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20 Type III — Low-Pressure Practice Questions & Answers

Every Type III — Low-Pressure practice question from the EPA 608 Certification Practice Test, with the correct answer and a short explanation.

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  1. 1. EPA Section 608 Type III certification authorizes a technician to service which kind of equipment?

    • A.Very high-pressure appliances using R-13
    • B.Motor-vehicle air conditioners using R-134a
    • C.High-pressure comfort air conditioners using R-22
    • D.Low-pressure centrifugal chillers using refrigerants such as R-11, R-123, and R-113✓ Answer

    Type III certification specifically covers low-pressure appliances—those using refrigerants that boil above 50 F at atmospheric pressure and operate partly under a vacuum, such as R-11, R-123, and R-113 centrifugal chillers.

    Source: 40 CFR 82.161 (Type III technician certification); 40 CFR 82.152 (definition of low-pressure appliance)Report a problem with this question

  2. 2. When recovering refrigerant, a low-pressure appliance must be evacuated to what level?

    • A.0 psig
    • B.4 inches Hg vacuum
    • C.10 inches Hg vacuum
    • D.25 mm Hg absolute✓ Answer

    The evacuation requirements table sets 25 mm Hg absolute for low-pressure appliances, and this level applies regardless of whether the recovery/recycling equipment was manufactured before or after November 15, 1993.

    Source: 40 CFR 82.156, Table (required levels of evacuation for appliances)Report a problem with this question

  3. 3. Why do air and moisture tend to leak INTO a low-pressure appliance rather than refrigerant leaking out?

    • A.The refrigerant chemically attracts water from outside
    • B.The refrigerant is heavier than air
    • C.Much of the system operates below atmospheric pressure (in a vacuum)✓ Answer
    • D.The compressor forces air backward through the seals

    Low-pressure refrigerants boil below atmospheric pressure at operating temperatures, so the low side sits in a vacuum; any breach therefore draws outside air and moisture inward instead of venting refrigerant.

    Source: 40 CFR 82.152 (low-pressure appliance definition); EPA Section 608 Type III programReport a problem with this question

  4. 4. What is the main hazard when moisture leaks into a low-pressure system?

    • A.Moisture makes the refrigerant flammable
    • B.Moisture combines with refrigerant and oil to form acids that corrode the system✓ Answer
    • C.Moisture instantly drops the system's electrical resistance to zero
    • D.Moisture raises the refrigerant's ozone depletion potential

    Water reacts with the refrigerant and lubricating oil to form acids, which corrode metal and break down the oil and motor insulation—one reason keeping a low-pressure machine leak-free and dry is critical.

    Source: EPA Section 608 Type III program; 40 CFR Part 82 Subpart FReport a problem with this question

  5. 5. Air (a non-condensable) trapped in a low-pressure chiller will:

    • A.Lower the head pressure below normal
    • B.Raise condenser pressure and reduce efficiency and cooling capacity✓ Answer
    • C.Improve heat transfer in the condenser
    • D.Have no effect because it condenses along with the refrigerant

    Non-condensable gases collect in the condenser and raise head pressure above normal, cutting efficiency and capacity; they must be removed by the purge unit.

    Source: EPA Section 608 Type III programReport a problem with this question

  6. 6. What is the purpose of the purge unit on a low-pressure chiller?

    • A.To remove non-condensables (mainly air) that leak into the machine✓ Answer
    • B.To add refrigerant to the machine automatically
    • C.To pressurize the machine for leak testing
    • D.To pump lubricating oil to the bearings

    Because a low-pressure machine runs in a vacuum and draws air in, the purge unit separates and removes accumulated non-condensables while minimizing the refrigerant lost in the process.

    Source: EPA Section 608 Type III programReport a problem with this question

  7. 7. If a low-pressure chiller's purge unit runs far more often than normal, this most likely indicates:

    • A.That the chilled water is too cold
    • B.An overcharge of refrigerant
    • C.A leak allowing air to enter the machine✓ Answer
    • D.That the rupture disk is set too high

    Frequent purging means large amounts of non-condensables are entering, which points to an air (and moisture) in-leak that must be located and repaired.

    Source: EPA Section 608 Type III programReport a problem with this question

  8. 8. When pressurizing a low-pressure appliance for leak testing, the pressure must NOT exceed:

    • A.150 psig
    • B.500 psig
    • C.235 psig
    • D.10 psig✓ Answer

    Low-pressure machines are fitted with a rupture disk commonly rated about 15 psig; keeping test pressure at or below 10 psig prevents bursting the disk and venting the charge.

    Source: EPA Section 608 Type III program (low-pressure leak-test pressure limit)Report a problem with this question

  9. 9. Why must you avoid pressurizing a low-pressure appliance above roughly 10 psig?

    • A.The refrigerant would become radioactive
    • B.The compressor would over-speed
    • C.The rupture disk (typically rated about 15 psig) could burst and release the charge✓ Answer
    • D.The refrigerant would freeze solid

    Low-pressure chillers use a low-set rupture disk as their pressure-relief device; exceeding its rating bursts the disk, venting refrigerant and forcing a disk replacement.

    Source: EPA Section 608 Type III programReport a problem with this question

  10. 10. On a low-pressure chiller, the rupture disk serves to:

    • A.Meter refrigerant into the evaporator
    • B.Indicate the oil level
    • C.Relieve excess internal pressure to protect the vessel✓ Answer
    • D.Purge non-condensables continuously

    The rupture disk is the pressure-relief device on low-pressure machines; it bursts to release dangerous overpressure and protect the vessel, since the machine normally operates at very low pressure.

    Source: EPA Section 608 Type III program; ASHRAE Standard 15Report a problem with this question

  11. 11. Why should compressed shop air or oxygen NOT be used to pressurize a low-pressure appliance for leak detection?

