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EPA 608 NEC 2023

EPA 608 Type 3 Exam Practice Test 2

Free EPA 608 Type III Exam Practice Test 2. 25 questions covering leak check pressure limits and rupture failure, air in low-pressure systems causing high head pressure, partial charge leak testing using external heat, rupture disk purpose, R-11 vacuum requirement before charging, compressor head pressure from incomplete evacuation, rupture disk opening pressure, purge unit contamination control, rupture disk location on evaporator, water circulation during evacuation, R-11 boiling point at atmospheric pressure, oil degas procedure, centrifugal vs reciprocating compressors, variable inlet guide vanes, 10 PSIG max recovery pressure, UV dye leak detection, filter drier replacement requirement, hot gas bypass surge prevention, chiller capacity range, R-245fa properties, rupture disk replacement procedure, comfort cooling leak threshold, two-phase recovery from low-pressure chillers, ASHRAE vacuum leak test, and EPA 608 certification requirements.

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The EPA 608 certification is required by law for any technician who purchases or handles refrigerants. It covers safe handling, leak detection, recovery, and environmental regulations.

Type I covers small appliances (≤5 lbs refrigerant), Type II covers high-pressure systems, Type III covers low-pressure systems, and Universal covers all three. Most HVAC technicians pursue Universal certification.

You must score at least 70% on each section of the exam. The Universal exam has four parts: core, Type I, Type II, and Type III.

Important Type III facts for this test: The maximum pressure for leak testing a low-pressure system is 10 PSIG — exceeding this risks bursting the rupture disk at 15 PSIG. Air entering a low-pressure system accumulates at the top of the condenser and causes high head pressure. A partial-charge low-pressure system can be leak-tested by raising the refrigerant pressure using an external heat source. When recharging an R-11 chiller, the system must first reach a vacuum of 16.9 in. Hg before charging liquid refrigerant.

25

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45 min

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70%

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EPA 608 Type 3 Exam Practice Test 2 — Question List

Question 1: In a low pressure system, if the maximum pressure setting exceeds during leak checking …………………….

Causes a rupture failure
Causes systems body failure
Increases the leak point

Question 2: If some amount of air exists in low pressure system …………….

Causes low head pressure
Causes high head pressure
Causes low suction pressure
Causes high suction pressure

Question 3: A partial charge low pressure system can be effectively leak checked by ……………

Compressed air
Pressurized liquid nitrogen
Adding high pressure HCFC-22 refrigerant
Increasing refrigerant pressure by adding external heat source.

Question 4: What is the purpose of rupture disks in low pressure chillers?

To relieve the pressure
To increase the pressure
To remove trapped moisture
To increase temperature in system

Question 5: When recharging refrigeration system with CFC-11, what vacuum is necessary in the shells before charging?

16.9 Hg vacuum
15.4 Hg vacuum
17 Hg Vacuum
14.7 Hg Vacuum

Question 6: What will happen if the refrigeration system is not evacuated fully?

Compressor head pressure rises
Moisture still remains in the system
Refrigerant vapour exists in the system
Evaporator coil may fail

Question 7: ………………. Is the Typical pressure for opening the rupture disk in the low pressure chillier

14 PSIG
15 PSIG
24 PSIG
12 PSIG

Question 8: What is the purpose of purge unit on chiller?

Minimizes the effects of contamination
Minimizes air leakage in to system
Purges the moisture and prevents it to enter in the system
Increases the efficiency of the system

Question 9: In a low pressure refrigeration system the rupture disk is connected to ………………..

Evaporator
Condenser
Receiver
Liquid pump

Question 10: The purpose of circulating water during the evacuation chiller refrigeration system is to …………..

Prevent the leakage of refrigerant to atmosphere
Prevent the freezing of water
Prevent the leakage of the air
Prevent freezing of refrigerant

Question 11: R-11 refrigerant has a boiling point of approximately 74.7°F at atmospheric pressure. Why does this property make R-11 useful in centrifugal chiller applications?

The high boiling point makes R-11 easier to condense in the condenser
R-11 boils just above room temperature, so at chiller operating temperatures it creates a vacuum in the evaporator — ideal for large centrifugal systems
R-11 boiling point has no relationship to operating pressure in the chiller
R-11 must be heated to 74.7°F before it can be used as a refrigerant

Question 12: Why must compressor oil be heated to 100°F before draining it from a low-pressure centrifugal chiller?

Hot oil flows faster — heating reduces viscosity so draining is quicker
Heating to 100°F drives dissolved refrigerant out of the oil before draining, minimizing refrigerant release
Cold oil damages drain fittings — heating prevents cracking of the oil pan
The 100°F requirement is for safety only — to prevent burns during the draining process

Question 13: Which statement correctly compares a centrifugal compressor to a reciprocating (piston) compressor?

Centrifugal compressors use pistons but are larger than reciprocating compressors
Centrifugal compressors use a rotating impeller with no pistons or valves, providing continuous flow at very large capacities
Centrifugal compressors are smaller and used only in residential equipment
Both centrifugal and reciprocating compressors operate the same way — only the refrigerant type differs

Question 14: How do variable inlet guide vanes (IGVs) prevent surge in a centrifugal chiller compressor at low load conditions?

IGVs inject oil into the impeller to lubricate it during low-load conditions when refrigerant flow is low
IGVs pre-spin refrigerant in the direction of impeller rotation, extending stable operation to lower loads and preventing surge
IGVs automatically slow the impeller speed when load decreases to match compressor output with demand
IGVs bypass excess refrigerant around the compressor to reduce the load on the impeller

Question 15: Why is 10 PSIG the maximum pressure allowed when recovering refrigerant from a low-pressure chiller evaporator?

