HVAC: EPA 608 CERTIFICATION STUDY GUIDE Questions with
Correct Solutions
Question:
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.
Question:
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
Question:
3. What type of lubricant is used with HCFCs?
Answer:
Alkylbenzene lubricant
Question:
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.
Question:
5. What is the trait of a hygroscopic lubricant?
Answer:
It absorbs (takes on) moisture
Question:
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
Question:
7. Dew Point
,Answer:
Occurs when saturation temp in evaporator causes refrigerant to change from liquid to vapor
Question:
8. Bubble Point
Answer:
Occurs when saturation temp in condenser changes refrigerant from vapor to liquid
Question:
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
Question:
10. Refrigeration Process
Answer:
transfer of heat from one place to another
Question:
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
Question:
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
Question:
13. Condenser
Answer:
Rejects heat from system and changes refrigerant from high-temp, high-pressure vapor into
high-pressure, high-temp liquid
Question:
14. Metering Device
, Answer:
reduces pressure of refrigerant and changes the high-pressure, high-temp liquid into low
pressure, low temp liquid.
Question:
15. Compound Gauge
Answer:
Typically blue and measures low pressure (psig) and vacuum (inHg).
Question:
16. High Pressure Gauge
Answer:
Red and measures high side (discharge) pressure. 0 to 500 psi
Question:
17. What does a compressor compress?
Answer:
Vapor
Question:
18. Why will refrigerant migrate to the crankcase in a compressor?
Answer:
Because of the vapor pressure difference between refrigerant and oil
Question:
19. What color is the high pressure gauge?
Answer:
Red
Question:
20. What color is the low pressure gauge?
Answer:
Blue
Question:
21. What needs to happen if oil has been contaminated by burnout?
Answer:
Triple evacuate system, install permanent filter-drier, conduct deep vacuum before
recharging
Correct Solutions
Question:
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.
Question:
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
Question:
3. What type of lubricant is used with HCFCs?
Answer:
Alkylbenzene lubricant
Question:
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.
Question:
5. What is the trait of a hygroscopic lubricant?
Answer:
It absorbs (takes on) moisture
Question:
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
Question:
7. Dew Point
,Answer:
Occurs when saturation temp in evaporator causes refrigerant to change from liquid to vapor
Question:
8. Bubble Point
Answer:
Occurs when saturation temp in condenser changes refrigerant from vapor to liquid
Question:
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
Question:
10. Refrigeration Process
Answer:
transfer of heat from one place to another
Question:
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
Question:
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
Question:
13. Condenser
Answer:
Rejects heat from system and changes refrigerant from high-temp, high-pressure vapor into
high-pressure, high-temp liquid
Question:
14. Metering Device
, Answer:
reduces pressure of refrigerant and changes the high-pressure, high-temp liquid into low
pressure, low temp liquid.
Question:
15. Compound Gauge
Answer:
Typically blue and measures low pressure (psig) and vacuum (inHg).
Question:
16. High Pressure Gauge
Answer:
Red and measures high side (discharge) pressure. 0 to 500 psi
Question:
17. What does a compressor compress?
Answer:
Vapor
Question:
18. Why will refrigerant migrate to the crankcase in a compressor?
Answer:
Because of the vapor pressure difference between refrigerant and oil
Question:
19. What color is the high pressure gauge?
Answer:
Red
Question:
20. What color is the low pressure gauge?
Answer:
Blue
Question:
21. What needs to happen if oil has been contaminated by burnout?
Answer:
Triple evacuate system, install permanent filter-drier, conduct deep vacuum before
recharging
