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EPA 608 Type III study materials
EPA 608 Type III study resources

EPA 608 Type III practice questions

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Question 1Low-pressure appliance refrigerant recovery, recycling, and reclamation

For a low-pressure appliance using R-11, what does EPA require the recovery equipment to be capable of achieving before the refrigerant is removed from the system?

  1. A vacuum of 25 inches of mercury
  2. A recovery cylinder weight of 80 percent
  3. A refrigerant temperature of 0°F
  4. A system pressure of 0 psig Correct answer.

Explanation

Low-pressure appliances such as R-11 and R-123 chillers must be evacuated to 0 psig (atmospheric pressure) before the refrigerant charge is considered recovered. Pulling below atmospheric is not required for the initial recovery step on these systems.

Question 2Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which refrigerant is most commonly associated with low-pressure centrifugal chillers covered under Type III certification?

  1. R-123 Correct answer.
  2. R-404A
  3. R-134a
  4. R-410A

Explanation

R-123 is the low-pressure refrigerant widely used in centrifugal chillers, boiling at about 82°F at atmospheric pressure. Technicians handling it must hold Type III certification because the appliance operates in a vacuum.

Question 3Low-pressure appliance refrigerant recovery, recycling, and reclamation

Because a low-pressure chiller operates below atmospheric pressure, what hazard is present when a line is opened without first recovering the charge?

  1. Air and moisture are drawn into the system Correct answer.
  2. The compressor oil freezes instantly
  3. Refrigerant sprays out under high pressure
  4. The rupture disc discharges refrigerant

Explanation

A low-pressure appliance sits in a vacuum during normal operation, so opening it to atmosphere pulls air and moisture inward. Moisture in particular can form acids and damage the motor windings and metering components.

Question 4Low-pressure appliance refrigerant recovery, recycling, and reclamation

What is the maximum allowable moisture content, in parts per million by weight, for reclaimed R-123 according to AHRI Standard 700?

  1. 100 ppm
  2. 20 ppm Correct answer.
  3. 50 ppm
  4. 10 ppm

Explanation

AHRI Standard 700 sets the reclaimed R-123 moisture limit at 20 ppm by weight. Reclaimers must verify purity to this specification before the refrigerant can be returned to a chiller.

Question 5Low-pressure appliance refrigerant recovery, recycling, and reclamation

Recovery equipment used on low-pressure appliances must be able to pull a vacuum of at least how deep, measured in inches of mercury, under standard conditions?

  1. 29.9 inches
  2. 10 inches
  3. 0 inches
  4. 25 inches Correct answer.

Explanation

EPA requires recovery machines for low-pressure appliances to achieve a vacuum of 25 inches of mercury, reflecting the need to remove refrigerant vapor from a system that already runs below atmospheric pressure.

Question 6Low-pressure appliance refrigerant recovery, recycling, and reclamation

Before transferring recovered R-123 into a recovery cylinder, why must the cylinder be evacuated?

  1. To lubricate the recovery compressor
  2. To remove non-condensables that would contaminate the charge Correct answer.
  3. To cool the cylinder for faster transfer
  4. To increase the cylinder's weight capacity

Explanation

A recovery cylinder holds air if it is not evacuated first, and that air will mix with the recovered refrigerant. Evacuating the cylinder removes non-condensables so the refrigerant meets purity expectations and can be reclaimed.

Question 7Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which safety concern is unique to handling low-pressure refrigerants such as R-123 compared with high-pressure refrigerants?

  1. Extreme cylinder overpressure at room temperature
  2. Spontaneous combustion on contact with air
  3. Asphyxiation in low-lying areas due to high vapor density Correct answer.
  4. Rapid evaporation causing frostbite

Explanation

R-123 vapor is denser than air and collects in pits, basements, and machine rooms, displacing oxygen. Technicians must monitor the space and ventilate before entering a low area where a leak may have occurred.

Question 8Low-pressure appliance refrigerant recovery, recycling, and reclamation

What does EPA require to be done with refrigerant recovered from a low-pressure appliance that will not be recycled or reclaimed on site?

