EPA 608 Type III Answer Explanations
Type III covers low-pressure appliances, especially the chiller concepts that can feel unfamiliar after studying small appliances or higher-pressure systems. These explanations are for learners preparing for the Type III section and for Universal candidates reviewing their final equipment category. The questions connect pressure readings, refrigerant recovery, air and moisture entering a system, purge operation, and the risks associated with water and refrigerant during service.
Begin by paying attention to pressure units. An absolute-pressure reading and a vacuum reading referenced to atmospheric pressure are not interchangeable. Next, consider what happens when a system operates below atmospheric pressure: a leak can draw air and moisture inward. That helps explain why questions about noncondensables, purge operation, and leak investigation belong together. Removing liquid alone also does not establish that recovery is complete.
For each missed question, identify whether the problem was a unit, a system behavior, or a regulatory distinction. Read the explanation before returning to the Type III study guide for the broader topic. Then try the matching practice test to see whether you can reason through a different phrasing. Chiller procedures depend on the equipment and manufacturer instructions, so use this page as an exam review companion rather than a universal service sequence.
Most-missed topics
Use these review prompts to catch common mix-ups in this question set; they are not a ranking based on learner scores.
- Absolute pressure: Table 1 specifies 25 mm Hg absolute for low-pressure appliances in both recovery-equipment date columns.
- Air infiltration: A leak in a system operating below atmospheric pressure can draw outside air and moisture inward.
- Purge operation: Noncondensables collect in the condenser; a purge removes them, but some refrigerant loss is possible.
- Remaining vapor: Removing bulk liquid does not mean the appliance is empty; recovery must reach the applicable required level.
Sources: EPA Section 608 definitions and 40 CFR § 82.156 recovery requirements. See each answer for related study material.
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Type III
What sets the safe leak-test pressure for a low-pressure chiller?
Correct answer: B. The manufacturer's test limit and equipment pressure ratings.
Follow the specific chiller's pressure limits, relief arrangement, and test instructions. Traditional study examples often use a 10 psig test limit with a 15 psig rupture disc, but those numbers must not be applied to every design.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
For a non-major repair on an R-123 low-pressure chiller under 40 CFR 82.156(a)(1)(ii), which method can raise pressure to no higher than 0 psig?
Correct answer: A. Controlled hot water
Controlled heat can raise refrigerant pressure. For refrigerants with normal boiling points at or below 85 F, such as R-123, methods requiring subsequent purging, such as nitrogen, are prohibited for this non-major-repair exception. Do not exceed 0 psig before opening. Source: 40 CFR 82.156(a)(1)(ii).
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
Where is the purge unit located in a low-pressure system?
Correct answer: A. The top of the condenser.
A conventional centrifugal-chiller purge takes its inlet from the upper condenser, where noncondensables accumulate. It separates and returns refrigerant while discharging noncondensables; some refrigerant loss is possible, so high-efficiency purging and leak repair matter.
In a low-pressure chiller, air and other non-condensables collect at the;
Correct answer: B. top section of the condenser.
Noncondensables accumulate in the condenser because they do not condense with the refrigerant at operating conditions. A purge unit removes them. This is not simply a matter of air floating above a heavier gas.
What can an acid test help assess after a suspected compressor burnout?
Correct answer: C. Whether acidic contamination is present.
Use appropriate testing and the manufacturer's cleanup procedure to assess contamination. Odor is not a safe or conclusive diagnostic method; do not intentionally inhale refrigerant.
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.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
During dehydration after refrigerant recovery, an approved dry-nitrogen break may help address:
Correct answer: A. Freezing of residual moisture during rapid evacuation.
A manufacturer-approved evacuation procedure may use nitrogen breaks and controlled warming to help remove trapped moisture. Nitrogen pressure alone does not provide the heat needed to melt ice. This is dehydration after recovery, not permission to vent a refrigerant-containing mixture.
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.
Recover bulk liquid first and then the remaining vapor using compatible equipment and the manufacturer's procedure. For a low-pressure appliance, Table 1 requires 25 mm Hg absolute in either equipment-date column. Source: 40 CFR 82.156(a).
The EPA-required evacuation level for recovery or recycling equipment used on low-pressure systems is
Correct answer: C. 25 mm of Hg absolute.
The low-pressure appliance recovery target is 25 mm Hg absolute for both pre-November-15-1993 recovery equipment and equipment manufactured or imported on or after that date. Absolute pressure in millimeters Hg is not the same as inches Hg vacuum. Source: 40 CFR 82.156(a), Table 1.