10 PSIG is the rated working pressure of R-11 recovery cylinders
The rupture disk bursts at 15 PSIG — 10 PSIG provides a safety margin to prevent disk failure during recovery
Above 10 PSIG, R-11 condenses back to liquid and cannot be recovered as vapor
10 PSIG is the legal maximum for any EPA-regulated refrigerant service operation

Question 16: Why is UV dye injection a practical leak detection method for large R-123 centrifugal chillers?

UV dye is only used in automotive A/C — not suitable for commercial chillers
UV dye circulates with refrigerant and oil, showing up under UV light at leak points — useful in complex chiller systems with hard-to-reach components
UV dye reacts with R-123 to create a visible color change without needing a UV light
UV dye is injected directly into the condenser water circuit to detect tube leaks

Question 17: After opening a low-pressure centrifugal chiller for repair, what must be done to the filter drier before returning the system to service?

The filter drier does not need replacement unless it is visibly damaged
The filter drier must be replaced — whenever the system is opened, moisture enters and the desiccant must be renewed
The filter drier should be dried in an oven and reused to save cost
The filter drier only needs replacement if the moisture indicator sight glass turns yellow

Question 18: What is the purpose of a hot gas bypass valve on a centrifugal chiller?

Hot gas bypass pre-heats the chilled water to prevent freezing during low-load operation
Hot gas bypass recirculates discharge gas to the evaporator, creating artificial load to prevent surge at very low cooling demands
Hot gas bypass cools the compressor motor by directing discharge gas over the motor windings
Hot gas bypass is used to recover refrigerant during service — it routes gas directly to recovery cylinders

Question 19: What types of buildings and facilities typically use large low-pressure centrifugal chillers (R-11, R-123)?

Only small convenience stores — centrifugal chillers are compact units for walk-in coolers
Large commercial buildings, hospitals, universities, airports, and data centers requiring 100 to 2,000+ tons of cooling
Residential homes — centrifugal chillers replace split systems in custom luxury homes
Automobile manufacturing only — low-pressure refrigerants are used exclusively in industrial processes

Question 20: What ozone depletion potential (ODP) does R-245fa have, and why does this make it suitable as a long-term low-pressure refrigerant?

R-245fa has ODP = 1.0 — the same as R-11 — but lower GWP
R-245fa has ODP = 0 — as an HFC with no chlorine, it has no ozone depletion; not subject to Montreal Protocol restrictions
R-245fa has ODP = 0.02 — the same as R-123 — because both are HCFC refrigerants
R-245fa has ODP = 0 but is banned in the United States due to its high flammability

Question 21: What is the correct replacement disk pressure rating when replacing a burst rupture disk on a low-pressure centrifugal chiller?

Use the highest pressure rated disk available — stronger is always better for safety
The replacement disk must be the same 15 PSIG rating as the original — using a different pressure rating risks either premature bursting or overpressure failure
Any disk rated for 10 PSIG or higher is acceptable as a replacement
The burst disk can be repaired with epoxy and reused if the hole is small

Question 22: A 1,500 lb R-123 centrifugal chiller used for air conditioning a large office building leaks 250 lbs of refrigerant over one year. Does this trigger a mandatory repair requirement?

No — 250 lbs is well below the 35% threshold for large commercial systems
Yes — 250 lbs is 16.7% of 1,500 lbs, which exceeds the 15% comfort cooling threshold, requiring repair within 30 days
No — the threshold only applies to systems with more than 5,000 lbs of refrigerant
Yes, but the technician only needs to add refrigerant — there is no requirement to repair the leak

Question 23: When recovering refrigerant from a large low-pressure chiller, why is the recovery connection made at the evaporator (bottom), and where does the refrigerant vapor exit?

Connect at the top of the condenser — all refrigerant exits as vapor from the highest point
Connect at the evaporator charging valve (lowest point) for liquid; vapor exits from the top. Recover liquid first, then vapor
Connect anywhere — pressure equalizes throughout the system regardless of connection point
Connect at the purge unit — the purge unit is the only proper connection point for refrigerant recovery

Question 24: After pulling a vacuum on a low-pressure chiller, the vacuum gauge reads 1 mm Hg. Over 15 minutes, the pressure rises to 2.5 mm Hg. According to ASHRAE guidelines, what does this indicate?

The system passed — a 1.5 mm Hg rise is within acceptable limits for large chillers
The system has a leak — ASHRAE guidelines indicate a rise from 1 mm to 2.5 mm Hg requires leak-checking before recharging
The rise is caused by air expanding — this is normal and no action is needed
The vacuum pump is faulty — the system is tight but the gauge is giving a false reading

Question 25: An HVAC contractor sends an apprentice to assist with servicing a low-pressure centrifugal chiller. The apprentice has not yet passed the EPA 608 exam. What may the apprentice legally do?

The apprentice can do anything — certification is only required when working alone
The apprentice may perform non-refrigerant tasks; all refrigerant handling must be done by or directly supervised by the certified technician on-site
The apprentice cannot enter the chiller room at all without EPA certification
The apprentice can recover refrigerant as long as the certified technician signs the service ticket afterward

Study Tip: The EPA 608 exam is closed book. Memorize: recovery is required before opening any refrigerant system. Venting refrigerant is illegal. Know the ODP and GWP values for R-22, R-410A, R-134a, R-32, and R-454B.

EXAM CARD EPA 608

Questions25

Time limit45 min

Pass score70%

RegulationEPA Section 608

DifficultyIntermediate

Last reviewedJun 2026

Timer starts immediately. Progress is auto-saved.

Source: EPA Section 608 (40 CFR Part 82)