  1. Store it in a certified recovery cylinder Correct answer.
  2. Vent it if the charge is small
  3. Discharge it through a filter-drier
  4. Burn it in a permitted incinerator

Explanation

Recovered refrigerant must be contained in a DOT-approved recovery cylinder until it is recycled or sent to a reclaimer. Intentional venting of R-123 and similar refrigerants is prohibited.

Question 9Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician is recovering R-123 from a chiller and the recovery machine's inlet pressure gauge reads 0 psig. What should the technician do next?

  1. Open the system to air to equalize pressure
  2. Continue until the gauge reads 15 inches of vacuum
  3. Add nitrogen to push out remaining vapor
  4. Stop recovery; the required endpoint has been reached Correct answer.

Explanation

For low-pressure appliances the recovery endpoint is 0 psig, so reaching that reading means the required recovery is complete. Continuing to a deeper vacuum is not mandated, and opening the system would admit air and moisture.

Question 10Low-pressure appliance refrigerant recovery, recycling, and reclamation

Recycling refrigerant on site differs from reclamation primarily in which way?

  1. Recycling requires shipment to an off-site processing facility
  2. Recycling is only permitted for high-pressure refrigerants
  3. Recycling removes oil and moisture but does not restore the refrigerant to AHRI 700 purity Correct answer.
  4. Recycling permanently alters the refrigerant's chemical structure

Explanation

On-site recycling cleans the refrigerant of oil, moisture, and particulates but does not verify it against AHRI Standard 700. Reclamation, done by a certified facility, restores the refrigerant to that specification.

Question 11Low-pressure appliance refrigerant recovery, recycling, and reclamation

Why is a low-pressure chiller's purge unit important to refrigerant management?

  1. It filters particulates from the lubricating oil
  2. It removes air and other non-condensables that leak into the system Correct answer.
  3. It reclaims refrigerant to AHRI 700 purity
  4. It removes moisture from the refrigerant charge

Explanation

Because the chiller runs below atmospheric pressure, air and moisture migrate inward. The purge unit removes accumulated non-condensables so they do not degrade capacity and efficiency.

Question 12Low-pressure appliance refrigerant recovery, recycling, and reclamation

A recovery cylinder for R-123 is filled to 90 percent of its capacity by weight. Why is this a problem?

  1. The refrigerant will decompose above 80 percent
  2. Liquid expansion could hydraulically rupture the cylinder Correct answer.
  3. The recovery machine will overheat
  4. The cylinder will no longer pass a hydrostatic test

Explanation

Recovery cylinders must not be filled beyond 80 percent of capacity to leave room for liquid expansion. Overfilling can cause hydrostatic pressure that ruptures the cylinder.

Question 13Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which statement correctly describes the EPA certification requirement for a technician servicing a low-pressure appliance?

  1. Type I certification covers low-pressure appliances
  2. Type II certification covers low-pressure appliances
  3. Type III certification covers low-pressure appliances Correct answer.
  4. No certification is needed for chillers

Explanation

Type III certification applies to persons who maintain, service, repair, or dispose of low-pressure appliances. Type I covers small appliances and Type II covers high-pressure and very high-pressure equipment.

Question 14Low-pressure appliance refrigerant recovery, recycling, and reclamation

When recovering refrigerant from a low-pressure appliance, why should the technician avoid pulling the system into a deep vacuum?

  1. It could vaporize the compressor oil and damage the machine
  2. It would exceed the EPA recovery requirement and risk moisture and air ingress Correct answer.
  3. It would void the recovery cylinder's certification
  4. It would convert the refrigerant into a non-condensable gas

Explanation

The required endpoint for low-pressure recovery is 0 psig. Pulling deeper than necessary adds time and increases the risk of drawing air and moisture into a system that already operates below atmospheric pressure.

Question 15Low-pressure appliance refrigerant recovery, recycling, and reclamation

A chiller using R-123 must be opened for a compressor replacement. What must be done with the refrigerant before the system is opened?

  1. Dilute it with nitrogen and release it
  2. Recover it to 0 psig and store it in a recovery cylinder Correct answer.
  3. Seal the system and let the refrigerant remain
  4. Vent it because the system is already at low pressure

Explanation

The refrigerant must be recovered to the required endpoint and contained before any service that opens the system. Venting is prohibited, and leaving the charge in place prevents safe entry to the system.

