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HVAC: EPA 608 Certification Study
Guide Questions and Correct Answers/
Latest Update / Already Graded
Are there drop-in replacements for R-12 systems? Why or why not?
Ans: No because the new refrigerants are incompatible with the oils and
lubricants used in R-12 systems.
What type of oil is used in R-134a and what oils will it mix with?
Ans: Ester based oils and they do not mix with other oils
What type of lubricant is used with HCFCs?
Ans: Alkylbenzene lubricant
What is difference b/w ternary blend a azeotropic blend?
Ans: Ternary blends are three-part mixtures whereas azeotropic blends
are blends of two or more compounds that act like a single compound.
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What is the trait of a hygroscopic lubricant?
Ans: It absorbs (takes on) moisture
What is temperature glide and what type of blend won't have it?
Ans: Temp. blend is the difference between the dew point and the
bubble point
Dew Point
Ans: Occurs when saturation temp in evaporator causes refrigerant to
change from liquid to vapor
Bubble Point
Ans: Occurs when saturation temp in condenser changes refrigerant from
vapor to liquid
Will the gases in a ternary blend leak at the same rate? Why or why
not?
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Ans: No because different refrigerants in blend have different vapor
pressures, causing them to leak at uneven rates
Refrigeration Process
Ans: transfer of heat from one place to another
Evaporator
Ans: Absorbs heat into system from space to be cooled. Absorption of
heat causes refrigerant to boil. Upon leaving, refrigerant changed to low
pressure, low temperature vapor
Compressor
Ans: Takes low pressure, low temp vapor and changes it to a high-temp,
high-pressure, superheated vapor and delivers it to the condenser
Condenser
HVAC: EPA 608 Certification Study
Guide Questions and Correct Answers/
Latest Update / Already Graded
Are there drop-in replacements for R-12 systems? Why or why not?
Ans: No because the new refrigerants are incompatible with the oils and
lubricants used in R-12 systems.
What type of oil is used in R-134a and what oils will it mix with?
Ans: Ester based oils and they do not mix with other oils
What type of lubricant is used with HCFCs?
Ans: Alkylbenzene lubricant
What is difference b/w ternary blend a azeotropic blend?
Ans: Ternary blends are three-part mixtures whereas azeotropic blends
are blends of two or more compounds that act like a single compound.
,2 | Page
What is the trait of a hygroscopic lubricant?
Ans: It absorbs (takes on) moisture
What is temperature glide and what type of blend won't have it?
Ans: Temp. blend is the difference between the dew point and the
bubble point
Dew Point
Ans: Occurs when saturation temp in evaporator causes refrigerant to
change from liquid to vapor
Bubble Point
Ans: Occurs when saturation temp in condenser changes refrigerant from
vapor to liquid
Will the gases in a ternary blend leak at the same rate? Why or why
not?
, 3 | Page
Ans: No because different refrigerants in blend have different vapor
pressures, causing them to leak at uneven rates
Refrigeration Process
Ans: transfer of heat from one place to another
Evaporator
Ans: Absorbs heat into system from space to be cooled. Absorption of
heat causes refrigerant to boil. Upon leaving, refrigerant changed to low
pressure, low temperature vapor
Compressor
Ans: Takes low pressure, low temp vapor and changes it to a high-temp,
high-pressure, superheated vapor and delivers it to the condenser
Condenser
