Metering Devices
Metering Devices
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Question 1 |
The refrigerant leaving the metering device is a _____.
A | low-temperature, low-pressure liquid/vapor mixture |
B | high-pressure, high-temperature liquid |
C | high-pressure, high-temperature vapor |
D | low-temperature, low-pressure liquid |
Question 2 |
If a capillary tube is too short, the _____.
A | head pressure will increase |
B | evaporator will be flooded with excess refrigerant |
C | evaporator will be starved of refrigerant |
D | condenser will be starved of refrigerant |
Question 3 |
When the cooling load increases across an evaporator in a system equipped with a high-side float
valve, the float valve _____.
A | is not affected |
B | shell fills completely with liquid refrigerant |
C | orifice opening size increases |
D | float ball lowers |
Question 4 |
A low-side float valve is the best metering device for use in a system _____.
A | in which evaporator superheat is critical |
B | with a DX evaporator |
C | with a constant load |
D | with a flooded evaporator |
Question 5 |
In a system containing TXV, what system operating parameter is maintained by the TXV?
A | Superheat |
B | Heat pressure |
C | Static pressure |
D | Subcooling |
Question 6 |
In a DX evaporator operating at design conditions, the refrigerant leaving the evaporator is a _____.
A | pure liquid |
B | liquid/vapor moisture |
C | superheated liquid |
D | superheated vapor |
Question 7 |
Under constant load conditions, the pressures above and below the diaphragm of a properly
adjusted, internally equalized TXV are _____.
A | both exactly 50 psi |
B | equal |
C | both zero |
D | different by the amount of evaporator pressure drop |
Question 8 |
What is the effect on the TXV of an increase in the cooling load?
A | Superheat decreases and causes the TXV to increase the flow of refrigerant. |
B | Superheat rises and causes the TXV to reduce the flow of refrigerant. |
C | Superheat rises and causes the TXV to pass more refrigerant. |
D | Superheat decreases and causes the TXV to reduce the flow of refrigerant. |
Question 9 |
If there is evidence that the TXV is hunting, the problem can be corrected by _____.
A | either adjusting the TXV or replacing it with a smaller one |
B | adding a thermal ballast outside of the sensing bulb |
C | either adjusting the TXV or replacing it with a larger one |
D | replacing the TXV with a larger one |
Question 10 |
The equalizer line of an externally equalized TXV is installed _____.
A | in the riser |
B | just downstream of the sensing bulb |
C | just upstream of the sensing bulb |
D | downstream of the trap |
Question 11 |
A metering piston for a fixed metering device is supplied both with the condenser unit and
evaporator unit of a split system. In most cases, you would install the metering piston supplied
with _____.
A | the condenser |
B | the evaporator |
C | either coil; they are both the same |
D | the larger coil, depending on whether the system is a cooling only or heat pump system |
Question 12 |
In a system with an automatic expansion valve, an increase in the heat load being handled by the
evaporator causes the _____.
A | suction pressure applied to the expansion valve to decrease |
B | automatic expansion valve to increase the amount of refrigerant fed to the evaporator |
C | expansion valve spring pressure to increase |
D | automatic expansion valve to reduce the amount of refrigerant fed to the evaporator |
Question 13 |
The size of the valve orifice is changed by a stepper motor in the _____.
A | externally equalized thermal expansion valve |
B | electronic expansion valve |
C | thermal electronic expansion valve |
D | internally equalized thermal expansion valve |
Question 14 |
Which of the following is true of TXV selection?
A | If too large a TXV is selected, it may cause compressor slugging. |
B | It may be undersized, but not oversized. |
C | If the TXV is too large, it will starve the evaporator. |
D | Any TXV will do because it can be adjusted to fit the system. |
Question 15 |
When installing the sensing bulb of a thermal expansion valve on a 1" suction line, the bulb should
be clamped _____.
A | near the bottom of the suction line |
B | on the top of the suction line |
C | on the bottom of the suction line |
D | at the mid-point on the side of the suction line |
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