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EPA 608 Type III
Practice Test

Type III covers low-pressure appliances: centrifugal chillers whose evaporator runs below atmospheric pressure. That single fact drives the whole section. Because the machine is under vacuum in normal operation, leaks pull air and water *in* rather than pushing refrigerant out, so purge units, non-condensable removal, freeze protection during recovery, and the ten-psig ceiling on pressurizing the vessel are the topics that dominate. It is a niche certification and a well-paid one.

30
Questions
25
Per Attempt
70%
To Pass
Lifetime
Cert Validity
Practice
Take the Type III Practice Test
25 questions drawn at random from a bank of 30. Every answer comes with an explanation, and you can retake it as many times as you like.
Question 1 of 250 correct so far
Machine room safety and exposure limits

Self-contained breathing apparatus for a chiller machine room should be stored:

Scope
What EPA 608 Type III Covers
Low-pressure appliances — centrifugal chillers operating below atmospheric pressure.
Low-pressure appliance characteristics
6 practice questions in the bank below.
Purge units and non-condensables
4 practice questions in the bank below.
Pressure limits and rupture discs
4 practice questions in the bank below.
Recovery and freeze protection
5 practice questions in the bank below.
Required evacuation levels
2 practice questions in the bank below.
Leak detection on a vacuum machine
3 practice questions in the bank below.
Refrigerant charging
2 practice questions in the bank below.
Machine room safety and exposure limits
4 practice questions in the bank below.
Who needs this section
Technicians and building engineers who work on large centrifugal chillers using R-11, R-123, or R-514A.

Key Takeaways

The EPA 608 Type III exam is 25 multiple-choice questions and requires 70% to pass. It covers low-pressure appliances — centrifugal chillers operating below atmospheric pressure. Certification never expires, and the exam is open-book.

  • Free practice bank: 30 questions, every answer explained
  • 25 questions per attempt, randomized · unlimited retakes
  • Core must be passed alongside any Type section
  • Exam cost is typically $20–$40 at an EPA-approved testing organization
Answer Key
All 30 Type III Questions Explained
The full bank with correct answers and the reasoning behind each one. Use it to study before you test, or to review after an attempt.

1. A low-pressure appliance is one that uses a refrigerant with a boiling point at atmospheric pressure:

  1. Above 10°F, so the evaporator operates in a vacuum
  2. Between −50°F and 10°F
  3. Below −50°F
  4. Exactly 32°F
Answer: A — Above 10°F, so the evaporator operates in a vacuum
R-11 boils near 75°F and R-123 near 82°F at atmospheric pressure, so the evaporator of a running centrifugal chiller sits below atmospheric pressure. Everything distinctive about Type III follows from that single fact — leaks draw air and water in rather than pushing refrigerant out.

2. Because a low-pressure chiller operates under a vacuum, a leak in the evaporator will:

  1. Release refrigerant to the machine room
  2. Draw air and moisture into the machine
  3. Have no effect until the machine is shut down
  4. Cause immediate high head pressure
Answer: B — Draw air and moisture into the machine
Air and water vapor enter through a leak while the machine runs, which is why non-condensables accumulate in low-pressure machines and why they need purge units at all. Refrigerant does escape when the machine is off and warms above atmospheric pressure, so both directions matter across a full cycle.

3. The function of a purge unit on a low-pressure chiller is to:

  1. Circulate oil through the compressor
  2. Add refrigerant automatically when the charge is low
  3. Remove air and moisture that have leaked into the machine, with minimal refrigerant loss
  4. Regulate condenser water flow
Answer: C — Remove air and moisture that have leaked into the machine, with minimal refrigerant loss
Non-condensables raise condensing pressure and cut capacity, so the purge separates them from refrigerant vapor and discharges them. High-efficiency purges lose only a fraction of the refrigerant that older units did, which is why replacing an aging purge is often the single highest-return emissions fix on a chiller.

