HVAC-R MIDTERM REVIEW
Temperature - Answers- Level of heat
Sensible heat - Answers- Causes rise in temperature
Heat flow - Answers- From warm to cold
Temperature scales - Answers- Fahrenheit, Rankine, Celsius, & Kelvin
BTU - Answers- Raises 1lb. of water by 1 degree
Latent heat - Answers- Causes change of state
Bourdon tube - Answers- Measures pressure above & below atmospheric pressure
Convection - Answers- Heat transferred by moving a medium such as air or water
Superheat - Answers- Difference between actual temperature and saturation
temperature
Refrigeration capacity - Answers- 1 ton removes 12,000 BTUs in 1 hour
Subcooling temperature - Answers- Difference between condensing pressure and liquid
line temperature
Metering device - Answers- Controls the flow of refrigerant
ACR lines insulation - Answers- Prevents condensation
ACR tubing grade - Answers- L (Capped & Dry)
Thermometers - Answers- Single or multiprobe instruments
Insulation - Answers- Should be on the low pressure/suction side of the system
Soft copper tubing lengths - Answers- 25' & 50' ft. rolls
Air oxyacetylene torch - Answers- Used for brazing and cutting
Size ½ inch in plumbing - Answers- Refers to ID (inside diameter)
Evaporator superheat - Answers- 13 degrees on an R22 system with 76 PSIG suction
and evaporator outlet temp of 58 degrees
Refrigeration system contamination - Answers- Air/non-condensable matter
, Solder for moderate pressures & temps - Answers- 50/50 tin-lead
Brazing temperature - Answers- Higher temperature than soldering
Brazing filler material - Answers- 15% - 60% silver
Steel pipes usage - Answers- For gas lines and water lines
Vacuum pumps - Answers- Remove air
Evaporator - Answers- Absorbs heat
Compressor - Answers- Moves refrigerant from low to high side
Ice melts in an ice box, why? - Answers- Absorbs heat from door opening & food placed
inside
R-12 can - Answers- White
R-22 can - Answers- Green
Subcooled liquid - Answers- Temperature drop after 100% condensing
Where does the heat in a condenser go on an air cooled unit? - Answers- Goes to the
air
Heat dissipation in water-cooled condenser - Answers- Goes to the water
Circulating fluid in a refrigeration system - Answers- Refrigerants & oil
Best vacuum pumps - Answers- 2 stage pumps
Most common/accurate vacuum gauge - Answers- Micron gauge
Gas for system sweeping - Answers- Nitrogen
Large evacuation hoses - Answers- Increase evacuation rate
Ozone location - Answers- Stratosphere
Refrigerant with zero ODP - Answers- HFC's
CFC's vs HCFC's - Answers- CFC's are more harmful due to chlorine
Greenhouse effect - Answers- Leads to global warming
Temperature - Answers- Level of heat
Sensible heat - Answers- Causes rise in temperature
Heat flow - Answers- From warm to cold
Temperature scales - Answers- Fahrenheit, Rankine, Celsius, & Kelvin
BTU - Answers- Raises 1lb. of water by 1 degree
Latent heat - Answers- Causes change of state
Bourdon tube - Answers- Measures pressure above & below atmospheric pressure
Convection - Answers- Heat transferred by moving a medium such as air or water
Superheat - Answers- Difference between actual temperature and saturation
temperature
Refrigeration capacity - Answers- 1 ton removes 12,000 BTUs in 1 hour
Subcooling temperature - Answers- Difference between condensing pressure and liquid
line temperature
Metering device - Answers- Controls the flow of refrigerant
ACR lines insulation - Answers- Prevents condensation
ACR tubing grade - Answers- L (Capped & Dry)
Thermometers - Answers- Single or multiprobe instruments
Insulation - Answers- Should be on the low pressure/suction side of the system
Soft copper tubing lengths - Answers- 25' & 50' ft. rolls
Air oxyacetylene torch - Answers- Used for brazing and cutting
Size ½ inch in plumbing - Answers- Refers to ID (inside diameter)
Evaporator superheat - Answers- 13 degrees on an R22 system with 76 PSIG suction
and evaporator outlet temp of 58 degrees
Refrigeration system contamination - Answers- Air/non-condensable matter
, Solder for moderate pressures & temps - Answers- 50/50 tin-lead
Brazing temperature - Answers- Higher temperature than soldering
Brazing filler material - Answers- 15% - 60% silver
Steel pipes usage - Answers- For gas lines and water lines
Vacuum pumps - Answers- Remove air
Evaporator - Answers- Absorbs heat
Compressor - Answers- Moves refrigerant from low to high side
Ice melts in an ice box, why? - Answers- Absorbs heat from door opening & food placed
inside
R-12 can - Answers- White
R-22 can - Answers- Green
Subcooled liquid - Answers- Temperature drop after 100% condensing
Where does the heat in a condenser go on an air cooled unit? - Answers- Goes to the
air
Heat dissipation in water-cooled condenser - Answers- Goes to the water
Circulating fluid in a refrigeration system - Answers- Refrigerants & oil
Best vacuum pumps - Answers- 2 stage pumps
Most common/accurate vacuum gauge - Answers- Micron gauge
Gas for system sweeping - Answers- Nitrogen
Large evacuation hoses - Answers- Increase evacuation rate
Ozone location - Answers- Stratosphere
Refrigerant with zero ODP - Answers- HFC's
CFC's vs HCFC's - Answers- CFC's are more harmful due to chlorine
Greenhouse effect - Answers- Leads to global warming
