: C. a compressor burn-out may have occurred.

A strong, acrid odor during recovery usually means a compressor burnout — overheated motor windings break down the oil and refrigerant into acidic byproducts. R-717 (ammonia) does have a sharp smell, but ammonia is rare in commercial AC and not typical of a normal recovery job. R-123 has a mild odor at high concentrations but doesn't smell 'strong' the way burnout byproducts do.

The Standard for machine room safety is;

Correct answer: A. ASHRAE-15

ASHRAE Standard 15 governs machinery-room safety: ventilation, refrigerant sensors, alarms, and emergency exits. ASHRAE 34 is the refrigerant safety classification (A1, B2L, etc.). AHRI-740 (formerly ARI-740) is the recovery equipment performance standard, not a machine room standard.

During evacuation of systems with large amounts of water, it may be necessary to;

Correct answer: A. increase pressure by introducing nitrogen to counteract freezing.

Pulling a deep vacuum lowers the boiling point of water until it flashes to vapor and chills enough to freeze inside tubes, blocking further evacuation. Adding dry nitrogen raises the pressure so the ice can melt and be drawn off as vapor on the next pull. Removing nitrogen or lowering pressure further would make the freezing problem worse.

Which of the following best describes the refrigerant recovery process from an R-123 system?

Correct answer: B. Start with liquid removal and then switch over to vapor recovery.

R-123 is a low-pressure refrigerant in a chiller — most of the charge sits as liquid in the evaporator. Recovering liquid first is much faster than pulling vapor, then you switch to vapor recovery to capture what's left. Running the compressor during recovery would not work because R-123 systems run under vacuum at normal operating conditions.

The EPA-required evacuation level for recovery or recycling equipment used on low-pressure systems is

Correct answer: C. 25 mm of Hg absolute.

EPA Section 608 sets the recovery/recycle target for low-pressure appliances at 25 mm Hg absolute when using equipment manufactured on or after Nov 15, 1993. The values in inches of Hg vacuum apply to high-pressure appliances; low-pressure systems are specified in absolute pressure because they normally operate below atmospheric.

Under Section 608, the owner must keep service records of ozone-depleting refrigerant added to a low-pressure system if the system charge is:

Correct answer: B. 50 pounds or greater.

Owners of appliances with a full charge of 50 pounds or more of ozone-depleting refrigerant must keep service records under the Section 608 leak-repair requirements. Other recordkeeping rules can apply to different appliances and refrigerants, and the venting prohibition remains broader.

📖 Related rule: § 82.154 — Prohibitions

A low-pressure comfort-cooling chiller containing 50 pounds or more of ozone-depleting refrigerant must be repaired if its annual leak rate exceeds ________ of the total charge.

Correct answer: A. 10 percent

A covered low-pressure chiller used for comfort cooling has a 10% annual leak threshold. Industrial process refrigeration uses 30%, and commercial refrigeration uses 20%. Pressure class does not set the threshold; appliance category does.

Because a low-pressure system operates below atmospheric pressure (in a vacuum),

Correct answer: B. leaks in gaskets or fittings will cause air and moisture to enter the system.

Low-pressure systems (such as R-123 chillers) run below atmospheric pressure during normal operation, so any breach in a gasket or fitting pulls outside air and moisture in rather than letting refrigerant out. That infiltrated air becomes a non-condensable that raises head pressure and triggers the purge unit, while moisture promotes acid formation.

📖 Related rule: § 82.154 — Prohibitions

Where is refrigerant added to a low-pressure system during the charging process?

Correct answer: D. The lowest access point on the system such as the evaporator charging valve.

A low-pressure chiller is charged through the evaporator charging valve, the lowest access point in the system. Charging vapor first at this point keeps liquid refrigerant from contacting the evaporator tubes while the chilled-water side is still cold, which would otherwise risk freezing the water and rupturing the tubes.

📖 Related rule: Core Study Guide

Under ASHRAE Standard 34, R-134a is classified as;

Correct answer: A. A1

R-134a is classified A1 under ASHRAE 34: 'A' for low toxicity, '1' for no flame propagation — the safest combination. B-class would mean higher toxicity (R-123 is B1; ammonia is B2L). Higher numbers (2, 2L, 3) indicate increasing flammability.