Question 16Low-pressure appliance refrigerant recovery, recycling, and reclamation

What is the purpose of a refrigerant identifier when recovering R-123 from a chiller?

  1. To measure the system's vacuum level
  2. To weigh the recovery cylinder
  3. To test the purge unit's efficiency
  4. To confirm the refrigerant type and detect contamination before recovery Correct answer.

Explanation

An identifier verifies that the refrigerant is what the system label indicates and flags cross-contamination or non-condensables. This protects the recovery equipment and prevents mixing refrigerants in the cylinder.

Question 17Low-pressure appliance refrigerant recovery, recycling, and reclamation

Reclaimed R-123 that meets AHRI Standard 700 may be returned to a chiller only if which condition is also met?

  1. It is dyed for leak detection
  2. It is mixed with virgin refrigerant of a different type
  3. Its purity is documented and it matches the system's specified refrigerant Correct answer.
  4. It is stored below 0°F

Explanation

Reclaimed refrigerant must meet the purity specification and match the refrigerant the system is designed for. Documentation from the reclaimer provides the evidence of compliance.

Question 18Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which practice best prevents moisture from entering a low-pressure chiller during recovery?

  1. Using a leak-free recovery setup and evacuating hoses and cylinders before use Correct answer.
  2. Recovering only the liquid portion of the charge
  3. Adding water to the recovery cylinder to absorb contaminants
  4. Leaving the system open to the room while the recovery machine runs

Explanation

Because the system is below atmospheric pressure, any opening admits moist air. Evacuating hoses and cylinders and maintaining leak-free connections minimizes that intrusion.

Question 19Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician recovers R-123 from a chiller and plans to send it off site for reclamation. Which container is acceptable for that shipment?

  1. The original chiller receiver
  2. A non-refillable disposable cylinder
  3. A DOT-approved refillable recovery cylinder Correct answer.
  4. A plastic drum rated for liquids

Explanation

Refrigerant shipped for reclamation must be in a DOT-approved refillable recovery cylinder. Disposable cylinders are not designed for transport and refilling.

Question 20Low-pressure appliance refrigerant recovery, recycling, and reclamation

Why does EPA prohibit venting R-123 even though the appliance operates at low pressure?

  1. The refrigerant is a non-condensable gas
  2. The refrigerant is flammable and would ignite
  3. The refrigerant is heavier than air and would not disperse
  4. The refrigerant has a high ozone depletion potential and is regulated Correct answer.

Explanation

R-123 is a regulated refrigerant with ozone depletion potential, so intentional venting is prohibited. Recovery and proper disposal or reclamation are required.

Question 21Low-pressure appliance refrigerant recovery, recycling, and reclamation

A chiller's purge unit is venting an unusually high volume of refrigerant along with non-condensables. What does this most likely indicate?

  1. The recovery cylinder is overfilled
  2. The refrigerant charge is too pure
  3. An air leak into the low-pressure system is allowing excess air to accumulate Correct answer.
  4. The purge unit is operating normally

Explanation

Excess air entering a sub-atmospheric system raises the purge load, and each purge cycle carries some refrigerant with it. A high purge rate points to an air leak that should be located and repaired.

Question 22Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which combination of conditions must be satisfied for reclaimed R-123 to be acceptable for reuse in a chiller?

  1. It meets AHRI 700 purity limits and is verified by a certified reclaimer Correct answer.
  2. It has been recycled on site and filtered once
  3. It has been recovered to 0 psig and stored for a week
  4. It has been blended with virgin R-11

Explanation

Acceptable reclaimed refrigerant must meet AHRI Standard 700 limits for moisture, acidity, and other contaminants, verified by a certified reclaimer. On-site recycling alone does not establish that purity.

Question 23Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician uses a recovery machine rated only for high-pressure refrigerants on an R-123 chiller. What is the most significant risk?

  1. The refrigerant will change phase too slowly
  2. The machine will recover the charge too quickly
  3. The cylinder will overfill automatically
  4. The machine may not achieve the required vacuum and could be damaged by operating outside its design range Correct answer.

Explanation

Low-pressure recovery requires equipment capable of 25 inches of mercury vacuum and compatible with the refrigerant. Using a high-pressure-only machine risks failing to meet the recovery requirement and damaging the compressor.