    • A.Air is itself a controlled refrigerant
    • B.Oxygen is illegal to store on site
    • C.It can introduce moisture and create a combustible or hazardous mixture with refrigerant and oil✓ Answer
    • D.It would make leak detection work too well

    Compressed air carries moisture (which forms acids), and air or oxygen combined with oil vapor under pressure can create a combustible mixture; dry nitrogen is used instead.

    Source: EPA Section 608 Type III program; ASHRAE safety guidanceReport a problem with this question

  12. 12. In a standing-vacuum (pressure-rise) test on a low-pressure machine, a rising pressure after the appliance is isolated indicates:

    • A.The purge unit has been switched off
    • B.The refrigerant is condensing normally
    • C.Air is leaking into the machine✓ Answer
    • D.The machine is fully charged

    With the machine evacuated and isolated, any pressure increase means outside air is leaking inward through a breach—consistent with how low-pressure systems fail.

    Source: EPA Section 608 Type III programReport a problem with this question

  13. 13. A leak in the condenser or evaporator tubes (the water side) of a low-pressure chiller is dangerous because:

    • A.Refrigerant will harmlessly flood the cooling tower
    • B.It raises the height of the ozone layer
    • C.Water can enter the refrigerant and form corrosive acids✓ Answer
    • D.It has no effect on the refrigerant

    A tube leak lets cooling water into the refrigerant circuit, where it reacts to form acids that corrode metal and degrade the oil and motor windings.

    Source: EPA Section 608 Type III programReport a problem with this question

  14. 14. EPA defines a 'low-pressure appliance' as one using a refrigerant that:

    • A.Boils above 50 F (10 C) at atmospheric pressure✓ Answer
    • B.Boils below -58 F at atmospheric pressure
    • C.Is always flammable
    • D.Contains no chlorine

    EPA classifies appliances by refrigerant boiling point; low-pressure refrigerants (R-11, R-113, R-123) boil above 50 F at atmospheric pressure, which is why their low side operates under a vacuum.

    Source: 40 CFR 82.152 (definitions of appliance pressure classes)Report a problem with this question

  15. 15. To open, service, or dispose of a low-pressure centrifugal chiller, a technician must hold at least:

    • A.Type I certification only
    • B.Type II certification only
    • C.EPA Section 608 Type III (or Universal) certification✓ Answer
    • D.No certification, because chillers are exempt

    Section 608 requires Type III certification to service or dispose of low-pressure appliances; a Universal certification (covering all types) also qualifies.

    Source: 40 CFR 82.161 (technician certification requirements)Report a problem with this question

  16. 16. Recovering refrigerant from a low-pressure appliance typically requires recovery equipment that can:

    • A.Pull the appliance down to a deep vacuum (25 mm Hg absolute)✓ Answer
    • B.Only reach 0 psig
    • C.Operate with no vacuum capability at all
    • D.Pressurize the appliance to 200 psig

    Because the required recovery level is 25 mm Hg absolute, recovery equipment for low-pressure machines must be able to pull a deep vacuum, unlike high-pressure recovery which only needs to reach 0 psig or a modest vacuum.

    Source: 40 CFR 82.156 (required levels of evacuation)Report a problem with this question

  17. 17. Why must a low-pressure appliance be raised above atmospheric pressure in order to find refrigerant leaks?

    • A.Leak detectors only work in direct sunlight
    • B.The regulations forbid vacuum testing
    • C.At its normal operating vacuum, refrigerant will not escape through a leak for a detector to sense✓ Answer
    • D.Refrigerant becomes invisible under vacuum

    Under vacuum, air is drawn inward rather than refrigerant pushed out, so a refrigerant detector finds nothing; positive pressure is needed to force refrigerant out through any leak.

    Source: EPA Section 608 Type III programReport a problem with this question

  18. 18. When using nitrogen to pressurize a low-pressure appliance, the technician must:

    • A.Use a pressure regulator (with relief valve) to keep pressure safely below the rupture disk rating✓ Answer
    • B.Fill until the rupture disk bursts to confirm the seal
    • C.Connect the nitrogen cylinder directly with no regulator
    • D.Apply the nitrogen at full cylinder pressure

    Nitrogen cylinders hold very high pressure, so a regulator with a relief valve is required to keep the appliance from being taken above about 10 psig, which would burst the rupture disk.

    Source: EPA Section 608 Type III program; ASHRAE Standard 15Report a problem with this question

  19. 19. The non-condensable gas that most commonly accumulates in a low-pressure chiller is:

    • A.Pure refrigerant vapor
    • B.Helium released by the purge unit
    • C.Air drawn in through leaks✓ Answer
    • D.Carbon dioxide from combustion

    Since the machine runs in a vacuum, atmospheric air leaks in and collects as non-condensables in the condenser, which is why the purge unit must remove it.

    Source: EPA Section 608 Type III programReport a problem with this question

  20. 20. Why is R-123 significant to Type III technicians?

    • A.It is a motor-vehicle air-conditioning refrigerant
    • B.It is a non-ozone-depleting hydrocarbon
    • C.It is a common low-pressure refrigerant used in centrifugal chillers in place of R-11✓ Answer
    • D.It is a very high-pressure refrigerant like R-13

    R-123 (an HCFC) is the principal low-pressure refrigerant used to replace CFC-11 (R-11) in centrifugal chillers, so servicing it falls under Type III certification.

    Source: 40 CFR 82.152 (low-pressure appliance refrigerant examples)Report a problem with this question

Practice questions modeled on the EPA Section 608 Technician Certification content (Clean Air Act §608; 40 CFR Part 82). Not affiliated with or endorsed by the U.S. Environmental Protection Agency or any approved certifying organization. Study the official EPA program materials before testing. Official EPA 608 →