To repair a chiller operating with R-22, the technician;

Correct answer: C. must have a Type II certification.

R-22 is a high-pressure refrigerant, so a technician working on a chiller using R-22 must hold Section 608 Type II certification (high- or very-high-pressure appliances). Type I covers small appliances, Type III covers low-pressure appliances, and Universal covers all three.

📖 Related rule: § 82.154 — Prohibitions

After all the liquid has been removed from an average 350-ton, low-pressure appliance, approximately how much vapor refrigerant remains in the system?

Correct answer: A. 100 pounds

After all liquid is removed from a typical 350-ton low-pressure chiller, roughly 100 pounds of refrigerant vapor remain in the system. That residual vapor must still be recovered down to the required final vacuum (25 mm Hg absolute for pre-1993 equipment, 25 mm Hg / 10 mm Hg per the rule depending on equipment age) before opening the appliance.

The rupture disk on a low-pressure chiller has a burst pressure of;

Correct answer: C. 15 psig

The rupture disc on a low-pressure centrifugal chiller has a burst pressure of 15 psig, set well below the design strength of the shell. This is why leak-test pressure is limited to 10 psig and why charging or pressurizing through the disc must always stay safely under 15 psig.

Which organization establishes the refrigerant safety group standard?

Correct answer: C. ASHRAE

ASHRAE writes Standard 34, which assigns each refrigerant a safety group like A1, B2, B2L based on toxicity (A/B) and flammability (1/2L/2/3). AHRI handles equipment performance certifications (like AHRI-740 for recovery machines). UL handles electrical safety, and ASE certifies automotive technicians — different scopes.

When leak testing a low-pressure chiller, the maximum pressure to use is;

Correct answer: B. 10 psig.

10 psig is the maximum allowed leak-test pressure on a low-pressure chiller. The rupture disc is rated at 15 psig, so capping the test at 10 psig leaves a safety margin and prevents accidentally venting the charge. Higher pressures are never necessary because controlled hot water or heater blankets are the preferred way to bring saturation pressure above atmospheric.

When charging a low-pressure system, refrigerant should be introduced to the system as a vapor to raise the system's saturation temperature to a minimum of;

Correct answer: B. 36 degrees.

Vapor must be added until saturation temperature reaches at least 36°F before any liquid refrigerant is introduced. This keeps the evaporator tubes from getting cold enough to freeze the water inside them, which would burst the tubes and ruin the chiller.

Which of the following refrigerants has a safety classification of B-1?

Correct answer: C. HCFC-123 (R-123)

R-123 is classified B1 under ASHRAE 34: 'B' indicates higher toxicity than 'A' refrigerants, '1' indicates no flame propagation. R-12, R-134a, and R-11 are all A1 (low toxicity, non-flammable). The B-class label drives stricter machine-room ventilation and sensor requirements for R-123 chillers.

How long would an equipment owner or operator have to retrofit or retire an appliance that has exceeded the threshold leak rate if the replacement appliance uses 50 pounds or more of an exempt refrigerant?

Correct answer: A. 24 months.

When an owner commits to retrofit or retire a leaking appliance instead of repairing it, the longer 24-month (one-year extension to the standard one-year window) timeline applies if the replacement uses 50 lb or more of an exempt refrigerant. Shorter answers (3, 12, 18 months) are interim deadlines that apply in other scenarios. The retrofit/retire option exists because tearing out and replacing large equipment takes time.

What type of equipment can be worked on with Type III certification?

Correct answer: C. Low-pressure

Type III certification covers low-pressure appliances — typically centrifugal chillers using R-11, R-123, or R-113 that operate below atmospheric pressure on the low side. Type I covers small appliances, Type II covers high- and very-high-pressure equipment, and Universal covers all three categories. Match the certification to the equipment pressure class.

📖 Related rule: § 82.154 — Prohibitions

The most efficient method of leak checking a charged low-pressure refrigeration unit is to;

Correct answer: A. pressurize the system using controlled hot water or heater blankets.

