Ac432 Part 2
AC432 part 2 practice
- 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
Correct Answer
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.
Correct Answer
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.
Correct Answer
B. The bulb pressure will reduce and the valve will close. -
- 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
Correct Answer
A. Compensate for excessive evaporator pressure drop -
- 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
Correct Answer
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
Correct Answer
B. Evaporator suction line superheat -
- 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
Correct Answer
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
Correct Answer
C. On the suction line between the evaporator and the compressor -
- 9.
When the load on the evaporator increases, the TX valve ____.
- 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
Correct Answer
A. Increases the flow of refrigerant -
- 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
Correct Answer
B. Has different characteristics from the system fluid -
- 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
Correct Answer
A. Feed refrigerant at a normal rate 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
Correct Answer
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
Correct Answer
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
Correct Answer
A. True -
- 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
Correct Answer
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
Correct Answer
A. True -
- 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
Correct Answer
A. True -
- 18.
A vapor-charged thermal bulb assembly responds faster than a liquid-charged thermal bulb assembly.
- A.
True
- B.
False
Correct Answer
A. True -
- 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
Correct Answer
B. False -
- 20.
A capillary tube controls the refrigerant flow into the evaporator.
- A.
True
- B.
False
Correct Answer
A. True -
- 21.
An AX valve works best when the evaporator load is constant.
- A.
True
- B.
False
Correct Answer
A. True -
- 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
Correct Answer
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
Correct Answer
A. True -
- 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.
Correct Answer
close, open - 25.
The two pressures that push to close a thermostatic expansion valve are the _____ pressure and the _____ pressure.
Correct Answer
spring, evaporator
evaporator, spring - 26.
When the quantity of refrigerant flow to an evaporator is reduced, the amount of superheat in the vapor leaving the coil will _____.
Correct Answer
rise - 27.
The correct term for a coil using a TX valve, capillary tubes, or restrictor is _____.
Correct Answer
direct expansion - 28.
The correct term for a coil using a low side float is _____.
Correct Answer
flooded - 29.
The TX valve maintains a constant _____.
Correct Answer
superheat or temp - 30.
The automatic expansion valve maintains a constant _____.
Correct Answer
pressure
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Mar 21, 2022Quiz Edited by
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Mar 10, 2010Quiz Created by
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