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.
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.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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.
Where is refrigerant added to a low-pressure system during the charging process?
Correct answer: D. The manufacturer-designated charging connection, commonly the evaporator charging valve.
Use the chiller manufacturer's designated charging connection and sequence. For a water-filled evaporator under deep vacuum, introducing liquid too early can cause rapid boiling and freeze damage. Port location alone does not make charging safe.
Under ASHRAE Standard 34, R-134a is classified as;
Correct answer: A. A1
R-134a is classified A1: lower toxicity and no flame propagation under Standard 34 test conditions. A1 does not mean harmless; exposure, oxygen displacement, frostbite, and pressure hazards remain.
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.
After recovering bulk liquid from a low-pressure chiller, what determines the amount of vapor still present?
Correct answer: A. Internal volume, refrigerant properties, pressure, and temperature.
Remaining vapor mass cannot be determined from cooling tonnage alone. Continue recovery to the applicable required level; do not assume liquid removal means an empty appliance.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
What determines a chiller rupture disc's rated burst pressure?
Correct answer: C. The specified disc rating and equipment design.
Read the equipment documentation and disc markings. A 15 psig disc is common in traditional low-pressure-chiller examples, but it is not a universal rating for all chillers.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
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.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
Before pressure-testing a low-pressure chiller, which limit must be checked?
Correct answer: B. The manufacturer's test limit and equipment pressure ratings.
Follow the specific chiller's pressure limits, relief arrangement, and test instructions. Traditional study examples often use a 10 psig test limit with a 15 psig rupture disc, but those numbers must not be applied to every design.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
Why is vapor commonly introduced before liquid when charging a deeply evacuated, water-filled low-pressure chiller?
Correct answer: B. To raise saturation temperature before liquid flashing can freeze the water.
Follow the manufacturer's minimum saturation temperature, water-flow requirements, and charging sequence. A temperature used in one chiller procedure is not a universal authorization to add liquid.
📖 Related rule: Core Study Guide — Refrigerant Cylinders and Handling
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.
Under Section 608, what is the usual time allowed to complete a required retrofit or retirement plan, absent a qualifying extension?
Correct answer: A. One year.
A compliant plan is generally developed within 30 days and completed within one year. Specific extension conditions are set out in 40 CFR 82.157(h)-(i); an exempt replacement refrigerant does not by itself establish a blanket two-year deadline.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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.
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.
Controlled warming can raise the saturation pressure of a charged low-pressure chiller for leak detection. Monitor pressure and follow manufacturer limits; heating does not automatically keep pressure below a relief-device rating.
In a dual-relief-valve changeover arrangement, how are the alternative relief paths configured?
Correct answer: B. In parallel through the approved changeover arrangement.
An approved dual-relief changeover arrangement provides alternative parallel relief paths while preserving required protection. Other engineered arrangements, such as a rupture disc with a relief valve, must follow the applicable code and manufacturer design.
When recovering one isolated compressor from a parallel rack while the rest remains charged, what must be addressed?
Correct answer: A. All refrigerant and oil-equalization paths into that section must be properly isolated.
Connected refrigerant and oil lines can feed refrigerant into the section being serviced. Follow the rack's isolation and recovery procedure and verify the required recovery level. Recovering an entire rack is a different scope.
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.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
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.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
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.
What can a rising standing-vacuum reading on a low-pressure chiller indicate?
Correct answer: C. Leakage, moisture evaporation, or outgassing that needs investigation.
Interpret a standing-vacuum test using the manufacturer's procedure, temperature conditions, hold time, and allowable rise. A rise is not a conclusive diagnosis of leakage alone.
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 noncondensables from a low-pressure chiller. A high-efficiency design separates and returns more refrigerant before discharging noncondensables, reducing refrigerant loss. Efficiency depends on the product and conditions.
📖 Related rule: Core Study Guide — Refrigerant Cylinders and Handling
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 conventional centrifugal-chiller purge draws noncondensables from the condenser, separates refrigerant, and returns recovered refrigerant to the system. The precise return arrangement is manufacturer-specific, and purging does not guarantee zero refrigerant loss.
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.
Excessive purge activity or collected moisture can indicate air/water ingress and should prompt investigation. Review the purge unit's operation and manufacturer diagnostics rather than treating one symptom as proof of an exact leak.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
What needs to be done to leak check a low pressure system?
Correct answer: C. Increase pressure using controlled hot water or heater blankets.