The most efficient way to leak-check a charged low-pressure unit is to raise saturation pressure above atmospheric using controlled hot water or heater blankets, then sweep with a leak detector. This avoids adding nitrogen or other gases to the charge and keeps test pressure naturally below the 15 psig rupture disc rating.

When installing more than one, pressure relief valves must be installed;

Correct answer: B. in parallel with each other.

Multiple relief valves are installed in parallel so each one can independently vent to atmosphere if pressure rises. Installed in series, only the first valve sees system pressure — the second is useless and a single blockage can defeat the assembly. Suction-line or compressor-head locations don't protect the high side of the system.

📖 Related rule: Core Study Guide

How must you recover refrigerant from a parallel system and why?

Correct answer: A. Isolate a parallel compressor system in order to recover refrigerant. Failure to isolate will cause an open equalization connection that will prevent refrigerant recovery.

Parallel compressor racks share equalization lines between compressors. If you don't isolate the section you're recovering from, refrigerant from the rest of the rack feeds back through those open connections and you'll never finish pulling the system down. Isolating with the rack's service valves closes those paths so recovery can complete.

Where do leaks commonly occur in low pressure systems?

Correct answer: D. Gaskets or fittings

Low-pressure (negative-pressure) chillers operate below atmospheric pressure on the low side, so leaks pull air IN rather than refrigerant OUT. The most common entry points are gasketed joints (tube sheets, water boxes, hand holes) and threaded fittings, since those are the system's mechanical seals.

Where do leaks commonly occur in open-drive type compressor systems?

Correct answer: C. Shaft seal

Open-drive compressors have an external shaft penetrating the housing, sealed by a mechanical shaft seal. That seal is the most common leak point because it must keep refrigerant in while a rotating shaft passes through it. Hermetic and semi-hermetic compressors avoid this leak path by enclosing the motor inside the refrigerant circuit.

Does refrigerant go out of the system in low pressure systems or does air and moisture go in?

Correct answer: B. Air and moisture enter because the system operates in a vacuum.

In a low-pressure system the low side runs below atmospheric pressure, so any leak draws air and moisture into the system rather than refrigerant out. That is why low-pressure chillers need a purge unit to continually remove the non-condensables that accumulate.

When should a low pressure system be leak checked according to ASHRAE guideline 3-1996?

Correct answer: C. When vacuum rises from 1 mm Hg to above 2.5 mm Hg during testing.

ASHRAE Guideline 3-1996 calls for leak-checking a low-pressure system when the standing vacuum rises from 1 mm Hg to above 2.5 mm Hg in 24 hours. That rate of pressure rise indicates either a leak or trapped moisture vaporizing, both of which need to be found and corrected.

What does a purge unit do and what is a high efficiency purge unit?

Correct answer: D. Removes air/non-condensables; high-efficiency purge expels very little refrigerant.

A purge unit removes air and other non-condensables that have leaked into the low-pressure system. A high-efficiency purge unit separates refrigerant from the purged gas before venting, so very little refrigerant is lost (typically less than 0.1 lb per pound of air purged) compared with older designs that vented significant refrigerant along with the air.

How does a centrifugal compressor purge unit work?

Correct answer: D. Takes its suction from the top of the condenser, removes the air from the system, and returns the refrigerant to the evaporator

A centrifugal-chiller purge unit takes suction from the top of the condenser, where non-condensables collect, separates refrigerant from air and moisture, vents the air, and returns the refrigerant to the evaporator. This keeps the system clear of non-condensables without losing the refrigerant charge.

📖 Related rule: Core Study Guide

What are visible ways to check for leaks in a low pressure system?

Correct answer: A. Excessive purge operation or steady moisture in the purge unit can indicate a leak.

Low-pressure chillers run a purge unit to remove non-condensables that leak in below atmospheric pressure. Frequent purging or accumulated moisture in the purge tank means air (and the moisture it carries) is entering through a leak. Low head pressure, increased compressor amps, or "improved efficiency" are not leak indicators.

What needs to be done to leak check a low pressure system?

Correct answer: C. Increase pressure using controlled hot water or heater blankets.

