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Ac432 Part 2

30 Questions
Electronic Quizzes & Trivia

AC432 part 2 practice

Questions and Answers
  • 1. 
    A refrigeration system is operating with a vapor charged thermostatic expansion valve. The thermal bulb is sensing a suction line temperature that is higher than the temperature that allows liquid to be present in the bulb. Any additional increases in the evaporator load will ____.
    • A. 

      Increase the bulb pressure and cause the thermostatic expansion valve to open

    • B. 

      Increase the evaporator pressure and cause the thermostatic expansion valve to close

    • C. 

      Decrease the spring pressure and cause the thermostatic expansion valve to open

    • D. 

      Have no effect on the position of the needle (pin) in the seat

  • 2. 
    If a thermostatic expansion valve's thermal bulb came loose from the suction line at the outlet of the evaporator, which of the following could result?
    • A. 

      The bulb pressure would increase and the thermostatic expansion valve would open.

    • B. 

      The superheat in the evaporator would decrease.

    • C. 

      Liquid refrigerant would flow back to the compressor.

    • D. 

      All of the above are correct.

  • 3. 
    If the thermal bulb assembly develops a leak, what will occur?
    • A. 

      All of the system's refrigerant will leak out.

    • B. 

      The bulb pressure will reduce and the valve will close.

    • C. 

      The valve will open to allow more refrigerant to flow.

    • D. 

      It will have no effect on system operation.

  • 4. 
    The purpose of an externally equalized thermostatic expansion valve is to ____.
    • A. 

      Compensate for excessive evaporator pressure drop

    • B. 

      Allow system to equalize faster

    • C. 

      Prevent the expansion valve from frosting up

    • D. 

      Allow refrigerant to expand in the compressor

  • 5. 
    The primary function of an expansion device is to ____.
    • A. 

      Produce a reduction in the pressure on the liquid refrigerant

    • B. 

      Regulate the flow of refrigerant into the evaporator

    • C. 

      Lower the boiling point of the refrigerant far enough below the temperature of the load to get the needed heat transfer rate

    • D. 

      All of the above

  • 6. 
    A thermostatic expansion valve controls refrigerant flow to the evaporator based on ____.
    • A. 

      Rate of liquid vaporization

    • B. 

      Evaporator suction line superheat

    • C. 

      External equalizer pressure

    • D. 

      All of the above

  • 7. 
    The purpose of a capillary tube is to ____.
    • A. 

      Regulate the refrigerant flow into the evaporator

    • B. 

      Lower the pressure of the liquid refrigerant

    • C. 

      Lower the boiling point of the refrigerant

    • D. 

      All of the above

  • 8. 
    The TXV sensing bulb is mounted ____.
    • A. 

      On the liquid line between the condenser and the TX valve

    • B. 

      At the inlet to the condenser

    • C. 

      On the suction line between the evaporator and the compressor

    • D. 

      On the compressor discharge line

  • 9. 
    • A. 

      Increases the flow of refrigerant

    • B. 

      Decreases the flow of refrigerant

    • C. 

      Maintains constant head pressure

    • D. 

      Decreases the pressure drop across the evaporator

  • 10. 
    The cross liquid charge bulb at the TXV contains fluid that ____.
    • A. 

      Has similar characteristics to the system fluid to prevent liquid refrigerant from entering the suction line

    • B. 

      Has different characteristics from the system fluid

    • C. 

      Causes the valve to stay open during the off cycle

    • D. 

      Follows the typical pressure-temperature relationship

  • 11. 
    Balanced port TX valves are used to ____.
    • A. 

      Feed refrigerant at a normal rate with low condenser entering air temperatures

    • B. 

      Feed refrigerant at a normal rate with high condenser entering air temperatures

    • C. 

      Stop refrigerant flow with high condenser entering air temperatures

    • D. 

      Stop refrigerant flow with low condenser entering air temperatures

  • 12. 
    The pressure limiting TX valve ____.
    • A. 

      Allows the compressor to operate at low condenser entering air temperatures

    • B. 

      Shuts off the condenser fan during hot pull down

    • C. 

      Maintains the full refrigerant flow rate during a hot pull down

    • D. 

      Limits the refrigerant flow rate to the compressor capacity

  • 13. 
    If the power element of a TX valve loses its charge, the ____.
    • A. 

      Coil will flood enough to feed liquid refrigerant out of the coil

    • B. 

      Valve will get cold enough to create frost on the body of the valve

    • C. 

      Refrigerant flow through the various circuits of the coil will become unbalanced

    • D. 

      Refrigerant flow to the coil will stop

  • 14. 
    A refrigeration system that continuously runs under high-load conditions (hot pull downs) would most likely use a thermostatic expansion valve with a vapor charged thermal bulb assembly.
    • A. 

      True

    • B. 

      False

  • 15. 
    An automatic expansion valve uses a thermal bulb to help control the amount of refrigerant being fed into the evaporator.
    • A. 

      True

    • B. 

      False

  • 16. 
    A refrigeration system requiring a "fast pull down" would most likely use a thermostatic expansion valve with a liquid - thermal bulb.
    • A. 

      True

    • B. 

      False

  • 17. 
    The step-motor valve uses a small motor to control the valve's port, which in turn controls evaporator superheat.
    • A. 

      True

    • B. 

      False

  • 18. 
    A vapor-charged thermal bulb assembly responds faster than a liquid-charged thermal bulb assembly.
    • A. 

      True

    • B. 

      False

  • 19. 
    As the load on an evaporator increases, the automatic expansion valve will open to allow more refrigerant to enter the evaporator.
    • A. 

      True

    • B. 

      False

  • 20. 
    A capillary tube controls the refrigerant flow into the evaporator.
    • A. 

      True

    • B. 

      False

  • 21. 
    An AX valve works best when the evaporator load is constant.
    • A. 

      True

    • B. 

      False

  • 22. 
    The pin or valve port piston of the electronic step-motor expansion valve can move a linear motion of 0.0783 inches/step.
    • A. 

      True

    • B. 

      False

  • 23. 
    Too high of pressure entering the compressor will cause the density of suction gases entering the compressor to increase.
    • A. 

      True

    • B. 

      False

  • 24. 
    As the evaporator load increases, an automatic expansion valve will _____ to reduce the evaporator pressure while a thermostatic expansion valve will _____ to reduce the evaporator superheat.
  • 25. 
  • 26. 
    When the quantity of refrigerant flow to an evaporator is reduced, the amount of superheat in the vapor leaving the coil will _____.
  • 27. 
    The correct term for a coil using a TX valve, capillary tubes, or restrictor is _____.
  • 28. 
    The correct term for a coil using a low side float is _____.
  • 29. 
    The TX valve maintains a constant _____.
  • 30. 
    The automatic expansion valve maintains a constant _____.
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