Controlled warming can raise the pressure of refrigerant in a charged low-pressure chiller for leak detection. Use the manufacturer's method and limits; do not assume a generic temperature or heating method is safe for every machine.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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.
Approved controlled heat can raise saturation pressure without introducing another gas. Monitor pressure and observe the equipment's test limits; warming does not automatically keep pressure below a relief-device setting.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
What is the risk of exceeding a low-pressure chiller's permitted test pressure?
Correct answer: B. It can activate relief protection or damage the equipment.
Overpressure can cause refrigerant release or equipment failure. Read the machine's specified test limit and relief ratings; a 10 psig example is not a universal burst threshold.
How should a water box be leak tested?
Correct answer: A. Remove water, then insert the leak-detector probe through the drain valve.
For a manufacturer-approved refrigerant-to-water-side leak check, drain and prepare the water box and use a compatible detector at the specified access point. Follow isolation and pressure limits. Other approved tube-testing methods may also be used.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
How should a suspected leaking chiller tube be tested?
Correct answer: C. Use the manufacturer's specified tube-test equipment and pressure limits.
Tube testing must suit the heat-exchanger design and suspected failure. Use approved equipment and limits; no single hydrostatic kit or visual check is a universal requirement.
📖 Related rule: Core Study Guide — Refrigerant Cylinders and Handling
Before servicing a low-pressure system's pressure-relief device, what should be verified?
Correct answer: C. The device rating, discharge arrangement, and manufacturer/code requirements.
Relief-device requirements are equipment-specific. Do not assume all low-pressure chillers and recovery machines use an identical rupture-disc 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.
Can the vapor remaining after liquid recovery be calculated from a chiller's cooling tonnage alone?
Correct answer: D. No; vessel volume, refrigerant, pressure, and temperature matter.
Cooling capacity is not refrigerant vapor mass. Continue recovery to the applicable limit rather than treating a quoted example such as 100 pounds as a universal value.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
How can you speed up the vapor recovery process?
Correct answer: B. Use manufacturer-approved appliance warming and suitable recovery-cylinder cooling.
An appropriate temperature/pressure difference can assist recovery. Heating the receiving cylinder generally increases backpressure rather than helping vapor flow into it. Use only approved methods and monitor cylinder fill and pressure.
Where the manufacturer's chiller recovery procedure requires water circulation, what must remain operating?
Correct answer: A. The system water pumps, recovery compressor, and recovery condenser water.
Maintain the specified water flow and recovery equipment operation to limit freezing and remove heat. Some procedures instead require draining particular circuits. Follow the machine-specific instructions; do not mix incompatible drain-and-circulate directions.
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.
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.
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.
How should water circuits be protected during chiller refrigerant recovery?
Correct answer: A. Maintain specified circulation or drain the affected water circuits as the manufacturer requires.
Recovery can lower refrigerant temperature and freeze water in heat-exchanger tubes. Follow the chiller's circulation or draining instructions; the water/refrigerant side arrangement differs among heat-exchanger designs.
Why may a manufacturer's oil-removal procedure call for controlled warming before draining?
Correct answer: B. To release dissolved refrigerant for recovery before the oil is removed.
Capture refrigerant released from oil using the specified procedure. Temperature and oil-handling limits are manufacturer-specific; do not apply an unsourced universal heating temperature.
📖 Related rule: Core Study Guide — Refrigerant Cylinders and Handling
Why can adding liquid refrigerant to a deeply evacuated, water-filled low-pressure chiller cause damage?
Correct answer: C. The liquid can boil rapidly and lower tube temperature enough to freeze water.
Rapid flashing can extract enough heat to freeze water in the tubes. Follow the manufacturer's vapor-first charging sequence, saturation-temperature criteria, and water-flow requirements.
When charging a low-pressure chiller whose instructions specify the evaporator charging valve and vapor first, what sequence should be followed?
Correct answer: A. Use that valve and introduce vapor before the specified liquid-charging transition.
Use the designated charging connection and manufacturer sequence. The purpose of vapor first is to manage freeze risk, not simply to choose the physically lowest port.
What determines when a water-filled low-pressure chiller can transition from vapor to liquid charging?
Correct answer: D. The manufacturer's saturation-temperature, pressure, and water-flow criteria.
Use the correct refrigerant saturation data and chiller procedure. A single pressure such as 16.9 inches Hg vacuum cannot serve as the transition point for every refrigerant and chiller.