A low-pressure system normally runs in a vacuum, so its saturation pressure must be raised above atmospheric before leak detectors can find a leak. The accepted method is to warm the refrigerant using controlled hot water or heater blankets until it reaches a measurable positive pressure (still under 10 psig).

What are ways you can increase the pressure in a low-pressure system for leak testing?

Correct answer: A. Controlled hot water and heater blankets.

Pressure in a low-pressure system can be raised for leak testing using controlled hot water or electric heater blankets to warm the refrigerant. Both methods raise saturation pressure naturally without adding any outside gas, keeping pressure below 10 psig and below the rupture-disc rating.

What can happen if you exceed 10 psig while pressurizing the system?

Correct answer: B. The rupture disc will fail

Low-pressure chillers (R-11, R-123) are protected by a rupture disc that typically vents around 15 psig, so pressurizing for a leak test above 10 psig risks blowing the disc and dumping refrigerant to atmosphere. Shaft seal failure and oil-oxygen explosions are not what 10 psig nitrogen pressurization causes on these machines.

How should a water box be leak tested?

Correct answer: A. Remove water, then insert the leak-detector probe through the drain valve.

A leak from a refrigerant tube into the water side won't show up while the box is full. Drain it, then insert the leak detector probe through the drain connection so it can sense any refrigerant escaping into the now-empty box. Pressurizing the empty box or testing water for refrigerant traces aren't standard methods.

What equipment should be used to test a tube?

Correct answer: C. Hydrostatic tube test kit

A hydrostatic tube test kit isolates and pressurizes a single tube with water; pressure loss reveals a leaking tube. Bore scopes can spot visible damage but won't catch pinholes. Removing tubes for bench testing isn't practical, and a flashlight can't reliably reveal small holes.

What are the typical pressure settings for rupture discs on low pressure systems and recovery equipment?

Correct answer: C. 15 psig

Rupture discs on low-pressure systems and on recovery equipment used with them are typically rated at 15 psig. The disc protects the equipment shell from over-pressurization, which is why leak testing is capped at 10 psig and recovery equipment used on low-pressure systems must have a high-pressure cutout below the rupture rating.

How should a technician recover refrigerant from a system using R-11 or R-123?

Correct answer: A. Remove liquid first, then recover the remaining vapor.

R-11 and R-123 are low-pressure refrigerants that sit mostly as liquid in the chiller. Recovering liquid first is much faster than vapor — liquid moves quickly through hoses, while pulling deep vacuum on a low-pressure system to clear vapor takes time. After the liquid is out, switch to vapor recovery to capture what's left in the cooler shell and tubes.

After removal of liquid, about how much vapor will remain in the system on a 350 ton R-11 chiller?

Correct answer: D. 100 lbs of vapor after all the liquid has been removed

A 350-ton R-11 chiller will still hold roughly 100 pounds of refrigerant vapor after all the liquid has been recovered. The technician must continue recovering vapor until the required final vacuum is reached; opening the system after only liquid recovery would vent that 100 pounds.

How can you speed up the vapor recovery process?

Correct answer: B. Use a heater on the recovery-vessel side to evacuate vapor faster.

Wait — to speed vapor recovery on a low-pressure chiller, you want pressure differential: warm the system being recovered, and keep the recovery cylinder cool so vapor condenses into it. Some manufacturers use a recovery vessel heater carefully to drive vapor off the appliance side, but heating the recovery cylinder itself raises pressure inside and slows recovery. Always check the equipment manufacturer's procedure.

In a system using a water cooled condenser, what components should be kept on?

Correct answer: A. The system water pumps, recovery compressor, and recovery condenser water.

During recovery on a water-cooled system, keep the chilled-water and condenser-water pumps running, the recovery compressor running, and the recovery unit's condenser water flowing. Maintaining water flow through both heat exchangers keeps refrigerant from freezing in the tubes and lets the recovery condenser reject heat efficiently.

How should a technician recover refrigerant from a system using R-11 or R123?

Correct answer: A. Remove liquid first, then recover the remaining vapor.

Where does the cooling water typically come from in a water cooled condensing system?

