HVAC EPA 608 Certification Study Guide
Questions & Answers
1.Are there drop-in replacements for R-12 systems? Why or why not?
Answer No because the new refrigerants are incompatible with the oils
and lubricants used in R-12 systems.
2.What type of oil is used in R-134a and what oils will it mix with?
Answer Ester based oils and they do not mix with other oils
3.What type of lubricant is used with HCFCs?
Answer Alkylbenzene lubricant
4.What is difference b/w ternary blend a azeotropic blend?
Answer Ternary blends are three-part mixtures whereas azeotropic
blends are blends of two or more compounds that act like a single
compound.
5.What is the trait of a hygroscopic lubricant?
Answer It absorbs (takes on) moisture
6.What is temperature glide and what type of blend won't have it?
Answer Temp. blend is the difference between the dew point and the
bubble point
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,7.Dew Point
Answer Occurs when saturation temp in evaporator causes
refrigerant to change from liquid to vapor
8.Bubble Point
Answer Occurs when saturation temp in condenser changes
refrigerant from vapor to liquid
9.Will the gases in a ternary blend leak at the same rate? Why or why not?
Answer No because different refrigerants in blend have different vapor
pressures, causing them to leak at uneven rates
10.Refrigeration Process
Answer transfer of heat from one place to another
11.Evaporator
Answer 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
12.Compressor
Answer Takes low pressure, low temp vapor and changes it to a
high-temp, high-pressure, superheated vapor and delivers it to the
condenser
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, 13.Condenser
Answer Rejects heat from system and changes refrigerant from high-
temp, high-pressure vapor into high-pressure, high-temp liquid
14.Metering Device
Answer reduces pressure of refrigerant and changes the high-pres-
sure, high-temp liquid into low pressure, low temp liquid.
15.Compound Gauge
Answer Typically blue and measures low pressure (psig) and vac- uum
(inHg).
16.High Pressure Gauge
Answer Red and measures high side (discharge) pressure. 0 to 500 psi
17.What does a compressor compress?
Answer Vapor
18.Why will refrigerant migrate to the crankcase in a compressor?
Answer Because of the vapor pressure difference between refrigerant
and oil
19.What color is the high pressure gauge?
Answer Red
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Questions & Answers
1.Are there drop-in replacements for R-12 systems? Why or why not?
Answer No because the new refrigerants are incompatible with the oils
and lubricants used in R-12 systems.
2.What type of oil is used in R-134a and what oils will it mix with?
Answer Ester based oils and they do not mix with other oils
3.What type of lubricant is used with HCFCs?
Answer Alkylbenzene lubricant
4.What is difference b/w ternary blend a azeotropic blend?
Answer Ternary blends are three-part mixtures whereas azeotropic
blends are blends of two or more compounds that act like a single
compound.
5.What is the trait of a hygroscopic lubricant?
Answer It absorbs (takes on) moisture
6.What is temperature glide and what type of blend won't have it?
Answer Temp. blend is the difference between the dew point and the
bubble point
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18
,7.Dew Point
Answer Occurs when saturation temp in evaporator causes
refrigerant to change from liquid to vapor
8.Bubble Point
Answer Occurs when saturation temp in condenser changes
refrigerant from vapor to liquid
9.Will the gases in a ternary blend leak at the same rate? Why or why not?
Answer No because different refrigerants in blend have different vapor
pressures, causing them to leak at uneven rates
10.Refrigeration Process
Answer transfer of heat from one place to another
11.Evaporator
Answer 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
12.Compressor
Answer Takes low pressure, low temp vapor and changes it to a
high-temp, high-pressure, superheated vapor and delivers it to the
condenser
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, 13.Condenser
Answer Rejects heat from system and changes refrigerant from high-
temp, high-pressure vapor into high-pressure, high-temp liquid
14.Metering Device
Answer reduces pressure of refrigerant and changes the high-pres-
sure, high-temp liquid into low pressure, low temp liquid.
15.Compound Gauge
Answer Typically blue and measures low pressure (psig) and vac- uum
(inHg).
16.High Pressure Gauge
Answer Red and measures high side (discharge) pressure. 0 to 500 psi
17.What does a compressor compress?
Answer Vapor
18.Why will refrigerant migrate to the crankcase in a compressor?
Answer Because of the vapor pressure difference between refrigerant
and oil
19.What color is the high pressure gauge?
Answer Red
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