4. A purge unit that is running far more often than normal indicates:

  1. The chiller is operating efficiently
  2. The refrigerant charge is too high
  3. The condenser water is too cold
  4. The machine has a leak allowing air into the system
Answer: D — The machine has a leak allowing air into the system
Purge runtime is the best leak indicator a low-pressure machine gives you — more air coming in means more purging. Tracking purge hours over time is standard practice, and a sudden increase should trigger a leak search rather than a bigger purge.

5. When pressurizing a low-pressure chiller for leak testing, pressure must never exceed:

  1. 5 psig
  2. 10 psig
  3. 25 psig
  4. 50 psig
Answer: B — 10 psig
Ten psig is the ceiling, because the rupture disc on a low-pressure machine is typically set at 15 psig and blowing it releases the entire charge to atmosphere. This limit is the single most-tested fact in Type III.

6. The rupture disc on a low-pressure chiller is typically rated at:

  1. 10 psig
  2. 15 psig
  3. 30 psig
  4. 150 psig
Answer: B — 15 psig
Fifteen psig is the standard setting, which is why the leak-test ceiling is 10 psig — a deliberate margin. The disc protects a vessel that was never designed for meaningful positive pressure, so treating it as a safety limit rather than a target is the whole point.

7. Which gas may be used to raise the pressure in a low-pressure chiller for leak testing?

  1. Dry nitrogen, regulated and limited to 10 psig
  2. Compressed air from a shop compressor
  3. Oxygen
  4. Carbon dioxide
Answer: A — Dry nitrogen, regulated and limited to 10 psig
Dry nitrogen through a regulator is the only acceptable choice, and the 10 psig limit still applies. Oxygen is an explosion hazard with oil, and shop air carries moisture into a machine where water contamination is a serious and expensive problem.

8. The required evacuation level for a low-pressure appliance before opening it for service is:

  1. 10 inches of mercury
  2. 25 mm of mercury absolute
  3. 15 inches of mercury
  4. 500 microns
Answer: B — 25 mm of mercury absolute
Twenty-five millimeters of mercury absolute — about 25,000 microns — is the low-pressure requirement, and it applies to equipment on both sides of the November 1993 manufacture date under the current table. The inches-of-mercury figures belong to high-pressure appliances.

9. During refrigerant recovery from a low-pressure chiller, the greatest risk to the machine is:

  1. Overheating the compressor motor
  2. Contaminating the oil
  3. Freezing water in the evaporator or condenser tubes and rupturing them
  4. Overfilling the recovery cylinder with vapor
Answer: C — Freezing water in the evaporator or condenser tubes and rupturing them
Pulling the machine into a deep vacuum lowers the refrigerant's saturation temperature and can drive tube-side water below freezing, splitting tubes. Standard practice is to drain or circulate the water, and to monitor temperature so the vessel stays above 32°F throughout recovery.

10. The recommended sequence when recovering a full charge from a low-pressure chiller is to:

  1. Recover vapor first, then liquid
  2. Heat the charge to 125°F before recovery
  3. Recover only vapor and leave the liquid
  4. Recover liquid first, then finish with vapor
Answer: D — Recover liquid first, then finish with vapor
Liquid moves far more refrigerant per minute, so taking the liquid first gets the bulk out quickly and leaves only the vapor tail for the slow part of the job. Heating the charge to 125°F is a cylinder-storage limit, not a recovery technique, and would be dangerous here.

11. To leak-test a low-pressure chiller that is under a vacuum, a technician can:

  1. Raise the pressure with controlled heat or regulated nitrogen to no more than 10 psig, then test
  2. Apply soap bubbles to the exterior while the machine is in a vacuum
  3. Pressurize to 50 psig with nitrogen for a clearer signal
  4. Run the machine at full load and listen
Answer: A — Raise the pressure with controlled heat or regulated nitrogen to no more than 10 psig, then test
A leak under vacuum draws air in, so bubbles will not form and an electronic detector has nothing to sniff. Raising pressure — using controlled warm water through the tubes or regulated nitrogen — makes the leak detectable, always staying below the 10 psig ceiling.