Correct answer: D. Cooling tower

Water-cooled condensers reject heat to circulating condenser water, which is then cooled at the cooling tower (evaporative heat rejection to outdoor air) and returned to the condenser. Evaporators and chillers are inside the building load loop — they absorb heat, not reject it. Deep wells aren't standard for typical commercial systems.

📖 Related rule: Core Study Guide

What parts of the system should be drained of water before recovering refrigerant?

Correct answer: A. The evaporator and the condenser.

On a water-cooled chiller, the evaporator and condenser shells hold the chilled-water and condenser-water loops around the refrigerant tubes. Drain those water circuits before recovery so the tubes don't freeze if the refrigerant pressure (and saturation temperature) drops below 32°F. Frozen water can rupture tubes and ruin the chiller.

How should a technician treat the oil before removal and why?

Correct answer: B. Heat oil to about 130F before removal to boil off dissolved refrigerant.

Refrigerant dissolves into compressor oil; if you drain cold oil, refrigerant escapes with it and vents to atmosphere — a violation of the venting prohibition. Heating oil to about 130°F drives the dissolved refrigerant back into vapor that the recovery machine can capture before the oil is drained. Injecting oxygen into the oil would create an explosion hazard.

Why should you never charge liquid refrigerant into a deep vacuum?

Correct answer: C. The liquid can boil rapidly and lower tube temperature enough to freeze water.

Liquid refrigacant entering a deep vacuum flashes to vapor almost instantly, and the heat for that phase change is pulled out of the surrounding tubes. On a low-pressure chiller the chilled-water temperature can drop below 32°F and freeze the tubes solid. Charging is therefore done with vapor until the system pressure rises above the freezing point of water, regardless of whether the cylinder was weighed.

At what point in the system should you charge a low pressure system and what should you start the charge with?

Correct answer: A. Charge through the evaporator charging valve as this is the lowest point on a low pressure system. First charge the system with vapor.

Low-pressure (negative-pressure) chillers are charged through the evaporator valve at the lowest point, beginning with vapor. Vapor charging first raises pressure above the freezing point of water in the chiller tubes; switching to liquid too early can flash-freeze the chilled water and split tubes. The condenser and purge valves are not the correct charge entry points on these systems.

📖 Related rule: Core Study Guide

How can a technician determine when it is safe to start charging with liquid refrigerant?

Correct answer: D. Refrigerant saturation reaches 36F or vapor pressure reaches 16.9 in. Hg vacuum.

Once chilled-water temperature is above 32°F (no freeze risk) and refrigerant saturation reaches 36°F (about 16.9 in. Hg vacuum for R-123), it's safe to switch from vapor to liquid charging. The 36°F figure provides margin above the freezing point of water in the chiller barrel — charging cold liquid sooner can freeze and split tubes.

What general standard does recovery / recycling equipment need to meet?

Correct answer: A. EPA-approved third-party certification, low-loss fittings, and required evacuation levels.

Recovery/recycling equipment must be tested and certified by an EPA-approved third-party lab (UL, ETL, etc.) to ARI/AHRI 740, must use low-loss fittings to minimize emissions during connect/disconnect, and must hit the required evacuation levels for the appliance type. Manufacturer self-certification, local code, or simple state-level approval don't substitute for the federal third-party certification.

📖 Related rule: § 82.154 — Prohibitions

What are the required levels of evacuation for low pressure systems for equipment manufactured before 11/15/1993 and/or after 11/15/1993?

Correct answer: A. 25 inches Hg before November 15, 1993; 25 mm Hg absolute after that date.

EPA Section 608 sets two recovery targets for low-pressure systems based on when the recovery equipment was built: 25 in. Hg vacuum for pre-Nov 15, 1993 machines, and a much deeper 25 mm Hg absolute for machines built on or after that date, reflecting improved equipment capability. The other answers swap the units or claim no standard exists, both of which are wrong.

Why should a technician wait a few minutes after reaching the required vacuum level and what should be done if the pressure begins to rise?

Correct answer: B. If the pressure rises, this indicates that there is still refrigerant in the system (liquid or trapped in the oil) and the recovery process must be repeated.

