Questions And Answers
Conduction is defined as heat energy that is - Correct Answer - moving through a solid substance
What is the primary purpose of a refrigeration system ? - Correct Answer - achieve and maintain a
temperature
What is a hazard of trapping liquid ? - Correct Answer - A possible release
How much can the pressure of trapped liquid increase per degree Fahrenheit of temperature increase -
Correct Answer - 100 to 150 psi
Mechanical refrigeration is a series of steps that - Correct Answer - moves heat energy from a space or
object to an area where it can do no harm
How does the refrigeration compressor maintain the temperature in the system evaporators ? - Correct
Answer - Drawing out vaporized refrigerant at a rate to maintain the desired evaporating pressure
Which natural refrigerant is considered to be non- flammable - Correct Answer - Carbon Dioxide
Heat energy always flows - Correct Answer - from an object at a higher temperature to an object at a
lower temperature
32 psia equals - Correct Answer - 17.3 psig
0 ° F is equal to - Correct Answer - -18 ° C
Why does the refrigerant in the condenser change state from vapor to liquid - Correct Answer - The
refrigerant loses heat energy to the surrounding environment
If a liquid is below its saturation temperature what is its condition ? - Correct Answer - Subcooled
What are the four necessary components of a mechanical refrigeration system ? - Correct Answer -
expansion device , evaporator , compressor , condenser
Superheat is found at which points of a typical system ? - Correct Answer - The compressor suction and
compressor discharge line
What are the replacement blended refrigerants called ? - Correct Answer - An azeotrope or zeotrope
https://www.stuvia.com/user/DREAMS
, What is one positive characteristic of halocarbon refrigerants ? - Correct Answer - They are usually not
flammable
What is the primary reason for concern about HCFC- 22 concentration in an engine room ? - Correct
Answer - Oxygen deprivation
O psig is equal to - Correct Answer - 14.7 psia
Discharge vapor from all compressors - Correct Answer - will contain some level of superheat
Which category of compressor " traps " a volume of refrigerant vapor prior to compression ? - Correct
Answer - Positive displacement
When suction pressure rises , the operator should - Correct Answer - start another compressor
The crankcase oil heater should be ON - Correct Answer - when the compressor is off .
Slugging is caused by - Correct Answer - oil or liquid refrigerant
What should be done if liquid refrigerant appears while draining oil ? - Correct Answer - Do what the
SOP states
Proper oil management for a refrigeration system requires that - Correct Answer - a log should record
all oil added to and removed from a system
When heat is added to saturated liquid refrigerant it will always - Correct Answer - evaporate
What effect does the addition of fins to evaporator coils have ? - Correct Answer - It increases the
efficiency of a unit by increasing the surface area
During hot gas defrost - Correct Answer - high pressure gas flows through and condenses in the
evaporator
Evaporative condensers - Correct Answer - derive their heat rejection capability from the evaporation of
water
Air cooled condensers usually have - Correct Answer - higher head pressures than evaporative
condensers
What are the two types high pressure receivers based on how liquid flows into them ? - Correct Answer
- Surge and through type
It is good practice to only fill a vessel how full with liquid ? - Correct Answer - 80 %
Bottling is defined as - Correct Answer - refrigerant held in the condenser due to the pressure difference
at the outlet of the condenser caused by active and inactive condenser circuits
https://www.stuvia.com/user/DREAMS