12. ASHRAE Standard 15 requires a machine room containing a chiller to have:

  1. A fire sprinkler above the compressor only
  2. A refrigerant monitor and alarm with mechanical ventilation
  3. A dedicated water supply
  4. No special provisions if the chiller is under 100 tons
Answer: B — A refrigerant monitor and alarm with mechanical ventilation
A refrigerant vapor detector, an alarm, and mechanical ventilation are the core requirements, because refrigerant is heavier than air and a release in an enclosed room is an oxygen-displacement hazard. Self-contained breathing apparatus should be available outside the room, not inside it.

13. R-123 has a much lower allowable exposure limit than R-11, which means a technician should:

  1. Use R-123 only outdoors
  2. Ignore the difference, since both are non-toxic
  3. Treat R-123 exposure more seriously and rely on monitors and ventilation
  4. Wear a dust mask when working near R-123
Answer: C — Treat R-123 exposure more seriously and rely on monitors and ventilation
R-123 carries a substantially lower occupational exposure limit than R-11, so the same concentration that would be tolerable with R-11 is not with R-123. Monitors, ventilation, and — for entry into a high-concentration area — supplied-air respiratory protection are the answer. A dust mask does nothing against vapor.

14. Water in the tubes of a low-pressure chiller is most likely to enter the refrigerant circuit through:

  1. The purge unit discharge
  2. The rupture disc
  3. The oil sump vent
  4. A tube leak in the evaporator or condenser bundle, drawn in by the vacuum
Answer: D — A tube leak in the evaporator or condenser bundle, drawn in by the vacuum
The tube bundle carries water on one side and refrigerant under vacuum on the other, so a tube failure pulls water straight into the charge. Water contamination is expensive to correct — it requires recovery, drying, and often reclamation of the entire charge — which is why tube-side leak testing is a routine part of chiller service.

15. When recovering refrigerant from a low-pressure chiller, the recovery machine should be sized so that:

  1. It can complete recovery quickly enough that the vessel does not cool toward freezing
  2. It runs as slowly as possible
  3. It matches the chiller compressor horsepower exactly
  4. It can also serve as the purge unit
Answer: A — It can complete recovery quickly enough that the vessel does not cool toward freezing
A large charge and an undersized machine means hours of recovery during which the vessel steadily cools — the freeze risk again. Type III recovery machines are sized for the charge and often used with the chiller's own heat source or circulating water to keep temperature up.

16. When adding refrigerant to a low-pressure chiller that is in a deep vacuum, refrigerant should be introduced:

  1. As liquid into the evaporator immediately
  2. As vapor until the pressure and temperature rise above freezing, then as liquid
  3. As vapor only, for the entire charge
  4. Through the purge unit
Answer: B — As vapor until the pressure and temperature rise above freezing, then as liquid
Charging liquid into a machine under a deep vacuum causes it to flash violently and can freeze the tubes. Bringing the pressure up with vapor first raises the saturation temperature above freezing; once the machine is safely above 32°F, the remainder can go in as liquid.

17. Purge unit efficiency is usually expressed as:

  1. The pounds of air removed per hour
  2. The horsepower of the purge compressor
  3. The amount of refrigerant lost per pound of air purged
  4. The percentage of runtime
Answer: C — The amount of refrigerant lost per pound of air purged
A purge must discharge non-condensables, and the question is how much refrigerant goes out with them. Older units lost several pounds of refrigerant per pound of air; modern high-efficiency purges lose a small fraction of that, which is both an emissions and a cost argument for upgrading.

18. Which refrigerant is used in low-pressure centrifugal chillers?

  1. R-410A
  2. R-134a
  3. R-404A
  4. R-123
Answer: D — R-123
R-123 is the classic low-pressure chiller refrigerant, succeeding R-11, with R-514A appearing in newer machines. R-134a is used in medium-pressure centrifugals, which fall under Type II — a distinction worth knowing before you show up to a chiller job with the wrong certification.