After the pump is shut off, vapor pressure has time to build back up from refrigerant that was still dissolved in the oil or trapped as liquid. A rising gauge therefore means more refrigerant is gassing off and recovery has to be run again; pressure that drops, or that rises and is treated as complete, would either be impossible or would leave refrigerant behind in violation of Section 608.

What should be done if a leak makes reaching the required vacuum level unattainable?

Correct answer: B. Evacuate the system to the lowest attainable level before a major repair.

Section 608 recognizes that a system leaky enough to prevent reaching the required vacuum cannot be held there, so before a major repair the technician evacuates to the lowest level that is reasonably attainable and documents it. Calling EPA, adding a second recovery unit, or scrapping the unit are not the prescribed responses.

What is considered to be a “major” repair according to the EPA?

Correct answer: A. Removal of any or all of the following components: the compressor, the condenser, the evaporator or an auxiliary heat exchanger coil.

Section 608 lists removing the compressor, condenser, evaporator, or any auxiliary heat exchanger coil as the components whose removal qualifies as a major repair. Major repairs trigger the deep-vacuum recovery and follow-up leak verification rules that do not apply to non-major work like changing a filter-drier.

📖 Related rule: Core Study Guide

Where is the rupture disc on a low pressure centrifugal system and where should the disc be vented to?

Correct answer: A. On the evaporator. Discharge from the disc should be vented to recovery tank

The rupture disc on a low-pressure centrifugal chiller is mounted on the evaporator shell, which is the largest vessel and the most likely point of dangerous overpressure. Discharge from the disc must be vented into a recovery tank rather than to atmosphere so that any released refrigerant is captured rather than vented.

What problem can using large vacuum pumps lead to and how can a technician prevent it?

Correct answer: B. Trapped water can freeze; add nitrogen to raise pressure and counteract freezing.

A high-capacity vacuum pump pulls the system down so quickly that any free water flashes, self-cools, and freezes inside tubes, blocking further evacuation. Adding dry nitrogen raises pressure so the ice melts and can be drawn off as vapor. Lowering voltage, opening the system to atmosphere, or charging liquid into a deep vacuum would each create new problems instead of fixing this one.

What step should you take for low pressure systems that will be sitting idle and why?

Correct answer: C. Raise pressure slightly above atmospheric pressure to prevent air accumulation.

Below atmospheric pressure, air and moisture leak inward through any seal. To prevent contamination during long shutdowns, raise refrigerant or nitrogen pressure slightly above atmospheric so any leak goes outward instead of inward. A holding vacuum (A) actually invites air in. Monthly cycling and weekly vacuum monitoring don't solve the leak-direction problem.

📖 Related rule: § 82.154 — Prohibitions

The preferred method for pressurizing a low-pressure system for leak testing is:

Correct answer: C. Controlled hot water or a built-in pressurizer; nitrogen is the next choice.

The preferred way to pressurize a low-pressure system for leak testing is to warm the refrigerant with controlled hot water or a built-in heating/pressurization device. If those are not available, dry nitrogen with a pressure regulator and relief valve is the next acceptable choice; pressure must stay below 10 psig in either case.

Excessive purge unit operation in a low-pressure chiller is a sign of:

Correct answer: B. Air and moisture leaking into the low-pressure system.

Excessive purge unit operation means the chiller is taking on more non-condensables than normal, which only happens when air and moisture are leaking in through a vacuum-side leak. Frequent purging signals the leak should be found and repaired; otherwise the system loses efficiency and accumulates moisture that produces acid.

The maximum pressure that should ever be used to leak-test a low-pressure centrifugal chiller is:

Correct answer: B. 10 psig

10 psig is the absolute maximum leak-test pressure on a low-pressure centrifugal chiller. Higher pressures could rupture the 15 psig disc, releasing the entire charge. The same 10 psig limit is set by the high-pressure cutout on recovery equipment used with these systems.

If a low-pressure appliance exceeds the applicable leak rate, the owner must:

Correct answer: A. Repair the leak within the required timeframe and perform verification tests.

