EPA 608 HVAC Certification Exam
Refrigerants Practice Questions
25 practice questions with detailed explanations — aligned to the EPA 608 HVAC Certification Exam.
Q1.Which refrigerant is an HCFC (Hydrochlorofluorocarbon)?
A.R-134aB.R-410AC.R-22D.R-12C. R-22Explanation: R-22 is the most common HCFC refrigerant. R-12 is a CFC, while R-134a and R-410A are HFCs.
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Q2.What is the phase-out date for the production and import of virgin R-22 in the United States?
A.January 1, 2010B.January 1, 2015C.January 1, 2020D.January 1, 2030C. January 1, 2020Explanation: The production and import of virgin R-22 was completely phased out in the US on January 1, 2020. Only reclaimed or existing stocks can be used.
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Q3.Which refrigerant has a Global Warming Potential (GWP) significantly lower than R-410A and is being used as a replacement in new equipment?
A.R-22B.R-12C.R-32D.R-404AC. R-32Explanation: R-32 (an HFC) has a GWP of 675, significantly lower than R-410A (GWP 2088), making it a preferred choice for newer, lower-GWP systems.
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Q4.What type of lubricant is used with HFC refrigerants like R-134a and R-410A?
A.Mineral OilB.AlkylbenzeneC.Polyol Ester (POE)D.Castor OilC. Polyol Ester (POE)Explanation: Synthetic Polyol Ester (POE) oil is required for HFCs because mineral oil is not miscible (does not mix) with HFC refrigerants.
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Q5.R-410A is a blend of which two refrigerants?
A.R-22 and R-134aB.R-32 and R-125C.R-125 and R-143aD.R-32 and R-134aB. R-32 and R-125Explanation: R-410A is a 50/50 binary blend of R-32 and R-125.
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Q6.Which refrigerant is considered a 'Very High Pressure' refrigerant?
A.R-22B.R-134aC.R-503D.R-123C. R-503Explanation: R-503 (and R-13/R-23) are very high-pressure refrigerants used in low-temperature cascade systems.
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Q7.What is the ASHRAE safety classification for R-1234yf?
A.A1 (Non-flammable)B.A2L (Mildly Flammable)C.A3 (Highly Flammable)D.B1 (Toxic)B. A2L (Mildly Flammable)Explanation: R-1234yf is an A2L refrigerant, meaning it is non-toxic but mildly flammable.
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Q8.The term 'Azeotrope' refers to a refrigerant blend that:
A.Separates into component parts when leakingB.Behaves like a single component refrigerant with a constant boiling pointC.Has a high temperature glideD.Is highly flammableB. Behaves like a single component refrigerant with a constant boiling pointExplanation: Azeotropes (like R-500 or R-502) act as a single substance. They do not fractionate and have a negligible temperature glide.
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Q9.R-407C is often used as a retrofit for which refrigerant?
A.R-12B.R-22C.R-502D.R-11B. R-22Explanation: R-407C is a common HFC replacement for R-22 in air conditioning applications, though it requires an oil change to POE.
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Q10.What is the Ozone Depletion Potential (ODP) of HFC refrigerants like R-134a?
A.1.0B.0.5C.0.055D.0.0D. 0.0Explanation: HFCs (Hydrofluorocarbons) do not contain chlorine, so they have an ODP of zero.
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Q11.Which refrigerant has the highest Global Warming Potential (GWP) among common HFCs?
A.R-134aB.R-32C.R-404AD.R-410AC. R-404AExplanation: R-404A has a very high GWP of 3,922, making it a primary target for phase-down under recent regulations.
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Q12.Zeotropic blends (400-series refrigerants) can leak from a system at uneven rates due to different vapor pressures. This is called:
A.DistillationB.FractionationC.SeparationD.SublimationB. FractionationExplanation: Fractionation is the change in composition of a blend because one component boils off faster than another.
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Q13.What does the 'a' (lowercase) signify in R-134a?