Question 24Low-pressure appliance refrigerant recovery, recycling, and reclamation

What is the correct sequence when preparing to recover refrigerant from a low-pressure chiller?

  1. Vent non-condensables, then recover liquid only, then seal the system
  2. Recover to a deep vacuum, then identify the refrigerant, then weigh the cylinder
  3. Open the system, then connect the recovery machine, then weigh the cylinder
  4. Connect and evacuate hoses and cylinder, verify refrigerant type, then recover to 0 psig Correct answer.

Explanation

Proper preparation includes evacuating hoses and the recovery cylinder, confirming the refrigerant with an identifier, and then recovering to the 0 psig endpoint. This order prevents contamination and air ingress.

Question 25Low-pressure appliance refrigerant recovery, recycling, and reclamation

Why is it inaccurate to say that recycling and reclamation are interchangeable for R-123 recovered from a chiller?

  1. Recycling certifies purity to AHRI 700 while reclamation only removes oil
  2. Recycling cleans the refrigerant on site, while reclamation restores it to AHRI 700 purity at a certified facility Correct answer.
  3. Recycling is illegal for low-pressure refrigerants
  4. Reclamation can only be performed by the equipment owner

Explanation

Recycling removes oil, moisture, and particulates at the job site but does not verify purity against AHRI Standard 700. Reclamation is performed by a certified facility and restores the refrigerant to that specification.

Question 26Low-pressure appliance refrigerant recovery, recycling, and reclamation

Under EPA regulations, recovered R-123 that has been recycled on site may be returned to the same low-pressure appliance only if which condition is met?

  1. It meets the AHRI 700 purity standard for new refrigerant
  2. It has been chemically analyzed by an independent laboratory
  3. It is returned to the same owner's appliance from which it was recovered Correct answer.
  4. It has been blended with virgin R-123 to restore its composition

Explanation

Recycling is a field-level cleanup that removes oil, moisture, and particulates but does not restore refrigerant to a specified purity standard. EPA allows recycled refrigerant to go back only into the same appliance (or another appliance owned by the same person), which is why records linking the recovered charge to its owner matter. Meeting AHRI 700 is the hallmark of reclamation, not recycling.

Question 27Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician is setting up recovery on an R-123 centrifugal chiller. Which connection point is normally used to withdraw the refrigerant charge?

  1. The purge unit discharge port
  2. The high-side liquid line service port
  3. The compressor discharge service valve
  4. The charging valve on the chiller evaporator Correct answer.

Explanation

On low-pressure chillers the refrigerant is drawn from the evaporator charging valve, where the charge sits as a low-pressure liquid/vapor. Recovery then proceeds until the required vacuum is reached. Purge discharge is a vent path for non-condensables, and high-side ports are associated with the higher-pressure condenser side.

Question 28Low-pressure appliance refrigerant recovery, recycling, and reclamation

What is the EPA-required evacuation level when recovering refrigerant from a low-pressure appliance that uses a non-hermetic compressor, if the technician does not use a system-dependent recovery device?

  1. 25 inches of mercury vacuum Correct answer.
  2. 15 inches of mercury vacuum
  3. 10 inches of mercury vacuum
  4. 0 inches of mercury

Explanation

For low-pressure appliances with non-hermetic compressors, the recovery requirement is 25 inches of mercury vacuum (measured at the appliance) when a recovery machine is used. This deep vacuum is achievable because low-pressure refrigerants boil at pressures near or below atmospheric. The 10 and 15 inch figures do not correspond to the low-pressure rule.

Question 29Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician recovers R-123 into a cylinder and ships it to a reclamation facility. Which documentation must accompany the shipment so the reclaimed refrigerant can later be certified?

  1. A signed statement that the refrigerant was never vented
  2. A laboratory analysis performed by the technician before shipping
  3. A copy of the technician's EPA certification card
  4. A record of the refrigerant's previous use and owner, kept with the cylinder Correct answer.

Explanation

Reclamation facilities need to know the source and history of the recovered refrigerant so they can process and certify it properly; this is why recovery records and cylinder labeling accompany the shipment. The technician does not certify purity or provide legal attestations about venting. Certification cards are not shipment documents.

Question 30Low-pressure appliance refrigerant recovery, recycling, and reclamation

Why must a recovery cylinder used for R-123 be checked for a current hydrostatic test date before filling?