19. Before entering a machine room where a large refrigerant release is suspected, a technician should:

  1. Ventilate the space and use self-contained breathing apparatus if the concentration is unknown
  2. Enter quickly and hold their breath
  3. Open a window and wait five minutes
  4. Enter with a colleague watching from the doorway
Answer: A — Ventilate the space and use self-contained breathing apparatus if the concentration is unknown
Refrigerant displaces oxygen and gives little warning before it impairs judgment. Ventilate first, monitor, and use supplied-air protection if the concentration is unknown — a filtering respirator will not help against oxygen deficiency, and holding your breath is how people are found unconscious at floor level.

20. A low-pressure chiller has been evacuated to the required level. Pressure then rises steadily with the recovery machine isolated. This indicates:

  1. The evacuation is complete and the machine is ready to open
  2. Refrigerant is still boiling out of the oil, or air is leaking in
  3. The rupture disc has failed
  4. The purge unit is operating correctly
Answer: B — Refrigerant is still boiling out of the oil, or air is leaking in
A rising vacuum means something is still adding to the pressure. Refrigerant coming out of solution in the oil is the benign explanation; an inward leak is the other, and both require action before the machine is opened. This is exactly why the rule expects the level to be reached and verified, not just briefly touched.

21. A ruptured disc on a low-pressure chiller should be:

  1. Patched and returned to service
  2. Replaced with a higher-rated disc to prevent recurrence
  3. Replaced with a disc of the correct rating, after determining why it ruptured
  4. Removed and the opening plugged
Answer: C — Replaced with a disc of the correct rating, after determining why it ruptured
A rupture disc is a one-time safety device and must be replaced with the correct rating — installing a higher-rated disc defeats the protection the vessel was designed around. Finding the cause matters just as much, since a disc rarely blows without a reason such as over-pressurization during service.

22. A standing vacuum test on a low-pressure chiller is used to:

  1. Measure the refrigerant charge
  2. Check condenser water flow
  3. Verify purge unit efficiency
  4. Determine whether the machine holds a vacuum, indicating it is leak-free and dry
Answer: D — Determine whether the machine holds a vacuum, indicating it is leak-free and dry
After evacuation, isolating the pump and watching the level over time distinguishes a tight, dry machine from one that leaks or still contains moisture. It is the same principle as the standing vacuum test on any system — it just matters more here, because a low-pressure machine spends its working life under vacuum.

23. Refrigerant recovered from a low-pressure chiller must be:

  1. Recovered into an approved container suitable for low-pressure refrigerant, never vented
  2. Recovered into a standard high-pressure DOT cylinder rated for R-410A
  3. Left in the machine and sealed
  4. Discharged into the machine room ventilation system
Answer: A — Recovered into an approved container suitable for low-pressure refrigerant, never vented
Low-pressure refrigerants are usually recovered into drums or tanks intended for them, since they sit below atmospheric pressure at room temperature. Whatever the container, the venting prohibition applies to R-123 and R-11 exactly as it does to any other refrigerant.

24. Compared with a high-pressure system of equal capacity, a low-pressure chiller typically:

  1. Holds a much smaller refrigerant charge
  2. Holds a much larger refrigerant charge, so a release is proportionally more significant
  3. Requires no leak monitoring
  4. Operates entirely above atmospheric pressure
Answer: B — Holds a much larger refrigerant charge, so a release is proportionally more significant
Large centrifugal machines hold hundreds or thousands of pounds, which is why they sit well above the 50-pound threshold for leak repair requirements and why a single incident matters. It is also why purge efficiency, tube integrity, and careful recovery practice carry real financial weight on this equipment.

25. Non-condensables accumulating in a low-pressure chiller will:

  1. Lower condensing pressure and improve efficiency
  2. Have no effect until the charge is low
  3. Raise condensing pressure, reduce capacity, and increase energy use
  4. Cause the evaporator to flood
Answer: C — Raise condensing pressure, reduce capacity, and increase energy use
Air occupies condenser volume and adds its own partial pressure, so the compressor works against a higher head for the same cooling. On a large centrifugal that shows up directly on the electric bill, which is why purge runtime is tracked as an operating metric and not just a maintenance detail.