A.It is an azeotropeB.It is an isomer (same chemical formula, different atomic structure)C.It contains ammoniaD.It is approved for automotive useB. It is an isomer (same chemical formula, different atomic structure)Explanation: The lowercase letter indicates an isomer—a molecule with the same chemical formula as R-134 but a different arrangement of atoms.
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Q14.Which class of refrigerants was the first to be phased out?
A.HCFCsB.HFCsC.CFCsD.HFOsC. CFCsExplanation: CFCs (like R-12) were the first to be phased out (production stopped in 1996 in developed countries) due to their high ODP.
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Q15.R-717 is the ASHRAE designation for:
A.Carbon DioxideB.AmmoniaC.PropaneD.WaterB. AmmoniaExplanation: R-717 is Ammonia, an efficient but toxic (Safety Class B2L) refrigerant used in industrial applications.
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Q16.Why is R-600a (Isobutane) becoming common in small household appliances?
A.It is non-flammableB.It has zero ODP and extremely low GWPC.It operates at very high pressureD.It mixes with mineral oilB. It has zero ODP and extremely low GWPExplanation: R-600a is an environmentally friendly hydrocarbon with negligible climate impact, though it is flammable (A3).
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Q17.Chlorine in the stratosphere converts ozone into:
A.NitrogenB.OxygenC.HydrogenD.Carbon MonoxideB. OxygenExplanation: The chlorine atom steals an oxygen atom from the ozone molecule (O3), converting it into standard oxygen (O2), which does not block UV rays.
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Q18.Which refrigerant is the standard high-pressure replacement for R-502 in commercial refrigeration?
A.R-134aB.R-404AC.R-123D.R-22B. R-404AExplanation: R-404A (or R-507) became the standard HFC replacement for R-502 in low/medium temp refrigeration, though it is now being phased down due to high GWP.
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Q19.What is the primary reason R-410A cannot be used in a system designed for R-22?
A.It is flammableB.It operates at pressures approximately 50-70% higher than R-22C.It is toxicD.It is too coldB. It operates at pressures approximately 50-70% higher than R-22Explanation: R-410A pressures are significantly higher. Putting it in an R-22 system would likely burst the components.
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Q20.If a system is charged with a zeotropic blend, what defines the 'Bubble Point'?
A.The temperature at which the first bubble of vapor forms in the liquid (used for subcooling)B.The temperature at which the last drop of liquid evaporatesC.The temperature at which the oil foamsD.The freezing pointA. The temperature at which the first bubble of vapor forms in the liquid (used for subcooling)Explanation: The bubble point is used to calculate subcooling for blends. It corresponds to the temperature where the liquid starts to boil.
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Q21.If a system is charged with a zeotropic blend, what defines the 'Dew Point'?
A.The temperature at which the first drop of liquid forms from vapor (used for superheat)B.The boiling pointC.The critical pointD.The triple pointA. The temperature at which the first drop of liquid forms from vapor (used for superheat)Explanation: The dew point is used to calculate superheat for blends. It corresponds to the vapor temperature where condensation begins.
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Q22.Which of the following refrigerants contains Chlorine?
A.R-134aB.R-410AC.R-123D.R-407CC. R-123Explanation: R-123 is an HCFC (HydroChlorofluorocarbon). It contains chlorine. The others are HFCs and do not.
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Q23.What color is the cylinder for R-22?
A.RoseB.Light BlueC.GreenD.OrangeC. GreenExplanation: Virgin R-22 cylinders are light green.
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Q24.What color is the cylinder for R-404A?
A.GreenB.OrangeC.RoseD.YellowB. OrangeExplanation: Virgin R-404A cylinders are orange.
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Q25.Propane cylinders used as a refrigerant (R-290) generally have:
A.A red band on the shoulderB.A green topC.A yellow bodyD.No specific markingA. A red band on the shoulderExplanation: Flammable refrigerant containers typically have a red band on the shoulder or top to indicate flammability danger.
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