  1. Because R-123 reacts with the cylinder lining after five years
  2. Because low-pressure cylinders must be tested every year
  3. Because DOT requires cylinders to be within their test interval to be legal for refrigerant service and transport Correct answer.
  4. Because the test date proves the cylinder was evacuated

Explanation

DOT regulations require refrigerant cylinders to be within their hydrostatic test interval to be legally filled and transported. An out-of-date cylinder cannot be used even if it looks sound. The test date says nothing about evacuation status or chemical compatibility.

Question 31Low-pressure appliance refrigerant recovery, recycling, and reclamation

During recovery from a low-pressure chiller, the technician notices the recovery cylinder becoming cold and frost forming on its lower half. What does this indicate and what action is appropriate?

  1. The cylinder is overfilled and must be emptied immediately
  2. The cylinder contains non-condensables and must be vented
  3. Refrigerant is boiling off as it enters and the cylinder may need warming or a slower transfer rate Correct answer.
  4. The recovery machine is running backward and must be shut off

Explanation

As liquid refrigerant enters a cylinder and evaporates, it absorbs heat, chilling the shell and slowing further transfer. Gentle warming within safe limits, or reducing the transfer rate, keeps recovery moving. Frost alone does not indicate overfill, contamination, or reversed flow.

Question 32Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which refrigerant is commonly used in low-pressure centrifugal chillers and is subject to the Type III low-pressure rules?

  1. R-123 Correct answer.
  2. R-404A
  3. R-134a
  4. R-410A

Explanation

R-123 is the low-pressure refrigerant most associated with centrifugal chillers and is covered by the low-pressure appliance rules. R-410A and R-404A are high-pressure blends, and R-134a is a medium-pressure refrigerant used in other equipment.

Question 33Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician is recovering R-123 from a chiller and the recovery machine's suction gauge shows the system pressure has dropped below atmospheric. Which statement best explains why continued operation is still needed?

  1. Because the chiller's compressor must be kept running during recovery
  2. Because the machine will not run at positive pressure
  3. Because the cylinder must be pressurized above atmospheric to accept refrigerant
  4. Because low-pressure refrigerants must be pulled to a specified vacuum to meet the recovery requirement Correct answer.

Explanation

Low-pressure refrigerants boil below atmospheric pressure at ordinary temperatures, so meeting the EPA evacuation level requires pulling the appliance into a vacuum. The recovery machine is designed to work in that range. Keeping the chiller compressor running is neither required nor safe during recovery.

Question 34Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which practice helps ensure that recycled R-123 is not contaminated with moisture before it is returned to a chiller?

  1. Storing the cylinder in direct sunlight
  2. Using a filter-drier in the recovery loop and keeping the system sealed Correct answer.
  3. Adding a small amount of virgin refrigerant to dilute any water
  4. Venting the recovery cylinder briefly before filling

Explanation

Moisture in a low-pressure chiller can form corrosive acids, so a filter-drier in the recovery circuit and prompt resealing of the system are standard precautions. Dilution does not remove water, and venting or heating the cylinder does not address contamination.

Question 35Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician recovers R-123 from a chiller, and the recovered refrigerant is later found to contain a significant amount of air. What is the most appropriate next step before the refrigerant can be reused?

  1. Vent the air from the top of the recovery cylinder and reuse the liquid
  2. Mix it with virgin R-123 to lower the air concentration
  3. Return it to the chiller as-is because air will be removed by the purge unit
  4. Send it to a reclamation facility equipped to remove non-condensables Correct answer.

Explanation

Air in recovered refrigerant must be removed by proper processing, which is beyond field recycling capability; a reclamation facility has the equipment to separate and certify the refrigerant. Relying on the chiller's purge to handle a contaminated charge is not acceptable, and venting or blending does not produce a compliant product.

Question 36Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which recordkeeping obligation applies to a technician who recovers R-123 from a low-pressure appliance?

  1. Filing a copy of the recovery with the local fire department
  2. Reporting the recovery to the refrigerant manufacturer
  3. Publishing the recovery total in a public log
  4. Recording the amount recovered and the date of recovery Correct answer.

Explanation

EPA requires records of refrigerant recovered, including amounts and dates, to document compliance with the venting prohibition. These records are kept by the service organization and made available on request. Reporting to a fire department, manufacturer, or public log is not required.