What requirements apply to Section 608 recovery/recycling equipment manufactured or imported on or after November 15, 1993?
Correct answer: A. EPA-approved third-party certification, low-loss fittings, and required evacuation levels.
Applicable equipment must meet EPA certification and performance requirements. EPA lists AHRI and UL for Section 608 certification; ETL listing under another program is not interchangeable. Source: 40 CFR 82.158.
Under Table 1, what recovery levels apply to low-pressure appliances using recovery equipment manufactured or imported before November 15, 1993 versus on or after that date?
Correct answer: A. 25 mm Hg absolute in both date columns.
Both date columns specify 25 mm Hg absolute for low-pressure appliances. Neither 25 inches Hg vacuum nor 10 mm Hg absolute is the Table 1 target for these appliances. Source: 40 CFR 82.156(a), Table 1.
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 reaching the recovery target, isolate and observe pressure as directed by the recovery procedure. Remaining liquid or refrigerant dissolved in oil can cause pressure rebound, requiring further recovery. Leaks and temperature changes can also affect the reading; investigate rather than assume every rise has one cause.
What should be done if a leak makes reaching the required vacuum level unattainable?
Correct answer: B. Isolate components where possible and apply the leaking-component recovery exception.
Isolate leaking and non-leaking components where possible. Recover non-leaking components to Table 1; recover leaking components to the lowest level attainable without substantially contaminating the refrigerant, no higher than 0 psig. The exception is not automatic permission to stop at 0 psig. Source: 40 CFR 82.156(a)(2).
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.
Removing a compressor, condenser, evaporator, or auxiliary heat-exchanger coil is a major repair. Apply the appropriate Table 1 recovery limit. Leak-repair verification duties arise separately when the appliance is covered by the applicable leak-repair program. Source: 40 CFR 82.152, 82.156, and 82.157.
Where should a low-pressure chiller's pressure-relief discharge be routed?
Correct answer: B. To the code-compliant discharge location specified by the manufacturer, commonly outdoors.
Follow the manufacturer's engineered relief piping and applicable code. Do not attach an ordinary recovery tank or otherwise obstruct the relief discharge. A venting prohibition does not justify defeating overpressure protection. Source: Trane CenTraVac installation guidance.
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.
During dehydration after recovery, rapidly evaporating free water can cool and freeze. Manufacturer-approved dry-nitrogen breaks and controlled warming may assist, but nitrogen pressure alone does not supply the heat required to melt ice. Follow the prescribed evacuation procedure.
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.
For a charged low-pressure chiller, a manufacturer-approved warming or pressurization arrangement can help limit air ingress while idle. Follow the specific storage procedure; adding nitrogen is not a universal choice and can create later purging requirements.
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.
Use manufacturer-approved controlled warming or pressurization for leak testing. Nitrogen use and test limits are equipment- and task-specific; the non-major-repair pressurization exception has separate restrictions in 40 CFR 82.156(a)(1)(ii).
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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 purging can indicate air ingress and warrants leak investigation and purge-unit checks. Do not assume every change in purge behavior has only one possible cause.
📖 Related rule: Core Study Guide — Refrigerant Cylinders and Handling
Which limit governs leak-test pressure on a particular low-pressure centrifugal chiller?
Correct answer: B. The manufacturer's specified test limit and applicable equipment/code ratings.
Traditional examples may specify 10 psig, but not every chiller has identical ratings. Follow the machine's actual service documentation and protect against exceeding its pressure limits.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
If a low-pressure appliance exceeds the applicable leak rate, the owner must:
Correct answer: A. Take the required repair/verification action or follow a compliant retrofit/retirement plan.
For a covered Section 608 appliance exceeding the trigger, meet the repair and verification requirements or the prescribed retrofit/retirement route and deadlines. Continued operation is not automatically prohibited in every circumstance during the allowed compliance period. Source: 40 CFR 82.157.
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.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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%
For Section 608 appliances with a full charge of 50 pounds or more of ozone-depleting refrigerant, the industrial-process-refrigeration trigger is above 30% annually. Commercial refrigeration uses 20%; comfort cooling and other covered categories use 10%. These are corrective-action triggers, not allowances to deliberately vent. Source: 40 CFR 82.157.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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%
For Section 608 appliances with a full charge of 50 pounds or more of ozone-depleting refrigerant, comfort cooling and other covered categories have a 10% annual trigger. Commercial refrigeration currently uses 20%, and industrial process refrigeration 30%; 20% is not merely a historical figure. Source: 40 CFR 82.157.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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
Removing liquid does not complete recovery: refrigerant vapor remains and must also be recovered. For a low-pressure appliance, the Table 1 target is 25 mm Hg absolute in both recovery-equipment date columns. The amount of remaining vapor depends on the appliance and conditions. Source: 40 CFR 82.156(a), Table 1.