When a low-pressure (or any) appliance exceeds its applicable leak threshold, the owner must repair the leak within the required timeframe and verify the repair with initial and follow-up tests. Continuing to vent or operate the appliance is illegal under Section 608. Scrapping is only required if the owner chooses retire-instead-of-repair, with its own documentation and timeline.

📖 Related rule: § 82.154 — Prohibitions

A Section 608 appliance containing 50 pounds or more of ozone-depleting refrigerant must be reported as a chronic leaker when it:

Correct answer: A. Leaks 125% or more of its full charge in a calendar year

Owners must report a covered 50+ lb ODS appliance that leaks 125% or more of its full charge in a calendar year. The report is due by March 1 of the following year and describes efforts to identify and repair the leaks. This chronic-leak trigger is separate from merely exceeding the category's repair threshold.

For a low-pressure industrial process refrigeration appliance with 50 pounds or more of ozone-depleting refrigerant, the allowable annual leak rate is:

Correct answer: C. 30%

Industrial process refrigeration over 50 lb gets the 30% annual allowable leak rate, regardless of whether the system is high- or low-pressure. The category (IPR) drives the threshold, not the pressure class. Comfort cooling is held to the stricter 10% rule.

For low-pressure comfort cooling appliances with 50 pounds or more of ozone-depleting refrigerant, the allowable annual leak rate is:

Correct answer: A. 10%

Low-pressure centrifugal chillers used for comfort cooling fall under the comfort cooling 10% annual leak threshold. Pressure class (high vs. low) doesn't change the limit — appliance category does. The 15% and 20% values are legacy thresholds; 35% was the old IPR number.

Recovery from a low-pressure system is sped up by:

Correct answer: B. Recovering liquid at the start of the recovery process.

Even on low-pressure systems, recovering liquid first is faster than vapor — most of the charge is in the chiller as liquid, and liquid moves through the hoses much more quickly than gas. After the bulk liquid is in the recovery vessel, switch to vapor recovery to clear the cooler shell. Cooling the cylinder below 0°F is unnecessary; just keep it cooler than the appliance.

In a low-pressure system, after liquid has been removed, the technician must also:

Correct answer: B. Recover the remaining vapor

After the liquid has been recovered, a low-pressure system still contains a substantial amount of refrigerant vapor (about 100 lb in a 350-ton chiller). The technician must continue recovering vapor down to the required final vacuum (25 mm Hg or 10 mm Hg absolute, depending on equipment age) before opening the system.

Before draining oil from a low-pressure chiller for analysis, the oil should be heated to approximately:

Correct answer: C. 130°F

Oil from a low-pressure chiller is heated to about 130°F before draining for analysis. Warming the oil reduces its viscosity so it drains cleanly and brings dissolved refrigerant out, giving a representative sample for acid-number and moisture testing.

During refrigerant evacuation of a low-pressure chiller, water in the chiller tubes should be:

Correct answer: B. Circulated or removed to prevent freezing.

As the chiller is pulled into a deep vacuum, the refrigerant temperature plummets and can chill the tubes well below 32°F. If chilled water is sitting still in the tubes it will freeze and burst them, so the water is either kept circulating with the chilled-water pump or fully drained before evacuation continues. Heating to boiling or leaving stagnant antifreeze are not standard procedures.

Recovery equipment used on low-pressure appliances must have a high-pressure cut-out switch that closes the unit down at no higher than:

Correct answer: B. 10 psig

Recovery equipment used on low-pressure appliances must have a high-pressure cutout that shuts the unit down at no higher than 10 psig. The cutout protects both the appliance's 15 psig rupture disc and the recovery unit itself from over-pressurization during the recovery cycle.

When recharging a low-pressure chiller, you must introduce vapor first because:

Correct answer: B. Adding liquid first could freeze water in evaporator tubes.

A low-pressure chiller is recharged with vapor first because adding liquid into the deeply evacuated evaporator would flash-cool the tubes and freeze the water inside them. Frozen water expands and bursts the tubes. Once vapor has raised saturation temperature above 36°F, liquid can be added safely.

📖 Related rule: Core Study Guide

Centrifugal low-pressure chillers should be charged through:

Correct answer: B. The evaporator charging valve.

