HVAC: EPA 608 Certification Study
Guide Questions With Verified
Solutions| ALREADY PASSED.
UPDATED
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.
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
What type of lubricant is used with HCFCs? - ANSWER
Alkylbenzene lubricant
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.
What is the trait of a hygroscopic lubricant? - ANSWER It
absorbs (takes on) moisture
, 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
Dew Point - ANSWER Occurs when saturation temp in
evaporator causes refrigerant to change from liquid to
vapor
Bubble Point - ANSWER 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? - ANSWER No because different
refrigerants in blend have different vapor pressures,
causing them to leak at uneven rates
Refrigeration Process - ANSWER transfer of heat from
one place to another
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
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
Condenser - ANSWER Rejects heat from system and
changes refrigerant from high-temp, high-pressure vapor
into high-pressure, high-temp liquid
, Metering Device - ANSWER reduces pressure of
refrigerant and changes the high-pressure, high-temp
liquid into low pressure, low temp liquid.
Compound Gauge - ANSWER Typically blue and
measures low pressure (psig) and vacuum (inHg).
High Pressure Gauge - ANSWER Red and measures
high side (discharge) pressure. 0 to 500 psi
What does a compressor compress? - ANSWER Vapor
Why will refrigerant migrate to the crankcase in a
compressor? - ANSWER Because of the vapor pressure
difference between refrigerant and oil
What color is the high pressure gauge? - ANSWER Red
What color is the low pressure gauge? - ANSWER Blue
What needs to happen if oil has been contaminated by
burnout? - ANSWER Triple evacuate system, install
permanent filter-drier, conduct deep vacuum before
recharging
What are three Rs of refrigeration? - ANSWER Recover,
recycle, reclaim
Guide Questions With Verified
Solutions| ALREADY PASSED.
UPDATED
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.
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
What type of lubricant is used with HCFCs? - ANSWER
Alkylbenzene lubricant
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.
What is the trait of a hygroscopic lubricant? - ANSWER It
absorbs (takes on) moisture
, 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
Dew Point - ANSWER Occurs when saturation temp in
evaporator causes refrigerant to change from liquid to
vapor
Bubble Point - ANSWER 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? - ANSWER No because different
refrigerants in blend have different vapor pressures,
causing them to leak at uneven rates
Refrigeration Process - ANSWER transfer of heat from
one place to another
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
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
Condenser - ANSWER Rejects heat from system and
changes refrigerant from high-temp, high-pressure vapor
into high-pressure, high-temp liquid
, Metering Device - ANSWER reduces pressure of
refrigerant and changes the high-pressure, high-temp
liquid into low pressure, low temp liquid.
Compound Gauge - ANSWER Typically blue and
measures low pressure (psig) and vacuum (inHg).
High Pressure Gauge - ANSWER Red and measures
high side (discharge) pressure. 0 to 500 psi
What does a compressor compress? - ANSWER Vapor
Why will refrigerant migrate to the crankcase in a
compressor? - ANSWER Because of the vapor pressure
difference between refrigerant and oil
What color is the high pressure gauge? - ANSWER Red
What color is the low pressure gauge? - ANSWER Blue
What needs to happen if oil has been contaminated by
burnout? - ANSWER Triple evacuate system, install
permanent filter-drier, conduct deep vacuum before
recharging
What are three Rs of refrigeration? - ANSWER Recover,
recycle, reclaim
