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21 Cards in this Set
- Front
- Back
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Define superheat |
Above saturation for a given pressure |
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What is the piping to the TXV called |
Liquid line |
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Where is the thermostatic expansion valve located in a refrigeration system? |
Liquid line before the evaporator |
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How is subcooling measured |
To measure liquid subcooling, attach your gauge manifold to the liquid line service port. ... The difference between the measured liquid line temperature and the saturated condensing temperature is the liquid subcooling |
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What are the four essential components that make up a refrigerant system? |
Compressor, condenser, TXV or metering device, evaporator |
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If you are feeding too much refrigerant into the vaporator what will happen to the pressure in the bulb and what will be the result action in the TXV? |
Pressure will go down and over stack liquid to your evaporator |
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What is the purpose of a vertical riser? |
vertical riser, reducing the overall pressure drop due to the suction line |
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What is the purpose of a double riser? |
A typical double riser has a smaller and larger riser. The two lines should be sized so that the total cross-sectional area is equivalent to the cross-section area of a single riser that would have both satisfactory gas velocity and acceptable pressure drop at maximum load conditions |
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Pressure drop in an evaporator is caused by what? |
Friction of refrigerant flowing through the tubes |
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List the six essential parts of a TXV |
Pushrod, bulb, spring, valve needle, valve seat, power element, |
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And external equalizer should always be attached to the top of a horizontal suction line, what is the purpose for this practice? |
The purpose of the external equalizer is to sense the pressure in the suction line AT THE ... In general, the TEV bulb should be installed on a straight section of horizontal suction line |
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Give the reasons as to why the distributor tubes into the evaporator are all equal lengths |
, it is essential the heat load on all circuits of the evaporator coil be the same |
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Should the remote Bowl be located on a vertical Riser? Why or why not? |
In general, the sensing bulb should be placed on a horizontal section of the suction line exiting the evaporator. If this is not possible, then it may be installed on a descending vertical |
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If you increase spring pressure what effects does it have on the operation of a TXV and the resulting superheat? |
TXV has only one function. It meters the flow of liquid refrigerant into the evap- orator in exact ... As this pressure increases, it tends to move the valve in an. “ opening |
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State the primary functions of the TXV |
To regulate the flow of refrigerant to the evaporator so that it enters at the same rate as it being removed by the compressor |
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What is the first step in analysis of TXV performance |
The pilot valve opens and closes in response to evaporator suction superheat. |
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What are two types of filter dryers? |
DCR FILTERS, CORE FILTERS |
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Why is filter dryers needed in refrigeration systems? |
To protect the system from any contaminants moisture Exedra in the system |
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Where is the filter drier typically installed in the refrigeration system? |
Before the TXV on the liquid line |
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When replacing the dryer on a replaceable cartridge Style what should you do to the new gasket before putting in the end plate? |
Lube or oil the gasket |
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What is the difference about a heat pump filter drier that makes it able to operate in both directions and have filtration occur through the outside of the core going both directions? |
When refrigerant flow meets a check valve in the allowed direction it will take the route of least resistance and go through the check valve and ignore the TXV |