Centrifugal low-pressure chillers are charged through the evaporator charging valve, the lowest point on the system. Charging at the lowest point ensures liquid pools properly in the evaporator and lets the technician control vapor-first, then-liquid sequencing without risking tube freeze.

📖 Related rule: Core Study Guide

For a low-pressure appliance being opened for a major repair, recovery equipment manufactured after November 15, 1993 must evacuate the system to at least:

Correct answer: B. 10 mm Hg absolute

A low-pressure appliance opened for major repair must be evacuated to 10 mm Hg absolute by post-November-15-1993 recovery equipment. This deep vacuum removes nearly all remaining refrigerant vapor before the system is opened. Pre-1993 equipment uses a less stringent 25 mm Hg absolute level.

For a non-major repair on a low-pressure appliance, the system may be pressurized using:

Correct answer: C. Controlled hot water or a built-in heating/pressurization device.

For a non-major repair on a low-pressure appliance, the system may be brought above atmospheric using controlled hot water or a built-in heating/pressurization device, raising the saturation pressure of the existing refrigerant. This avoids introducing nitrogen or other gases and keeps pressure under the 15 psig rupture disc rating.

After reaching the required recovery vacuum on a low-pressure system, the technician should:

Correct answer: B. Wait several minutes and watch for pressure rise from remaining refrigerant.

On a low-pressure system, refrigerant dissolved in oil or trapped as liquid takes time to gas off. After the recovery target is reached the technician shuts the recovery unit off and watches the gauge for several minutes; a rising pressure means more refrigerant is still vaporizing and recovery has to continue. Reconnecting immediately, venting vapor, or refilling oil would each leave refrigerant behind or release it.

A "major" repair on a low-pressure appliance includes:

Correct answer: A. Replacing a compressor, condenser, evaporator, or auxiliary heat exchanger coil.

A major repair on a low-pressure appliance includes replacing the compressor, condenser, evaporator, or auxiliary heat exchanger coil. Major repairs trigger the deep-vacuum recovery requirement (10 mm Hg absolute on post-1993 equipment) before the system can be opened.

📖 Related rule: Core Study Guide

The purpose of a purge unit on a low-pressure chiller is to:

Correct answer: B. Remove non-condensables such as air and moisture that leaked in.

A purge unit removes non-condensables (air and moisture) that leak into the low-pressure chiller through its vacuum side. Without purging, those gases collect in the top of the condenser, raise head pressure, reduce capacity, and let moisture form acids that attack the system.

At standard atmospheric pressure (0 psig), R-123 boils at approximately:

Correct answer: C. 82°F

R-123 is a low-pressure refrigerant whose normal boiling point is about 82°F at atmospheric pressure, which is why R-123 chillers run in a vacuum on the low side. The very cold boiling points (-40°F, 0°F) belong to high-pressure refrigerants like R-22 or R-12, and 200°F is far too high for any common HVAC refrigerant.

ASHRAE Standard 15 requires equipment rooms to be equipped with:

Correct answer: A. A refrigerant or oxygen-deprivation sensor appropriate for the refrigerant.

ASHRAE 15 requires a sensor sized to the specific refrigerant's hazard — a refrigerant-specific sensor for toxic refrigerants like R-123, or an oxygen-deprivation sensor for asphyxiating ones like R-134a or R-410A. The sensor triggers an alarm and emergency ventilation. Skipping the sensor when the room is 'normally unoccupied' doesn't relieve the requirement.

Under ASHRAE Standard 15, equipment rooms containing R-123 specifically require:

Correct answer: B. A refrigerant sensor for R-123.

R-123 is a Class B1 refrigerant — higher toxicity than A-class refrigerants — so ASHRAE 15 requires a refrigerant sensor specifically calibrated for R-123 in any equipment room containing it. CO2 monitors, flame detectors, or no sensor wouldn't catch an R-123 leak at the toxicity-driven trigger level. The sensor must alarm before the TLV-TWA is exceeded.

Not affiliated with the EPA. For study practice only. EPA regulations change over time — always verify current rules with official EPA materials and your testing provider.