When an oil-service procedure calls for warming a low-pressure chiller's oil, what controls the temperature and handling method?
Correct answer: C. The chiller manufacturer's procedure and applicable recovery requirements.
Use the specified service procedure and recover refrigerant released from oil. Do not apply a generic heating temperature to every chiller or oil-sampling task.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
During refrigerant evacuation of a low-pressure chiller, water in the chiller tubes should be:
Correct answer: B. Circulated or removed to prevent freezing.
Pressure reduction and refrigerant evaporation can chill heat-exchanger tubes and freeze water. Maintain specified circulation or drain the affected circuits as required by the chiller manufacturer.
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
Low-pressure recovery equipment is typically set to shut down at no higher than 10 psig, below the 15 psig rupture disc on low-pressure chillers. This is the standard exam answer; the value is an equipment setting, not a number stated in 40 CFR 82.158.
When recharging a low-pressure chiller, you must introduce vapor first because:
Correct answer: B. Adding liquid first could freeze water in evaporator tubes.
Liquid entering a deep vacuum can flash and extract heat rapidly, risking frozen water and damaged tubes. Follow the manufacturer's vapor-first sequence and transition criteria; a generic 36 F figure alone is not authorization to charge liquid.
For a centrifugal chiller with a designated evaporator charging valve, which connection should be used under its charging procedure?
Correct answer: B. The evaporator charging valve.
Use the manufacturer's designated charging connection and sequence. Its suitability follows from the equipment design, not a universal rule that every lowest port is a safe charging port.
For a low-pressure appliance being opened for a major repair, recovery equipment manufactured or imported on or after November 15, 1993 must evacuate the system to at least:
Correct answer: B. 25 mm Hg absolute
Low-pressure appliances must reach 25 mm Hg absolute under Table 1 before opening for a major repair. The same target applies in both recovery-equipment date columns; newer equipment does not change it to 10 mm Hg absolute. Source: 40 CFR 82.156(a), Table 1.
Under the non-major-repair exception for an R-123 low-pressure appliance, what can raise pressure to no higher than 0 psig before opening?
Correct answer: C. Controlled hot water or a built-in heating/pressurization device.
Use controlled heat in accordance with the appliance instructions. For refrigerants boiling at or below 85 F at standard atmospheric pressure, methods requiring later purging, such as nitrogen, are not permitted under this exception. Do not pressurize above 0 psig before opening. Source: 40 CFR 82.156(a)(1)(ii).
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
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.
After reaching the recovery target, isolate and observe pressure as directed by the recovery procedure. Remaining liquid or refrigerant dissolved in oil can cause pressure rebound, requiring further recovery. Leaks and temperature changes can also affect the reading; investigate rather than assume every rise has one cause.
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 involves removal of the compressor, condenser, evaporator, or auxiliary heat exchanger coil. For a low-pressure appliance, the applicable Table 1 recovery target is 25 mm Hg absolute for either equipment date. Source: 40 CFR 82.156(a), Table 1.
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.
📖 Related rule: § 82.157 — Appliance Maintenance and Leak Repair
At standard atmospheric pressure (0 psig), R-123 boils at approximately:
Correct answer: C. 82°F
R-123's normal boiling point is about 82 F at standard atmospheric pressure. It therefore operates below atmospheric pressure at typical chilled-water evaporator temperatures. This value should not be used for another refrigerant.
📖 Related rule: Type III Study Guide — Low-Pressure Appliances
How should a machinery-room refrigerant detector be selected?
Correct answer: A. The refrigerant hazards and applicable equipment, code, and standard requirements.
Select and configure detection and ventilation for the actual refrigerant and applicable requirements. An oxygen sensor alone is not a universal substitute for detecting halocarbon refrigerant exposure or flammability hazards.
Under ASHRAE Standard 15, equipment rooms containing R-123 specifically require:
Correct answer: B. A refrigerant sensor for R-123.
R-123 has safety classification B1. Use detection suitable for R-123 and the applicable machinery-room exposure requirements; a CO2 monitor or flame detector does not measure R-123 concentration. Apply the adopted code/standard edition and equipment instructions.