Question 37Low-pressure appliance refrigerant recovery, recycling, and reclamation

A chiller using R-123 has a nameplate charge of 800 pounds. A technician plans to recover the charge with a recovery machine. Which statement best describes the cylinder capacity planning needed?

  1. Multiple cylinders sized by weight and fill limit are needed to hold the full charge Correct answer.
  2. Cylinder size is irrelevant because R-123 is recovered as a gas only
  3. The charge can be stored in the chiller's receiver without cylinders
  4. One 125-pound cylinder is sufficient because R-123 is a low-pressure refrigerant

Explanation

Recovery cylinders have a weight-based fill limit, typically 80 percent of capacity, so a large charge must be split among enough cylinders. Low operating pressure does not reduce the mass that must be stored. The chiller receiver is part of the appliance and cannot serve as storage during service.

Question 38Low-pressure appliance refrigerant recovery, recycling, and reclamation

What is the primary reason a low-pressure chiller's purge unit is monitored during and after recovery work?

  1. It removes air and moisture that enter the machine and limits refrigerant loss Correct answer.
  2. It pressurizes the chiller for leak testing
  3. It filters oil before it returns to the compressor
  4. It indicates how much refrigerant has been recovered

Explanation

A purge unit pulls non-condensables out of the chiller and minimizes the refrigerant that escapes with them. Elevated purge activity signals air in-leakage, which is a refrigerant-management concern. The purge does not measure recovered quantity, pressurize the machine, or filter oil.

Question 39Low-pressure appliance refrigerant recovery, recycling, and reclamation

A technician must verify that reclaimed R-123 is acceptable for charging a customer's chiller. Which evidence best supports that conclusion?

  1. A pressure test showing the cylinder holds vacuum
  2. A statement that the refrigerant was recycled on site
  3. A label showing the refrigerant was recovered from a chiller
  4. A certificate or analysis showing compliance with AHRI 700 Correct answer.

Explanation

Reclaimed refrigerant must be certified to AHRI 700 purity before it can be sold or used as reclaimed refrigerant. A recovery label, a recycling claim, or a vacuum check does not establish chemical purity. The certificate ties the batch to the required standard.

Question 40Low-pressure appliance refrigerant recovery, recycling, and reclamation

Which situation would require a technician to stop recovery and investigate before continuing?

  1. The cylinder weight increases during recovery
  2. The recovery machine's discharge pressure rises steadily as the cylinder fills
  3. The appliance pressure stops dropping and remains steady well above the target vacuum Correct answer.
  4. The recovery machine's fan runs continuously

Explanation

A pressure that plateaus above the required evacuation level usually signals a leak, a closed valve, or refrigerant trapped in another part of the system. Continuing to run the machine will not achieve the required vacuum. Rising discharge pressure, increasing cylinder weight, and a running fan are normal during recovery.

Question 41Low-pressure system servicing and refrigerant handling practices

On a low-pressure centrifugal chiller, what is the primary purpose of the purge unit?

  1. To remove non-condensable gases that accumulate in the condenser Correct answer.
  2. To circulate chilled water through the evaporator bundle
  3. To filter moisture out of the liquid refrigerant charge
  4. To raise the evaporator pressure before startup

Explanation

Low-pressure systems operate below atmospheric pressure, so air and other non-condensables can be drawn into the machine and collect in the condenser, raising head pressure and reducing efficiency. The purge unit removes these gases while limiting refrigerant loss.

Question 42Low-pressure system servicing and refrigerant handling practices

A low-pressure chiller holds refrigerant at approximately what pressure while operating?

  1. Well above atmospheric pressure
  2. Below atmospheric pressure Correct answer.
  3. At the cylinder's saturation pressure
  4. Exactly at atmospheric pressure

Explanation

Low-pressure machines such as R-11, R-123, and R-1233zd evaporators run in a vacuum, below atmospheric pressure. This is why air infiltration and purge operation are central concerns on these systems.

Question 43Low-pressure system servicing and refrigerant handling practices

Why must a low-pressure chiller be leak-tested with a method that does not require pressurizing the machine above atmospheric pressure?