26. Self-contained breathing apparatus for a chiller machine room should be stored:

  1. Inside the machine room next to the chiller
  2. In the service technician’s vehicle only
  3. In the building lobby
  4. Outside the machine room, where it can be reached without entering a contaminated space
Answer: D — Outside the machine room, where it can be reached without entering a contaminated space
Equipment you have to enter the hazard to retrieve is not protection. Storing it immediately outside the room means a technician can gear up before entry, which is the entire scenario the requirement exists for.

27. Before recovering the charge from a low-pressure chiller, condenser and chilled-water circuits should be:

  1. Drained, or kept circulating warm water, to prevent tubes from freezing as the vessel cools
  2. Left full and static
  3. Pressurized to 50 psig
  4. Isolated and vented to atmosphere
Answer: A — Drained, or kept circulating warm water, to prevent tubes from freezing as the vessel cools
Static water in the tubes is exactly what freezes when the refrigerant side is pulled into a deep vacuum. Draining removes the risk; circulating water keeps the bundle above freezing while recovery proceeds. Either is acceptable, doing neither is how tube bundles split.

28. Oil in a low-pressure chiller is typically:

  1. Circulated with the refrigerant throughout the system
  2. Contained in a separate sump serving the compressor bearings and gears, largely isolated from the refrigerant circuit
  3. Not used at all
  4. Injected into the evaporator to improve heat transfer
Answer: B — Contained in a separate sump serving the compressor bearings and gears, largely isolated from the refrigerant circuit
Centrifugal machines lubricate bearings and the gear train from a dedicated sump rather than relying on oil circulating with the refrigerant, as a reciprocating system does. Oil analysis on that sump is a standard predictive-maintenance tool and often the earliest warning of moisture or acid in the machine.

29. A low-pressure chiller loses vacuum overnight after evacuation. The technician should first:

  1. Charge refrigerant and return the machine to service
  2. Replace the rupture disc
  3. Determine whether the rise is from a leak or from moisture still boiling, then locate and repair any leak
  4. Raise the pressure to 25 psig and listen
Answer: C — Determine whether the rise is from a leak or from moisture still boiling, then locate and repair any leak
A vacuum that rises and then stabilizes near a value consistent with water vapor points to remaining moisture; one that keeps climbing toward atmospheric points to a leak. Charging over either problem guarantees a repeat failure, and 25 psig would exceed the 10 psig ceiling and risk the rupture disc.

30. Refrigerant added to a low-pressure chiller should be:

  1. Any refrigerant of similar boiling point that is available
  2. Added only while the machine is running at full load
  3. Mixed with nitrogen to raise pressure
  4. The refrigerant specified by the manufacturer, since substituting changes capacity, materials compatibility, and safety classification
Answer: D — The refrigerant specified by the manufacturer, since substituting changes capacity, materials compatibility, and safety classification
Low-pressure machines are engineered around a specific refrigerant — impeller design, materials, seals, and the safety classification of the machine room all follow from it. Substituting is not a field decision, and mixing refrigerants makes the entire large charge unreclaimable.
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FAQ
EPA 608 Type III Questions
How many questions are on the EPA 608 Type III exam?
The Type III section is 25 multiple-choice questions. 25 multiple-choice questions taken with Core, proctored and open-book, 70% to pass. Fewer technicians hold Type III than any other, which is exactly why chiller work pays.
What score do I need to pass EPA 608 Type III?
You need 70% — 18 of 25 questions — to pass. Each section is scored independently, so passing Core does not offset a failing Type III score, and you must pass both to be certified for type iii work.
Who needs EPA 608 Type III certification?
Technicians and building engineers who work on large centrifugal chillers using R-11, R-123, or R-514A. Low-pressure appliances — centrifugal chillers operating below atmospheric pressure.
Is this practice test the real EPA 608 exam?
No. This is free study material written from the published rule in 40 CFR Part 82, Subpart F — it does not reproduce exam content. The real exam is proctored and administered by an EPA-approved certifying organization, and it is open-book, so bring your study guide.
Does EPA 608 Type III certification expire?
No. Section 608 certification is issued for life under the current rule. There is no renewal requirement and no continuing education, though you must keep proof of certification at your place of business.
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