  1. The purge unit cannot run while pressurized
  2. The rupture disc would open immediately
  3. The evaporator shell is not designed for positive pressure Correct answer.
  4. The refrigerant would decompose under pressure

Explanation

Low-pressure shells are built for vacuum service and have limited positive-pressure capability, so they must not be pressurized beyond their design limits. Leak detection is typically done with the machine in a vacuum using sensitive electronic leak detectors or by pressurizing with dry nitrogen only within approved limits.

Question 44Low-pressure system servicing and refrigerant handling practices

What is the required condition of a recovery cylinder before it is used to recover refrigerant from a low-pressure chiller?

  1. It must be evacuated and DOT-approved for the refrigerant Correct answer.
  2. It must be filled with nitrogen first
  3. It must be equipped with a purge unit
  4. It must be painted a light color

Explanation

Recovery cylinders must be DOT-approved for the refrigerant service and evacuated before use so that air and moisture are not introduced into the recovered refrigerant. Using a non-approved or un-evacuated cylinder risks contamination and unsafe pressure.

Question 45Low-pressure system servicing and refrigerant handling practices

When recovering refrigerant from a low-pressure chiller, why is a liquid-vapor recovery approach often used rather than vapor-only recovery?

  1. It avoids the need to monitor pressures
  2. It is required by the Clean Air Act for all systems
  3. It eliminates the need for a recovery cylinder
  4. It is generally faster because liquid transfer moves more mass Correct answer.

Explanation

Withdrawing liquid refrigerant transfers mass much faster than pulling vapor alone, so many technicians use a liquid recovery step followed by vapor recovery to reach the required evacuation level. The choice of method does not change the required final vacuum.

Question 46Low-pressure system servicing and refrigerant handling practices

A technician is recovering refrigerant from a low-pressure chiller and the recovery machine begins to cavitate. What is the most appropriate response?

  1. Throttle the liquid feed or switch to vapor recovery Correct answer.
  2. Shut off the recovery machine permanently
  3. Add nitrogen to the chiller to push the liquid
  4. Increase the liquid valve opening fully

Explanation

Cavitation indicates the recovery machine is receiving more liquid than it can handle. Reducing the liquid feed or shifting to vapor recovery protects the compressor and keeps recovery efficient.

Question 47Low-pressure system servicing and refrigerant handling practices

Under EPA regulations, what evacuation level must be reached before a low-pressure appliance is opened for repair?

  1. 25 inches of mercury Correct answer.
  2. 10 inches of mercury
  3. 0 inches of mercury
  4. 29 inches of mercury

Explanation

For low-pressure appliances, the required evacuation level is 25 inches of mercury vacuum before the system is opened. This is a lower absolute vacuum requirement than for high-pressure systems because of the machine's design and pressure characteristics.

Question 48Low-pressure system servicing and refrigerant handling practices

Which refrigerant is commonly associated with low-pressure centrifugal chillers and requires specific handling under Type III rules?

  1. R-123 Correct answer.
  2. R-404A
  3. R-134a
  4. R-410A

Explanation

R-123 is a low-pressure refrigerant widely used in centrifugal chillers and falls under Type III servicing. R-410A and R-404A are high-pressure blends, and R-134a is a medium-pressure refrigerant.

Question 49Low-pressure system servicing and refrigerant handling practices

Why is it important to prevent air from entering a low-pressure chiller during servicing?

  1. Air raises condenser pressure and reduces efficiency Correct answer.
  2. Air increases the refrigerant charge
  3. Air lowers the evaporator temperature
  4. Air improves heat transfer in the evaporator

Explanation

Because the machine runs below atmospheric pressure, any opening can draw air in. Non-condensables collect in the condenser, raise head pressure, and degrade capacity and efficiency while increasing purge losses.

Question 50Low-pressure system servicing and refrigerant handling practices

What is the purpose of a rupture disc on a low-pressure chiller?

  1. To release refrigerant if internal pressure exceeds the shell limit Correct answer.
  2. To separate oil from the refrigerant
  3. To measure the refrigerant charge level
  4. To regulate refrigerant flow to the evaporator

Explanation

The rupture disc is a pressure-relief device that protects the low-pressure shell from overpressure by venting refrigerant if internal pressure rises above the design limit. It must be replaced if it has ruptured.